Area Forecast Discussion
Issued by NWS Portland, ME

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394 FXUS61 KGYX 110258 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1058 PM EDT Thu Jul 10 2025 .SYNOPSIS... Scattered showers will continue into tonight along with low clouds and fog. Clearing tomorrow except for a isolated shower across the interior in the afternoon. The Bermuda high will be in place through the weekend, supplying mostly dry and warm weather. The ridge breaks down for the start of the new work week, with a return of hit and miss showers. Heat will begin to build by the middle of the next week once again. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
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The shields were up and held for much of the evening across the forecast area. The 11.00z GYX sounding observed nearly zero instability...and SPC mesoanalysis placed a sharp north/south gradient of MUCAPE just east of the CT River. As a result any strong convection that did form over VT and eastern NY tended to fall apart rather quickly as it approached. Now with the loss of daytime heating and synoptic forcing for ascent weakening...I have scaled back PoP overnight. It should not be much more than isolated to widely scattered...and mainly confined to the higher terrain if it does form at all. Otherwise marine layer will continue to slosh back inland...with clouds lowering already. Visibility will also tend to gradually drop towards sunrise...so I added some areas of fog near the coast...especially from Casco Bay and points south. Today will see the slow eroding of the low clouds again. Daytime heating will support scattered convection...largely tied to terrain heating since we lack a more synoptic scale lifting mechanism. There is a fairly well defined MCV present across Lake Michigan at this hour...and that could spark more widespread convection. Current model forecast have it over NY in the afternoon...but it will warrant some monitoring this morning to see if that forecast remains on track. Winds will be a little more southerly than easterly today...and so temps should be a few degrees warmer than what we saw yesterday.
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&& .SHORT TERM /7 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Weather Impacts: * No significant weather impacts expected * Dense morning fog on the coast can`t be ruled out Friday...Shortwave trough pushes through for tomorrow with westerly flow expected. Slightly drier air moves into the region with partial clearing expected as morning fog and stratus burns off. This should lead to clearing by the afternoon for all areas. CAM guidance shows potential for a few convective showers or weak storms over the terrain tomorrow afternoon. Overall areas coverage looks limited and severe parameters are weak. Not expecting and significant storms at this time but will let the night shift take another look. Friday Night...Clearing is expected, with potential for some fog development. Overall no weather impacts expected with high pressure in control. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Overview: High pressure will be over the Gulf of Maine come Saturday morning. This will keep mostly dry conditions through the forecast area Saturday and Sunday, but will need to watch for afternoon showers or storms near stalled boundary to the west. Additional showers and storms will organize along a incoming cold front Sunday night through Monday. This front will lead to broad ridging into midweek, allowing for another potential stretch of day with hot temperatures. Details: Saturday: While high pressure will be moving out of the Gulf of Maine through the day, onshore flow and high PWATs over the region will tend to bring afternoon showers or thunderstorms. Global models are hinting at a rather large footprint of QPF in NH through the afternoon and early evening. However in the absence of better jet dynamics and lifting feature, believe precip chances will lie close to topographic features vs. a widespread rainfall. This also aligns with diurnal trend of instability before coverage tails off in the evening. Sunday-Monday: A cold front will advance eastward out of the Great Lakes Sunday. Ahead, onshore flow moderates temperatures w/ areas remaining dry through much of the afternoon. PoPs begin to increase into the evening hours as weak forcing arrives while any daytime instability remains. Presently little conviction on coverage here as low levels are dry. Present rain chances focus on Sunday night-Monday associated with the frontal approach through Mon evening. Because the parent low drives north and occludes over Hudson Bay Sunday, forward progression slows. The result is precip influence from the boundary potentially through Mon night into Tuesday. There will be instability ahead of the front to bring the chance for thunder, mainly during the afternoon. Elevated instability will bring the chance for a few rumbles overnight and evenings as well. On the heels of that weather maker, a return to hot temperatures appears likely should the front move through by Tuesday afternoon. Daytime highs into midweek could again top out in the upper 80s to lower 90s with dewpoints reaching the upper 60s to around 70 degrees. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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Short Term...Highly variable conditions expected thru mid morning. Closer to the coast and across southern NH areas of IFR or lower will be possible due to marine fog and stratus. Elsewhere some patchy MVFR CIGs are likely anywhere along and south of the higher terrain. VIS/CIGs will scatter out towards midday...but some lingering MVFR CIGs remain possible. Scattered SHRA/TSRA are possible in the afternoon...but are not likely at any particular TAF site. Fri night once again areas of IFR are possible as marine moisture moves back inland. This will tend to target more western ME...but I cannot rule it out as far south as PSM. Similar scattering out is expected Sat...along with scattered SHRA/TSRA during the afternoon. Long Term...MVFR to IFR ceilings return Friday night into Saturday morning. Additionally, stratus may build down during the late evening hours leading to vis restrictions due to fog. While fog will tend to thin into the Sat morning hours, ceilings remain MVFR to IFR through the day. LIFR is probable Saturday night along with additional fog development.
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&& .MARINE...
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Short Term...Areas of fog will be possible over the coastal waters...especially from Casco Bay south. Some improving visibility is likely during the day...but fog is expected to thicken and move back towards the coast during the evening and overnight hours. This will tend to occur mostly north of Casco Bay into Sat morning. Otherwise winds and seas will remain below SCA thresholds. Long Term...Conditions remain below SCA through the period. There will be the chance for marine stratus and fog to cause reduced visibility through this weekend and into early next week.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Dumont LONG TERM...Cornwell AVIATION...Cornwell/Dumont MARINE...Cornwell/Dumont