MATTNOYES.NET - Weather Website & Blog

Dry Daylight...Wintry Mix Tonight...Damaging Winds For Some, Wet Wednesday for Most

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Weather Summary: 

Midday Update:  Trends continue to indicate that damaging winds are likely through eastern New England on Wednesday, especially from mid-morning through mid-afternoon.  Winds gusts to hurricane force will be possible on Cape Cod and the Islands, as well as the coast of Maine, and scattered power outages are likley in most of Eastern New England, including the Boston Metropolitan area.  We'll continue to monitor this threat carefully - cool ocean temperatures will try to mitigate the wind threat a bit, but concern is that this won't be enough to keep wind gusts of over 70 mph from mixing to the surface in exposed locations and over the water, so mariners should plan to stay in port Wednesday unless you're ready for hurricane force gusts over the water, properly secure vessels in areas exposed to southeast winds, and costal residents should be advised that southeast facing shorelines may see some minor coastal flooding at the time of high tide either side of noon Wednesday.

Previous Discussion:

Dry and cold arctic air continues to modify significantly on Tuesday, but will hold on in the lower and middle levels of the atmosphere for widespread sunshine through high altitude clouds the first half of the day.  But a Tuesday morning surface analysis places a storm center over the Western Great Lakes with an attendant series of fronts spread across the Eastern United States - from an eastward moving, moisture-laden cold front in the Mississippi Valley, to a warm front pushing northward across the Mid-Atlantic and heading for New England.  This warm front marks the leading edge to warmth and moisture at ground level, but aloft, this new airmass has already begun streaming into New England, and is marked by cirrus clouds spreading into the upper levels of the atmosphere.

This influx of moisture aloft will allow clouds to lower and thicken later Tuesday, as precipitation will move gradually up the Eastern Seaboard and close in on New England.  Though this increase in clouds will slow our temperature rise by filtering the sunshine, many communities in Southern New England will still rise above the freezing mark.  As precipitation spreads into Southwestern CT around 4 or 5 PM, then, it will fall as a light mixture of rain and snow.  This band of precipitation will migrate northeast across the remainder of Southern New England Tuesday evening, reaching Worcester around 7-8 PM as mostly snow, and then continuing to spread northeast - you can always follow the precipitation on radar through my homepage, www.mattnoyes.net.  Admittedly, there's some uncertainty with this band of precipitation - our guidance products insist on holding precipitation off until later in the overnight period (around midnight) but it's typical to see a thrust of warm and moist air spread precipitation northward faster than forecasted, and I want to stay on the ball with this regard.  While there won't be a lot of moisture that falls with this initial burst of precipitation - less than an inch of snow in most of Southern New England - temperatures will drop close to or below freezing as the band moves through, and roads may become slick for the first part of the overnight.  After midnight, most of Southern New England will see a turn to plain rain showers that will fall periodically, however, as temperatures rise.  Farther north across the Mountains of Northeast Vermont, New Hampshire and Maine, snow will fall Tuesday night and a plowable snow is likely with accumulations either side of half a foot.  See accumlation forecast maps for details of Southern and Northern New England.

The Tuesday night precipitation will be the result of the warm and moist surge of air ahead of the approaching storm center - not the passage of the actual storm.  New Englanders will wait until Wednesday for this storm and its attendant cold front to move through, and before its passage, persistent southerly winds will help to flood New England - especially Southern New England - with mild air, and temperatures are likely to rise into the 50's on Wednesday amidst periods of rain, heavy at times, areas of fog and gusty winds.  Even the mountains of the north, after Tuesday night snow, will be unable to ward off this warm air, and will see a transition to rainfall, with freezing rain in the deeper valleys of the White Mountains and Mountains of Maine that are most protected from a southeast wind.  In Northern Maine, the time table is delayed by about 8 hours, but the results are similar, with a few inches of Wednesday morning snow changing to Wednesday afternoon sleet, snow, freezing rain and rain. 

With a widespread 1"-2" of rain expected through much of New England, flooding is a concern for many riverbank communities, especially where flooding has already occurred and will be aggravated.  Thunderstorms are likely to swing through New England Wednesday afternoon with the passage of a cold front and as the center of low pressure moves north of New England, and winds ahead of this front will gust over 40 mph in most locales, over 55 mph in the mountains, and up to 70 mph along the coast of Maine and the South Coast of New England!  I wouldn't be surprised to see some areas record hurricane force gusts (74 mph or greater) and these winds will bring a threat for scattered power outages to coastal and hilltop locations, especially.

While colder air will be poised to charge in behind this departing storm center, it does not appear as though the same magnitude of arctic cold will be available that we saw this time around, and that will mean a signficantly modified chill for Wednesday night and Thursday, and a quicker return to warmer air.  But remember that a change in airmass often is marked by clouds and sometimes by precipitation - we'll see that play out again late Thursday and Thursday night as the next shot of chill recedes, as well.  As a result, I have increasing clouds in the forecast for Thursday with a chance of flurries or perhaps a period of light snow or snow/rain mix Thursday night.  Behind this disturbance, however, milder air will have returned to New England, and temperatures will respond - even with limited sunshine through clouds - on Friday.

As for the overall pattern and changes that may be in store...we are likely in the process of turning the corner this week, but it will not be a sudden or abrupt change, and instead we may ease toward a colder pattern over the next couple of weeks.  The overall weather setup will feature a strong bulging of warm air from the lower latitudes (southern areas) of North America persisting for at least a couple of weeks longer.  At the same time, cold air building over Alaska will begin spilling into Canada little by little.  The result of this evolution here in New England will be the availability of shots of shallow cold air near the surface over the next 10-14 days, while the active stream of energy and moisture will continue to feed off the Pacific Ocean and across the Lower 48.  What this means for us is a delicate balance for a couple of weeks between cold air pulses, and warmth/moisture returns.  Time this out right, and we're looking at snow...propensity will be for rain especially in southern New England with Northern New England and the mountains hanging onto every cold shot of air, and the words of meteorologists as to how long the cold can hold as each successive storm draws near.  It's undeniable, though, that the overall TREND will be to cool things off in New England over the next two weeks.  And as the active pattern continues, that means the overall TREND will gradually be toward a colder and snowier scenario.  As mentioned over the past couple of weeks - this could make for a very interesting and active February and March.

Have a great Tuesday!

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, January 17 at 1:55 PM

A truly extraordinary meteorological specimen is in the making for NewEng over the next 30 hours.  What will make this storm so amazing is entirely different from the last storm - it's not the power of a deepening low right over us with a powerful backlash and tremendous baroclinic zone feeding its intensification, but instead this time is the difference between a 1032 mb high east of NewEng, and this 980 mb low that will be closing in.  The tightening pressure gradient will be the driving force behind a potentially destructive wind event for Eastern New England.

But let's not get too far ahead of ourselves and take this one step at a time.  Cirrus clouds have continued to spill into NewEng from time to time but the sharp isentropic lift associated with moderate 850 mb and 700 mb positive theta-e advection moving northeast toward NewEng is truly creating a rapid thickening of clouds, so there may not be a ton of cirrus to precursor the leading thrust of warmth and moisture.  Some subtle changes have been evidenced in the last couple of model runs that modify but do not negate the thought process laid forth yesterday regarding this initial band of precip slated for this evening.  The first subtle change is that the sharp speed convergence at 850 mb is deflected westward, from western NewEng into NY state as compared to yesterday's guidance products.  This will mean my envisioned heavier bursts of precip embedded in the band will probably verify in these areas, rather than over the heart of NewEng.  Still, moderate positive theta-e advection comes thru from about 6 PM Southwest CT to 10 or 11 PM Southern NH, and this will be enuf to carry a band of precip thru.  I really don't see this starting as freezing rain or sleet for most of NewEng - the thermal profile, though marginal, is entirely subfreezing excepting Southern half of CT, RI, SE MA.  Esp MA Pike northward is subfreezing, and Merrimack Valley/Srn NH is subfreezing through 06Z!  I am using the NAM thermal profile preferred over the GFS, but this is done on sound reasoning of superior NAM handling of boundary layer due to higher resolution, upward vertical motion cooling parcels due to expansion, and the dry air that's in place in the lower levels.  So, given that the speed convergence is centered farther west, I've lowered my thinking on the burst of evening/night snow for Southern NewEng from 1"-2" to generally an inch or less (maps included in wx summary above).  Still, falling after dark and in a subfreezing environment, this will have an impact on roadways and the like.  Thereafter, I can justify a period of sleet and perhaps some brief freezing rain through the Worcester Hills and Berkshires, but southeast winds get cranking even tonight and this will scour out cold air at the surface rather quickly.  Farther north, my thinking from yesterday holds of a general 4-8" mountain snow, though I've limited amounts in Northern Maine (Aroostook County) given a strong SE flow's ability to carry warmer air into this area.

