MATTNOYES.NET - NEW ENGLAND WEATHER ANALYSIS

The Ride Home - Tuesday, June 23, 2009 - Episode #22

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It's been wet!  The dog is loving it, most humans are hating it.  The pattern should break after our huge, slow, upper-level low departs, bringing a more progressive, brighter, milder, though still active pattern for the next few weeks.

Sunday evening prospectus, June 21, 2009

A relatively quick prospectus tonight to outline what's developing this week.

The longwave pattern features our stalled upper level low south of New England that will weaken gradually, producing showers of a more scattered nature as it fills, then finally being swept northeast as rising heights move across the Northeast.  This allows for a long-range pattern that will feature much higher average 500 mb heights across the Northeastern United States, indicating the average temperature will be noteably higher for the start of July, though it's interesting to note that the mean trough position remains over Eastern Canada, the Eastern Great Lakes and New England, varying in longitude from time to time, but producing a pattern that should bring thunderstorms every few days, and the potential for shots of cooler Canadian air behind each cold front, though not as cool as the recent spade of chilly weather, with average high temperatures near or slightly above normal over the period from late this week through the first week of July, with above normal temperatures likely during the first half of that timeframe.

In the shorter range, the most immediate effect on our weather is clearly the storm center stalled to our south.  Surface and low-level convergence bands have been focusing ocean moisture to produce bands of steady rain that have been migratory in the northeast flow across Eastern New England.  Even mesoscale models have great difficulty nailing the location of these convergent bands and that's likely to continue to be the case in the coming days, but the general agreement among guidance is to carry steady and at times heavy rain that's been offshore of the Cape onto Cape Cod late Sunday night into Monday morning, with another batch of steady and heavy rain possibly rotating onshore to the Midcoast of Maine late Monday/Monday evening.  Northeast winds will continue gusting to 40 and perhaps 45 mph on Monday based upon mixing to 925 mb, though worth noting the NMM wind gust algorithm indicates perhaps 40-42 knot gusts on Cape Cod late Monday.

Of course, this continuing northeast wind will force water up against the coastline, and as mentioned in NWS products, coastal flooding on northeast facing shorelines will continue to be a possibility through Tuesday high tide cycles with new moon on Tuesday and though the tide is not astronomically all that high midday Monday, the midnight Monday night high tide is quite high and should pose problems for many communities.

Each day on Tuesday and Wednesday, bands of rainfall will become less impressive, more breaks of sun will emerge in Northern and Western New England, but moisture will hold tough for lots of clouds on Tuesday, then on Wednesday any breaks are likely to fill back in as diurnal heating fills low level stratocu back in again.  Thursday brings a westerly wind or even a northwesterly wind and this dries us out effectively with downsloping, and warm advection keeps coming from the west, very quickly moderating the atmosphere.  Upstream highs in this airmass have been in the 80s, and we should make that jump for the end of the week.  Of course, as mentioned in the longwave pattern synopsis, shortwaves will continue traversing New England in the upper level flow, and this will breed periodic scattered thunderstorms that will be largely diurnally driven.

That's all for tonight - see you on TV in a few hours!
Matt

Sunday evening prospectus, June 14, 2009

Convective feedback will continue to be an issue this week, but to a lesser extent than the past two weeks.  This previous weekend's forecast was a tremendous challenge, but - as described in Friday morning's post (below) - *was* discernible with a great deal of effort to see through the convective issues that were affecting timing and intensity.  Did you expect this weekend's weather to be the way it was?  If you read Friday's post or saw the forecast on my Quick Forecast Page, chance are good you were prepared.  If not, you may have encountered some surprises.  Check out Friday's post to find out why weather has been tricky to predict in the Northeast the past couple of weeks.

