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MIDWEEK WARMUP UNDERWAY...MEANWHILE, ANOTHER QUAKE ROCKS BAR HARBOR, MAINE

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:

Another earthquake has rocked the Bar Harbor, Maine, area, epicentered just four miles south-southeast of the town at 8:07 PM Monday night.  This quake is still being evaluated by the United States Geological Survey, but as of this writing is pegged at a 3.9 magnitude quake.  Damage reported from Acadia National Park included a closed road due to fallen rocks, and burst water pipes.  You can access more information on this quake from the USGS by clicking here.  Certainly, three earthquakes in three weeks all centered near one town makes for interesting conversation and is thought-provoking, and while not common, this can and does happen as fault lines experience varying degrees of activity.

Weatherwise, Tuesday morning sunshine will continue to dim behind increasing clouds from northwest to southeast through the day as moisture increases in advance of a quick-moving disturbance at the jet stream level.  This disturbance produced heavy thunderstorms from Chicago through the Eastern Great Lakes Monday and Monday night, and will continue to carry at least scattered showers with embedded thunder into New England by Tuesday afternoon.  Ahead of the storm, its counter-clockwise circulation of air has aided in transporting warmth into New England.  This warmth was responsible for sending high temperatures soaring into the 80s and 90s through the nation's midsection the last couple of days and while our warmth won't rival those numbers, high temperatures will land some 6-8 degrees above normal in New England Tuesday afternoon.  Though showers will extend in scattered form across Northern New England from west to east Tuesday, as the incoming disturbance moves east it will encounter increasingly dry air, and this will allow many of the showers and embedded downpours to weaken, though certainly late afternoon and early evening may bring a shower to even eastern parts of Southern New England.  These showers will dry up quickly Tuesday night with the passage of the jet stream disturbance aloft, though pockets of fog are likely to develop, especially in valleys.

The trend of fast-paced disturbances will continue into mid-week, as warmth rebounds on Wednesday ahead of an approaching strong Canadian disturbance.  An increase in southwest winds will boost temperatures much above normal Wednesday afternoon - especially in Southern New England - though the surface cold front associated with the incoming disturbance will help to generate widespread showers and thunder later Wednesday from northwest to southeast, taking most of the night to press through Southern New England but finally clearing out Thursday and leaving fall air in its wake.  Any storms that develop Wednesday afternoon and evening will pack the potential to deliver locally damaging winds to some communities, as winds just a few thousand feet off of the ground will be whipping out of the southwest at over 60 mph.  Winds that will change direction near the surface - along a weak warm front serving as the leading edge to the deeper warmth over Southern New England - will enhance the potential for damaging thunderstorms in Central New England.  As the band of rain and thunder transitions to a band of rain and embedded downpours while slowly shifting south Wednesday night, it will usher in a shot of cool and dry fall air for the end of the week.  At this point, it appears as though this dry air will remain locked in place into the weekend, holding a developing storm to our south along the Mid-Atlantic coastline, keeping us dry.  Admittedly, it will be a bit of a close call for Southern New England, but so far the weekend looks quite promising.

Have a great Tuesday!

Technical Discussion:  Lots going on behind the scenes today...will update again tomorrow.

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, October 2 at 1:55 PM

Clouds waited for diurnal effects to fill in but the process has begun as of this writing and will continue to rapidly fill the sky as convective temp has been reached in most spots thanks to cool air aloft and abundant low level moisture available for convective growth.  Brightest locales will be far Srn/SW NewEng.  Have included gusts to 20 mph given mixing to 925 mb and winds to 25 kts progged at that level.

Cu should diminish after sunset and winds slacken which will allow cooling, tempered by moderate warm advection in the mid and lower levels.  This warm advection comes in advance of an approaching shortwave currently moving across the Midwestern US that will move steadily E in the westerlies.  Decent agreement on a morning passage of assoc midlevel moisture in Nrn NewEng, and afternoon passage in Srn NewEng.  Shouldn't disregard the amount of moist advection occurring in advance of the shortwave, either, which brings 850 mb Tds of +11 C on Tue and is sufficient to boost SBCAPE to over 1000 J/kg.  Initial concern for me was that the NMM in particular may be exercising its occasional bias of bringing  llvl moisture in too quickly, but analysis of llvl theta-e progs from current data show this is a rather impressive moist tongue to be reckoned with, so felt comfortable in adding chance thunder to my shower chance for Tue.

