Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 210704 AFDGYX Area Forecast Discussion National Weather Service Gray ME 304 AM EDT Mon May 21 2018 .SYNOPSIS...
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High pressure will move out to sea south of New England today. A warm front lifts into New England on Tuesday, spreading showers into the area. A cold front drops south through the region Wednesday. Weak low pressure tracks along the international border late Thursday into Friday. A frontal system tracks into the area for the holiday weekend bringing widespread showers.
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&& .NEAR TERM /THROUGH TODAY/...
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Warming and drying downsloping winds are expected to develop today behind a departing cold front with high pressure building in from the west. Today will be sunny with high temperatures in the 70s most locations, with mid to upper 70s likely for interior spots. It will be warmest over southern NH where Manchester and Nashua will approach 80 degrees. Winds will be WNW and around 10 MPH with higher gusts, especially over the mountains. RH values drop into the 20-30% range, with higher RH values across the north. This is due to fast moving flow aloft, which will keep moisture along the Canadian border from around 850-700mb in particular. Thus, the lower RH values and borderline higher wind gusts are not juxtaposed, so a Red Flag Warning can be avoided at this time. Will be issuing a statement to impress the still dangerous fire weather conditions.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
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Tonight expect weak SW flow along with increasing cloud cover from the SW as the next system approaches. This will yield temperatures in the 40s north with lower 50s along the coast and over southern NH. On Tuesday temperatures will warm into the upper 60s and lower 70s, with readings capped there by clouds and rainfall. In particular a warm front will spread showers across northern New England mainly in the afternoon and evening. Higher QPF will be wrung out along the Whites and the western Maine mountains, but expect less than a quarter inch there with basin average less than a tenth in many places. Farther east and south will see less rain through Tuesday evening.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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As we continue into the middle of the week split flow continues over the western CONUS with an upper level trough centered over Quebec. That split flow will begin to break down towards the end of the week with the cut off low reforming eastwards allowing for a tropical moisture source into the eastern CONUS by the end of the weekend. For Wednesday we`ll see showers across the area as a short wave dives through the low over Quebec. A rumble of thunder is possible in the afternoon as K index climbs to near 30 as the upper level vort max moves through. Thursday and Friday will see high pressure over the region as the upper levels ridge begins to progress eastwards. A sea breeze will impact the coast throughout the end of the week keeping high temperatures lower along the water. Inland temperatures will climb into the upper 70s on Thursday and into the 80s on Friday under mostly sunny skies. Saturday starts a pattern shift as a cut off low begins to form over the southeast US. This will allow for a flow of tropical moisture northwards bringing rain for the end of the weekend. The formation of the cut off low will be key in the timing and strength of the precipitation and that will be the feature to watch through this week as we look ahead to the holiday weekend.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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Short Term...Mainly VFR through tonight. Valley fog continues this morning at KLEB/KHIE with LIFR conditions. This should improve by 11Z or so. Gusty westerly winds expected this afternoon before diminishing this evening. Long Term... Generally prevailing VFR through the weekend. A few showers on WEdnesday may briefly drop conditions to MVFR through the mountains. High pressure builds in for the end of the week and holds through the weekend. Widespread rain will develop Saturday night into Sunday with IFR possible.
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&& .MARINE...
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Short Term...Winds will gust into the lower 20s offshore today, but winds should stay below SCA criteria, with an occasional gust to 25 kts possible for an hour or two over the outer waters. Long Term... High pressure will build in through the end of week. By Thursday night developing southerly flow will gradually push conditions to near SCA over the outer waters by Friday night.
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&& .FIRE WEATHER...
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Minimum RH values will fall to 20-30 percent this afternoon, and westerly winds will be around 10 MPH gusting to near 20 mph at times. However, these two conditions do not occur in the same place, and red flag criteria is not expected to be met. Still, a statement will be issued addressing the potential for hazardous fire weather conditions.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...None.
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&& $$ NEAR TERM...Hanes SHORT TERM...Hanes LONG TERM...Curtis

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