Otherwise, the next few days will feature a gradual improvement to our weather, though the same upper level low that produced rain for much of New England the first half of Sunday will only slowly move east, meaning a cyclonic flow lingers over the region.  This cyclonic flow will spiral vorticity maximums overhead, and this will be evidenced by numerous showers and thunderstorms developing on Monday, especially as diurnal heating maximizes low level instability.  With a light easterly wind, there will be a stabilization near the seashore that will minimize convective initiation processes there, while the upper level cold pool that lingers west of the upper low, over Western and Northern New England, will help to focus heavier convection, especially where orographic lift assists.  There are two items for consideration here: 1) whether/where an easterly wind will hold a low-level marine deck in place, and 2) whether flash flooding will be a concern.  To the first point, it does look like we start with a decent coverage of low altitude gray clouds Monday AM, then find a gradual breaking up...only to fill back in with the aforementioned diurnal instability.  Fog will be found in many spots that rained Sunday, owing to ample boundary layer moisture, and especially thick in the eastern quarter of New England where the light onshore flow further saturates the atmosphere.  As to the flash flooding issue, there are signals of two to two and a half inches of rain in heavier convection from the MM5 and WRF, though the placement varies from Southwest NH to Western MA in the respective models.  I think nailing down the exact location is very difficult but the location of the cold pool and a lingering surface convergence zone at the periphery of the well-developed east wind suggests southwest or Central NH may be the zone to watch.  Flash flood guidance values are about 2.5"-3.0", so I think this is at least worth watching as isolated flash flooding is possible with weak winds aloft meaning slow moving cells.

Tuesday and Wednesday will feature a strengthening anticyclone over the coast of Maine and expanding across Eastern New England, and this will actually mean a dry air advection from the east - so one day after worrying about a marine layer, we'll probably see morning clouds linger longest in the CT River Valley on Tuesday morning and dry air presses west from the surface high center, meaning the best chance of a shower would be in Western New England, and by Wednesday, most spots should be dry and sunny.

The end of the week turns unsettled again as the longwave pattern features yet another upper level low digging across the Great Lakes and into the Northeast.  Before that happens bulk of rainfall extends from Ohio Valley to Southern Mid-Atlantic as they are squished between our anticyclone and warm, summer air across the south...with a low slowly cranking up off coast of North Carolina.  This low bears close watching, as it will be sitting over warm Gulf Stream waters and in very weak steering flow, and we very well may see close-in development of a low that may start cold core but turn warm core as it fires convection over the warm waters.  Though this system is forecasted to stay well south of New England and drift off the coast, it's something that I'll be paying attention to in the back of my mind, not only because it's an interesting hybrid feature that's fun to watch for wind/waves/rain down south, but also because a digging shortwave Thu/Fri into the Northeast means it's not entirely impossible that part or all of this energy/moisture is drawn northward.  Either way, slug of warm and moist advection Thu brings clouds and rain back.  We will be north of surface warm front, which means back to cool air.  High Thu is a bit of a crapshoot because it depends on timing of precip commencement, but based on current estimation of midday arrival, this may allow lower 60s before dropping with rain moving in.  By Friday, warm front struggles to displace cool and dense air, meaning 50s and 60s seem likely with coolest temperatures east.  The upcoming weekend will hinge heavily upon front placement, which depends on timing/intensity of low pressure winding from Eastern Lakes to New England, but right now I'm thinking convectively active Saturday, especially during the afternoon Central and South (though perhaps cooler and more showery north, where the warm front may not succeed in passing thru), then perhaps a more pronounced warm sector on Sunday with afternoon convection possible again.

That's it for now...here's to another week of fun! :)

Matt

Friday heavy rain verifies...thunder, for most, does not; difficult forecasts could be the rule for New England in this pattern

After billing the round of downpours that would move through New England as a "heavy rain and energetic thunderstorm" event, I was heartily disappointed in my forecast - or perhaps I was disappointed in nature's failure to live up to my forecast - with a verification of heavy rain but a notable absence of thunder.

The rain certainly was quite impressive, with storm total amounts of one to two inches across Northern and Central New England, and convective downpours producing even higher amounts of 1.5" to 2.25" in Southern New England.  This rain was timed rather inconveniently for the morning drive, and resulted in traffic accidents across New England and airport delays across the Northeast.  So, from the public impact perspective, the forecast verified well, and the broadcaster in me knows that the public was adequately prepared for a rainy morning and will view the forecast as successful.  The meteorologist in me (and for many of you who read this site) focuses on the science, though, and I'm unimpressed with the convection from this morning with regard to its lighting productivity.  Any good scientist must go back and review what went wrong in the experiment (in this case, the forecast!) in hopes of improving upon it the next time.

