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GRADUAL IMPROVEMENT ON TUESDAY LEADS INTO SUMMER WEATHER TO ROUND OUT THE WEEK

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

General Weather Summary:

NEW EXCITING FEATURE!  Thanks to the folks at answers.com, you can now double click on just about any word in my discussions to find out what a term means - no more trying to guess what weather terms mean!  If there's a word you don't know, double click on it, and chances are good you'll get a description.  This is a phenomenal learning tool for those who take an interest in weather, or who simply want to gain a more complete understanding of the forecast, and works best using Internet Explorer.  Please note that the page must be loaded completely for this feature to work, and a "refresh" can assist if the feature is sluggish.

The weather pattern of late, both with regard to "feel" and with regard to meteorology, has been more remniscent of autumn in the past two weeks with frequent deliveries of cool, dry air, and periods of clouds and rain everytime deeper warmth and humidity attempts a comeback.  Monday was just another example of such a pattern, with some locales recording their lowest high temperature of the entire 2007 summer season, more than halfway into summer!  Nonetheless, we're recovering Tuesday, and the remainder of the week will bring summery conditions for all six states.

A gray start in many areas has readily given way to sunshine, though a few pockets of thicker cloud cover linger for some of Central New England and the Maine Midcoast.  These clouds, and the early morning fog that lifted and burned off, all were the result of a conflict of airmasses over New England with our cool and dry air of the weekend reluctantly releasing its grasp on the region while a southerly wind flow ushers deep tropical warmth and moisture northward.  With an upper level storm stalled and spinning to our west, across the Eastern Ohio Valley, and a large fair weather ridge anchored over the Northwestern Atlantic, a steady and well-established southerly wind flow will continue through most levels of the atmosphere throughout the week, introducing a tropical airmass that will warm handily with solar input.  Though this air has been transitioning into New England on Tuesday and temperatures range from the 70s to middle 80s, largely dependent upon sunshine, the results of this new airmass will be more evident through the remainder of the week.  In fact, as temperatures shoot well into the 80s and some spots in New England hit 90 degrees, and the measure of the amount of moisture in the air remains high, with dewpoints in the upper 60s to near 70, the heat index value or "feels like" temperature will be in the lower 90s.  With a continued southerly flow of wind through the end of the week, warm and muggy conditions will remain in place with daily variations in weather determined largely by the intensity and frequency of any energetic disturbances that float through the atmosphere over New England.  With a setup that features a big upper level storm to our west, and a big high pressure ridge to our east, it won't only be near the ground that southerly winds blow, but also at the jet stream level, so any disturbances heading our way will be moist and ready to fire thunderstorms, coming out of the Gulf of Mexico and Western Atlantic.  The first round of isolated thunder should come Wednesday afternoon, though coverage of any storms would be limited.

The coverage of thunderstorms appears even lower on Thursday, with a likely break between disturbances, though it's important to keep in mind that we're dealing with a weather pattern in which timing and intensity of disturbances bank heavily on the evolution of the storm to our west, and the speed of the jet stream winds aloft.  It is possible that as we near the end of the week, the timing and strength of each disturbance will become clearer, and the forecast will need to be tweaked.

By Friday, the upper level storm that had been sitting over Ohio and Pennsylvania will dislodge as it's picked up by the jet stream winds, sagging slightly south out of Canada and ejecting this disturbance northeast out of the Eastern Great Lakes and heading toward Southern Ontario and Quebec.  The result will be an increased chance of showers and thunderstorms Friday afternoon after a muggy blend of sunshine and building puffy cumulus clouds.  The passage of that disturbance will tug cooler air south out of Canada, pressing a cold front southward into New England ever so slowly for the upcoming weekend.  In fact, with a surface storm center developing along the front over the Great Lakes, this front may stall over the far North Country, meaning most of New England will find continued warm and humid conditions with repetitive thunderstorms Saturday and Sunday.  Though neither of these days appear to be washouts at this point, so much moisture packed into a tropical airmass implies any storms that develop may have some hefty rainfall and may grow to be rather strong during each afternoon Saturday and Sunday.

Overall, it's important to acknowledge that this pattern is changing the pattern I thought may finally evolve - one featuring a shot of deep heat.  Though it'll still be hot and muggy, and for many in the general public it will feel plenty warm at the end of this week, meteorologically this will be another missed opportunity at getting into the deep and impressive heat from the Western and Central United States.  Don't get me wrong - I have no problem on a personal level with not approaching 100 degrees, but with the upper level storm just to our west, it becomes extremely difficult to get deep Western heat into New England in the near-term, and instead our heat, while summery, is coming from due south, rather than from the west and southwest.  In fact, indications are that we remain in a pattern that features oscillations between a few days of heat and humidity, then a returning shot of cool air, and so forth, meaning the unsettled clash of airmasses with occasional cool and mostly cloudy days, as well as muggy days of thunderstorms, may continue to make appearances over the coming few weeks.

Have a wonderful Tuesday.

Technical Discussion: Yesterday's below...none today.

Matt

Matt's Technical Meteorological Discussion: Updated Monday, July 23 at 2:05 PM

In typical NewEng fashion, as the clouds and cool air remain locked in for most, Nantucket has broken out into beautiful sunshine and the Cape may soon follow.  It appears this is the result of the tropical air infusing extreme SE areas, and this poses the question of how cloud cover is going to play out on Tuesday.  For now, clouds will continue to thicken N after a great day while complex setup takes shape.  Positive theta-e advection today is progressing north at 850 and 700 mb, and will be followed by sharply negative theta-e advection overnight Monday night into Tuesday.  This is mirrored aloft and skies clear above about 900 mb.  Beneath that, however, the concern focuses upon inversion strength on Tuesday, as boundary layer will remain quite moist Mon Ngt and this is likely to lead to lots of clouds and areas of fog Mon Ngt into Tue AM, with scattered light showers still a possibility Mon Ngt given moisture and vorticity lobe rotating through.  With presence of inversion Tue AM, mixing will be dependent upon kicking up wind, and winds should be quite light with dying sfc low reflection riding overhead.  Where winds increase a bit...and where relative humidity is lower...we should find sun breaking through, and this includes far Southern NewEng and far Northern NewEng, respectively.  Elsewhere, unless the winds can kick up more than expected either at the surface or 850 mb, it'll be tough to get more than just breaks of sun between lots of clouds.

This should turn around very quickly Wed with good mixing, increased wind field and with tropical air in place temps should come up quickly.  Tropical cumulus will pop Wed, Thu and Fri with a weak shortwave streaming north out of the Gulf of Mexico and up the Eastern Seaboard touching off isolated thunder Wednesday.  Appears as though we may find a break in the action on Thu between shortwaves and therefore at this point I'm carrying a dry day, tho certainly timing of shortwaves can change this and I'm also aware that at least an isolated to widely scattered storm would be possible regardless, given abundant ambient relative humidity, and even though ridge is building over us, one would think the deep southerly flow implies enough tropical moisture is present to boost CAPE high enough to overcome any weak capping.  But, again, with no obvious trigger at this point, figured a drier forecast is best representative of NewEng and will re-evaluate tomorrow.