After dealing with this winter weather, take your pick on the next angle to tackle.  I suppose for the purposes of this discussion we'll cover rainfall since I think it's a bit more straight-forward, but from a public perspective it should be wind, wind, wind in your forecasts.  As for the rain, though, expect 1-2" widespread but greater than 2" won't be hard to achieve through the mountains of Northern NewEng, and likely draped SW through Central/Western MA, as well.  How ironic that as we deal with a mostly rain scenario, the GFS and NAM are in tremendously good agreement on total QPF - when is the last time this happened during a snow event?  If this were snow I'd be scared to death because model agreement like this is so hard to find in these dynamic events!  But, smoke 'em if you got 'em and enjoy the millions of dollars we've paid as taxpayers for the number crunching.  But while you're enjoying the agreement, also notice the tremendous forcing resulting in intense 500 mb upward vertical motion lined up a la squall line from NY to NC.  It's climatologically difficult to darn near impossible to get surface based severe convection in NewEng with a deep south and southeast flow preceding the frontal boundary given marine modification of the airmass, but this is so much energy - over 40 units of vorticity - that it should overpower this factor, especially given the availability of moisture in a saturated column.  One area that I think needs to be especially on guard for severe convection is New Jersey where a marginally severe thunderstorm event happened last time around, and this time there's more surface and low-level based instability, and winds are south to even south-southwest which will mitigate overall ocean squelching of the convective instability, and with 700 mb flow in this region of over 100 knots (WOW!) in nearly unidirectional flow, the potential for dangerous gusts in momentum transfer alone is significant.  Here in NewEng, there may not be a ton of lightning given lift decreasing before reaching high enough into warm midlevels to tap sufficient ice nuclei, but far be it from me to get fancy on this and I think what we have going is fine.

This brings us to what is looking more and more like a destructive wind event for parts of Eastern NewEng on Wednesday.  I don't have a time in my recent memory in which the guidance has been so insistent over so many runs on such strong winds widespread through Eastern NewEng.  I have to share two things: 1) I've begun to hit the damaging wind threat hard, 2) It's with great hesitancy that I do this.  The reasons for hitting it hard are extensive, but can be summarized as follows:  A tightening pressure gradient as mentioned at the beginning of this discussion will funnel air across the Atlantic waters south of NewEng and up the Eastern Seaboard.  Core of strong winds extends not only through the mid-levels but also down to the top of the boundary layer, with 85 knots progged at 950 mb early to mid afternoon Wednesday.  The problem here is that with the passage of the warm front early in the day, most of Southern and Central NewEng is warm sectored wtih mixing indicated by bulk richardson number extending well up into the atmosphere to at least 940-925 mb on average across Eastern Southern NewEng.  Now to the reason I meet with hesitancy, which is the cool ocean waters that will, as always, try to impose a shallow cool dome for a protective inversion.  More often than not, it seems this inversion wins out, but the most likely method of breaking this and keeping a mixed and therefore windy atmosphere is through pressure gradient force, rather than ageostrophic flow.  So, given tremendous agreement, all of these considerations, and the most important consideration that we're talking about a significant human impact from this potential wind event, the responsible thing to do is to hit it hard.  This means advising folks of possible effects on daily life as well as marine impact for commercial fishermen.  Coastal flooding not impossible at time of high tide before noon at southeast facing shorelines, though worst wind comes later, so it's a close call, but a heads-up has been given in my broadcasts.

Rapid wind shift will be accompanied by cooler air late Wednesday, but certainly not the flash freezes of last storm this past weekend.  That being said, temps will fall below freezing in cold advection by midnight Wednesday night, and there's likely still going to be standing water, so icing will still be a concern.

Next series of shortwaves skirt NewEng Thu with orographically induced snow showers, esp early, and mid-level clouds elsewhere Thu night.  Still intervals of these clouds Fri with a few shortwaves dampening as they encounter SW flow aloft with broad ridging building SE of NewEng.  Low level SW wind should stay active Fri, and felt comfortable - even with somewhat limited sunshine - of boosting temps just a scosh more than I had them.

Really bringing the warm air on for Sat in advance of digging shortwave and developing surface low that will bring rain later Saturday or Sat Night - have seen ECMWF solution of emphatically swinging cold front through before this storm, but at this point have to buy the more consistent and agreed upon solution of taking this front into NewEng, then allowing it to retreat in SW flow ahead of approaching low to perhaps afford North Country snow, but rain elsewhere with a shot of chilly air ready to drop in briefly behind it.  Big motivating force in going with this milder solution is the expansive and still strengthening anticyclone near Bermuda, and the northward retreat of the high pressure bubble Friday night into Saturday from the Upper Lakes into Southern Canada.

That's all for today - tomorrow should be interesting for one and all.  Good luck.

Matt

Biting Arctic Chill Starts the Week...Warmer Air to Return

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Weather Summary:  What a weekend!  The cold air left behind dramatic changes in weather the past couple of days brought temperatures below zero in some spots Monday morning, and will leave a cold and blustery day for all of New England.  This arctic blast comes behind the departing storm center that was intensifying as it moved through New England - bringing over 2" of rain to some areas, over half a foot of snow to others, and a messy accumulation of ice, snow and flash freezes to many.

The Monday morning weather map features a storm center located over the Midwestern United States, available moisture streaming out of the Pacific Ocean and over the Gulf Coast States, a new storm pushing into the Pacific Northwest, and close to home, a brisk northwest flow of cold arctic air sandwiched between a departing strong storm and an area of Canadian high pressure.  One "bright" side to cold arctic air is that it's dry - and that will mean plenty of sunshine across New England to start the workweek.  The only exceptions to this rule will be found from extreme Eastern Maine to Northern Maine, closest to our departing storm, and where some moisture wrapping around the storm center will throw clouds and flurries from east to west.  The mountains of Vermont, New Hampshire and Northwest Maine also will see a few flurries today as a west-northwest wind pushes up against the mountainfaces.  Elsewhere in New England, the brilliant sunshine will certainly be tempered by the chill - winds gusting over 30 mph through the day will mean wind chill values ("feels like" temperatures) running in the teens in Southern New England at the warmest time of the day, and below zero across Northern New England!

Though a few high-altitude cirrus clouds will spill into New England late Monday and Monday night as moisture and slightly warmer air begin to return aloft, otherwise dry conditions and a diminishing wind will allow temperatures to tumble Monday night.  We should find enough dry (and cold) air holding on in the lower and middle levels of the atmosphere Tuesday morning for widespread sunshine through high altitude clouds, though clouds will thicken later Tuesday as the Midwestern storm center begins to shift its energy eastward, and interacts with the available moisture along the Gulf Coast, driving warmth and moisture toward the Northeastern United States.

Initially, as precipitation spreads into New England from the southwest, temperatures at ground level will be either side of freezing.  Just off the surface, however, subfreezing temperatures will allow for snow to develop - mixed with rain in warmer locales - and a wintry mix will develop from southwest to northeast across Southern New England for the tail end of the evening commute.  Right now, I would expect a band of precipitation to develop in Fairfield County (southwest) CT around 2 PM as a very weak mix of sleet, freezing rain and some snowflakes.  This band should gain some steam as it moves northeast, transitioning to mostly snow as it moves through Hartford around 5 PM, and reaches Worcester around 7 PM.  Conditions are favorable for this band to develop aloft, though admittedly, I'll be curious to see if dry air near the surface limits how productive this band of precipitation will be.  Regardless, my current thinking is that a quick burst of 1"-2" of snow could fall with this band in many areas of Southern New England northeast of Hartford before the surge of mild and moist air aloft overwhelms the cold and changes snow to rain overnight Tuesday night.  Rain showers will fall periodically Tuesday night, though farther north across the Mountains of Northeast Vermont, New Hampshire and Maine, snow will fall Tuesday night and a plowable snow is likely with accumulations of 4"-6" possible by Wednesday morning through the mountainous terrain.

