Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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357 FXUS61 KGYX 190725 AFDGYX Area Forecast Discussion National Weather Service Gray ME 325 AM EDT Fri Jul 19 2024 .SYNOPSIS... A dry and seasonable pattern is expected through the upcoming weekend and into early next week. High pressure will slide south of the region through Saturday. Outside of a few mountain showers Saturday night...the next chance for precipitation across the area does not arrive until next Tuesday in the form of showers and thunderstorms ahead of a cold front. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Seasonable and pleasant today as dewpoints have fallen 10+ degrees in the past 24 hours for much of the area. The responsible cold front pushed offshore overnight, allowing this drier air to take hold after a week of humid conditions. Mostly sunny skies are expected today, but some cu development is possible through the mid to late afternoon as PBL depth increases. Model soundings are very dry aloft, and this should keep these clouds fairly flat. Only standout item today would be a sea breeze developing early this afternoon and pushing inland. This will offer a wind shift as well as curb afternoon temps a degree or two as it pushes inland. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Another refreshing night in store tonight as daytime mixing ceases and skies remain mostly clear. Radiational cooling should be favored, and have went lower in temps across the valleys in the Whites as well as some common locations through the ME Lakes Region and Midcoast. Temps overall fall into the 50s, but would expect to see some locations dip into the upper 40s across the north. NW temp advection is lighter Saturday, and the area will be poised north of high pres passing to the south. This should allow area temps to rebound compared to Friday, pushing into the mid to upper 80s away from the immediate coast. Dry air remains in the region, but there may be an increase in high level cirrus as moisture arrives aloft. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... High Impact Weather Potential: Minimal through early Tuesday. Chances for showers and thunderstorms increase for Tuesday- Thursday though confidence is low on any severe weather/hydro threats at this range. --Pattern and Summary-- The longwave pattern is expected to remain rather stable through the long term forecast period with a substantial longwave ridge located along the spine of the Rocky Mountains with troughs on either side of this over the eastern Pacific and eastern North America. This will keep the flow aloft generally from the west northwest or west with H5 heights and T8s pretty close to...or just above seasonal norms. Through early next week...the modified Canadian airmass will keep the weather quiet and dry. By the middle of next week...the eastern trough will reload as energy drops into the Great Lakes region...allowing our flow to back southwesterly and allow a frontal system to move through the region to end the forecast period with what will likely be the most active portion of the forecast weather- wise. --Daily Details-- Saturday night through Monday: A cold front crosses the area Saturday night with a few mountain showers....but frontal timing and thinning moisture plume suggests little overall rainfall. Drier and somewhat cooler air sinks in from the north for Sunday...with decreasing clouds and mountain high temperatures in the 70s. Further south...T8s won/t change too much from on Saturday...and therefore 80s are again expected for highs. The drier airmass will allow for more substantial cooling Sunday night with some mountain valley locations likely reaching the upper 40s while 50s to just above 60 is likely further south. High pressure remains in control through Monday with some weak moisture return as the flow aloft begins to back ahead of the next shortwave/cold front dropping into the Great Lakes region. Generally neutral temperature advection should allow for similar daytime highs...mid/upper 70s in the mountains and 80s to the south. Tuesday through Thursday: The second half of the long term forecast turns more active as the eastern trough initially reloads over the Great Lakes...with a positive tilt allowing the flow over the northeast to turn more southwesterly...allowing for building moisture. A weak front dropping into the region Tuesday may spark some showers and thunderstorms with this trend continuing through Wednesday as the flow remains generally parallel to the front causing it to stall and service as a llevel focus for lift. Global ensembles differ on the eventual evolution of the upstream positively tilted trough across the Mississippi Valley and additional shortwave energy diving out of Canada. With the likelihood that the overall trough axis remains west of our longitude through Thursday will necessitate a continuation of shower/storm chances with building humidity but temperatures close to seasonal norms with clouds and precipitation potential. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... Short Term...Outside of some overnight valley fog near HIE/LEB, terminals remain VFR through Saturday. Terminals along the coast will see an afternoon seabreeze cause a wind shift before slackening overnight. Long Term...VFR conditions should persist through Tuesday morning with some morning fog possible each morning at HIE/LEB. Tuesday afternoon will bring a chance of restrictions given a chance for showers and thunderstorms. && .MARINE... Short Term...Breezy today and again Saturday, but values will remain below SCA levels. Waves trend to 2 to 3 ft over much of the coastal waters as high pressure approaches the Mid Atlantic during the first half of the weekend. Long Term...Winds/waves are expected to remain below SCA levels through the long term forecast period Saturday night-Tuesday. Thunderstorms are possible over the waters by Tuesday afternoon. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Cornwell SHORT TERM...Cornwell LONG TERM...Arnott