Area Forecast Discussion
Issued by NWS Portland, ME

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791 FXUS61 KGYX 260823 AFDGYX Area Forecast Discussion National Weather Service Gray ME 423 AM EDT Sun May 26 2024 .SYNOPSIS...
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A stationary front will settle across central New England today, bringing some unsettled weather this afternoon into Monday. A more organized system approaches Monday evening bringing widespread showers Monday night into Tuesday. An upper level trough crosses the region Wednesday through Friday with more scattered showers and near seasonable temperatures.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Elevated instability combined with forcing from a weak wave will continue rain showers early this morning. Can`t rule out a rumble of thunder early, but showers have struggled to build high enough to create pulses. There will be a dry break this morning prior to building sfc heating. Breaks in the clouds will help temps rise into the 70s again today, with some low 80s in southern NH. These highs will be in proximity to a stalled front left by the passing wave this morning. As diurnal heating takes place, convective temps will be met and forcing along this stalled boundary should spur on some showers and thunderstorms this afternoon, mainly for southern NH and into the interior ME/NH lakes region. CAMs have been fairly consistent bringing deeper storms into southern NH, although placement and exact coverage is tricky due to the wavering front and weak low level shear. Model soundings do portray a good balance of shear/CAPE this afternoon, and can`t rule out storms that feature locally enhanced wind gusts and small hail. Backbuilding may also promote rainfall that trains, leading to the possibility of ponding or urban flooding. On the other side of the coin, the mid levels are quite dry, so warm rain processes are less likely.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
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Surface CAPE falls off this evening, with just some elevated instability left over to sustain weakening showers late. Onshore flow will keep the low levels moist, and with forcing still in the region, will likely see some isolated showers or drizzle continue for the overnight period into Monday morning. As onshore flow increases, would expect these showers/drizzle to push northward through Mon morning. Moisture depth improves Monday afternoon, and will see shower coverage increase amid PWATs pushing around 1.5". The increased coverage should also make for excessive clouds that limit daytime highs to the upper 50s to around 60. Can`t rule out a rumble of thunder early, but much of this instability may be lost before arriving to NH/ME.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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Overview: A return to a more unsettled pattern is in store for much of next week as a series of fronts associated with upper level lows cross over Northern New England. Temperatures will generally be near climatological averages. Impacts: Moderate to locally heavy rainfall is possible Monday night as deep southerly flow interacts with an advancing warm front. The greatest potential for heavy rainfall will be across the mountains. Forecast Details: Low pressure will cross into southern Quebec on Monday night, sending a sfc warm front northward over Northern New England. Deep sub-tropical southerly flow will help to push precipitable water values up to around 1.50", with NAEFS standardized anomalies approaching +2 to +3 standard deviations. This combined with forcing from the front could result in moderate to locally heavy rainfall overnight, especially over southeasterly facing higher terrain due to upslope flow. Lows will primarily be into the 50s to lower 60s. There remains differences amongst global and ensemble based guidance on the timing of a trailing cold front, with the ECMWF favoring a slower arrival and thus more prolonged period of rain into part of Tuesday while the GFS is has the front crossing earlier in the day. Nevertheless, would expect at least scattered showers through part of the day with highs into the 70s to lower 80s depending on how much clearing can be achieved. Drier conditions are then likely Tuesday night with lows into the 50s. Another front then may cross on Wednesday, possibly resulting in additional scattered showers... especially during the afternoon due to daytime instability. A weak area of low pressure may then develop along this front into Thursday, with scattered showers possible along with cooler high temperatures. High pressure then looks to build to our west Friday through the first half of next weekend but stalled low pressure near Nova scotia will result in northeasterly flow and seasonably cool temperatures.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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Short Term...VFR today with SHRA early, and then again this afternoon for southern NH terminals and parts of interior ME. TS possible for far southern NH locations this afternoon. A trend towards MVFR/IFR is likely this evening and overnight for most locations outside of LEB/HIE. Drizzle and SHRA continues overnight into Mon morning, with SHRA coverage increasing into the afternoon. Long Term...More widespread -RA develops Monday night into early Tuesday with MVFR to IFR restrictions possible. Mainly VFR is then likely later Tuesday through the middle of next week, although patchy FG may develop at night. Winds will primarily be out of the south-southeast with gusts nearing 20 kts.
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&& .MARINE...
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Short Term...Below SCA criteria, but will see showers and perhaps a thunderstorm on the southern coastal waters this afternoon. Drizzle or fog may reduce visibility overnight into Monday morning. Long Term...South easterly wind gusts could approach 25-30 kts Monday night into Tuesday with seas of 4-6 ft across the outer waters and 1-3 ft in the bays. Winds and seas will then decrease towards mid-week behind a cold front.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Beach Hazards Statement from noon EDT today through this evening for MEZ023>028. NH...Beach Hazards Statement from noon EDT today through this evening for NHZ014. MARINE...None.
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&& $$ NEAR TERM...Cornwell SHORT TERM...Cornwell LONG TERM...Tubbs