The trick heading into Wed is how the atmosphere behaves behind Tue shortwave.  That is, at first it seems self-evident that warmth returns until late Wed shortwave comes swinging thru, and my morning fcst reflected the return of this warmth.  I fear, however, that I failed to give proper respect to the density of a fall airmass, as the rules are changing now that we've transitioned from summer.  In summer, an airmass rebound of warmth like this would be easy to believe, but this time of the year, even a slight southward tug of cool fall air behind the lead shortwave means we have more work to erode the cool surface dome.  I don't think this is going to have major implications on my forecast for NewEng from this AM, but I do think there are some important subtle details that can be garnered from properly understanding this interaction, namely that there should be at least a band of BKN midlevel clouds - probably altocumulus - that will start over Srn NewEng Wed AM then shift across the north and thicken with the approach of the next shortwave.  It certainly appears as though this warm front will be able to surge north thru most of Srn/Central NewEng, but Nrn NewEng is likely to find the thickening clouds leading directly into showers assoc with approaching wave.  Farther south, where warm air does rebuild well, instability rises again to over 1000 J/kg, and with better dynamic forcing I would expect more widespread rain and thunder certainly than what I'm expecting on Tue.  With 850 mb llvl jet cranking from the SW to 60 kts across Central/Nrn NewEng by later Wed, severe weather is a decent potential.  Let's be sure not to grow lax to this potential for thunderstorm damage and remember that this time of the year is often a potent severe weather producer given the combination of baroclinicity and dynamics.  This was evidenced in Friday's tornado in Berwick, ME, and given backing flow along and ahead of warm front pushing into Ern NH/Wrn ME on Wed afternoon/evening, the atmosphere will be primed to pull a similar stunt.

The forecast becomes more straight-forward thereafter as longwave trof migrates E thru NewEng with SE US ridging extending N this weekend and anomalous cold the end of this week transitioning to anomalous warmth later in the weekend - and likely strongly anomalous given the combination of a high pressure cell shifting S of NewEng, the heat building in the nation's Southern, Central and Northern Plains, where sfc max temps were near 100, in the 90s, and 80s respectively, combined with a downsloping flow Sun.

That's all for today.

Matt

NATIONAL WEATHER SERVICE CONFIRMS F1 TORNADO IN MAINE FRIDAY AFTERNOON...NOW WE TURN ATTENTION TO A BRIEF WARMING TREND!

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:

What a weekend!  Storms Friday afternoon brought a confirmed tornado to North Berwick, ME, around 3 PM, when residents spotted a funnel cloud and about a dozen homes were damaged.  For a complete run-down on the strong F1 tornado from the National Weather Service click on the following file:

Download 033006_North_Berwick_Tornado.txt

Meanwhile, rains totaled more than two inches in wetter locales on Sunday, while the banded nature of the rain meant others in New England - sometimes near to the communities that were soaked - picked up only a few hundredths of an inch of rain!  Finally, Hurricane Isaac is crossing the Grand Banks today, with Tropical Storm Warnings in place for Newfoundland around Cape Race and St. Johns.  Nonetheless, while it's an active weather pattern, the sensible weather for New England won't be all that exceptional in the immediate term.

In fact, the storm that delivered banded Sunday rains has slowed off the Maine coastline for the time-being, and areas of rain, heavy at times, will continue to fall over Downeast Maine with showers extending north all the way into Aroostook County through the afternoon.  For the remainder of New England, enough dry air has moved in to prohibit widespread showers, though plenty of lingering moisture in the lower few thousand feet of the atmosphere combined with cool air aloft will make conditions favorable for plenty of clouds to crop up through the day, with most spots recording more clouds than sun, except in Connecticut and southwestern Massachusetts where slightly warmer air will mean more sunshine.  As clouds billow elsewhere in New England, though, a few sprinkles are possible, with a few heftier showers in the mountains of Vermont, New Hampshire and Maine.

The setting of the sun Monday evening will lessen the difference between warmer ground at the surface and colder air aloft, allowing clouds to disintegrate for many areas.  A combination of partly cloudy skies and slackening winds will allow temperatures to cool overnight, especially in sheltered valleys.  With warmer air streaming in aloft, however, and more warmth to follow in the lowest levels of the atmosphere on Tuesday, temperatures will warm above seasonal norms on Tuesday afternoon.  With a fast-paced weather pattern and the jet stream sending disturbances sailing east toward New England, morning sunshine is likely to give way to increasing clouds, and the passage of the jet stream level disturbance Tuesday afternoon will probably touch off at least a few showers across New England, with a thunderstorm not out of the question in an isolated locale.