In this case, I remarked in my forecast discussion here yesterday that vertical motion forecasts indicated air would be lifting to about 300 mb, where the temperature was a frigid -36 degrees Celsius.  This was plenty cold enough for effective and frequent lightning production, for which I usually key in on the -20 Celsius isotherm.  The first problem was that forecasts for vertical motion in the guidance products appear to have been overdone.  Here's a time-height cross section, with time advancing from left to right, from the NMM guidance product's Thursday 12Z cycle, courtesy of coolwx.com's graphical interface.  Notice the lift extending to 300 mb.  When cross-referenced with the same time-height cross section of temperature, the extension of the lifting motion into the cold air is quite apparent.   Though I haven't included it here, I did check the relative humidity forecasts, too, to ensure we had cloud production throughout the entire layer of lift.

Contrast that forecast with the next set of time-height cross sections: the NMM Friday 06Z cycle, run just prior to the arrival of the heaviest rain, and there's been a substantial decrease in how deeply the lift extends into the sky - by about 100 mb, now lifting to about the 400 mb level.  When cross-referenced with temperatures at this level, they're much warmer than 300 mb and just barely reach - or perhaps fall just short of - the threshold of -20 C.

So, why the difference in the forecast?  Though I'm tempted to pin it on the lack of surface based instability, I think that's inaccurate.  I knew yesterday that I was discounting surface-based convective parameters in my forecast, and I always worry that perhaps confidence has built too strong, leading to a weak arrogance, and I wrongly overlooked a parameter that was either lacking or present.  I don't think that's the case here, though, because the key was the mid-level dynamic lift and assistance from the tremendous isentropic lift we examined near the 850 mb level.  The latter definitely verified, and verified well, hence, the tremendous rain and rainfall rates.  The former - the dynamic lift - evolved a bit differently than predicted, as the vorticity broke into several pieces, thereby speeding up arrival of the first rain band on Thursday night and also meaning the primary shortwave to traverse New England on Friday morning was weaker.  This led to less mid-level upward vertical motion, meaning the cloud top fell shy of the all-important threshold.  As for what caused this erroneous forecast of vorticity, it appears largely an issue with convective parameterization in the guidance products.  Changes are always being made to the equations run in the guidance, and recent changes have rendered the NMM and GFS (especially the GFS) vulnerable to significant convective feedback.  Essentially, this is when the model spins up thunderstorms, then allows those thunderstorms to continue redeveloping, even if the atmosphere wouldn't necessarily favor it.  Thunderstorm clusters release latent heat of condensation, and in the model they almost become their own heat engines, much like hurricanes do in real life.  This causes the model to keep cranking out more and more thunderstorms, stronger and stronger, far longer into the forecast period than it should.  This has been a bigger problem here in the Northeast this spring than in the past *several* years, and is something we're struggling with behind the scenes literally everyday.  In fact, I turned to one of our interns yesterday and said, "How are we even getting forecasts right?!  We should be failing every time!"  Of course, we're not failing every time, but that's hugely because we're keeping our eye on the bigger picture and trying to decipher details from the overall weather pattern, rather than specific model details.