Fri and Sat should bring numerous convective cells with organization owing to strong shortwave and then surface front pushing southward.  Of course, all the while, upper low to our west is prohibiting the significant warmup that I finally thought might be for real at the end of this week.  Yes, ridging builds over us, but this sets up a deep tropical flow from the south, which is humid and warm deep through the atmosphere but not a chunk of the searing Western heat, and with another northern shot trying to intrude by Sunday, one has to wonder what our chances are of getting any of this warmth, or whether this upper low permanently sends the deep warmth sailing into Canada.  That's something I'll try to look at here later in the week.

Matt

TUESDAY PODCAST: NO PODCAST TUESDAY DUE TO TECHNICAL PROBLEM

Podcast is expected to return Wednesday morning, as usual.

PLENTY OF CLOUDS BEGIN THE WEEK...DECIDEDLY MORE SUMMERY SOON, THOUGH

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

General Weather Summary:

NEW EXCITING FEATURE!  Thanks to the folks at answers.com, you can now double click on just about any word in my discussions to find out what a term means - no more trying to guess what weather terms mean!  If there's a word you don't know, double click on it, and chances are good you'll get a description.  This is a phenomenal learning tool for those who take an interest in weather, or who simply want to gain a more complete understanding of the forecast, and works best using Internet Explorer.  Please note that the page must be loaded completely for this feature to work, and a "refresh" can assist if the feature is sluggish.

After a great weekend regionwide, conditions have quickly deteriorated to begin the workweek.  Arriving to the northeast is a chunk of the tropical wave we left off examining at the end of last week, and though the heaviest rain will fall immediately southwest of New England on Monday, cloudy and relatively cool conditions will linger through the start of the week, with a more substantial warmup in store from midweek onward.

For now, the surge of tropical warmth and moisture associated with the tropical wave and its reflective low pressure system off the Eastern Seaboard are resulting in a clash of airmasses across the Northeast - from New England through the Mid-Atlantic.  This clash of comfortable air remaining from the weekend and incoming warmth and humidity is evident by a swath of clouds and rain pushing north and west off of the Atlantic.  The heaviest rain on Monday will continue falling from the Northern Mid-Atlantic into Southwestern Connecticut, spreading northwest across Upstate New York.  In Southwest Connecticut, up to an inch of rain may fall all tolled Monday afternoon.  Farther north and east, however, rain is far less organized, falling as showers in most of Southern New England.  These showers are touched off by the onset of warmer and more humid air, and will wane by late Monday morning until the next advancement of tropical air comes in a few thousand feet above our heads, mid to late afternoon Monday.

To our west, a large upper level storm is swirling over Pittsburgh, Pennsylvania.  Though this expansive counter-clockwise spin was steered to Pennsylvania by the jet stream winds aloft that steer storm systems and act as a thermostat, keeping cool air to the north and warmth to the south, the jet stream has since departed northward into Canada, and left this upper level storm behind.  So what does that mean for the weather?  It means that the storm won't get much push from upper level winds in the coming days, and will stay virtually stalled, while areas beneath its pool of cool air and atmospheric energy will find cooler temperatures and increased cloud cover.  While that doesn't bode all that well for the Ohio and Allegheny Valleys, closer to home we'll see less dramatic influences.  For awhile, New England will be a less-than-perfect place to be, weatherwise, with plenty of moisture lingering from a mostly cloudy Monday, and the cloud-forming battle of airmasses actually lifting north, spreading clouds over even the North Country overnight Monday night, while the remainder of New England will find continued clouds, scattered light rain showers, and areas of fog.  By Tuesday morning, much drier air will be moving in several thousand feet above our heads, but winds aloft will be rather light, and near the surface our wind will be near calm, making it a real challenge to break through morning cloud cover, and therefore making it rather likely that we'll find a mostly cloudy Tuesday in a lot of spots, with the best chance for sunshine in Northern Maine, for a few hours around midday in extreme eastern Southern New England, and also in far Southern New England Tuesday afternoon.  Nonetheless, the clouds will be thinner, conditions a bit brighter, and temperatures a bit warmer with a weaker flow off of the ocean.

By Wednesday, the stalled upper level storm will continue to swirl to our west, while drier air aloft continues to gradually eat away at lower altitude clouds, especially as winds begin to increase.  The result should be areas of morning clouds and fog Wednesday morning, followed by emerging sunshine.  Given persistent and deep southerly flow developing between the aforementioned storm and its counter-clockwise airflow to our west, and a large fair weather cell over the Western Atlantic with a clockwise flow of air, a tropical airmass will be in place and will warm handily with solar input.  As temperatures shoot well into the 80s and in some spots in Southern and Central New England hit 90 degrees, and the measure of the amount of moisture in the air remains high, with dewpoints in the upper 60s to near 70, the heat index value or "feels like" temperature will be in the lower 90s.  With a continued southerly flow of wind through the end of the week, warm and muggy conditions will remain in place with daily variations in weather determined largely by the intensity and frequency of any energetic disturbances that float through the atmosphere over New England.  With a setup that features a big upper level storm to our west, and a big high pressure ridge to our east, it won't only be near the ground that southerly winds blow, but also at the jet stream level, so any disturbances heading our way will be moist and ready to fire thunderstorms, coming out of the Gulf of Mexico and Western Atlantic.  The first round of isolated thunder should come Wednesday afternoon, though coverage of any storms would be limited.

The coverage of thunderstorms appears even lower on Thursday, with a likely break between disturbances, though it's important to keep in mind that we're dealing with a weather pattern in which timing and intensity of disturbances bank heavily on the evolution of the storm to our west, and the speed of the jet stream winds aloft.  It is possible that as we near the end of the week, the timing and strength of each disturbance will become clearer, and the forecast will need to be tweaked.

By Friday, the upper level storm that had been sitting over Ohio and Pennsylvania will dislodge as it's picked up by the jet stream winds, sagging slightly south out of Canada and ejecting this disturbance northeast out of the Eastern Great Lakes and into Southern Ontario and Quebec.  The result will be a much greater chance of showers and thunderstorms Friday afternoon after a muggy blend of sunshine and building puffy cumulus clouds.  The passage of that disturbance will tug cooler air south out of Canada, pressing a cold front into New England for another good chance of thunderstorms amidst warmth, humidity and sunshine on Saturday, before the shot of drying and clearing behind the front attempts a more meaningful advance southward into New England.