The Tuesday night precipitation will be the result of the warm and moist surge of air ahead of the approaching storm center - not the passage of the actual storm.  New Englanders will wait until Wednesday for this storm and its attendant cold front to move through, and before its passage, persistent southerly winds will help to flood New England - especially Southern New England - with mild air, and temperatures are likely to rise into the 50's on Wednesday amidst periods of rain, heavy at times, areas of fog and gusty winds.  Even the mountains of the north, after Tuesday night snow, will be unable to ward off this warm air, and will see a transition to rainfall, with freezing rain in the deeper valleys of the White Mountains and Mountains of Maine that are most protected from a southeast wind.  In Northern Maine, the time table is delayed by about 8 hours, but the results are similar, with 4"-6" of Wednesday morning snow changing to Wednesday afternoon sleet, snow, freezing rain and rain.  Chances are good the heaviest rain falls Wednesday morning through midday before the attendant cold front sweeps through, winds shift to the west, and precipitation tapers significantly, unlike the last storm which featured a pronounced wraparound band of precipitation behind the storm center.

While colder air will be poised to charge in behind this departing storm center, it does not appear as though the same magnitude of arctic cold will be available that we saw this time around, and that will mean a signficantly modified chill for Wednesday night and Thursday, and a quicker return to warmer air.  But remember that a change in airmass often is marked by clouds and sometimes by precipitation - we'll see that play out Tuesday night as the current shot of arctic air lets go, and we may see it again late Thursday and Thursday night as the next shot of chill recedes, as well.  As a result, I have increasing clouds in the forecast for Thursday with a chance of flurries or perhaps a period of light snow Thursday night.  Behind this disturbance, however, milder air will have returned to New England, and temperatures will respond - even with limited sunshine through clouds - on Friday.

As for the overall pattern and changes that may be in store...we are likely in the process of turning the corner this week, but it will not be a sudden or abrupt change, and instead we may ease toward a colder pattern over the next couple of weeks.  The overall weather setup will feature a strong bulging of warm air from the lower latitudes (southern areas) of North America persisting for at least a couple of weeks longer.  At the same time, cold air building over Alaska will begin spilling into Canada little by little.  The result of this evolution here in New England will be the availability of shots of shallow cold air near the surface over the next 10-14 days, while the active stream of energy and moisture will continue to feed off the Pacific Ocean and across the Lower 48.  What this means for us is a delicate balance for a couple of weeks between cold air pulses, and warmth/moisture returns.  Time this out right, and we're looking at snow...propensity will be for rain especially in southern New England with Northern New England and the mountains hanging onto every cold shot of air, and the words of meteorologists as to how long the cold can hold as each successive storm draws near.  It's undeniable, though, that the overall TREND will be to cool things off in New England over the next two weeks.  And as the active pattern continues, that means the overall TREND will gradually be toward a colder and snowier scenario.  As mentioned over the past couple of weeks - this could make for a very interesting and active February and March.

Enjoy your Monday - be sure to bundle up...kids and adults alike!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, January 16 at 1:25 PM

Cold dense air well in place across NewEng today and tight pressure gradient cranking out west-northwest/northwest wind wtih gusts over 30 for at least a time in most spots this afternoon.  Obviously bitter cold wind chill values the weather headline, especially in Northern NewEng where chills stay below zero most of the day.

Cirrus clouds to the southwest drying up as they try to nudge into NewEng but should make gradual progress as flow aloft backs.  Still, with dry and cold arctic airmass and only a gradual increase in thinning cirrus overnight with a slackening surface wind, temps will drop rapidly.  Deeper valleys will decouple and should fall below zero in Northern NewEng, remainder of the area may maintain just enough wind to keep a weakly mixed boundary layer.

Sunshine through high clouds starts Tuesday but clouds thicken as increasing moisture over the area Tue afternoon, and most importantly, this happens in conjunction with elongated vorticity lobe dropping SE out of Canada and over NewEng to help enhance lift.  There's the easy part of the forecast...now the challenges.

Precipitation likely going to start sooner than model forecasts Tue eve - trend is slower in the guidance but 700 mb speed convergence is strong over Southern NewEng by 00Z Wed with 45-50 kts over SW CT, and under 15 kts SW flow over NE MA.  This convergence, coupled with moderate 700 mb positive Theta-E advection and strong 850 mb Theta-E advection is the perfect recipe for a burst of precip along this midlevel warm front.  Throw in the aforementioned elongated vort lobe and this is the perfect recipe for an "oops" band of snow with emedded bursts of moderate precip and perhaps even a few elements of heavy snow in there.  The great question here is are we going to see this band as a midlevel snow burst that never reaches the ground due to low dewpoint and instead expends most of its moisture simply trying to saturate the atmosphere, or will we see this verify at the surface.  While the truth probably lay somewhere in the middle, I think there are plenty of factors arguing for this band to reach the surface even beyond what's mentioned above, and specifically the forecasted surface wind shift from the east that should assist in bringing surface dewpoints up.  The brief-worded result to this long-winded explanation is that precip develops sooner and a bit more intense than indicated by the models - with the band reaching Fairfield County, CT, by 2 PM (though still in the formative process as speed convergence and warm/moist advection are just beginning to organize - which means weaker upward vertical motion likely will result in a more ice and liquid based ptype in these areas), Hartford by 5 PM as mostly snow for the brief burst, and Worcester by 7 PM as all snow with some heavier elements embedded in the band.  This means I'm effectively tossing the GFS thermal profile in the trash, which I don't think is a bad move given the dense arctic air that's in place, the NAM's higher resolution and better handling of surface and low-level cold, and the dry dewpoints that will favor evaporative cooling.  While QPF is rather unimpressive in the guidance, bands like this can put out a quick one or two inches and I've been adlibbing this in the forecast on-air.  All of that being said, caution must be exercised until we can get at least one of the guidance products leaning in this direction, and if I can't find enough evidence Tuesday morning to keep this line of thought, I will drop it accordingly.  But for now, I think we're onto something here, and it wouldn't be an unprecedented occurrence, for sure, as incoming warm and moist airmasses behind departing arctic ones often hold these kinds of surprises.

Regardless, warm air wins the battle overnight Tue night and after only the light accumulations mentioned above with orographic enhancements (though perhaps falling in a short period of time) precip changes to rain in Southern NewEng.  The mountains of Northern NewEng, however, will dam the cold air not only at the surface but through much of the lower levels of the atmosphere as well.  This will allow snow to fall for much of the night in the mountains, though keep in mind that we're only dealing with a warm and moist advection burst, not the deep lift associated with the passage of the storm center - at least not until Wednesday.  As a result, plowable amounts are likely to fall Tuesday night in the mountains with a rough early estimate of 4"-6" from the mountains of Central and Northern VT, east thru the Whites and into the Mountains of Maine.

The most important question for Northern NewEng comes Wednesday morning - how fast does the warm air take over?  This is critical to answer because the heaviest precip sets into these areas wtih strong isentropic lift just after 12Z Wed.  At this point, I would believe another couple of inches would be possible of very heavy wet snow before finally a mix and change to sleet, then a mix and change to freezing rain occurs all between 12Z and 18Z Wed.  Many areas will change to rain around this time where they haven't done so already, but the potential is there for extended icing in the protected valleys of the Northern White Mountains and the mountains of Maine where shelter from a southeast wind would allow cold air to stay dammed into the afternoon and over half an inch of precip would fall.  In Northern Maine, a similar solution of half a foot followed by a mix with snow, sleet and freezing rain is likely, though the timeframe will be delayed by about 8 hours from the rest of the North Country.

Given a faster and flatter storm track, the wraparound from this upcoming storm will not even slightly resemble the previous storm, and therefore the cold front will effectively mark the end of the moisture and aside from orographic exceptions, and end to the lift.  So, bonus snowfall on the back of the low pressure system is not anticipated aside from the typically topography driven mountainous areas that favor a west wind.

The next shot of cold for Wednesday night and Thu behind this storm is nothing like the one we're in as of this writing.  There is, however, another vorticity lobe racing east later Thu, and after morning sunshine and a developing SW wind, this system will charge thru NewEng Thu eve and night.  Not a lot of moisture to work with, though a northward retreating baroclinic zone under a moderate warm advection regime will favor a west to east oriented band of precip.  Exact placement depends on antecedent location of thermal boundary and vort path, but Central and Northern NewEng seem most likely right now.

Mild air to stream back in Fri in advance of next shortwave.  At this point, looks like next weekend starts with this as a mainly rain event, but I'm not going to go on record as saying that in public forecasts, given my belief that we're in line for several borderline events.  Please reference last paragraph of weather summary above for my thoughts on what this low-latitude ridging, coupled with shots of Northern stream shortwave trofs will mean for the rest of this month.

Have a great start to your week, my friends!

