Area Forecast Discussion
Issued by NWS Portland, ME

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357 FXUS61 KGYX 111919 AFDGYX Area Forecast Discussion National Weather Service Gray ME 319 PM EDT Tue Jun 11 2024 .SYNOPSIS...
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Scattered showers and thunderstorms develop tomorrow as an upper level low continues to slowly move through, with the most widespread shower activity expected across the higher terrain. Temperatures moderate on Thursday ahead of an approaching cold front. The front crosses New England on Friday, with high pressure building in behind the front for the weekend. The high moves offshore early next week, setting up a moderating trend with warm temps likely next week.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Scattered showers will continue across the interior this afternoon and early evening. Some remaining elevated instability could keep a handful going into the evening, but generally expect dry conditions for tonight. Not terribly confident in the cloud forecast overnight. Daytime cu should dissipate with loss of daytime heating, but moist layer remains around 850mb. So its possible this cu just flattens and causes occasional broken sky conditions overnight. This complicates temp trends overnight, as well as the chance for fog formation. Where clear skies do develop, think at least valley fog will be possible...especially towards the Kennebec valley and Midcoast.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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Almost a repeat day of Tuesday for Wednesday. Again instability builds across the interior with HREF probs favoring around 500-700 j/kg of SBCAPE. This will promote airmass/popup showers. Showers or storms in the afternoon may pack a little more in the way of heavy downpour considering the amount of CAPE, but shear is negligible. This low of value compared to the instability will see showers with shorter lifecycles, but slow moving. While the slow storm motion will be favorable for isolated nuisance flooding in poor drainage areas, the lack of shear maintenance will keep this threat low. Shower activity dwindles in the evening with the loss of daytime heating. More in the way of fog development will be possible overnight, again in the valleys but also along the immediate coast.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Overview... A cold front passes through to close out the week, with high pressure bringing dry and seasonable conditions for the weekend. The high moves offshore next week, setting up an extended warming trend with a ridge building across the eastern US. Details... A cold front approaches New England from the west on Thursday, with increasing southerly flow bringing in warmer temps ahead of the front. Temps warm into the 80s across most spots, with mid to upper 70s expected along the coastline. Any showers or thunderstorms are expected to hold off until after dark. Weakening showers and a few thunderstorms reach into northern areas during the overnight hours as the front approaches. The front then crosses during the daytime on Friday. Showers are still likely across northern areas early on Friday, but the better chance for thunderstorms looks to be across southern areas where more daytime heating can occur before the front`s arrival. Some strong storms will be possible with the front as dew points climb into the 60s during the day on Friday, but the timing of the front will be important to see if we end up with anything more widespread or severe. A delayed frontal passage of only a couple hours increases this threat, so we`ll be monitoring it over the next couple of days. The front clears the coast Friday night, with high pressure building in from the northwest for the weekend. The high brings much drier air and mainly sunny conditions. Temps look seasonable on Saturday, with northwesterly downslope flow allowing the coast to warm to near 80, while the mountains stay mainly in the mid to upper 60s. Saturday night looks crisp in most spots, with lows mainly in the 40s and dry conditions. Temps begin to moderate on Sunday as the high moves overhead, with highs mainly ranging from the mid 70s to low 80s. A seabreeze develops during the afternoon along the coast as the high moves offshore, knocking back temps along the coast in the afternoon. The high moves offshore and begins to strengthen through midweek, likely centered between Nova Scotia and Bermuda. This is the sign at the surface of a building ridge across the Northeast and Great Lakes next week, helping to bring some potentially significant heat to New England next week. Temperatures steadily moderate early next week, with highs into the 80s for most areas in increasing southwesterly flow, except for the MidCoast which holds in the 70s. Temps likely then warm to near 90 in a lot of spots by Tuesday. Afterwards, the heat looks poised to continue to build through midweek as the ridge builds. As with the prospect of any period of heat in New England from this far out, there are still of lot of different factors that can serve as spoilers that we need to remain mindful of. There will likely be leftover MCSs transiting the ridge from the Plains, and uncertainty on whether these will move through New England or north of the area. There are prospects of a cut off low developing south of Atlantic Canada, with the chance of this delivering a back door front with easterly flow by late next week. So while all signs are pointing towards heat at this point, there are still other factors we need to remain mindful of as the possible peak of the heat remains over a week away.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/...
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Short Term...VFR. Some valley fog or coastal fog will be possible beginning tonight and perhaps lasting through Wed. SHRA this afternoon across interior terminals will again occur Wed afternoon, subsiding overnight. Long Term...VFR conditions are expected on Thursday, then some showers and storms bring brief restrictions to most terminals Friday afternoon. VFR then prevails from Friday night through early next week.
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&& .MARINE...
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Short Term...Below SCA conditions with waves 2 to 3 ft and southerly flog. Marine fog development will be likely over the next 24 to 36 hours as humid conditions arrive. Long Term...SCA conditions are possible Thursday night and Friday ahead of a cold front. The front crosses the waters Friday night. Fair conditions are then expected for the weekend and early next week as high pressure settles along the Eastern Seaboard.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Cornwell SHORT TERM...Cornwell LONG TERM...Clair