Overall, it's important to acknowledge that this pattern is changing the pattern I thought may finally evolve - one featuring a shot of deep heat.  Though it'll still be hot and muggy, and for many in the general public it will feel plenty warm at the end of this week, meteorologically this will be another missed opportunity at getting into the deep and impressive heat from the Western and Central United States.  Don't get me wrong - I have no problem on a personal level with not approaching 100 degrees, but with the upper level storm just to our west, it becomes extremely difficult to get deep Western heat into New England in the near-term, and instead our heat, while summery, is coming from due south, rather than from the west and southwest.

I'll keep you posted as the weather pattern evolves!

Matt

Matt's Technical Meteorological Discussion: Updated Monday, July 23 at 2:05 PM

In typical NewEng fashion, as the clouds and cool air remain locked in for most, Nantucket has broken out into beautiful sunshine and the Cape may soon follow.  It appears this is the result of the tropical air infusing extreme SE areas, and this poses the question of how cloud cover is going to play out on Tuesday.  For now, clouds will continue to thicken N after a great day while complex setup takes shape.  Positive theta-e advection today is progressing north at 850 and 700 mb, and will be followed by sharply negative theta-e advection overnight Monday night into Tuesday.  This is mirrored aloft and skies clear above about 900 mb.  Beneath that, however, the concern focuses upon inversion strength on Tuesday, as boundary layer will remain quite moist Mon Ngt and this is likely to lead to lots of clouds and areas of fog Mon Ngt into Tue AM, with scattered light showers still a possibility Mon Ngt given moisture and vorticity lobe rotating through.  With presence of inversion Tue AM, mixing will be dependent upon kicking up wind, and winds should be quite light with dying sfc low reflection riding overhead.  Where winds increase a bit...and where relative humidity is lower...we should find sun breaking through, and this includes far Southern NewEng and far Northern NewEng, respectively.  Elsewhere, unless the winds can kick up more than expected either at the surface or 850 mb, it'll be tough to get more than just breaks of sun between lots of clouds.

This should turn around very quickly Wed with good mixing, increased wind field and with tropical air in place temps should come up quickly.  Tropical cumulus will pop Wed, Thu and Fri with a weak shortwave streaming north out of the Gulf of Mexico and up the Eastern Seaboard touching off isolated thunder Wednesday.  Appears as though we may find a break in the action on Thu between shortwaves and therefore at this point I'm carrying a dry day, tho certainly timing of shortwaves can change this and I'm also aware that at least an isolated to widely scattered storm would be possible regardless, given abundant ambient relative humidity, and even though ridge is building over us, one would think the deep southerly flow implies enough tropical moisture is present to boost CAPE high enough to overcome any weak capping.  But, again, with no obvious trigger at this point, figured a drier forecast is best representative of NewEng and will re-evaluate tomorrow.

Fri and Sat should bring numerous convective cells with organization owing to strong shortwave and then surface front pushing southward.  Of course, all the while, upper low to our west is prohibiting the significant warmup that I finally thought might be for real at the end of this week.  Yes, ridging builds over us, but this sets up a deep tropical flow from the south, which is humid and warm deep through the atmosphere but not a chunk of the searing Western heat, and with another northern shot trying to intrude by Sunday, one has to wonder what our chances are of getting any of this warmth, or whether this upper low permanently sends the deep warmth sailing into Canada.  That's something I'll try to look at here later in the week.

Matt

MONDAY PODCAST: PLENTY OF CLOUDS BEGIN THE WEEK...DECIDEDLY MORE SUMMERY SOON, THOUGH

The Quick Weather Synopsis is now a Podcast!  You can either click on the audio controls above the forecast on the main homepage, or to subscribe to the Monday-Friday podcast (updated on all days I'm working):

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The daily file you will receive is Daily_Weather_Synopsis.mp3

GREAT WEEKEND AHEAD...WATCHING TROPICAL WAVE FOR MONDAY

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

General Weather Summary:

NEW EXCITING FEATURE!  Thanks to the folks at answers.com, you can now double click on just about any word in my discussions to find out what a term means - no more trying to guess what weather terms mean!  If there's a word you don't know, double click on it, and chances are good you'll get a description.  This is a phenomenal learning tool for those who take an interest in weather, or who simply want to gain a more complete understanding of the forecast, and works best using Internet Explorer.  Please note that the page must be loaded completely for this feature to work, and a "refresh" can assist if the feature is sluggish.

A fantastic weekend is in store for most of New England as a steady feed of tropical moisture stalls safely offshore, though this ribbon of moisture will be watched carefully as a developing storm center along it may carry some rain back into New England on Monday.

In the meantime, pleasant and drier air is streaming into New England, while an intense upper level storm sprials over Northern New York.  This storm is packed with energy and cold air aloft, and the difference between cold air aloft and warming ground will make plenty of puffy cumulus clouds across New England today, with the most clouds found closest to the disturbance in Northern New England.  In fact, the combination of a cool northwest wind, building clouds and resultant scattered showers will all combine to keep North Country locales in the 60s and lower 70s for high temperatures Friday afternoon!  Farther south, cool air will be gradually moving southeast across Southern New England, as the surface cold front driven by the upper level disturbance rides slowly southeast.  Ahead of this front - marked by a wind shift and a drop in dewpoint temperatures, or the measure of the amount of moisture in the air - temperatures will rise into the 80s and a sticky feeling persists in especially Southeastern Massachusetts.  It's through extreme eastern New England that the best chance of redeveloping showers and embedded thunder exists Friday, especially with the passage of the front between 11 AM and 4 PM, perhaps lingering into the early evening on Cape Cod.  Folks in these areas can monitor for showers through the radar links at right, though the scattered nature of precipitation will mean that much of Eastern New England enjoys a pleasant Friday.

Any showers and thunder that develop should move east of New England Friday evening, leaving a great evening for outdoor activities and a quiet, cool night.  A light breeze will remain active from the northwest, limiting fog development to only the deeper valleys.  Saturday's crisp dawn will yield a mostly sunny day for most communities, mixed only with fair weather clouds Saturday afternoon.  Meanwhile, the surface front that moved through Friday will continue to focus moisture and precipitation just off the coastline.  That same pesky surface front will remain stalled off the coastline as a tropical wave located near the Dominican Republic as of this writing turns north.  Though the heart of this wave will be torn apart and then head east of Maine, at least a piece of the moisture will likely be drawn northwest around the energetic disturbance that will still be spinning over the Northeast, settling across the Mid-Atlantic.  This swath of moisture is likely to bring periods of rain, possibly heavy, on Monday, and if a reflection at the surface develops south of New England, this rain would be coupled with a gusty and cool northeast wind.  This will bear close watching as the tropical wave and the stalled front will link up for a heavy rain producer, and the biggest question will be where the heaviest rainfall amounts are recorded - over the ocean, or over New England! 

