Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 130717 AFDGYX Area Forecast Discussion National Weather Service Gray ME 317 AM EDT Wed Mar 13 2024 .SYNOPSIS...
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Warm and mainly dry today and Thursday. Waves of low pressure will cross New England Thursday night and Friday bringing snow showers to the mountains and rain showers south of the mountains. Saturday looks to be break in systems before a trough develops over the Great Lakes and additional systems approach Sunday through early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Weak 500 MB ridge build in this morning, with weak wave trying to crash into late today and overnight. Will see cirrus move in from the W this afternoon, with probably some mid level clouds come in late as well, although I think for sky we move from sunny this morning to p/sunny mid to late afternoon. The HRRR is only the mesoscale to show some showers move in across the central and srn CWA this afternoon, with all the others, including ensembles like the HREF/SREF keeping the bulk of any shower in the N very late today and overnight, so this is the forecast I’ve gone with. Winds become very light today allowing sea breeze to develop this afternoon, so maxes end ranging from the mid upper 40s in the mtns, to the low 50s along the coast and into interior western and central ME, and into the upper 50s in interior S NH.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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Those isolated showers move through the mtns and the N overnight, and could be RA or SN or a mix, but likely snow across the higher terrain, although won;t be enough to worry much about accums. Give what will amount to a BKN-OVC at times in many spots, and despite light winds, decoupling will not be widespread, but some late rad cooling may occur late over the srn half of NH, where some clearing may occur before sunrise. Lows range from around 30 in the mtns and the colder spots to the mid 30s. Although any lower to mid level clouds clear out in the morning there will be a lot of cirrus around on Thursday, and will start to thicken more in the afternoon ahead of the next system. Once again light winds will be the rule with a sea breeze developing again. It’ll probably be a few degrees warmer inland areas of NH and SW ME, but similar maxes on the coast and interior central ME, with highs 45-50 in the mtns, low to mid 50s on and near the coast, and around 60 in interior S NH.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Precipitation is expected to overspread the region Thursday night (generally after midnight) into Friday morning as a wave of low pressure rides along a stationary boundary. Temperature profiles support mostly rain outside of the mountains, but should the cooler NAM be onto something, light snow could be seen farther south toward the lakes regions of NH/ME and over into the Augusta region. This round of precip should shift east of the area by the afternoon hours, but additional energy aloft may yield additional light precipitation through the rest of the day into the evening. Model guidance, including ensembles, is in overall pretty good agreement with QPF being around 0.50" with this system, maybe a little higher in a few areas. Going into Friday night, low pressure will pull to the east away from the area, and flow will switch to northwesterly as weak high pressure builds in. This will keep a chance of upslope rain/snow showers in across the north and mountains through Saturday with generally dry but still party-mostly cloudy conditions elsewhere. Max temps on Saturday will be mostly in the mid 40s to lower 50s. The weather pattern stays unsettled from Sunday into early next week with a broad upper low encompassing much of eastern Canada, which will send multiple shortwaves through New England. The first is expected Saturday night into Sunday which will send a cold front through sometime during Sunday along with another round of light precip (ensemble means favoring 0.25" to 0.50" QPF). The northern track of the low should keep p-type as rain outside of the mountains, and while confidence is high we`ll see precip Saturday night and/or Sunday, PoPs have still been capped at 50-60% due to some discrepancies in timing. For Monday and Tuesday of next week, low-level flow is expected to become northwesterly, meaning a chance of upslope rain or snow showers in the mountains, which could be enhanced at times as additional shortwaves cross through. These waves could also bring a few showers south of the mountains, but the chances will be lower.
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&& .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
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Short Term...Although clouds move in late today and overnight, cigs will remain at VFR through tonight and into Thursday. Winds will be light as well. Long Term...Low pressure will bring a round of precip Thursday night through Friday in the form of mostly rain, but light snow can`t be ruled out a AUG and HIE. Terminals can expect ceilings to lower to MVFR to IFR through the overnight hours along with reductions in visibility. Precipitation should come to an end later in the day Friday or the early part of Friday night with most sites returning to VFR by daybreak Saturday. The exception as usual will be HIE, with MVFR ceilings prolonged through Saturday along with a chance of a rain or snow shower. There may be a shower elsewhere, but confidence is low at this time. Another low pressure and frontal boundary could bring more flight restrictions Saturday night and Sunday.
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&& .MARINE...
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Short Term...Winds/seas now below SCA and then will continue diminish through this morning. Winds stay light and seas remain 2 ft or less this afternoon through Thursday. Long Term... Long Term...A weak area of low pressure will slide eastward across the waters Thursday night into Friday, and it`s possible gusts could reach SCA level out of the E/SE ahead of the low Friday morning and again out of the north later in the day on Friday. Weak high pressure keeps conditions below SCA levels on Saturday, but southerly winds could exceed SCA levels on Sunday as a low pressure and cold front approach and then cross the waters later in the day. Low pressure is expected to remain generally east or northeast of the waters early next week, promoting offshore flow.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...None.
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&& $$ NEAR TERM...Cempa SHORT TERM...Cempa LONG TERM...Combs

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