Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
136 FXUS61 KGYX 170609 AFDGYX Area Forecast Discussion National Weather Service Gray ME 209 AM EDT Sun Aug 17 2025 .SYNOPSIS... A cold front will bring the chance for some showers and storms today, followed by cooler fall-like weather for the start of the work week. An area of low pressure will approach the region by mid-week, bringing a period of unsettled weather. High pressure builds in from the north through the end of next week as Hurricane Erin passes by well offshore. && .NEAR TERM /THROUGH TODAY/... A short wave trough will approach from the NW today with it`s associated height falls and attendant cold front. The airmass will be able to heat up substantially prior to the cold frontal passage, with highs well into the 80s and lower 90s. Instability and deep layer shear will be supportive of thunderstorms, some strong to severe and will favor the coastal plain based on frontal timing. Low level lapse rates will be very steep which will favor widely scattered areas of wind damage. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...Showers and storms sink south off the coast in the 7-9PM window. The drier air and clearing skies north of the mountains should allow that area to drop into the low to mid 40s. South of the mountains, where influence from the front may take a little longer, has a better chance of bottoming out in the low to mid 50s, with some upper 50s along the southern coast. Winds south of the mountains also look quite breezy post front south of the mountains with some 15-20mph gusts possible through the midnight hour. High pressure building in on Monday will mean sunny, dry, and much cooler weather. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... - Below normal temperatures beginning of forecast period - Very dry airmass in place on Tuesday - Showers possible for western areas on Wednesday, drought continues! - Erin passes well offshore on Thursday bringing a high surf threat Tuesday will be a quiet and cool day with a cool airmass in place as a Canadian surface high is centered over the area. Min RH should drop below 35% in some areas with full solar insolation on the drought stricken landscape. By Wednesday a weak shortwave trough aloft passes overhead. Guidance is showing around a 40% pop chance with showers possible, especially across NH but wetting rain chances look limited for most of the area. This will be the best chance for rain still though until later next weekend most likely. On Thursday Erin will make its closest approach to the area, but will still be well south of the area by at least 500 miles. One very interesting thing is how guidance keeps Erin a major hurricane so far north. The biggest impact will be the long period swell that will bring dangerous high surf and rip currents to the coastline on Thursday into Friday. This will have to be watched for high surf advisories. Besides this there will be north winds keeping the region dry once again. By the end of the week, temperatures will be on the upswing with southwest return flow and increasing temperatures. Will have to keep on eye on how gusty winds get on Saturday ahead of the next possible rain maker. && .AVIATION... Short Term...Other than valley fog and brief restrictions from showers and thunderstorms this afternoon, mainly VFR conditions are expected tonight through Monday night. Long Term...No significant aviation weather impacts expected through this period with limited stratus incursions expected as high pressure and relatively low dewpoints keep the threat for low marine stratus low through most of the week. Some valley fog is possible at KLEB and KHIE. .MARINE... Short Term...Seas and wind gusts stay mostly below SCA criteria through this period. The exception is overnight Sunday when gusts around 25kts behind a cold front moving over the waters may bring a few hours of SCA conditions. Showers and thunderstorms are possible late this afternoon and evening as the front makes it`s approach. A special marine warning or two is possible. Long Term...Seas will be on the increase through week with a long period swell from Erin expected to reach the Gulf of Maine by Thursday and last into Friday with high period waves of up to 10 feet. This will lead to a period of SCA. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Dumont