As for deeper summer heat, there's plenty of that to go around in the Western and Central United States, and once we kick out our stubborn energetic disturbance aloft, and push the surface front farther east by the middle to end of next week, heat should come on strong to the northeast, perhaps bringing a heat wave by week's end, and an extended stretch of hot weather may persist into the start of August.

Enjoy the weekend.

Technical Discussion: None today.
Matt

Matt's Technical Meteorological Discussion: Updated Thursday, July 19 at 1:55 PM

It's been awhile since the last techie discussion, and they come much fewer and farther between than the "old days."  This is largely because of time constraints on my end with lots of live coverage during this active severe weather season for New England, and thanks to lots going on behind the scenes.  Nice to be back in the saddle, however, and I appreciate those of you who still look for this discussion as a way to get inside my meteorological mind, as twisted as it may be!  I'm excited about the new feature, too, from answers.com, where you can double click on any word in the discussions and a definition should pop up.  Many of you in the past have let me know you find the technical discussions, in particular, to be great learning tools, and this should tremendously enhance the learning potential.  Sometimes you may have to reload the page to get it to work (if it doesn't work on the first try) and I've found it works better with Internet Explorer than Mozilla (I use both, so I try it with both), and I've yet to see if it knows some of the fancy words, but this technical discussion will be a good way to find out...so let's dig in!

This is certainly an exciting 24-36 hours we're heading into!  An anomalously strong upper level low has been digging southeast across Southern Canada and the Great Lakes, heading toward the Northeastern United States.  If we dig this entire system in without any severe weather in New England, I'll be shocked, as the amount of vorticity alone is awfully menacing, as is the influx of cold air aloft creating instability aloft.  Surface based instability, however, is lacking with CAPE (convective available potential energy) values limited thanks to limited insolation.  This is, of course, especially true across the northeast half of New England, where we're on the cold side of a very sluggish warm front that will have no hope of crossing the region this afternoon.  Northeast of this front, temps hover in the 60s thanks to stubborn clouds beneath the inversion, while south of it we've both been able to break out into some sun and are in the warm sector.  It is, however, a dirty warm sector, defined by clouds of varying levels and thicknesses that have been limited the diurnal heating effects and thereby limiting our instability parameters.  The wind profiles, however, look fantastic for rotating supercells, so really it is instability in the lower levels that is our limiting factor.  But there are a few factors that will have influence later today and tonight, keeping my concern for severe weather in Central and Southern New England.  The first is that while sun may be limited, it is present, and that's helping to nudge surface based instability up, and the second is that there will be stronger destabilization aloft as the upper low center draws closer and numerous shortwaves continue to traverse in the fast jet stream flow aloft.  The result should be several lines of convective development between the Eastern Great Lakes and the Eastern New England Seaboard Thursday afternoon through Thursday night.  Given a continued south and then southwest flow tonight, I don't think the normal rule of weakening convection after dark applies in this instance, and the severe weather threat may last through the entire first half of the night.  Given high precipitable water values, heavy rainers should be found with all storms.  Cold enough aloft for good lightning production - at least after this first round of afternoon stratiform/convective mix over New England - and my buddy Josh Darr reports an amazing lightning show in Chicago last night - that's the stuff that should head our way tonight.  As for damage potential, again, I see increasing instability as providing the need to keep us on our toes for strong wind, and certainly the south-southeast boundary layer windflow increases helicity values throughout New England into the night.  In fact, given the strength of the vorticity maximum and its associated circulation, I would be surprised if we don't see at least a tornado or two between Central New York and Western New England by the time this event is over.  It does, however, appear as though activity will taper in intensity after midnight.

And speaking of over, when is the event over?  Not by Friday morning, even though convection should be just a weak shadow if its former self - if for no other reason than the slow progression of the surface front.  With areas of fog present in valleys but an atmosphere eager to mix or in the case of Southern New England, already mixed by morning, clouds will burn for some sunshine Fri AM.  With mild air in place and some of the best insolation we've seen in the past few days, temps will rise and surface based instability will probably exceed Thu values as temperatures may exceed Thu values, too!  The convergence and airmass upheaval associated with the cold front is likely to generate new convection along the front Fri midday through middle afternoon before shifting east, perhaps lingering into the eve on Cape Cod and eastern ME.

Of course, from that point on the question thru the week has been how far east the front goes before stalling.  It certainly seems like a given that the front will stall considering the upper level low will stall over us for the weekend, and without any deep atmospheric push, the front will have nowhere to go.  In recent cycles of the guidance, however, it has become apparent that this front should, indeed, push just far enough east to put New England on the dry and pleasant side of a sharp dividing line, ensuring a good weekend.  I really couldn't believe Sat and Sun being entirely dry, however, thanks to the upper level cool pool, and am glad to see the 12Z runs returning some convective precip in the afternoons, which makes sense given the cold air aloft and instability cumulus that will billow in response.  Still, it appears as though the weekend will be remembered quite favorably by many.  As for temps, have gone above MOS guidance Fri thru Sun with good mixing of dry airmass encouraging adiabatic warming of air parcels.

Perhaps the greatest interest of the entire period comes early next week.  Today's 12Z run is now the fourth in a row that the GGEM is printing out a major coastal low on Monday that will incorporate not only energy from our stalled upper low, but also additional shortwave energy rotating around the base of the Eastern US jet stream trough, spawning a low pressure center development off the North Carolina Outer Banks.  There has been one change, though, that the Canadian is no longer putting out a direct strike from the southeast by Tropical Storm or Hurricane Chantal, which it's forecasting to develop from the tropical wave currently moving out of the Leeward Islands and heading NW toward the Bahamas.  The concern here isn't so much just that the Canadian has been showing this potential - afterall, just last week it projected a hurricane into Miami - but moreover that it has support from both additional guidance and from reality not necessarily of a TS/Hurricane strike but at least of a merger of tropical wave and shortwave energy.  On the guidance side, NOGAPS, UKMET and now to some extent the NMM are jumping on board with carrying the wave northwest then north.  The GFS keeps the tropical wave farther east, but it's also trying to move it into the western periphery of the subtropical ridge, perhaps too close to the ridge center as the wave merges with the present upper low evident on water vapor.  The GFS and Canadian Ensemble members, as you may expect, are split, while the ECMWF is alone in holding nearly everything at bay along the Southern Mid-Atlantic coastline.  I mentioned that reality supports a solution that at least lends some credence and concern over an interactive if not merging scenario of the tropical and extratropical vorticity centers, and the reason for this is that Central Atlantic ridge that is not going to be eager to break down, while deep southerly flow runs parallel to the East Coast, and would favor bringing the wave close to the upper low and developing surface feature later Sunday.  The upper low smushed right into the SW periphery of the Atlantic ridge is the wild card here, as the Canadian takes the entire entity with the tropical wave and moves it northwest, around the periphery of the Atlantic ridge that expands handily into the Western Atlantic on its north side, thereby steering the upper low and tropical wave into NewEng.  Though this extreme scenario seems a bit unlikely, I would expect at least a piece of the tropical wave to be ejected by the upper low and continue NW, at least becoming available to be tapped by the low over the Mid-Atlantic.  So, while the Canadian is probably overdone in its strength of the system owing to a displacement of the upper low that is unlikely, at this point I think it's necessary to acknowledge the potential for heavy rain on Monday, as even a failed merger or miss from the tropical tap entirely would probably still afford afternoon convection with very heavy rain as moisture becomes entrained into the deep cyclonic circulation overhead.

