


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
628 FXUS61 KGYX 170547 AFDGYX Area Forecast Discussion National Weather Service Gray ME 147 AM EDT Fri Oct 17 2025 .SYNOPSIS... Low pressure south of Nova Scotia loosens its grip on the region today as it drifts east and high pressure builds in from the west. High pressure settles south of New England Saturday and moves east Sunday in response to trough swinging through the Great Lakes. This trough will send a frontal system into New England Sunday night and Monday bringing chances for some beneficial rain. Troughing lingers over the Northeast through the middle of next week with additional chances for showers. && .NEAR TERM /TODAY/... At the upper levels, a low continues to spin out over the ocean with a ridge axis located to our west over the Midwest. High pressure will start to move into the region at the surface through the day but the pressure gradient will remain fairly tight through the morning and early afternoon, leading to more breezy winds out of the north and diminishing cloud cover. Additionally, there could be some patchy frost this morning, especially across our western zones where winds are quicker to diminish. Today will be a touch warmer than yesterday with highs mainly in the lower 50s to lower 60s. A few readings in the 40s are likely across the mountains. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... Winds will diminish tonight and we should have clear skies so conditions should be ripe for radiational cooling. For lows tonight, utilized a blend of NBM and the NBM 10th percentile to nudge temperatures a bit closer to what we expect. Forecast lows will range from the low to mid 20s north and across the mountains, to the low/mid 30s south and a long the coast. With the light winds, widespread frost is likely overnight. In coordination with the neighbors, will hold off on any headline decisions for now, but frost/freeze products may be needed tonight for some southern New Hampshire and interior zones. The ridge axis moves overhead on Saturday, leading to another slight warmup and plenty of sunshine with highs mainly ranging from the mid 50s to the mid 60s. We should start to see some increasing cloud cover across New Hampshire during the later afternoon hours but the forecast will remain dry. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... 01Z NBM Update...No significant changes noted in the latest NBM other than a slight increase in PoPs Sunday night into Monday and Tuesday night into Wednesday. There is a spread amongst ensembles with respect to QPF Sunday night into Monday with the GEFS mean QPF around 0.25 to 0.5 inches and the ECMWF/CMC ensembles around 0.75 inches with higher amounts in the mountains. Overall looks like some beneficial rain by Monday evening. Unsettled conditions likely persist into the middle of the week with another possible frontal system crossing around Wednesday. Previously... Pattern Overview: A ridge moves east Sunday for continued mostly dry weather and above normal temperatures. The pattern then becomes increasingly unsettled as multiple upper level lows look to pass through the region next week. Impacts and Key Messages: * Temperatures trend above normal through the weekend * The pattern becomes increasingly unsettled next week with multiple disturbances to keep an eye on Details: Sunday and Monday: The ridge axis shifts eastward over the Gulf of Maine Sunday increasing the southwesterly flow aloft and warming 850mb temperatures to around +11C. This looks to be the warmest day with temperatures south of the mountains able to climb into the mid- to upper 60s, and into the low to mid 60s to the north under mostly clear skies. Clouds build in during the evening and overnight as a potent trough approaches the region. This keeps Sunday night mild with lows only able to fall into the 40s areawide, with the coastline hovering around 50F. Models have come into slightly better agreement regarding timing of the front Monday, but the positioning of the low is still up in the air as the Euro continues to cut off the low over the Mid Atlantic, while the GFS has an inside runner that whips off to the northeast. The GFS solution is faster and drier with ensemble probabilities of greater than a half inch less than 30%. The Euro solution would result in a more prolonged event with probabilities greater than a half inch in the 30-50% range. Tuesday-Thursday: The main difference in the above solutions mainly effects Tuesday`s outcome. As mentioned the GFS solution is in and out on Monday making for a mostly dry Tuesday. The Euro has the low crawling eastward continuing showers through the day Tuesday. The QPF looks light and largely inconsequential if the Euro ends up correct, but the difference between a dry day and light showers is, so this will have to be watched. There is decent agreement in another upper low swinging in right behind this one midweek and taking the southern/coastal track. This one being at the end of the forecast period means there is plenty of time for further developments, but an early look at ensemble probabilities for the Wednesday-Thursday period suggest another round of mostly light showers with probabilities of greater than a half inch less than 30% in both suites. Stretching this out to look at the probability of greater than an inch accumulating from both events yields a 40-60% chance from the Euro ensemble suite and 20-40% for the GFS suite. As has been said many times over the past few months, beneficial rain may be on the way, but it won`t be a drought buster. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term...AUG and RKD continue to see MVFR ceilings holding on early this morning, but we should start to see improvement here over the next few hours as the stratus deck continues to erode to the east. Otherwise, VFR conditions should prevail through at least Saturday. Some patchy fog will be possible across the valleys and coastal areas Saturday night. Long Term...VFR likely prevails Sunday before ceilings begin to thicken and lower after 00Z Monday. Monday could be a mix of MVFR and potentially lower conditions as showers move through the region. This may result in fog Monday night if the showers come to an end. Tuesday may also feature some showers, but even if it does not, ceilings likely remain largely MVFR. && .MARINE... Short Term...Gusty north northwest winds should continue through the morning. Marginal gales outside of the bays will transition to SCAs at some point early this morning. SCA conditions will also linger in the bays this morning. High pressure builds in later today and winds/seas will continue to gradually diminish. Long Term...Winds and seas will be below SCA thresholds Sunday. Southerly winds increase Sunday night into Monday along with building seas ahead of a cold front. SCAs will likely be need for winds and seas during this time period. Winds drop below SCA thresholds Monday night while elevated seas may necessitate SCAs into Tuesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Gale Warning until 8 AM EDT Friday for ANZ150-152-154. Small Craft Advisory until 8 AM EDT Friday for ANZ151-153. && $$ NEAR TERM...Hargrove SHORT TERM...Hargrove LONG TERM...Baron/Schroeter