Matt

Dense Fog Far South to Spread North Friday Night...Windswept Rain on the Way...Blizzard Conditions Possible in Green Mountains

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  Warm and moist air is rushing northward ahead of an approaching storm center, and will bring areas of low clouds, drizzle and fog to Southern CT and RI for our Friday.  Elsewhere, this push of moisture will be thwarted by sunshine warming the ground, which warms the air, and thereby lowers the relative humidity as the temperatures rise.  The net result of this process should be a halt to the northward progression of this low altitude cloud deck...which can be monitored through the visible satellite imagery and links to surface observations from my homepage.  Where the clouds don't move in, temperatures rise handily into the 50's and some spots will come close to touching 60 degrees in Southern New England.  Northern New England will find nearly full sunshine and these golden rays combined with a southerly wind will bring temperatures into the 50's in many communities.

Once the sun sets, however, expect the fog, drizzle and low altitude clouds across extreme southern New England to race northward and envelope most of Central and Southern New England just after suppertime with fog...locally dense...and drizzle.  This all happens as southerly winds increase in the counterclockwise flow around the approaching storm center and moist air - air with higher dewpoint temperature - is thrust northward, colliding with the cool and dry airmass that's been in place.  The primary center of low pressure will translate east Friday night into Saturday - moving out of the Ohio Valley and across Pennsylvania.  As the moist flow continues ahead of the storm, showers of rain will develop late Friday night across most of New England.

Saturday, this storm center passes just south of the Southern New England coastline.  With a strong feed of moisture already established from both the Pacific and the Gulf of Mexico into this storm Friday morning, the low pressure center will remain moisture laden as it taps Atlantic moisture, as well.  With plenty of energy aloft, rain production should be quite efficient with this storm, and a widespread one to two inches of rain are likely to fall across New England on Saturday.  The rain will fall heavily at times - beginning in earnest Saturday morning and lasting through most of the day.  With mild temperatures and falling rain, snow will melt quickly across Northern and Western New England, and rivers will rise in response.  As a result, low lying areas along riverbanks should be prepared for flooding this weekend.  Additionally, urban street flooding and hydroplaning will be a concern, especially in communities where snowmelt occurs in addition to the rainfall.  Finally, southeast winds along coastal locales and hilltops of Southern New England may gust over 45 mph during the day Saturday, with the possibility of embedded thunderstorms along Cape Cod and the Islands where a tropical moisture feed will spill northward over the Atlantic.

Saturday night, the center of low pressure will draw southeast of New England, and encounter a significant slug of moisture and energy zipping northward off the Eastern Seaboard.  The interaction of these two systems will result in a deepening storm center that pulls northward from just off of Chatham, MA, to just east of Lubec, ME, overnight Saturday night.  The combination of a strengthening storm center and its shift east and north will allow winds to swing around from the northwest in many areas and this will yank colder air down from Canada.  The result will be a changeover from rain to snow after suppertime Saturday evening in the Central and Northern Green Mountains.  Overnight Saturday night, most of Vermont will change to snow and up to a foot of accumulation is possible between Saturday night and Sunday morning along the spine of the Green Mountains, with frequent northwest wind gusts over 40 mph for near-blizzard conditions Saturday Night.  By Sunday morning, snow should be falling in the White Mountains and the Berkshires, as well, where lesser amounts but still plowable snow are likely to fall, with amounts nearing half a foot in the Northern and Northwest White Mountains, and perhaps similar amounts in the Berkshires.  This band of snow wrapping around the western periphery of the departing low pressure center on Sunday will be the last organized band of precipitation left in New England after Sunday morning rains exit Central and Eastern Maine.  As the storm center pulls farther east, this band of snow will also pull east.  While it is likely to hold together as it moves over the remainder of New England late Sunday afternoon and evening after a day of scattered rain changing to snow showers, blustery winds and falling temperatures into the 20's, it will be in a significantly weakened form of its former self.  Still, some accumulating snow is a possibility for most of the remainder of New England late Sunday under this band.

By Monday, dry air at middle and upper levels of the atmosphere spills in.  With a surface wind flow out of the north and northwest, many areas will dry out enough for mostly sunny skies, though the brisk winds and temperatures will keep a chill in the air.  Across the mountains, continued snow showers will be possible in scattered form.  Tuesday looks dry at this point, with warmer southwest winds taking hold again, before our next disturbance moves in for midweek.

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, January 13 at 2:20 PM

Dense fog was racing northward this morning and the only thing that saves the day for most of Southern NewEng is the sunshine boosting temps and reducing RH in the nick of time.  HFD to PVD points south couldn't be saved - where the fog and stratus were in by dawn were destined to be locked in thru the day.  As soon as diurnal heating is gone and temps fall, clouds, fog and drizzle will race northward to envelope most of Central/Southern NewEng.  Northern areas to take a bit longer to moisten up but will meet with the same fate by late tonight.

Showers develop tonight in increasing isentropic lift tho main dynamic lift doesn't come thru until Saturday and this will be the time for heaviest rainfall.  Huge model diffs pose tremendous problems from both a total QPF standpoint and a wraparound deformation band perspective.  NAM at 00Z was out to lunch - the only model still to show a cutoff low off the Southeast US coast.  12Z has come around but still is remarkably dry for most of NewEng.  Model spread is significant among operational and ensemble guidance which makes this a low forecastability situation.  I favor the GFS for a number of reasons including vorticity advection, upper level trof position, inflow of Atlantic moisture to diminishing surface convergence zone, sharp baroclinic zone, abundant available moisture and associated tropical moisture feed to name a few.  That being said, GFS is probably overdoing QPF a bit with its 3"+ amounts in Vermont, but a general 1-2" QPF event with localized amounts to 3" certainly seems like a good bet based on all of the ingredients.

As for ptype - a big difference here as well regarding how fast cold air comes charging in.  I like only a slightly faster solution than the GFS for bringing cold air in, and I can tell you that this continues to be a setup that favors significant snows in the Green Mountains in a very short period of time.  True that upslope flow is not ideal for long as winds come more NNE than NNW by Sunday morning, but for a time Sat Ngt NNW wind teams up with plenty of llvl moisture and surge of cold/dry air coupled with upper level trof approaching and swinging thru.  These components are all important - cold/dry air will literallly wring out available moisture as Tds drop, and dynamics should allow for significant forcing esp with orographic enhancement.  I see no reason why a foot of snow can't be recorded in a very short period of time with this Sat Ngt burst - which actually begins changing over as soon as 5-7 PM Sat eve in the higher terrain in a rapid NW to SE, top down changeover.  If the solution I'm buying of a slightly modified GFS is correct, one of the heaviest axes of QPF will be over the White Mountains, where heavy rain also should change to heavy snow but not until around or after midnight Sat Ngt, yet still a half foot of snow may fall.  The Berkshire forecast is heavily dependent upon whether this solution is correct for the deformation band.  As of the 12Z runs, there is honestly too much disagreement in the guidance to nail down a hard and fast solution but I favor a deformation band from the Berks up the Greens and a precip shield of snow extending east into the Whites with a rain/snow line in Maine trudging east by Sunday morning.  The possibility also exists of a Sunday morning Champlain Valley deformation band given the NNE wind profile that will be establishing.  Farther NE, in Maine, even after a changeover to snow there's still about .50-.75" QPF to fall, so a solid 8" looks probable in Northern ME, and even the Mountains of ME may come up to these amounts.

Elsewhere, Sunday features scattered showers of rain quickly transitioning to scattered showers of snow as cold advection transports wind gusts over 40 mph to the surface in many areas thru the day.  This downward momentum fights organized lift, but as deformation band wraps east, though QPF is little, RH values in the mid levels indicate the band may hold together enough for some snow accumulation even in Central and Eastern Southern NewEng Sun eve and night.

By Monday, drier air in at mid and upper levels and downslope flow drying out the low levels most areas tho snow showers continue upslope regions.  Tuesday temps rebound with SW flow returning and clouds increase late ahead of next system.

Matt

Thunder for Some Wednesday Eve...Windswept Weekend Rain May Become Windswept Snowstorm for Some...Blog to Resume Friday

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  A quick note:  Thursday will be the NECN/American Red Cross New England wide blood drive.  I'm thrilled to be the spokesman for this event, and will be at the Dedham location of the American Red Cross, so will not be able to post a discussion.  After today (Wednesday), discussions will resume Friday morning.