Of course, the forecasting fun won't stop there, as the next question revolves around when the heat finally makes it back into New England.  Not that I'm eager for it anytime soon, as I've rather enjoyed the lack thereof, but we can't get the global warming hype going unless we can get active tropics and record heat all in the same week, so why not take care of both at the same time?  OK, so perhaps there is a bit of sarcasm in that remark, but seriously, there has been some major heat as any weather enthusiast or even someone who has turned to a news outlet knows over the past several weeks.  This heat has resulted in a remarkable 87 wildfires all raging as of this writing, all but one of which is along or west of the Rocky Mountains, with the 87th burning in Virginia.  This heat is expansive, and it means business.  One has to think it can only be so long before it breaks into New England, but of course, in order to do that we need to break down the Northeast US trough.  It hasn't been that easy to do this year, and the operational GFS, should one have bought it all along, has been leading the way on breaking down the northeast US trough "in just a little while longer."  Seriously, the operational GFS has been singing the tune of expanding warmth in two weeks for much longer than two weeks.  This time, however, it looks to me like the heat is for real.  Not only have we seen consistent signals for the last several days from the GFS and Canadian Ensembles, but rising heights in the Aleutians and falling heights over Greenland will both help to reconfigure the longwave pattern, while the Northern Hemisphere undergoes a change in wave pattern, with fewer, less amplified longwaves in the Westerlies.  These factors should contribute to a ridge/trof/ridge pattern from AK thru the Wrn US to the Central and Eastern US, as the trough in Greenland should be far enuf east to allow expanding heights into NewEng.  The amount of available heat is significant, and if the way I'm expecting this to shake out actually comes to fruition, we'd be talking about an extended stretch of 90s for most NewEng cities from Thu 7/26 to the first or second day of August, with 100+ heat a possibility BOS thru Srn ME.  Will this verify?  The guidance has encouraged forecasters to believe this earlier in the season, but this time there is a better indication of it in the longwave forecast, so I think we have a better chance.  We'll see!

For now, keep an eye on that tropical wave and the Monday scenario!!

Matt

FRIDAY PODCAST: GREAT WEEKEND AHEAD...WATCHING TROPICAL WAVE FOR MONDAY

The Quick Weather Synopsis is now a Podcast!  You can either click on the audio controls above the forecast on the main homepage, or to subscribe to the Monday-Friday podcast (updated on all days I'm working):

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VIGOROUS DISTURBANCE TO BREED VIGOROUS THUNDERSTORMS ACROSS THE NORTHEAST...WEEKEND FORECAST IS LOOKING UP

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

General Weather Summary:

NEW EXCITING FEATURE!  Thanks to the folks at answers.com, you can now double click on just about any word in my discussions to find out what a term means - no more trying to guess what weather terms mean!  If there's a word you don't know, double click on it, and chances are good you'll get a description.  This is a phenomenal learning tool for those who take an interest in weather, or who simply want to gain a more complete understanding of the forecast, and works best using Internet Explorer.  Please note that the page must be loaded completely for this feature to work, and a "refresh" can assist if the feature is sluggish.

An intense upper level disturbance will rotate southeast out of Canada and toward the Northeastern United States Thursday into Friday, delivering numerous showers and thunderstorms as it drags a surface cold front toward our region.  After the front passes through New England on Friday, it will stall just off of our eastern coastline, but far enough to bring drier air into New England for the weekend.

For now, this unusually strong disturbance for this time of the year is visible on satellite imagery, spiraling across the Eastern Great Lakes and riding the jet stream winds aloft - the river of air that steers our storms and acts as a thermostat for the atmosphere.  To the north of the jet stream lay cool and relatively dry air, to the south lay deep warmth, and along the battlezone beneath the jet stream is New England!  The combination of a clash of airmasses and the incoming upper level storm will be the ingredients necessary to produce numerous areas of rain and thunder Thursday afternoon, evening and night, then perhaps again on Friday.  This clash of airmasses is evident at the surface as a frontal boundary - the dividing line between two distinctly differing environments usually marked by a wind shift.  Though Thursday's winds are relatively light regionwide, there is a bit more of a southeast component to the wind north of this front, which is laid out from Northern Vermont to Cape Ann, Massachusetts, as of this writing, but should progress north to the northern New Hampshire Seacoast by day's end.  To the north of this front - including northern New Hampshire and all of Maine - is noticeably cooler air that will hold afternoon temperatures in the 60s and lower 70s, while south of the front more sunshine makes an appearance and assists in shooting temperatures into the 80s.

All the while, both satellite and radar imagery can be used in tracking the approach of a bundle of rain and thunder that has moved east out of Ohio today and will continue tracking across New England.  Though the thunderstorms encompassed by this area of rain produced no severe weather in Upstate New York Thursday morning, the areas in Central and Southern New England that saw sunshine early Thursday have warmed enough to feed some of these thunderstorms, and severe weather will remain a possibility for these areas Thursday afternoon through Thursday night.  The timing of associated showers and thunder will be between 12 and 2 PM in Western New England, 2 PM and 4 PM for Central New England, and 4 PM to 6 PM farther east, though Southeastern Massachusetts and Cape Cod may not get into any showers until around or after dusk, as the eastward progress of the rain will be hindered on its south flank thanks to a cooler flow of air off the ocean on a southerly wind.

Nonetheless, any storms Thursday afternoon through Thursday night - with the most storms likely to occur after dark Thursday night thanks to the approach of our major upper level disturbance - will have the potential to produce very heavy rain, lots of lightning, damaging winds and perhaps some hail.  One tricky part of this round of storms is that the winds are favorable for some low-level rotation, and therefore an isolated tornado, but with limited sunshine it's a tough call as to whether conditions would favor strong enough storms for a tornado to develop.  It should go without saying, though, that this is a day to monitor the radar links at right, and utilize either the link for Active Watches, Warnings and Advisories at left, or the WeatherBug utility which downloads no software to your system but advises you of any alerts for your zip code.  In addition to the threat for severe thunderstorms, if some communities are hit by recurring storms Thursday afternoon through night, a few flash flood warnings may be required.  Aside from the rain and thunder, expect mild and muggy conditions Thursday night with areas of fog.

