Area Forecast Discussion
Issued by NWS Portland, ME

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613 FXUS61 KGYX 021755 CCA AFDGYX Area Forecast Discussion National Weather Service Gray ME 155 PM EDT Wed Jul 2 2025 .SYNOPSIS... A cold front moves offshore tonight providing our area with fair dry weather and lower humidity. Another front will approach Thursday afternoon with showers and thunderstorms, a few of which could be strong to severe. That front will usher in a much drier air mass for Independence Day, with temperatures in the 70s and 80s and comfortable relative humidities. The weekend will gradually get warmer and more humid with shower chances mainly confined to the mountains on Sunday. && .NEAR TERM /THROUGH TONIGHT/... A modest drop in humidity was observed across the region as a cold front stalled near the coast. This boundary combined with a sea breeze could support a few pop-up showers in the Midcoast this afternoon. The front will slowly proceed further offshore overnight before washing out. Clearing skies and calm winds behind it will allow temperatures to cool into the upper 50s to mid 60s from N to S. Can`t rule out some pockets of valley fog, but coverage will be patchy at best. The only exception will be concerns for sea fog development from the midcoast eastward, likely to impact coastal communities in that area late tonight into the early morning. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
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Key Messages - Approaching front will bring rain and thunderstorms Thursday, with gusty winds possible. An upper-level trough dipping southeastward out of Quebec tomorrow will pivot its attendant cold front through the local area early in the late afternoon/evening. The height falls aloft combined with modest instability support expanding widely scattered shower and thunderstorms. Overall moisture is expected to be quite a bit lower than the last few days, with PWATs only around 1.25" for the majority of the event, limiting the heavy rain potential. Although tomorrow`s moisture content is not expected to be as high, surface heating promoted by mostly sunny skies will allow for temperatures to rise swiftly into the upper 70s and low 80s. These warm temperatures may allow for MUCAPE values of 1000+ J/kg for a few hours in the afternoon. This, coupled with moderate 0-6km bulk shear values of 30-40 kts could allow for severe weather in the afternoon and evening. As a result, the SPC has our area in a Marginal (level 2/5) Risk for severe weather, with damaging winds and hail as the main threats. Storms are currently expected to initiate in the mountains in northwestern Maine and northern New Hampshire before moving 43towards the coast throughout the evening. The most likely time for storms is 1-7 pm, possibly impacting any early 4th of July celebrations. Any severe threat would most likely be during the afternoon and early evening hours. There are still some disparities between hi-res guidance, with some models placing the front back in northwestern ME by peak heating hours whereas others already have the front nearing the coastal areas. Additionally, while low level lapse rates appear favorable, relatively weak mid level lapse rates could limit the amount of instability as well as the threat for hail. As a result, gusty winds look like the most likely threat with DCAPE values of 600-700+ likely. Drier air will filter in behind the frontal passage, with lowering dewpoints and clearing skies. This will support a cool night with lows in the 50s.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... A more comfortable airmass settles in Friday featuring highs mainly in the mid 70s to lower 80s with lower dewpoints/humidity. As the upper low crosses into the eastern part of Maine, it may set off a few showers and a storm or two across northern areas, but the vast majority of the area will stay mostly to partly sunny and dry. Friday night temps will be mostly in the 50s, but northern valleys may see the upper 40s. Mostly dry conditions are expected over the weekend as a 500mb ridge steadily builds in, although models are hinting at a weak wave moving in on the northwest flow aloft, which may bring a few showers across the north Saturday night. Otherwise, the building ridge will bring a warming trend with highs in the low to mid 80s Saturday, and by Sunday, lower 90s are possible across portions the area as 850mb temps are progged to get to around +19C with humidity also creeping back upward as a front approaches from the north. Speaking of the front, there`s been a slowing trend in its approach, so chances for precip have continued to decline for Sunday with most expected to stay dry at this point, except maybe far northern areas where PoPs remain at 20-30%. The front begins pushing southward early next week with the higher chances for showers and thunderstorms coming Monday into Tuesday. It looks to remain hot Monday, and then temperatures may come down Tuesday into Wednesday depending on how far south the front progresses. && .AVIATION /17Z WEDNESDAY THROUGH SUNDAY/... Short Term...VFR conditions in place with only high clouds (20k ft) draped over southern terminals from a stalled frontal boundary. High humidity and nearly-calm conditions over the waters could produce some marine fog over the midcoast, with some IFR conditions possible at RKD late tonight/early Thursday. Otherwise VFR conditions likely. Widespread MVFR cigs and vis expected to start by 17-19z and linger through 00Z with hit/miss convection. Some stronger storms may also pose a risk of gusty winds up to 35-40 kt at times, but confidence too low to include Prob30 at this time. Long Term...Mainly VFR Friday with a couple of showers possible, mainly north of an AUG-HIE line. Over the weekend, prevailing VFR during the day, but there may be valley fog at night. A front approaching from the north may bring a chance of showers and storms as early as Sunday, but it`s more likely showers and storm hold off until Monday. && .MARINE... Short Term...Washed out frontal boundary will stall just of the coastal waters tonight. SW flow will continue with speeds generally less than 15KT, enhanced by an afternoon thermal gradient. Tonight winds will ease further and turn to the north or variable as the front weakens and drifts further offshore. Winds will back to the SW ahead of another weak front Thursday, but again winds will remain 10- 15kt or less generally. Seas will generally be 1-3 ft with weak winds and <1ft swells of 9 seconds. Long Term...SCA conditions not expected Friday with offshore flow behind a frontal boundary...but may become more variable in the afternoon as a seabreeze tries to develop. High pressure becomes centered southeast of the waters over the weekend into early next week as a frontal boundary approaches. The pressure gradient may become tight enough to bring SCA conditions as south to southwest winds increase in the late Saturday through Monday timeframe. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Jamison SHORT TERM...Venarsky LONG TERM...Combs