This weekend will be an excellent test-run.  The large-scale pattern shows a pattern favorable for shortwaves to traverse New England with a trough axis just to our west.  This would support periodic scattered showers and thunderstorms ahead of the passage of each shortwave.  The problem if you look too closely at the details is that there are actually DOZENS of small vorticity maximums crossing the region, which is why the NMM, for example, keeps virtually constant precipitation going through the interior all weekend long.  The best model of late has been the convective-friendly WRF, and that indicates a good part of New England will be rain-free for quite awhile on Saturday, with scattered afternoon storms that will be most numerous in Northern New England, and across Connecticut.  This matches well with the lower-resolution ECMWF, which - thanks to its lower resolution - is not falling prey to the same amount of convective feedback.  The result *should* be a Saturday that allows for sun to burn through morning clouds and fog for most spots, bringing temperatures into the 70s before any of the scattered afternoon convection fires.  Of course, there's always the possibility of isolated or widely scattered activity sooner near any convergence boundaries, but for most of New England, I still think Saturday looks like a good day with a decent amount of sun after a gray start for some, especially where there's a renewed storm Friday evening that will leave fresh low-level moisture.  The axis of the vorticity maximum doesn't swing thru until Sunday 18Z, so this means Sunday will be a bit more convoluded with the potential for showers and thunder to linger in the cyclonic vorticity advection ahead of the shortwave, and especially near convergence boundaries, Saturday night.  Convection probably wouldn't wait long to refire on Sunday - perhaps as soon as mid-morning - and would grow more numerous with diurnal heating until the vort axis moves east Sunday afternoon and anticyclonic vorticity advection moves in.  Another shortwave follows for Monday.

This is the type of thought-process that must be conducted each day, then repeated each time the forecast is updated.  A focus on more precise details from the models will lead to certain disaster in the forecast, because of the recent degradation of the guidance to adequately handle convection/thunderstorms.

Rare morning thunderstorm event on Friday...torrential rain, frequent lightning likely...localized damage less likely but possible

General Weather Summary has been posted on WeatherNewEngland.com and can be linked to by following the General Weather Summary link at the top of this page.

Moisture loaded area of low-pressure moving northeast across the Midwest as of this writing is a 1005 mb low over Southern Illinois.  After producing numerous severe thunderstorm and tornado reports ahead of the low last evening, heaviest precipitation for the time being has shifted to the north side of the circulation, on the cool side of a mostly stationary front that runs through Ohio and eventually off the Mid-Atlantic coast.  I say "mostly stationary" because in the increasing pressure gradient squeeze between a bubble high over the Mid-coast of Maine, and the wave of low pressure over the Midwest (mostly driven by the high), a southerly wind has forced warmth and mositure northward into Pennsylvania and New York, including Syracuse, resulting in a tongue of high theta-e air.  The leading edge to the warm and moist advection has prompted thunderstorm development in Upstate New York as the dynamic lift ahead of the developing shortwave moves east and combines with 1000-2000 J/kg of CAPE.  In NewEng, after yesterday's few breaks of sun I expected the same if not a few more regionwide today, and while that's the case in Northern/Western areas, I think an objective analysis would find breaks equally sparse if not more so in Southern New England.  This has been the product of low-level warm advection already underway, further solidifying the cap and also providing isentropic lift in the lowest 10K feet, as evidenced by the eruption of a cluster of morning thunderstorms south of Montauk.  This warm advection will only strengthen with the approach of the low and the strengthening of the gradient, and this will prompt thick fog development along the South Coast tonight, especially just prior to midnight, and that fog will migrate north with the leading edge of deep warmth that will set up in Southern New England.  Eventually, after midnight, temperatures will rise in Southern New England so that areas near and south of the MA Pike start in the 60s Fri AM, with thick fog into Central New England on the leading edge of the warmth and humidity.