As the major jet stream disturbance nears New England, the winds around it will grow weaker, as the ribbon of storm steering wind in the atmosphere heads northward, leaving this storm behind in much weaker steering winds.  The result will be for this energy to only very slowly move east across New England on Friday, and the attendant cold front will also be sluggish to push through with its associated ribbon of moisture, showers and thunderstorms.  The result is likely to be a diminishment in showers and storms Friday morning, but a resurgence of storms along the cold front for especially the eastern half of New England firing up around 11 AM, perhaps pushing onto the Cape and eastern Maine while clearing other locales by evening, then offshore Friday night.

The scenario of a slowing upper level storm sets up an interesting dilemma for meteorologists, as this means the surface front we've been dealing with - the focus of moisture, the dividing line between airmasses and the focus of heaviest precipitation - will also stall, and the most important question is where it stalls.  By Friday night, nearly all indications are that the front will be stalling safely offshore, allowing a developing wave of low pressure to ride north along it, producing lots of rain, but doing so just far enough east to remain offshore Friday night and Saturday.  The result, therefore, is for a few possible showers Saturday and Sunday afternoon in the mountainous and hilly terrain thanks to the upper level storm moving directly overhead, but with the primary feed of moisture east of New England, it's likely that most communities will find two enjoyable, pleasant days, with high temperatures near or slightly below normal.

During the early to middle part of next week, the same pesky surface front will be stalled off the coastline as a tropical wave from the Bahamas turns north.  This wave is evident as a line of showers and thunderstorms by the Leeward Islands, and will move northwest over the Bahamas, then curling north as it's ushered northward, parallel to the coast, by southerly wind flow around the back of a high pressure cell east of Bermuda.  Obviously, this will bear watching as the tropical wave and the stalled front are likely to link up for a heavy rain producer, but my question to answer in time will be where this interaction takes place - over the ocean, or over New England.  If the two link up under favorable conditions, a tropical storm may even develop over the Western Atlantic waters, so this is clearly something that I'll be watching like a hawk the next few days.  As for deeper summer heat, there's plenty of that to go around in the Western and Central United States, and once we kick out our stubborn energetic disturbance aloft, and push the surface front farther east by the middle to end of next week, heat should come on strong to the northeast, perhaps bringing a heat wave by week's end, and an extended stretch of hot weather may persist into the start of August.

Have a great Thursday.

Matt

Matt's Technical Meteorological Discussion: Updated Thursday, July 19 at 1:55 PM

It's been awhile since the last techie discussion, and they come much fewer and farther between than the "old days."  This is largely because of time constraints on my end with lots of live coverage during this active severe weather season for New England, and thanks to lots going on behind the scenes.  Nice to be back in the saddle, however, and I appreciate those of you who still look for this discussion as a way to get inside my meteorological mind, as twisted as it may be!  I'm excited about the new feature, too, from answers.com, where you can double click on any word in the discussions and a definition should pop up.  Many of you in the past have let me know you find the technical discussions, in particular, to be great learning tools, and this should tremendously enhance the learning potential.  Sometimes you may have to reload the page to get it to work (if it doesn't work on the first try) and I've found it works better with Internet Explorer than Mozilla (I use both, so I try it with both), and I've yet to see if it knows some of the fancy words, but this technical discussion will be a good way to find out...so let's dig in!

This is certainly an exciting 24-36 hours we're heading into!  An anomalously strong upper level low has been digging southeast across Southern Canada and the Great Lakes, heading toward the Northeastern United States.  If we dig this entire system in without any severe weather in New England, I'll be shocked, as the amount of vorticity alone is awfully menacing, as is the influx of cold air aloft creating instability aloft.  Surface based instability, however, is lacking with CAPE (convective available potential energy) values limited thanks to limited insolation.  This is, of course, especially true across the northeast half of New England, where we're on the cold side of a very sluggish warm front that will have no hope of crossing the region this afternoon.  Northeast of this front, temps hover in the 60s thanks to stubborn clouds beneath the inversion, while south of it we've both been able to break out into some sun and are in the warm sector.  It is, however, a dirty warm sector, defined by clouds of varying levels and thicknesses that have been limited the diurnal heating effects and thereby limiting our instability parameters.  The wind profiles, however, look fantastic for rotating supercells, so really it is instability in the lower levels that is our limiting factor.  But there are a few factors that will have influence later today and tonight, keeping my concern for severe weather in Central and Southern New England.  The first is that while sun may be limited, it is present, and that's helping to nudge surface based instability up, and the second is that there will be stronger destabilization aloft as the upper low center draws closer and numerous shortwaves continue to traverse in the fast jet stream flow aloft.  The result should be several lines of convective development between the Eastern Great Lakes and the Eastern New England Seaboard Thursday afternoon through Thursday night.  Given a continued south and then southwest flow tonight, I don't think the normal rule of weakening convection after dark applies in this instance, and the severe weather threat may last through the entire first half of the night.  Given high precipitable water values, heavy rainers should be found with all storms.  Cold enough aloft for good lightning production - at least after this first round of afternoon stratiform/convective mix over New England - and my buddy Josh Darr reports an amazing lightning show in Chicago last night - that's the stuff that should head our way tonight.  As for damage potential, again, I see increasing instability as providing the need to keep us on our toes for strong wind, and certainly the south-southeast boundary layer windflow increases helicity values throughout New England into the night.  In fact, given the strength of the vorticity maximum and its associated circulation, I would be surprised if we don't see at least a tornado or two between Central New York and Western New England by the time this event is over.  It does, however, appear as though activity will taper in intensity after midnight.

And speaking of over, when is the event over?  Not by Friday morning, even though convection should be just a weak shadow if its former self - if for no other reason than the slow progression of the surface front.  With areas of fog present in valleys but an atmosphere eager to mix or in the case of Southern New England, already mixed by morning, clouds will burn for some sunshine Fri AM.  With mild air in place and some of the best insolation we've seen in the past few days, temps will rise and surface based instability will probably exceed Thu values as temperatures may exceed Thu values, too!  The convergence and airmass upheaval associated with the cold front is likely to generate new convection along the front Fri midday through middle afternoon before shifting east, perhaps lingering into the eve on Cape Cod and eastern ME.

Of course, from that point on the question thru the week has been how far east the front goes before stalling.  It certainly seems like a given that the front will stall considering the upper level low will stall over us for the weekend, and without any deep atmospheric push, the front will have nowhere to go.  In recent cycles of the guidance, however, it has become apparent that this front should, indeed, push just far enough east to put New England on the dry and pleasant side of a sharp dividing line, ensuring a good weekend.  I really couldn't believe Sat and Sun being entirely dry, however, thanks to the upper level cool pool, and am glad to see the 12Z runs returning some convective precip in the afternoons, which makes sense given the cold air aloft and instability cumulus that will billow in response.  Still, it appears as though the weekend will be remembered quite favorably by many.  As for temps, have gone above MOS guidance Fri thru Sun with good mixing of dry airmass encouraging adiabatic warming of air parcels.