This trend of fast-paced disturbances will continue into mid-week, as warmth rebounds on Wednesday ahead of an approaching strong Canadian disturbance.  An increase in southwest winds will boost temperatures much above normal Wednesday afternoon, though the surface cold front associated with the incoming disturbance will help to generate widespread showers and thunder later Wednesday from northwest to southeast, taking most of the night to press through Southern New England but finally clearing out Thursday and leaving fall air in its wake.  This fall air will lock in dry air through the end of the week and into the weekend, and though that means sunshine, it also means another shot of below normal temperatures.

In the tropics, Isaac has been stealing the show in the North Atlantic as he crosses Newfoundland, Canada, today, but no other systems are showing signs of immediate development.  While waves have been building to 25 feet with the center of Isaac, the bulk of these waves will end up in the Canadian Maritimes from the Laurentian Fan through the Grand Banks.  Swell is already arriving to the waters of Southern New England, however, and will peak at 5-7 feet later Monday with an 11-13 second period and an offshore wind helping to churn the waves up.  Thereafter, swell is expected to decrease through midweek.

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, October 2 at 1:55 PM

Clouds waited for diurnal effects to fill in but the process has begun as of this writing and will continue to rapidly fill the sky as convective temp has been reached in most spots thanks to cool air aloft and abundant low level moisture available for convective growth.  Brightest locales will be far Srn/SW NewEng.  Have included gusts to 20 mph given mixing to 925 mb and winds to 25 kts progged at that level.

Cu should diminish after sunset and winds slacken which will allow cooling, tempered by moderate warm advection in the mid and lower levels.  This warm advection comes in advance of an approaching shortwave currently moving across the Midwestern US that will move steadily E in the westerlies.  Decent agreement on a morning passage of assoc midlevel moisture in Nrn NewEng, and afternoon passage in Srn NewEng.  Shouldn't disregard the amount of moist advection occurring in advance of the shortwave, either, which brings 850 mb Tds of +11 C on Tue and is sufficient to boost SBCAPE to over 1000 J/kg.  Initial concern for me was that the NMM in particular may be exercising its occasional bias of bringing  llvl moisture in too quickly, but analysis of llvl theta-e progs from current data show this is a rather impressive moist tongue to be reckoned with, so felt comfortable in adding chance thunder to my shower chance for Tue.

The trick heading into Wed is how the atmosphere behaves behind Tue shortwave.  That is, at first it seems self-evident that warmth returns until late Wed shortwave comes swinging thru, and my morning fcst reflected the return of this warmth.  I fear, however, that I failed to give proper respect to the density of a fall airmass, as the rules are changing now that we've transitioned from summer.  In summer, an airmass rebound of warmth like this would be easy to believe, but this time of the year, even a slight southward tug of cool fall air behind the lead shortwave means we have more work to erode the cool surface dome.  I don't think this is going to have major implications on my forecast for NewEng from this AM, but I do think there are some important subtle details that can be garnered from properly understanding this interaction, namely that there should be at least a band of BKN midlevel clouds - probably altocumulus - that will start over Srn NewEng Wed AM then shift across the north and thicken with the approach of the next shortwave.  It certainly appears as though this warm front will be able to surge north thru most of Srn/Central NewEng, but Nrn NewEng is likely to find the thickening clouds leading directly into showers assoc with approaching wave.  Farther south, where warm air does rebuild well, instability rises again to over 1000 J/kg, and with better dynamic forcing I would expect more widespread rain and thunder certainly than what I'm expecting on Tue.  With 850 mb llvl jet cranking from the SW to 60 kts across Central/Nrn NewEng by later Wed, severe weather is a decent potential.  Let's be sure not to grow lax to this potential for thunderstorm damage and remember that this time of the year is often a potent severe weather producer given the combination of baroclinicity and dynamics.  This was evidenced in Friday's tornado in Berwick, ME, and given backing flow along and ahead of warm front pushing into Ern NH/Wrn ME on Wed afternoon/evening, the atmosphere will be primed to pull a similar stunt.

The forecast becomes more straight-forward thereafter as longwave trof migrates E thru NewEng with SE US ridging extending N this weekend and anomalous cold the end of this week transitioning to anomalous warmth later in the weekend - and likely strongly anomalous given the combination of a high pressure cell shifting S of NewEng, the heat building in the nation's Southern, Central and Northern Plains, where sfc max temps were near 100, in the 90s, and 80s respectively, combined with a downsloping flow Sun.

That's all for today.

Matt