Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
240 FXUS61 KGYX 032214 AFDGYX Area Forecast Discussion National Weather Service Gray ME 614 PM EDT Wed Sep 3 2025 .SYNOPSIS... A disturbance moving through Quebec will bring chances for showers and isolated storms this afternoon, mainly north of the foothills. A trough swinging into the Great Lakes will send a cold front towards New England, bringing increasing chances for showers Thursday night into Friday. Another front approaches for Saturday perhaps allowing for more substantial rainfall and thunderstorms over a wider area. High pressure moves in early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 615 PM Update...Isolated showers and thunderstorms continue in the mountains early this evening. They will continue to trend downward and eventually dissipate over the next hour or two with the loss of daytime heating. Previously... Latest RAP13 analyzes a 500mb shortwave in the process of moving across northern New England. Lift from this trough will continue to kick off scattered showers and storms in the mountains this afternoon with more isolated coverage farther south toward the foothills where subsidence increases and moisture is less favorable. Forecast soundings reveal pretty low freezing levels at around 7,500 ft AGL, and with a few hundred J/kg of CAPE, storms could produce small hail. Dry low levels will also support a gusty wind threat. Showers and storms will wane this evening with the loss of daytime heating and as the trough lifts off to the north and east. Skies are expected to clear out behind the wave tonight with good radiational cooling with lows in the mid 40s to lower 50s for most. Valley fog is again expected tonight, and guidance is hinting at higher fog coverage (and potentially dense) across western ME from the coast to the foothills, where I have opted for "areas" wording rather than "patchy". && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Once the fog lifts by 9 AM or so Thursday morning, shortwave ridging will move overhead and bring a dry and mostly sunny day. Southerly flow will be increasing ahead of a frontal boundary with somewhat breezy conditions of 20-25 mph at times. Highs will again be in the mid 70s to low 80s for much of the region, although the Midcoast may be a few degrees cooler with the winds directly off of the Gulf of Maine. A shortwave will continue to push the frontal boundary toward New England Thursday evening. Moisture will steadily increase, but there will still be some dry air to overcome initially. I have slowed the onset of rain showers slightly, but western NH should start seeing precip by late evening to around midnight with a north and eastward expansion through Thursday night. Highest amounts and chances will be across western and northern NH extending into the western ME mountains and foothills where 0.10" to 0.25" of rainfall will be possible by daybreak Friday. More fog is on the forecast with guidance favoring western ME, where it could be dense in some areas. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... A broad upper-level low over eastern Canada and mid-level troughing will allow for a few periods of rain and storms through the weekend. The first arrives Friday morning, though showers are bound to be more scattered once they arrive in NH and Maine. This is because mid- level troughing present is situated to the west and nearly uniform SW winds aloft should usher in drier low-level air. This drier air will be short lived, as it moves eastward and a stream of low-level moisture originating from the remnants of Eastern Pacific TC Lorena flows into the Northeast. This flow of moisture should continue through the weekend, and daytime heating Saturday morning should allow for convective initiation in the afternoon. Storms should have ample moisture to work with from the aforementioned moisture stream and heavy downpours appear possible with some storms that develop. Gusty winds might be a possibility as well, with some forecast soundings already showing 30-40kt winds could down to the surface. The upper-level low shifts eastward Sunday morning, and conditions start to improve on Sunday as dry air works in from the west throughout the day. High pressure works into the area next Monday, with it likely sticking around through the week. Very dry and cool conditions are expected, with high temperatures in the mid-70s. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... Short Term...Can`t completely rule out a brief shower/storm at HIE and AUG this afternoon, but chances are too low for TAF inclusion. Otherwise, expect fog development again tonight, especially at RKD-AUG and LEB- HIE...where IFR-LIFR restrictions look likely. Once fog clears out Thursday morning, all should see prevailing VFR during the day, but it will be on the breezy side with southerly winds gusting to around 20 kt. Fog and low stratus are again possible Thursday evening and night with increasing chances for showers. Long Term... Lowered restrictions are expected on Friday, with restrictions continuing through Sunday morning. VFR expected Sunday through the end of next week. && .MARINE... Short Term...Winds will be primarily southerly today through Thursday night, which will increase gradually Thurs-Thurs night as a cold front approaches from the west. However, winds and seas are expected to remain below SCA levels with wind gusts expected to remain around 20 kt. Marine fog and stratus remains possible, especially east of Portland and Cape Elizabeth. Long Term... Southerly winds are expected on Friday, with winds and seas increasing to SCA thresholds by the end of the day. These conditions are likely to continue through the end of the day Saturday. Seas lower to 2-4ft and winds shift to westerlies Saturday night. Winds will also weaken to 4-8kts by daybreak Sunday. Mostly light and variable winds, with seas of 2-4 feet are expected through most of next week. && .FIRE WEATHER... Southerly winds will increase Thursday with gusts of 20 to 25 mph possible. These winds combined with RH falling to 35 to 40 percent over much of NH and 40 to 50 across interior Maine could make for increased fire sensitivity. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Combs/Ekster SHORT TERM...Combs LONG TERM...Palmer AVIATION...Combs MARINE... FIRE WEATHER...