Perhaps the greatest interest of the entire period comes early next week.  Today's 12Z run is now the fourth in a row that the GGEM is printing out a major coastal low on Monday that will incorporate not only energy from our stalled upper low, but also additional shortwave energy rotating around the base of the Eastern US jet stream trough, spawning a low pressure center development off the North Carolina Outer Banks.  There has been one change, though, that the Canadian is no longer putting out a direct strike from the southeast by Tropical Storm or Hurricane Chantal, which it's forecasting to develop from the tropical wave currently moving out of the Leeward Islands and heading NW toward the Bahamas.  The concern here isn't so much just that the Canadian has been showing this potential - afterall, just last week it projected a hurricane into Miami - but moreover that it has support from both additional guidance and from reality not necessarily of a TS/Hurricane strike but at least of a merger of tropical wave and shortwave energy.  On the guidance side, NOGAPS, UKMET and now to some extent the NMM are jumping on board with carrying the wave northwest then north.  The GFS keeps the tropical wave farther east, but it's also trying to move it into the western periphery of the subtropical ridge, perhaps too close to the ridge center as the wave merges with the present upper low evident on water vapor.  The GFS and Canadian Ensemble members, as you may expect, are split, while the ECMWF is alone in holding nearly everything at bay along the Southern Mid-Atlantic coastline.  I mentioned that reality supports a solution that at least lends some credence and concern over an interactive if not merging scenario of the tropical and extratropical vorticity centers, and the reason for this is that Central Atlantic ridge that is not going to be eager to break down, while deep southerly flow runs parallel to the East Coast, and would favor bringing the wave close to the upper low and developing surface feature later Sunday.  The upper low smushed right into the SW periphery of the Atlantic ridge is the wild card here, as the Canadian takes the entire entity with the tropical wave and moves it northwest, around the periphery of the Atlantic ridge that expands handily into the Western Atlantic on its north side, thereby steering the upper low and tropical wave into NewEng.  Though this extreme scenario seems a bit unlikely, I would expect at least a piece of the tropical wave to be ejected by the upper low and continue NW, at least becoming available to be tapped by the low over the Mid-Atlantic.  So, while the Canadian is probably overdone in its strength of the system owing to a displacement of the upper low that is unlikely, at this point I think it's necessary to acknowledge the potential for heavy rain on Monday, as even a failed merger or miss from the tropical tap entirely would probably still afford afternoon convection with very heavy rain as moisture becomes entrained into the deep cyclonic circulation overhead.

Of course, the forecasting fun won't stop there, as the next question revolves around when the heat finally makes it back into New England.  Not that I'm eager for it anytime soon, as I've rather enjoyed the lack thereof, but we can't get the global warming hype going unless we can get active tropics and record heat all in the same week, so why not take care of both at the same time?  OK, so perhaps there is a bit of sarcasm in that remark, but seriously, there has been some major heat as any weather enthusiast or even someone who has turned to a news outlet knows over the past several weeks.  This heat has resulted in a remarkable 87 wildfires all raging as of this writing, all but one of which is along or west of the Rocky Mountains, with the 87th burning in Virginia.  This heat is expansive, and it means business.  One has to think it can only be so long before it breaks into New England, but of course, in order to do that we need to break down the Northeast US trough.  It hasn't been that easy to do this year, and the operational GFS, should one have bought it all along, has been leading the way on breaking down the northeast US trough "in just a little while longer."  Seriously, the operational GFS has been singing the tune of expanding warmth in two weeks for much longer than two weeks.  This time, however, it looks to me like the heat is for real.  Not only have we seen consistent signals for the last several days from the GFS and Canadian Ensembles, but rising heights in the Aleutians and falling heights over Greenland will both help to reconfigure the longwave pattern, while the Northern Hemisphere undergoes a change in wave pattern, with fewer, less amplified longwaves in the Westerlies.  These factors should contribute to a ridge/trof/ridge pattern from AK thru the Wrn US to the Central and Eastern US, as the trough in Greenland should be far enuf east to allow expanding heights into NewEng.  The amount of available heat is significant, and if the way I'm expecting this to shake out actually comes to fruition, we'd be talking about an extended stretch of 90s for most NewEng cities from Thu 7/26 to the first or second day of August, with 100+ heat a possibility BOS thru Srn ME.  Will this verify?  The guidance has encouraged forecasters to believe this earlier in the season, but this time there is a better indication of it in the longwave forecast, so I think we have a better chance.  We'll see!

For now, keep an eye on that tropical wave and the Monday scenario!!

Matt

THURSDAY PODCAST: VIGOROUS DISTURBANCE TO BREED VIGOROUS THUNDERSTORMS ACROSS THE NORTHEAST...WEEKEND FORECAST IS LOOKING UP

The Quick Weather Synopsis is now a Podcast!  You can either click on the audio controls above the forecast on the main homepage, or to subscribe to the Monday-Friday podcast (updated on all days I'm working):

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Or, you can open ITunes.  Under "Advanced," select "Subscribe to Podcast." For the URL, copy and paste this: http://www.mattnoyes.net/matt_noyes_weather_blog/rss.xml

You can also use the "Subscribe to Podcast" link in the upper left corner of the main page.

The daily file you will receive is Daily_Weather_Synopsis.mp3

AND SO IT BEGINS...A WEATHER PATTERN THAT WILL BRING PERIODIC RAIN AND THUNDER INTO THE START OF THE WEEKEND

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis linked to the daily forecast at the top of the page, a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow by mid-afternoon. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

General Weather Summary:

NEW EXCITING FEATURE!  Thanks to the folks at answers.com, you can now double click on just about any word in my discussions to find out what a term means - no more trying to guess what weather terms mean!  If there's a word you don't know, double click on it, and chances are good you'll get a description.  This is a phenomenal learning tool for those who take an interest in weather, or who simply want to gain a more complete understanding of the forecast, and works best using Internet Explorer.  Please note that the page must be loaded completely for this feature to work, and a "refresh" can assist if the feature is sluggish.

The advertised weather pattern has arrived, meaning periods of rain and thunder will be quite pesky through the remainder of the week.  That said, challenges will remain with regard to timing and intensity of each disturbance and associated areas of rain, and there will also be times of limited precipitation, when New Englanders will be able to be out and about.