Wednesday morning finds a storm center trucking northeast across Illinois, with another low pressure wave developing over the Upper Ohio Valley in association with an energetic disturbance that's headed for New England.  The counter-clockwise flow of air around this area of low pressure will bring a southerly wind flow to New England today, ushering mild air into the region.  This milder air has already begun to glide over our cool surface airmass, and the result has been a thin band of snow, sleet, freezing rain and rain across Northern New England.  This band of precipitation will set up shop either side of the Canadian border on Wednesday and extend across Central and Northern Maine where road conditions will be slick for a time, until temperatures nudge above the freezing mark.  For the remainder of New England, most spots will be mostly dry through Wednesday under cloudy skies, excepting persistent showers near the Canadian border.  Still, the active southwest breezes will push temperatures near 50 in many Southern New England locales!

A few showers are likely to develop through Connecticut, Rhode Island and Southeastern MA around 3 or 4 PM, and will expand northward Wednesday evening as the energetic upper level disturbance driving the approaching storm circulation will be directed over New England by the jet stream winds aloft - the fast river of air high in the sky that steers our storm systems and acts as a thermostat for the atmosphere.  With the passage of this disturbance Wednesday evening and night, rain is likely to fall heavily at times with embedded thunderstorms, and a few of these storms may bring some small hailstones or locally gusty winds. 

Normally, those who follow the weather would expect to find a shot of cold air ready to pour in behind a departing strong disturbance in the middle of January.  Sure enough, cold air will briefly spill into New England early Thursday morning, and snow showers will fall across the mountains of Northern New England as a result, but the bubble of cold air is just that - a bubble!  It's small, it's fast moving, and by Thursday afternoon, it's gone, as a progressive flow of weather systems under a prevailing southwest flow of jetstream winds aloft will allow warmth to spread back toward New England.  Aside from the morning mountain snow showers, lingering clouds early Thursday should give way to increasing sunshine and a brisk westerly wind.  The result will be a rebound of temperatures into the 50's on Thursday and Friday on average across New England.

By Saturday, a strong storm will be cranking up while moving east across the Eastern Great Lakes and into New England.  A well established tap of Gulf of Mexico moisture should be associated with this circulation, and warm air will continue to stream northward on very busy southerly winds to begin the weekend.  It's likley that the passage of this storm will bring a Saturday filled with periods of rain, heavy at times, and embedded thunderstorms once again.  As this storm winds up tightly over New England, cold air will be pulled southward out of Canada, and a shot of deep chill will drop into our area.  If this cold air comes in soon enough - and it appears as though it will - Saturday late afternoon and evening may bring a heavy dumping of snow to the northern mountains.  Regardless, the mountains will pick up accumulating snow Saturday night into Sunday as a moist northwest "upslope" flow collides with the mountain faces and forces air upward, creating periods of heavy snow.

But it may not only be the mountains that have to be on the lookout for snow.  Even as the primary area of low pressure strengthens east of New England later Saturday, pulling cold air southward out of Canada, more significant energy will be found just off the Southeastern U.S. seaboard, and will be moving northward.  As this energy feeds into the ongoing storm center, it will continue to feed moisture and warmth into the eastern side of the circulation.  With all of New England on the western side of the storm by Sunday, cold air will be in place for all locales.  As this energy feeds into the storm, I am quite certain it will allow for precipitation to wrap around the back of the storm and fall as snow on Sunday.  The real question here will be the exact position of the storm - a farther north and east solution would mean this "wraparound" accumulating snow falls across Eastern Maine...and solution farther south and closer to the coast would mean most of Eastern New England, including Eastern MA, would see a windswept heavy snow.  At this point, I feel the storm will be close enough to warrant putting a chance of this snow in the forecast for even these southern areas.

This colder air is just one example of why skiers, snowboarders and snowmobilers alike should not lose hope from this milder finish to the week.  While this thaw has been an extended one, those of us in the North Country know that snow has still been falling, and though we'll take a hit with rain later this week, the pattern should return to a bit more normal feel by the middle of next week, and cold air begins building in Alaska late this week, which means that we're refilling the cold air well...which will come in handy for winter-lovers later in the season, especially February into March.

Happy Hump Day!

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, January 11 at 10:10 AM

Once again, strapped for time this week with in-house training.  Also please note top of Wx Summary...no discussion tomorrow since I'll be live in the field thru the day.

Short term features few changes - warm air should spill northward to ease winter conditions that appeared with light wintry mix in North Country this AM and most areas go to rain showers.  Still, many areas outside of this band of enhanced low and midlevel forcing will stay dry most of today, until showers creep northward late afternoon.  Still expected very heavy but short-lived rain event for first half of tonight with embedded thunder and possibility of localized high wind gust interior CT/RI away from ocean water enhanced low-level inversion.  Small hailstones are possible with low wet bulb zero in heavier convection.

I'm betting the NAM is overdoing the cold air in the low levels Thu and Fri, and have held onto a warmer solution, but certainly the higher resolution low level guidance offered by the NAM does pose reason for concern.  That being said, NAM has underforecasted low level temps last several days and don't want to make the wholesale changes it's suggesting at this point given southwest and progressive flow.

Big storm Saturday appears a bit more progressive, though what's happening is a tightening of the baroclinic zone and this will lock in the likelihood of a significant dumping of snow on the mountains of Northern NewEng.  Southern NewEng is a much tougher call.  Canadian operational at 00Z went gung ho on a blowout wraparound wind-driven snowstorm for all of Eastern NewEng on Sunday.  The ECMWF came around from its cutoff solution and was similar in nature to the GGEM prog.  GFS was more progressive and held wraparound to eastern ME, while GFS Ensemble Mean held QPF into most of Eastern New Eng - but to a much lesser extent - and closely resembled Canadian Ensemble means.  New GFS Ensemble runs just coming in are more progressive, yet much stronger, with the storm.  This is a tough line to walk with regard to a forecast for Eastern MA - one of the highest populated areas...but for now I'm keeping a chance of snow in these areas for wraparound with the best chance in Eastern ME.

Out of time for today, unfortunately...

Matt

Warmth to Expand Northward This Week

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  The Tuesday morning surface analysis places an area of high pressure centered over Southern Pennsylvania and the Panhandle of Maryland, and a storm center moving northeast across Arkansas, pulling warm air northward ahead of it, and enough cold air behind it for Oklahoma snow.  Here in New England, away from this area of low pressure and on the northern side of the clockwise flow of air around the high pressure, fair weather cell to our south, our Tuesday features mostly sunny skies as dry and cool Canadian air settles over New England.  Breezes will remain active from the west through the day, and this direction of wind produces a "downsloping" flow of air - that is, air flowing down the slopes of the mountains and hills of Northern and Western New England.  This descending motion of air means that the air actually encounters increasing atmospheric pressure along its trip - that is, the barometric pressure is always higher at lower elevations.  The increased pressure on the air compresses it, and temperature of the air responds by warming.  As a result, this warming process of the air will help to counteract most of the chill associated with the airmass, and temperatures will still rise above normal in most parts of New England.  In the mountains of Northern and Western New England, these winds instead result in air sloping UP the mountainfaces ("UPslope" flow), and therefore we'll see a bit more chill and a few more clouds with scattered snow showers in these areas.

The energetic and moisture laden storm moving into the Ohio Valley later Tuesday will continue to tap warmth and moisture from the Gulf of Mexico, and drag both northward toward New England over the next 36 hours.  The result will be a surge of mild and moist air toward the Northeast on Wednesday, and by Tuesday night we'll already begin to see an increase in high altitude cirrus clouds.

Clouds will thicken on Wednesday with the slow approach of this system, and more directly, the moisture streaming north ahead of the storm circulation.  A few showers are possible late in the day on Wednesday, but most of the day should be relatively dry, and with breezes increasing from the south, temperatures should be able to rise well into the 40's to near 50 in most communities.  Wednesday evening, the energetic upper level disturbance driving the approaching storm circulation will be directed over New England by the jet stream winds aloft - the fast river of air high in the sky that steers our storm systems and acts as a thermostat for the atmosphere.

With the passage of this disturbance Wednesday evening and night, rain is likely to fall heavily at times with embedded thunderstorms, though the air may be just cold enough across Northern New England for snow to fall in the higher terrain only.  Lingering clouds early Thursday should give way to increasing sunshine and a brisk westerly wind, but with very little cold air available to dislodge southward behind this storm, and the jet stream winds lifting to the north of New England, warm air will be poised to move back into the six-state region.  The result will be a rebound of temperatures into the 50's on Thursday and Friday on average across New England.