There are so many dynamic factors converging for this event, but the most intriguing are in the lowest 10K feet.  First, though, let's start higher with...dynamics!  Dynamic lift will increase through the night with the passage of the shortwave.  It's actually partly owing to the strong vorticity *minimum* that crossed New England today that we see such strong cyclonic vorticity advection in Western New England Thu Eve that will touch off showers and thunder in scattered form out of NY State and into far Western NewEng.  The broad expansion of CVA/PVA will mean a broad expansion of lift, and this will promote deep cloud growth.  The driving force here, though, is in the lower levels.  At the surface, a frontal boundary extending into Upstae NY is the main focus on the weather map, but a careful hand-analysis today indicates both lower pressure and surface convergence in Northern VT to Central ME.  This boundary will focus heavy precipitation tonight, and is the realistic basis for the 2"+ QPF numbers coming out of the NMM for Northern New England.  This is below flash flood guidance but is likely to spark street and small stream flooding overnight.  Locally higher amounts are possible.  What is most impressive, however, is the tremendous convergence in the lower levels, evident beautifully at 850 mb.  I'm including an image from the College of DuPage models page, which clearly shows the 850 mb low level jet punching across New England at 12Z Friday with 45-50 kt SW wind encountering a 5 kt NE wind!!!  This is going to produce amazing lift.  Add to this the tremendously tight theta-e gradient and resultant isentropic lift, and we're looking at a potent low-level setup for a system with a history of producing energetic thunderstorms.  As the low level center crosses Central/Northern NewEng, the trough axis swings southeast across Southern New England Friday morning, and when it encouters the deep warmth and humidity in place, quite a show will let loose.  Torrential rains will drop at least one to two inches of rain Friday AM, though some spots may see locally more, and this will come in a short time during the Fri AM commute.  Additionally, the combo of low and mid level features will force lift so deep in the atmosphere - up o 300 mb - that cloud top temperatures may cool as low as -36 to -40 C.  This is plenty cold enough (and then some!) for frequent lightning production from ice nuclei aloft.  I think the real question will be how much of a damaging wind threat is there, and my guess is that the strongest cells will get damaging gusts to the ground, though it's going to be a touch and go situation based on radar analysis Fri AM.  I'm on the fence here because dynamics are awesome and lift is incredible, but the column is saturated (not much dry air to work with, unless the negative theta-e advection settling in behind the trough axis sparks a squall line on the back side) which limits downdraft potential, and there will still be a shallow inversion in place, even though temps will have risen so much.  The inversion is just that, though - shallow...and weak.  A strong enough cell will bust through it and bring damaging wind to the ground, so that potential needs to be acknowledged.  Finally, one has to at least consider in the back of his or her mind that, in a situation like this, there is going to be a strongly veering wind with height, and this favors embedded rotation.  Especially if we develop the expected tropical tap, that becomes more of an issue to consider.  At this point, I certainly wasn't anywhere near willing to mention it in the public package of forecast products, but I will be carefully watching the Hartford to Providence stretch north to the MA Pike (just far enough inland to be away from the stronger ocean stability, but far enough south to be unstable).  This is not a surface based CAPE of LI situation, but rather an elevated event for many areas, but if the cap breaks and it becomes surface based, that's when things like this become important.

Rain is out by late Friday.  The weekend looks like more showers/thunder thanks to multiple shortwaves.  Sunday is still very uncertain in my opinion, but am playing first half of day optimistic with advancing storms blossoming afternoon.  Will see.

Matt

The Ride Home - June 8, 2009 - Episode #21

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Following on the heels of last night's Sunday Evening Prospectus, today's Ride Home touches up some of the details that have changed or become more clear in the last 18 hours.

For those interested, the initial plan I laid out of going to the gym turned into a fast stop at Wendy's, and now several hours more of work to go, but work from home.  Alas, another brilliant idea dimmed by harsh reality!  :)

Sunday evening prospectus, June 7, 2009

It's been awhile since I've composed one of these, eh?  As mentioned in some previous Ride Home posts, it's been a busy stretch, but I continue to work to get as much back on track as possible.  With Danielle Niles, my sidekick and nearly-twin (though she isn't nearly as old as this aging meteorologist), taking this week off, yours truly will be flying solo and it's important to get well spun-up this eve.  Creating some graphics for tomorrow's shows from home, but first and foremost is getting a solid handle on the weather pattern.

An initial look at the national weather shows severe weather erupting through the nation's midsection, indicative of plentiful upper level energy crossing the country.  Convective cells embedded in Pacific Northwest rain have prompted a tornado warning in southeastern Washington State, while deep thunderstorms flare off the Florida coast.  Meanwhile, closer to home, two lines of downpours with convective elements race across the Northeastern United States - one across Northern New England, and the other racing east across the Southern Tier of New York.  Satellite imagery fills in a few more gaps - a cloud mass traversing the Ohio Valley appears to have eyes on New England, and though the deep northern energy spawning Western and Central United States severe weather looks ready to move northeast into Canada, the active southern stream carries shortwaves that will interact with a front draped from the Ohio Valley to the Northeast.  Nailing the location of this front, and timing of shortwaves interacting with it, will be key to the forecast each day this week.