One surge of showers and rain moved from southwest to northeast across New England Wednesday morning, serving as evidence of the first major thrust of warmth and moisture through the atmosphere, and the collision with our previous cooler, drier air that has been in place.  This clash of airmasses aloft is serving to crank out showers, thunderstorms and areas of rain, while at the surface the leading edge of deep summer warmth is defined by a warm front that has been slowly pressing northward toward the South Coast of New England.  Ahead of this front, winds are light and somewhat variable, though predominantly out of the southeast, which introduces a marine component to the air and limits how warm temperatures can rise Wednesday afternoon.  Of course, the biggest limiting factor is the lack of sunshine and areas of rain.  In the most significant surge of rain, numerous thunderstorms erupted in New Jersey early Wednesday morning, moving east to bring flooding to New York City, then producing damaging winds across Long Island, where a tornado warning was issued for a storm showing possible rotation mid-morning Wednesday.  As the thrust of warm and humid air aloft made its way farther north into New England, the severe weather threat largely subsided due to cool air near the surface, but rain continued falling heavily and occasional lightning has still been observed.  Though I expect that area of solid and at times very heavy rain to move over Southeastern New England - especially Rhode Island and Southeastern Massachusetts - Wednesday afternoon, prompting urban street flooding and a hydroplaning threat in these areas, showers will also continue across most of the remainder of New England.  The difference between these areas, though, is that the strong downpours in southeastern areas will dump an inch of rain in a relatively brief period of time, while the remainder of New England will find off-and-on rain that will produce lighter rainfall amounts.  As warmth continues to press northward along the South Coast, renewed scattered strong thunderstorms are at least a slight possibility in Central and Southern New England Wednesday evening, with scattered showers and thunder still in the forecast for the overnight, though the overall coverage and intensity will both wane significantly.

Thursday may dawn with at least some scattered showers and thunderstorms, as a weak upper level disturbance moves over New England coincident with a continued feed of warm air on a southerly wind deep through the atmosphere, but the bigger effect is likely to come from fog, which may be quite thick through much of New England.  This fog would lift into a layer of low altitude clouds in many areas before breaking up and burning off, giving way to at least some sunshine through plenty of bubbling, heavy cumulus clouds in a steamy environment.  Any sun we see would boost temperatures into the middle 80s, not only making the day somewhat uncomfortably humid, but also providing increasing fuel for new thunderstorms.

All the while, an unusually strong disturbance for this time of the year will be spiraling southeast out of Canada and across the Eastern Great Lakes.  This disturbance will be riding the jet stream winds aloft - the river of air that steers our storms and acts as a thermostat for the atmosphere.  To the north of the jet stream lay cool air, to the south lay deep warmth, along the corridor of wind is our parade of disturbances and below the jet stream is New England!  This combination of a clash of airmasses and available energetic disturbances will be what's needed to generate recurring rounds of rain and thunder, and the next anticipated round on Thursday will come with the approach of this strong upper level storm Thursday afternoon.  Likely to last into the evening as they're driven by the ample energy aloft, storms that develop will grow severe, producing damage in New England Thursday afternoon and likely lasting through Thursday night as the heart of the unusually strong disturbance draws ever-closer.

As the jet stream disturbance nears New England, however, the winds around it will grow weaker, as the ribbon of storm steering wind in the atmosphere heads northward, leaving this storm behind in much weaker steering winds.  The result will be for this energy to only very slowly move east across New England, and therefore its associated ribbon of moisture, showers and thunderstorms will also be slow to pass, keeping periods of rain in the forecast on Friday - especially through middle afternoon.  Thereafter, the upper level storm will grind to a halt over New York and Western New England. as the jet stream fits to a pattern that leaves the Western United States baking with intense heat, while the Eastern United States turns remains unsettled.  This pattern will persist into the weekend, as a large storm in the Eastern Pacific Ocean pulls down enough cool air to carve a dip in the jet stream - referred to as a "trough" - just off the West Coast. When a trough develops, cool air is able to penetrate southward in the dipping jet stream, meaning a slug of cool air will meander southward just off the Western United States coastline. The opposite reaction in this case will be for the jet stream to bubble northward over the Western United States and Rocky Mountains, extending north into Western Canada as a "ridge," beneath which hot and dry air will expand across the Western half to two-thirds of North America.  Such a sharp bubble in heat, though, will displace cool Canadian air, sending it spilling southward through Eastern Canada and into the Northeastern United States, accompanied by energetic disturbances all the while.  The largest and strongest of these disturbances is the one that will draw near at week's end, eventually slowing overhead.

The scenario of a slowing upper level storm sets up an interesting dilemma for meteorologists, as this means the surface front we've been dealing with - the focus of moisture, the dividing line between airmasses and the focus of heaviest precipitation - will also stall, and the most important question is where it stalls.  As the front moves slowly from west to east across New England on Friday, numerous showers and thunderstorms will move east with it.  By Friday evening, nearly all indications are that the front will be stalling safely offshore, allowing Friday evening activities the flexibility to go off without a  hitch.  I'm not willing to bet the farm on this solution just yet, however, as the strength of the jet stream disturbance moving overhead should be sufficient to generate scattered showers later Friday and Friday evening, and it's not impossible the upper level energy will exert enough influence to stall the front sooner and farther west than currently anticipated, which would keep lots of moisture around Friday night.  So while the trend looks promising, the jury is still out.  Friday night into early Saturday a wave of low pressure will ride north along this front, producing lots of rain, but until the position of the front can be settled, it remains to be seen whether this small storm center would be of concern to us.  Nonetheless, Saturday should bring at least scattered showers and a chance of thunder in even the brightest scenario, owing to the cold air above our heads associated with the upper level storm, and the temperature differences that cold air will establish contrasted to the warmth at ground level.

During the early to middle part of next week, the same pesky surface front will be stalled off the coastline as a tropical wave from the Bahamas turns north.  Obviously, this will bear watching as the two are likely to link up for a heavy rain producer, but my question to answer in time will be where this interaction takes place.  As for deeper summer heat, there's plenty of that to go around in the Western and Central United States, and once we kick out our stubborn energetic disturbance aloft, and push the surface front farther east by the middle of next week, heat should come on strong to the northeast, perhaps bringing a heat wave by week's end, and an extended stretch of hot weather may persist into the start of August.

Enjoy your Wednesday.
Matt

WEDNESDAY PODCAST: AND SO IT BEGINS...A WEATHER PATTERN THAT WILL BRING PERIODIC RAIN AND THUNDER INTO THE START OF THE WEEKEND

The Quick Weather Synopsis is now a Podcast!  You can either click on the audio controls above the forecast on the main homepage, or to subscribe to the Monday-Friday podcast (updated on all days I'm working):

Easiest way is to subscribe by clicking here!

Or, you can open ITunes.  Under "Advanced," select "Subscribe to Podcast." For the URL, copy and paste this: http://www.mattnoyes.net/matt_noyes_weather_blog/rss.xml

You can also use the "Subscribe to Podcast" link in the upper left corner of the main page.

The daily file you will receive is Daily_Weather_Synopsis.mp3