By Saturday, a strong storm will be cranking up while moving east across the Eastern Great Lakes and into New England.  A well established tap of Gulf of Mexico moisture should be associated with this circulation, and warm air will continue to stream northward on very busy southerly winds to begin the weekend.  It's likley that the passage of this storm will bring a Saturday filled with periods of rain, heavy at times, and embedded thunderstorms once again.  As this storm winds up tightly over New England, cold air will be pulled southward out of Canada, and a shot of deep chill will drop into our area on Sunday.

This colder air is just one example of why skiers, snowboarders and snowmobilers alike should not lose hope from this milder finish to the week.  While this thaw has been an extended one, those of us in the North Country know that snow has still been falling, and though we'll take a hit with rain later this week, some cooler air makes a brief appearance next weekend, the pattern should return to a bit more normal feel by the middle of next week, and cold air begins building in Alaska late this week, which means that we're refilling the cold air well...which will come in handy for winter-lovers later in the season.

Enjoy your Tuesday!

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, January 10 at 10:00 AM

Poor excuse for winter chill in place today is offset by downsloping flow most areas.  Well defined low level pocket of high RH advecting east this morning is assisting in orographically induced snow showers in upslope favored areas and these mountainous areas will be mostly cloudy thru the day, tho temps regionwide come above climatological values.  Deeper valleys that decoupled overnight will quickly mix today.

Overnight, radiative inversion allows for widespread cooling, tho increasing high cirrus clouds thru the night in advance of well defined and strong vorticity maximum moving NE out of AR today.  Surface circulation to race into the Great Lakes while losing its identity as it truly becomes absorbed into a larger scale warm front associated with low pressure center moving thru Southern Canada.  Technically, there will be a trailing cold front with this weak storm over the OH Valley and that front will cross NewEng in association with the vort max tonight, but the bubble of cool air behind the system is so small and so short-lived, that the end result is an opening of a west and southwest flow for mild air to pour northeast later this week.  This was not well handled in my forecast from last week, when I leaned toward a flatter solution, racing a shortwave south of us today with snow.  Instead, the amplification and slowing of the vort max well to our south and west has allowed the warm air to open northward, but there's no sense in denying what is the inevitable, and that's why...given the pattern that's evolved...we certainly can't deny the degree of warmth that's spreading in.  Low level temps from 850 mb to the surface easily support surface temps into the 50's for most of Central/Southern NewEng the latter half of this week.  The mitigating factor will be cloud cover, of which there should be an increasing amount on Wed ahead of incoming system.

Rain Wed eve and first part of night (noting faster trend with each model run) should fall very heavily in parts of Southern NewEng with convective elements throughout and thunder likely for especially CT, RI, South Coastal areas.  Possible to see thunder spread farther north.  There is the need to review this situation for potential strong to severe convection in these locations Wednesday evening.  An inversion will be in place for most of the day, but a 50+ knot low level jet from the southwest Wed eve will try to mix this inversion out...at least just interior from the coastline in CT (cool Long Island Sound will keep inversion intact along immediate shoreline)...and though surface based CAPE is weak, elevated CAPE more significant and LI's follow same thinking.  And 50+ knot winds are deep - extending all the way beyond 500 mb - so it should be quite easy for convective elements to mix these winds down at least to the inversion...and where holes have been punched in the inversion the threat exists for these winds to reach ground level.

Quick moving system is out by second half of Wed Ngt and as mentioned above, don't expect any noticeable chill behind it.  Mild air quick to flood the Northeast on Thu and continue into the upcoming weekend.  Have to believe ECMWF solution of cutting off low over SE US is overdone, which the ECMWF does have a bias toward, so have opted for the much agreed upon GFS/Canadian solution of bringing a tightly wrapped storm thru the Northeast with a strong baroclinic zone that will lead to windswept rain, thunder and mild conditions Saturday with the potential for flooding rains in areas of high snowpack...then transition to blustery and cold with mountain snows late Saturday night and Sunday with a decent accumulating potential in the upslope favored areas of northern and especially northwestern NewEng.

As for the longer range pattern, expect Sunday's cold to stick around into Monday which may set up a weak overrunning snow event later Monday or Monday night.  Thereafter, tight call on rain/snow line for a near-midweek storm next week as lingering energy in South-Central US ejects NE at same time building anticyclone slides SE across Northern Plains and Upper Lakes.  Regardless of ptype line, looks like return to somewhat closer to normal regime comes in after this midweek storm.  Building cold in Alaska will grow stronger last half of January and may hold February fun.

Have a great day.

Matt

North Country Snow...Southern New England Warmth to Win Out By Week's End

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  A relatively weak area of low pressure sliding across Northern New England Monday is dragging warm air northward from the Mid-Atlantic.  The transition between chilly air that's been in place, and incoming warmth, will create plenty of clouds for New Englanders to start the workweek.  In Northern New England, snow will accumulate 3"-5" in the mountains, 1"-2" in lower elevations, while Southern New England stays mainly dry save for a few morning snow showers in Southern NH and Northern MA.  As a warm front - the leading edge to warmer air here at ground level - moves through New England Monday afternoon, winds will swing around from the southwest in Southern New England, and a few breaks of sunshine are possible in some communities late.  This warmer wind flow will help to nudge temperatures into the 40's and even near 50 in a few Southern New England locales.  Farther north, where snow will fall and clouds hold tough, temperatures will be kept down and winds will take longer to swing out of a northeast and easterly direction.

The same storm center bringing in the warmer air is also tapping a well of cooler temperatures across Eastern Canada, and the counterclockwise flow of air around the storm center will help to drag some of this colder air southward as the center of low pressure passes east of New England Monday night.  The surface cold front trailing south of the storm center marks the leading edge to a westerly wind direction, and a slow bleed southward of the cooler air that will move into New England Monday night on an active breeze.

Tuesday features mostly sunny skies as dry and cool Canadian air settles over New England.  Breezes will remain active from the west through the day, and this direction of wind produces a "downsloping" flow of air - that is, air flowing down the slopes of the mountains and hills of Northern and Western New England.  This descending motion of air means that the air actually encounters increasing atmospheric pressure along its trip - that is, the barometric pressure is always higher at lower elevations.  The increased pressure on the air compresses it, and temperature of the air responds by warming.  As a result, this warming process of the air will help to counteract most of the chill associated with the airmass, and temperatures will still fall above normal in most parts of New England.  In the mountains of Northern and Western New England, these winds instead result in air sloping UP the mountainfaces ("UPslope" flow), and therefore we'll see a bit more chill and a few more clouds with scattered snow showers in these areas.

Last week I'd mentioned the possibility of snow later on Tuesday as a fast-moving disturbance was to ride just south of New England.  The weekend weather pattern evolution proved this thinking to be flawed, as this energetic disturbance will not scoot just south of New England, but instead will strengthen while dropping south toward the Tennessee River Valley.  The change in path of this upper level storm means two things:  1) A delay in the arrival of this system (which is why I've explained above that Tuesday should be a dry day), and 2) A more prolonged flow of mild air into New England, meaning when the disturbance finally moves through, it will likely bring rain rather than snow, and open the atmospheric flow for warmer air to stream into the Northeastern United States.

Increasing clouds Tuesday night will thicken on Wednesday with the slow approach of this system, and more directly, the moisture streaming north ahead of the storm circulation.  As warm and moist air moves into New England, a few showers are possible during the day on Wednesday.  With breezes increasing from the south, temperatures should be able to rise well into the 40's in most communities.  Wednesday night, the upper level storm will be directed over New England by the jet stream winds aloft - the fast river of air high in the sky that steers our storm systems and acts as a thermostat for the atmosphere.

With the passage of this disturbance Wednesday night, rain is likely to fall heavily at times with embedded thunderstorms.  Lingering clouds and rain early Thursday should give way to increasing sunshine and a brisk westerly wind, but with very little cold air available to dislodge southward behind this storm, and the jet stream winds lifting to the north of New England, warm air will be poised to move back into the six-state region.  The result will be a rebound of temperatures to near 50 on Thursday, and if all goes as it appears right now, over 50 as a New England average on Friday.

Skiers and snowmobilers alike should not lose hope from this milder finish to the week, however.  While this thaw has been an extended one, those of us in the North Country know that snow has still been falling, and though we'll take a hit with rain later this week, some cooler air makes a brief appearance next weekend, the pattern should return to a bit more normal feel by the middle of next week, and cold air begins building in Alaska late this week, which means that we're refilling the cold air well...which will come in handy for winter-lovers later in the season.

Have a great Monday!

Technical Discussion:  Lots in-house this week with training on new on-air system.  Nothing technical today...I will try to be as explicit as possible in the Weather Summary.

