


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
880 FXUS61 KGYX 180536 AFDGYX Area Forecast Discussion National Weather Service Gray ME 136 AM EDT Mon Aug 18 2025 .SYNOPSIS... A cold front will bring a round of showers and a few thunderstorms today, followed by cooler weather for the start of the work week. A weak trough will trigger some showers Wednesday, followed by high pressure building in from the west. Temperatures will warm back into the 80s by late week. && .NEAR TERM /THROUGH TODAY/... High pressure continues to build southward today with fair weather and cooler temperatures. Early morning valley fog will lift quickly after sunrise. && .SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/... High pressure crests overhead tonight into Tuesday morning. Good radiational cooling is expected, with a few readings in the north possibly bottoming out in the upper 30s if clouds do not thicken too early. Dry with highs in the 70s on Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... No notable changes to the long term forecast as the week remains mainly dry and seasonably cool. The best chance for a few showers arrives Wednesday. The main focus will be the increasing surf and rip currents from Hurricane Erin passing offshore, starting by late Wednesday. These peak on Friday, and likely continue into the weekend. Temperatures also begin to moderate during this timeframe. Previously... Key messages -Overall trend favors below normal temperatures and rainfall for much of the extended. -Warming trend for late week into the weekend Looking at a cold start on Tuesday with many locations in the 40s, and with light winds we can expect steam fog over inland water bodies. High pressure will dominate on Tuesday with just a few fair wx cumulus clouds. Return flow out of the S will try to bring in some moisture, but daytime mixing will counteract much of it keeping dewpoints <50F. Clouds drift in Tuesday night as a shortwave swings across the area. This feature will have dynamics to support scattered showers, but models are starting to recognize the moisture-starved airmass ahead of it and have backed off on both POPs and QPF. Most areas will be lucky to get 0.1" out of this system, with best probs in the north. Cloud cover will keep temps a few degrees cooler on Wednesday, with 60s to low 70s for most areas. Mainly dry conditions are expected Wed night through Fri as high pressure slides east. Ridging aloft will support warming temperatures for both Fri and Sat, with highs in the 80s returning. The next chance for rain is likely to be associated with a cold front Sunday, but low confidence on coverage at this point. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Short Term...Winds will be breezy this morning with most terminals likely to see northerly gusts up to 15kts at times and coastal terminals like PWM and PSM could see gusts around 20kts. Wind gusts will begin to relax late this morning before going onshore. VFR ceilings prevail except for early morning valley fog early this morning and early Tue morning. Long Term...There will be localized river valley fog through midweek that will cause localized reductions, especially across the northern terminals. Otherwise, large area of Canadian- sourced high pressure will expand across the region providing widespread VFR conditions through the entire TAF period except perhaps Wed in scattered showers. && .MARINE... Short Term...Any SCA gusts should weaken by late morning with winds going locally onshore this afternoon. SCA conditions are not expected then through Tuesday. Long Term...Conditions will gradually deteriorate as long period swell from Erin makes its way to the Gulf of Maine. Looking at long period swells of 12-15 sec reaching the area Wednesday, growing to 17-20 sec Thu into Fri. Wave heights will peak on Friday with SCA conditions likely with seas >5` for much of the coastal area. High rip current threat all but guaranteed, and a good chance for high surf conditions for at least the Midcoast. Winds during this time will be <10kt with predominantly offshore flow. && .GYX WATCHES/WARNINGS/ADVISORIES...AVIATION... MARINE... ME...None. NH...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ150- 152-154. && $$ NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Clair/Jamison