Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
992 FXUS61 KGYX 311026 AFDGYX Area Forecast Discussion National Weather Service Gray ME 626 AM EDT Sun Aug 31 2025 .SYNOPSIS... Upper low exits to the northeast this morning with high pressure gradually building in from the west. High pressure will bring mostly dry days into the 70s and cool nights. High pressure shifts offshore mid week as a trough swings through the Great Lakes. This trough will send a frontal system towards New England late in the week for the next chance at some wetting rains. && .NEAR TERM /THROUGH TODAY/... 625 AM Update...Just minor changes to align with observations early this morning as the forecast remains in good shape. Previous Discussion... Impacts and Key Messages: * No significant weather impacts are expected. The upper low becomes an open trough centered over Atlantic Canada today leaving our area under northwesterly flow. This drier air moving in aloft combined with high pressure building in at the surface should keep clouds and showers minimal compared to yesterday (Saturday). I would still expect some kind of a diurnal cumulus field during the afternoon hours, but we should get more sun overall. Temperatures will be able to climb a little higher today with areas south of the mountains reaching into the mid- to upper 70s, and into the low to mid-70s to the the north. && .SHORT TERM /TONIGHT THROUGH MONDAY/... Impacts and Key Messages: * No significant weather impacts are expected. Tonight: Subtle 500mb height rises and high pressure continuing to build into the region will help to further clear skies and calm winds overnight. This should allow for locations to decouple and for radiational cooling to drive temperatures down into the low to mid- 40s north of the mountains, and into the upper 40s and low 50s to the south. High pressure becoming centered over the region keeps winds calmer in the higher terrain tonight, but apparent temperatures will still end up close to the freezing mark so any one hoping to do some mountain camping should plan accordingly. Monday: Monday might end up on the cloudier side as another upper low approaches the region, this time from the southwest. The morning hours should be mostly sunny to partly cloudy with high clouds advancing into the area from the southwest. By the afternoon a thicker lower deck looks to move in with New Hampshire and far western Maine noticeably cloudier by sunset. This likely makes for a pretty uniform high temperature gradient as areas south of the mountains climb into the upper 70s before clouds inhibit heating. Areas to the north where it will stay clearer longer will also be able to warm into the mid- to upper 70s. Lastly, the midcoast and west central Maine have the best chance of staying mostly clear through the day and therefore may see temperatures around 80. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... 01Z NBM Update...No significant changes with the latest NBM with high pressure likely to dominate the weather pattern through the balance of the week. While the late week trough looks impressive with ensembles showing a decent signal for measurable precipitation, there are some similarities to recent frontal systems with the higher PWAT air being shunted offshore. The NBM brings likely PoPs to the area Friday which seems reasonable. Previously... Key Message: Temps below normal to start the period but turning more seasonable thru the remainder of the week. Continued dry until the late week frontal passage. Impacts: No significant weather impacts anticipated beyond maintaining/deepening drought conditions. Forecast Details: The core of the cold anomalies begin to lift out Mon...so moderating conditions are expected thru the remainder of the week. Surface high pressure will be hanging on thru Mon night however...and I did adjust some of the interior valleys down a few degrees to account for lingering radiational cooling effects. I also continued to add valley fog in the forecast as long as high pressure is in control. While we have been very dry...the recent rain...evapotranspiration...and climatological peak of radiation fog all suggest at least patchy fog possible. The main story continues to be the lack of rain in the forecast. After the drink yesterday there is not much rain to speak of until at least Thu night or Fri. A cold front will cross the region but forcing will be weakening with time and by no means is this a lock for wetting rains. Drought conditions may continue to expand. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... Short Term...Any valley fog will clear quickly this morning. High pressure building over the region will lead to VFR ceilings and light winds prevailing through Monday. Dry weather will begin to limit fog development, but HIE and LEB could see it tonight. Long Term...Generally VFR conditions thru the extended. Local IFR or lower in valley locations where fog is expected. Given the dry weather this may stay limited to HIE and LEB. && .MARINE... Short Term...Wind gusts and seas remain below SCA criteria through Monday as high pressure builds over the waters. Winds are generally northwesterly with a seabreeze this afternoon. Winds shift southeasterly Monday afternoon. Wind gusts are expected to be less than 15kts, with seas less than 3ft. Long Term...Ridging and surface high pressure will remain in control and dominate weather thru the end of next week. As a result winds and seas are expected to remain below SCA thresholds. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR/SHORT TERM...Baron LONG TERM...Legro/Schroeter