Matt

Coastal Graze Friday...Chilly Saturday...Some Sunday Snowflakes

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  Breaks of sunshine Friday morning in Eastern parts of Southern New England are the result of a wedge of dry air that was driven northward behind Thursday's disturbance.  These sunny breaks won't last long, as moisture is abundant in the lower levels of the atmosphere, and low-altitude gray clouds will fill back in, bringing an overcast afternoon to all of New England.  With cold air aloft, and relatively warm air at ground level, "instability" exists in the atmosphere - favorable conditions for snow showers to develop - and this will lead to a smattering of snow showers with a few heftier squalls across the mountainous and hilly terrain of Northern and Western New England, likely extending east across most of the state of Maine by Friday afternoon.

Meanwhile, the energy center we've been following together in this discussion that's been racing across the Southeastern U.S. has come off the coastline and is resulting in the development of a coastal storm chock full of moisture off the coast of North Carolina.  This storm center will truck northward during the day on Friday, and pass well southeast of Nantucket.  A few factors will help to ensure the bulk of this moisture stays offshore.  The first is a cold front that's crossing New England during the day Friday.  This surge of chilly air will result in steady or even falling temperatures through the day in the far North Country, and will help to push most of the approaching moisture offshore.  The second factor is the speed of this approaching system, which will have trouble wrapping significant moisture around its western periphery given its steady northeast motion.  Still, enough moisture is likely to wrap around the back of this system to bring light rain to Cape Cod by late afternoon, and by sometime around 9 PM, the air is likely to turn cold enough to change rain to snow on the Cape, depositing about an inch anywhere east of the Canal.

As this storm races away from New England, a drying northwest wind will become more active, and these breezes will carry cold - but also dry - air through New England to yield a cold night with gradually clearing skies.

Saturday morning should begin with sunshine for many areas, and this sunshine will stick around through most of the day as New England finds ourselves between the departing storm, and an incoming energetic disturbance racing east across the Great Lakes.  In between these systems, winds will be brisk, and this in combination with high temperatures only in the middle and upper 20's will result in a chilly day throughout the six state region.  Saturday evening, clouds will increase in the upper levels of the atmosphere, which will have little effect aside from helping to keep Saturday night temperatures a touch milder than they'd be otherwise.  There should be no problem for the Saturday night Patriots game, but do be sure to bundle up, Pats fans, as temperatures will be in the lower 20's and a light wind will still be blowing.

The upper level energy center ejecting out of the Great Lakes will bring light snow on Sunday.  At this point, it appears as though a few inches of snow are likely to fall in the mountains of Northern New England, perhaps a couple of inches in the higher terrain of the Berkshires, and only a light accumulation is likely in Southern New England.  While snow will fall only periodically on Sunday, I do expect clouds to linger for most of the day.

Expect Monday to bring cool and breezy conditions behind this departing disturbance, before another energetic upper level disturbance dives east-southeast across the Ohio Valley, passing south of New England and perhaps developing quickly enough to bring a shot of accumulating snow to the area, and especially to Central and Southern New England.

The bottom line of this pattern is that nobody should be expected an extended period of significantly warmer weather than what we've had anytime soon.  While the air a few thousand feet above our heads will stay warmer than normal, near-surface domes of cold air will continue to penetrate southward from Canada from time to time.  While these may not contain bitter arctic air by New England standards each time, each installment will be plenty cold enough to allow for accumulating snow to fall if the cold air matches up with the frequent disturbances that will race through New England over the next few weeks.

Have a wonderful weekend!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, January 6 at 2:00 PM

Short term challenge is Cape Cod and Eastern ME - still diffs between NAM and GFS, dry and wet respectively.  Either way, looks too warm for much snow on the tail end as moisture shuts down quickly, so going with light rain late afternoon and evening, changing to snow Cape after 9 PM, then probably only a dusting.  Eastern ME likely to pick up a dusting to 1" overnight as bulk of moisture stays offshore.  Elsewhere, increasing NW winds overnight will assist in pulling down cold Canadian airmass and with Tds crashing and winds relaxing across the far north as cold advection lets up late, some valleys will come down near zero in the north...widespread teens elsewhere.

Saturday looks on track with going forecast, though I actually tweaked down my already cold numbers just a touch - cold start begets cold finish given no airmass change thru the day and tho sunshine will aid in mixing, temp profile favors middle 20's.  Downslope will help a bit on the coastal plain, but most spots should not excede 30.  Xpct incr clouds Sat ngt ahead of next vort.

Trend of vort has been faster in the guidance over the past few runs - now midlvl moisture arriving overnight Sat Ngt, but low level moisture lingers and most of Sunday should bring clouds and periods of snow - both early in the day in low level warm advection ahead of shortwave, and later in the day with passage of the vort.  Best snow will be along tightest baroclinic zone which will be focused in Northern NewEng where a few inches may fall.  Farther south, looks like much less significant event for Southern NewEng.

Monday should be cooler and quiet between systems but the Tuesday shortwave has lots of potential.  GFS lovers would say, what Tuesday shortwave?  GFS keeps it progressive and swings it thru by Monday, but Canadian is keying in on it and this amplifying short passing south of NewEng with a developing mid and low level center has been signalled for several days for Tuesday, so I'm not willing to drop the potential for a more significant snow for Central/Southern NewEng from the forecast right now.  This should become much more clear over the weekend, of course.

Speaking of the weekend - enjoy it!

Matt

Nuisance Wintry Mix South...Accumulating Snow North...Chilly Air Still Pegged for the Weekend

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  An energetic disturbance racing across New England today has provided bands of precipitation, falling as heavy snow at times through parts of Northern and Western New England.  In Southern New England, excepting the Berkshires, the morning shot of snow that moved through was associated with warm and somewhat moist air surging northward ahead of the approaching low pressure center.

The remainder of Thursday will feature disorganized showers of snow, sleet, freezing rain, and eventually plain rain across Southern New England, decreasing in both coverage and intensity as the day progresses and the upper level disturbance driving this weather moves east across New England.  Additionally, increasing south winds will help to boost temperatures above freezing in most if not all Southern New England locales.  Farther north, directly under the forecasted path of this disturbance, an additional two to four inches of snow will fall today from the higher terrain of the Berkshires, to the Southern Greens to the Lakes Region of New Hampshire to interior Southern Maine, points north.  At times, visibility will drop to below half a mile in these bursts of heavier snow.  You can follow the progress of the snow through radar imagery on my homepage, www.mattnoyes.net.

By Thursday night, winds will swing around and come from the northwest, which is a favorable direction to keep snow showers lingering in the mountains of the North Country with another fluffy couple of inches in the higher terrain, but gradually dry out the lower levels of the atmosphere elsewhere in New England.  Still, some black ice will be possible in all areas, where the light wintry mess that melted during Thursday will refreeze.

An upper level energy center moving across the Lower Mississippi River Valley on Thursday will round the base of a jet stream "trough" - or dip in the jet stream winds that steer our storm systems - Thursday night, and will turn north traveling parallel to the East Coast on Friday.  At this point, here's how Friday's weather is breaking down:  Lingering low level moisture will result in lots of clouds for most areas, especially in the mountains where scattered snow showers will continue.  Along the coastal plain, "downsloping" northwest winds (sloping down the hills and mountains of New England) will allow for breaks of sunshine at times between the clouds.  This downsloping flow not only serves to dry the air, but also can warm it slightly, so even though cooler air will be draining southward, this warming effect should offset any noticeable temperature difference, and most areas will be comparable to Thursday's temperatures.

Meanwhile, the energy center racing northward off the U.S. East Coast will continue to make meteorologists anxious with its close passage to New England.  Indications are that MOST of the moisture associated with this storm should stay offshore, especially given its quick speed which will help to keep much moisture from wrapping around the back of the storm center.  Still, I have to believe that enough moisture may wrap to the west side of the circulation for some light snow to fall on the Outer Cape and Nantucket Friday evening and night.  At this point, it still doesn't look like a big deal, but as I mentioned...we'll keep a careful eye on this coastal creature.

Regardless of the western periphery of this storm, it's a fast mover and will be way up into far Eastern Canada by Saturday.  Behind the storm, though, northwest winds will become active and this will leave a breezy, chilly day on Saturday, though any morning clouds should steadily give way to increasing sunshine.  It looks right now like the Patriots will play Jacksonville under mostly clear skies, temperatures in the lower 20's, and a west wind at about 10-12 mph in Foxborough.

Though our Saturday will bring quiet weather, another energetic but fast moving disturbance (much like Thursday's) will come racing eastward across the Great Lakes.  This system will bring increasing clouds to New England Saturday night into Sunday, with snow developing for most areas of New England Sunday afternoon, with a few inches likely in the mountains of Northern and Western New England, and a lighter snowfall likely farther south and east.

