Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
774 FXUS61 KGYX 010549 AFDGYX Area Forecast Discussion National Weather Service Gray ME 149 AM EDT Mon Sep 1 2025 .SYNOPSIS... Mostly fair weather continues through mid week as high pressure remains in control. A disturbance moving through Quebec will bring chances for showers Wednesday afternoon, mainly along and north of the mountains. A trough swinging into the Great Lakes will send a cold front towards New England Friday that will bring better chances for showers. Troughing remains over the Northeast into next weekend bringing continued chances for showers. && .NEAR TERM /TODAY/... Impacts and Key Messages: * No significant weather impacts are expected. High pressure remains in control at the surface today as an upper low slowly moves northward over the Mid-Atlantic. This will push clouds into the region from the southwest, with much of the area being partly to mostly cloudy, by sunset. Despite this increase in cloud cover temperatures should still be able to climb into the mid- to upper 70s areawide, with some locations touching 80F. The abundance of dry air in the low and mid-levels should preclude any chance for showers, even in the mountains. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... Impacts and Key Messages: * No significant weather impacts are expected. Tonight: The upper low continues its northward journey becoming more centered over the eastern Great Lakes overnight. This will continue to push clouds through the area and because of this, I am hesitant that any location will stay clear long enough to see efficient radiational cooling, so have stuck with the NBM lows. Expect temperatures to stay more in the low to mid 50s south of the mountains, and in the upper 40s and low 50s to the north. Cloud cover along with the lower level dry air may limit fog development as well, but at least some patchy fog in the valleys is a good bet. Tuesday: The upper low becomes an open wave Tuesday that then swings east into our area. This shortwave trough combined with diurnal heating likely develops a cumulus field over the mountains and foothills. The added lift makes mountain showers and even an isolated rumble of thunder possible during the afternoon. With PWATs modeled around 0.75", don`t expect anything too significant out of any showers/storms that do develop. High temperatures look to end up similar to today (Monday), climbing into the mid to upper 70s areawide. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... 01Z NBM Update...No significant changes with the latest NBM other than a slight uptick in shower chances in the mountains and north Wednesday afternoon. Otherwise, after a period of mostly dry weather this week an approaching cold front will bring chances for showers Friday with PoPs holding around 60 to 70 percent. Previously... An upper-level low to the north, combined with some instability generated from daytime heating may allow for a few diurnally driven convective showers north of the White Mountains on Wednesday. However, these storms should be pretty isolated and most places up there may only see a few hundredths of an inch of rain, if anything. A similar setup is likely for Thursday, though drier air from high pressure will wiggle onshore and allow for dry air to penetrate farther inland. This additional dry air should prevent showers from developing in the mountains on Thursday. By the end of the week, a more robust 500mb trough develops and tries to swing to the south but is likely remain to the west of New England. A cold front and a northward moving shortwave over the Atlantic Ocean may allow for some measurable rainfall during the day on Friday and potentially continuing into Saturday as well. At this time, confidence is highest to see measurable rainfall across western NH and the interior, though the ECMWF 10th percentile QPF shows at least a good quarter of an inch of rain is expected most places Friday and Saturday. Weather over next weekend looks to remain cool and somewhat unsettled. Notable drought relief is not expected despite a potentially wet end of the week. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Short Term...Valley fog will clear early this morning bringing impacted terminals back to VFR. VFR then prevails at all terminals through the day. Ceilings will begin to thicken, but should stay mostly VFR overnight. The increased cloud cover may also limit fog development tonight. Skies clear Tuesday with a chance for an isolated thunderstorm in the mountains. Long Term...Mainly VFR Wednesday through Thursday with the exception being favorable conditions for nighttime valley fog at KLEB and KHIE. An approaching cold front will bring clouds and chances for showers Thursday night and Friday that will bring potential for at least MVFR conditions. && .MARINE... Short Term...Wind gusts and seas remain below SCA criteria through Tuesday as high pressure remains in control over the region. Light northeasterly winds prevail today and tomorrow with seabreezes developing each afternoon. Wind gusts will generally be less than 10kts, with seas less than 3ft. Long Term...High pressure will remain over the Northeast Wednesday and Thursday with winds and seas below SCA thresholds. Southerly winds will increase late Thursday into Friday ahead of a cold front with winds and seas approaching SCA thresholds Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR/SHORT TERM...Baron LONG TERM...Palmer/Schroeter