The longwave pattern for the upcoming week should feature a weakening of the pronounced trough over the Western United States, while an upper low and associated trough linger east of New England, over Newfoundland.  Though the western trough may weaken in the days to come, the mean trough position remains there and east of New England, leaving weak ridging over the Eastern Great Lakes.  New England, meanwhile, remains on the cusp of the confluent flow bridging weak ridging to our west, and the upper low to our east.  This will allow for a wavering frontal boundary with repetitive shortwaves - affirming what the current analysis described above hints at.

In fact, 500 mb height and vorticity progs indicate a shortwave each day, by in large, but there is tremendous disagreement among guidance solutions after 60 hours on the evolution of, intensity and timing of shortwaves.  Most of this disagreement is owing to convective feedback issues and the differing convective parameterization schemes that lead to variable handling of thunderstorms, and how they feedback on atmospheric pattern evolution.  In the short range, there is good agreement that the shortwave prompting showers and downpours Sunday evening will continue moving east-southeast across New England, prompting showers across Southern New England overnight, as dynamic lift shifts across the region.  Behind the showers, clearing skies will move into the North, but this will also prompt fog and low-altitude cloud development for those areas where Sunday evening rain left abundant boundary layer moisture.

Though showers will be done Monday morning in Southern New England as drier air advects southward in the mid-levels, plentiful moisture at and below 850 mb will leave a gray stratus deck early, that will slowly break up from north to south as dry air aloft erodes the deck.  Some of Western CT - and, indeed, most of CT - may stay mostly cloudy throughout Monday, as the Nutmeg State will be on the eastern side of a strengthening baroclinic zone over Upstate New York, associated with the warm and moist advection ahead of a potent shortwave and upper low in the Upper Great Lakes, and its clash with the confluent cyclonic flow east of New England.  This leaves shortwave ridging over Eastern New York, meaning upper level diffluence over Upstate NY, and that will promote rain in that area later Monday.  In fact, it's the same shortwave that touched off Sunday evening thunderstorms in the Central Plains that will shoot east in the fast Westerly winds, providing a shot of warm and moist advection to New England on Monday night, allowing rain to move east out of New York State as a 45-55 kt mid-level jet punches across the state line.  With a surface low on the eastern tip of the Upper Peninsula of Michigan, under the upper low, a triple point low over Upstate New York beneath the upper level diffluence, and a bubble high over the Eastern Gulf of Maine feeding cool air west into New England, this provides not only excellent directional and speed convergence throughout the lower several thousand feet of the atmosphere, but also a situation of differential advection on Tuesday, with cold advection at the surface and meaningful warm and moist advection aloft.  Add to this the fact that the surface wind is bringing a long fetch across Atlantic waters, and this only increases available moisture to the atmosphere, with the differential advection providing extremely effective processes for efficient precipitation production on Tuesday.  As for precipitation amounts, highest amounts of around or over an inch seem most likely in Southern New England, with lesser amounts but still a meaningful .50-1.0" of rain in Northern and Central New England.

Though some dry air will become ingested into the cyclonic swirl of the upper low on Wednesday, allowing for some sunshine in many areas, the amount of energy involved with the upper low is quite impressive, and dependent upon timing of the upper level cold pool, thunderstorms with vigorous updrafts and hail are possible in especially Northern ME (the new severe weather capitol of New England, it seems) on Wednesday afternoon.  Will have to see how this plays out, but cold pool does appear impressive enough to trigger convection, even though boundary layer is quite cool.  Incidentally, for those wondering why Aroostook County, in the northern tip of Maine, has seen two tornado touchdowns (three if you include the skipping tornado of last weekend as two...but it was one storm with a skipping tornado, it seems) and a sleu of severe weather, it's certainly not the abundance of warmth and humidity, as normally is viewed as necessary for fuel in severe weather events.  Rather, it's the presence of extreme COLD air aloft, several thousand feet above the ground, much like what we're looking at for a potential on Wednesday.  It's this cold air aloft - abnormally cold air - that provides the difference between relatively warm surface air (even if only 55-60 degrees, it's warm compared to up high in the sky) and cold air above that is termed "instability," and promotes deep vertical cloud growth that produce thunderstorms.