Expect Monday to bring cool and breezy conditions behind this departing disturbance, before another energetic upper level disturbance dives east-southeast across the Ohio Valley, passing south of New England and perhaps developing quickly enough to bring a shot of accumulating snow to the area, and especially to Southern New England.

The bottom line of this pattern is that nobody should be expected an extended period of warmer weather anytime soon.  While the air a few thousand feet above our heads will stay warmer than normal, near-surface domes of cold air will continue to penetrate southward from Canada from time to time.  While these may not contain bitter arctic air by New England standards each time, each installment will be plenty cold enough to allow for accumulating snow to fall if the cold air matches up with the frequent disturbances that will race through New England over the next few weeks.

Enjoy your Thursday!

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, January 5 at 1:45 PM

Vort max quite impressive as it passes thru...sprial obvious on both satellite and radar imagery.  Cold cloud tops and radar dBz maxes coordinate well with below .25 mile visibility in heavy snow.  These bursts and bands of heavy snow follow the track of best cyclonic vorticity advection.  Without much low level inflow to work with, it's easy to shut down precip behind the vort, and wake subsidence is allowing sun to expand northeast toward CT...certainly not impossible to get some of this into parts of Southern NewEng by the end of the day.  Otherwise, southerly wind and relatively warm boundary layer allows daytime highs to rise above freezing for most of Southern and Western NewEng which means more melting followed by a refreeze tonight.  Upslope flow in Northern NewEng will offset subsidence behind vort and allow for areas of snow to persist tonight in the mountains.

Friday all eyes should be turned to the coastal storm.  Yesterday I mentioned by uneasiness with a possible interaction between the weak upper low over Northern NewEng and the vort racing parallel to the coastline.  I'm not anymore comfortable with this today.  500 mb RH on the NAM consistently illustrates wraparound cloud shield over Cape Cod, and that's been enough to keep me concerned, but now, of course, GFS is backing precip in over the Cape.  So, the forecast holds of a chance of light snow on Cape and Islands later Friday afternoon into evening.  This storm is racing by, so it wouldn't last long, and the other question is whether we're going to have a ptype issue.  With a northwest wind that certainly doesn't favor rain...though diurnal heating should get temps into the upper 30's on the Cape with dewpoints around 30.  This would obviously yield a wet bulb of over 32 at the surface, so we'd be dealing with a mainly rain scenario...but with Tds in the middle to upper 20's inland and that NW flow, and 925 mb temps (barely) below zero, I think it's wisest to keep a light snowfall accumulation potential in for Cape Cod where a couple of inches are possible on the outer cape.

Not much change to the thinking for Saturday...or for Sunday with the incoming vort.  Monday should be a break in the action with a shot of greatly modified chill before Tuesday's shortwave takes a path favorable for Southern NewEng snow as long as it can close off a low and/or midlevel center quickly enough as it draws near.

Have a great day.

Matt

Energetic System En Route for Tonight...Chillier Weekend In Store

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary:  A break between systems today as yesterday's storm continues to thrive over the open Atlantic, and a new one races in from the west.  Unlike our Tuesday storm, however, the next in line is racing from west to east and will not bring as much available moisture.  Still, clouds will increase ahead of this system later Wednesday.

Wednesday morning starts with black ice on especially Southern New England roadways where melted snow and slush froze during the overnight.  A stubborn patch of low altitude clouds will be difficult to erode across parts of Eastern MA and immediate coastal New Hampshire and Maine as a result of persistent northeast wind flow.  Farther inland, sunshine blends with pop-up low level cumulus, and increasing high altitude cirrus clouds ahead of the next weather system.  The combination of sunshine and a relatively mild airmass still in place across the region will allow temperatures to rebound above freezing in most of Southern and Western New England on Wednesday.  In the State of Maine and Northern New Hampshire, the expansive cold air dome of high pressure established over Eastern Canada continues to feed cold air southward.

Expect light snow to move east out of New York State and spread over most of New England by Thursday morning - but while snow will be falling for the morning commute, it should fall lightly enough to avoid any signficant problems on treated roadways.  Secondary roads, however, will see this light snow falling atop refrozen slush and black ice, so some caution is advised for Thursday morning's drive.  After sunrise Thursday, diurnal effects of sunshine - even through the clouds and falling snow - should be enough to warm surface temperatures enough to mix and eventually change the precipitation over to rain showers.  From the Berkshires to the Green Mountains, then east to the Lakes Region and Southern Maine points northward, the precipitation will stay as snow on Thursday.  Total accumulations across the mountains of the North should be on the order of 2"-4" by the time the snow winds down later Thursday, except along the Maine coast where a southeast wind will usher in a shallow marine layer of warmth.  Farther south, less than an inch of snow is expected excepting the Berkshires.

This weather system won't really depart from New England Thursday night...but rather just sit over Northern New England as the jet stream flow that steers our storms will reconfigure on a south to north steering pattern just off the Eastern Seaboard.  The result will be for a new bundle of energy to pivot around the base of the carved out East Coast trough, and shoot northward parallel to the coastline but offshore on Friday.  While it doesn't appear as this storm will pass close enough to bring direct effects on New England Friday, it will turn low level winds onshore north of a leftover frontal boundary that will be draped across the New Hampshire seacoast.  The result of this will be the development of an instability axis...which may focus snows along and north of the northern New Hampshire or Southern Maine coastlines on Friday while the North Country stays mostly cloudy with scattered snow showers.  Farther south, enough dry air will be in place to keep Friday a relatively dry day.

Provided this coastal storm misses on Friday night, Saturday will be a windy, chilly and mainly dry day behind the storm to our east.  By Sunday, yet another fast-moving energetic disturbance will be racing east from the Great Lakes (similar to the Thursday system) and this will spread snow...perhaps mixed with rain south...from west to east later in the day.

So, though ski and snowmobile country missed out on this past event, little by little we'll add to the base in the mountains.

Have a great day!

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, January 4 at 2:10 PM

Quick note off the bat that I will get this techie discussion out as often as possible but it may be more brief than normal the next few weeks - perhaps considerably so.  We're doing a lot behind the scenes here which is making for long and busy days, but I will put out what I can regularly.

Next vort max for tonight producing swath of warm advection precip in isentropic lift across New York.  Vort looks like it crosses Northern NewEng tonight into Thu and while I'm going for a general 2-4" higher terrain and upslope favored areas will see more.  Southern half of NewEng will see less impressive amounts as no warm conveyor into this disturbance means you need good cyclonic vort advection to crank precip out at a decent rate.  Boundary layer temps should be cold enuf for snow most areas tonight and profile marginally cold enuf at 850.  Biggest public impact for morning drive - aside from seeing flakes in the air - will be potential for convective elements of heavier snow embedded in precip area, and coating of snow over black ice from refreezing snowmelt.  I expect Berkshires to pick up higher totals.

As jetstream flow goes more meridional, vort stalls over Northern NewEng.  This prevents drier air from working in so low level moisture leaves cloudy skies and scattered snow showers for most of Northern and Western NewEng on Fri.  Meanwhile, surface reflection sits under the vort as new strong vort rounds trough along SE US coast.  Flow is favorable to race this vort northward parallel, though offshore, of the East Coast.  This flow is so fast that it will be difficult to wrap warm advection around west side of vort and therefore the concern at this point seems low for the surface low to wrap enough precip west of the low track to affect NewEng.  There are two things we need to watch, though, both related to the stalled weak upper low over Northern NewEng and its interaction with the northward racing vort.  The first concern is that these two don't link up enough to pull the southern vort westward - even a small interaction could do it and these two are flirting dangerously close with one another.  The second concern is that even without a direct interaction, a weak Norlun instability trough is possible on Friday as low level flow comes onshore ahead of northward racing low and meets with stalled/decaying frontal boundary draped over New Hampshire/Maine seacoast, and while there's not much to work with, an area of light snow is possible in the convergent zone around this trough.  In summary, there's a lot going on right over us on Friday, so plenty to keep an eye on.

Saturday looks like cold and wind come around the back of the system as it departs.  Sunday is the next shortwave that races in with a swath of warm advection rain and snow.

Have a good day.

Matt

Blog to Resume on Wednesday

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net.  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Weather Summary: 

TUESDAY UPDATE:  Storm speaks for itself today...have been doing so much live coverage just won't have time to update today.  Please be sure to tune in today and check back tomorrow when I will resume daily discussions.