Differences become quite pronounced by Thursday.  Operational NMM, GFS and GGEM (global Canadian) forecasts indicate a break in the action between shortwaves, with New England in confluent and still cyclonic flow.  The GFS, Canadian and ECMWF Ensembles all indicate significant precipitation possible.  In essence, a blend of both solutions seem reasonable - rather close, perhaps, to the Operational ECMWF.  That is, the height and vorticity pattern support a break in the action with drier and cool air in place as the upper low pulls east.  But that also means that as the next shortwave approaches, there is going to have to be a very substantial slam of warm and moist advection that takes place, in an effort to displace the anomalously cool air that followed the midweek upper low.  This should mean a return of unsettled weather later Thursday lasting into Friday, and once again we may find a decent shot of precipitation given the amount of isentropic lift that takes place.  How much rain?  Though it's early to say, the Ensemble solutions indicate a widespread inch of rain is possible here.

So, the potential exists for a couple of inches of rain (at least) for some parts of the region this week, especially in Southern New England.  Admittedly, one can find reason to be a bit gunshy on this, considering last week's front remained stalled just south of New England, delivering heavy rain to the Mid-Atlantic, and this can raise concerns that the front may do the same thing again this week.  That seems unlikely, however, given that the jet stream is lifting north, and therefore this should actually increase confidence, not decrease it.  This same pattern, just slightly farther south, produced a couple of 1.5"+ rainfall events in New Jersey last week, and may do the same in New England this week.  As for any severe weather threat like was seen in the Mid-Atlantic last week, that's not impossible, especially as the aforementioned cold pools drift overhead, but also seems far less likely here in New England, given our proximity to cool bubbles of Canadian high pressure that severely retard any pockets of instability from developing, and rather increase the potential for the precipitation producing differential advection.  Flooding?  Not likely.  At least not in the first event, and probably not in the second.  Antecedent dry conditions have 12 and 24 hour flash flood guidance over 3" right now.

Next weekend?  Early to say in such an uncertain pattern, but I'd have to say that the combination of a developing southerly boundary layer flow with a broad trough aloft would mean near or slightly warmer than normal temperatures with increasing humidity and a chance of thunderstorms - possibly strong - each day.  We'll see how close to reality that becomes.

Enjoy your week - I'll hope to update here with either written discussions or more likely some Ride Home video blog updates.  I'll also get some General Weather Summaries out on WeatherNewEngland.com, our NECN Weather Team website.  I'm up in about 6 hours but would like to crank a few graphics out for tomorrow's show before bed, so may be up for a couple more hours.  Either way, see you on air in the morning.

Matt

The Ride Home - Thursday, June 6, 2009 - Episode #20

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I truly hope to issue these much more frequently than weekly, FYI.  There was a time when I was issuing extensive written discussions daily for months (years!) on end.  That day may return, but right now there's a lot on the plate between public appearances, sprucing up our look at NECN (you'll see those developments unfolding this summer), and, yes, adjusting to the wonders of married life!

Nonetheless, I am still always thinking, sleeping and breathing meteorology, and this pattern of late has been stagnant yet intriguing all the while.  The stalled front across the Mid-Atlantic has been enough to lull Northern New Englanders to sleep occasionally, only to be rudely awakened by another tornado on the ground as another powerful and abnormally cold Canadian disturbance comes crashing through and delivers a frost behind it.  Another round of severe storms is possible in the FAR North Country this weekend, though Southern New England turns attention to the tricky interactions on the northern side of the wavering stationary front, and the ripples of low pressure traveling along it...