


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
747 FXUS61 KGYX 171733 AFDGYX Area Forecast Discussion National Weather Service Gray ME 133 PM EDT Fri Oct 17 2025 .SYNOPSIS... High pressure settles south of New England Saturday and moves east Sunday in response to a 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 next week, allowing for additional disturbances, and chances of rain, to enter the region. && .NEAR TERM /THROUGH TONIGHT/... Upper ridge axis continues to inch towards the forecast area today...and should be close to overhead by sunrise Sat. So skies are expected to remain mostly clear tonight and good radiational cooling conditions are forecast. Opted to blend a little MOS and 25th percentile NBM forecast to bring low temp forecast more in line with expectations. There will probably be some frost out there...but mainly in the zones where growing season has ended. At this time no frost headline are planned. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... Slow moderation in temps is anticipated on Sat. Under the influence of surface high...subsidence will limit mixing...plus warmer temps aloft will not have arrived yet. Still looking at fairly widespread 60s even into the northern valleys. By Sat night increasing cloud cover and continued WAA will keep temps on the warmer side. Generally low temps will be at or above freezing for the majority of locations. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Pattern Overview: The ridge pushes off to the east Sunday giving way to what looks like an active week. Models are in decent agreement on a train of upper level disturbances moving through the region over the course of the work week. Impacts and Key Messages: * The weather pattern turns active next week, with multiple chances for widespread showers. Rainfall amounts remain uncertain, but significant impacts are not expected at this time. Details: Sunday: The ridge axis moves off to the east Sunday increasing southwesterly flow aloft ahead of a potent trough over the Great Lakes Region. This warms 850mb temperatures to around +11C and skies should remain clear enough through the peak heating hours for surface temperatures to climb into the mid- to upper 60s areawide. Flow turns onshore at the surface as low pressure approaches from the west, so the immediate coast may stay a bit cooler as the ocean temperature now well into the 50s. The upper low cuts off Sunday night and thicker cloud cover builds in out ahead of it keeping low temperatures on the mild side (mid- to upper 40s areawide). A few showers are possible heading toward sunrise Monday, but the bulk of the precipitation holds off. Monday and Tuesday: The latest developments in regards to the first disturbance early in the week is that confidence in precipitation timing has increased, but rainfall amounts remain uncertain. The GFS has come on board with the Euro, having the low taking the southerly track (The Canadian remains an outlier), but in turn the Euro is starting to follow the GFS in speeding the system up. The GFS is still the fastest, but this increases confidence in seeing a period of drier weather at some point on Tuesday. There has been a notable uptick in QPF in the Euro ensemble suite with probabilities of greater than a half inch now 60-80% (the higher probabilities are in the mountains), but the GFS ensemble suite remains unimpressed and is holding steady with probabilities of 20-40%. As mentioned yesterday, this is likely due to the progressiveness of the system, the GFS wants Tuesday to be mostly dry, while the Euro has showers at least into Tuesday evening. There are a few other considerations that have me leaning toward the Euro solution, the first being that PWATs are going to be modest. The axis of higher PWATs remains offshore, but over our area they are currently modeled around one inch. The second is that it looks like we will have a ~50kt low level jet overhead, so some jet dynamics are bound to come into play here, developing some heavier showers. That being said, we will also have to keep a close eye on the potential for a wind threat to develop. The global models have the tight gradient and low level jet, but their lower resolution is assuming it will be too cloudy to mix any gusts down and can`t resolve a convective wind threat. Don`t be surprised if this becomes a talking point as this system begins to creep into the CAMs, but for now expecting generally 25-30 mph gusts on Monday seems reasonable. Wednesday-Friday: There is decent agreement among the global models that the pattern remains active through the work week, with another upper low swinging in behind the first one Tuesday night/Wednesday morning. This is then followed by a weaker open wave late in the week. I will leave it at that to avoid too much speculation (and writing a tome), but the takeaway should be to keep a close eye on your forecast as we work out the details of each one (and maybe keep a raincoat or umbrella handy next week). && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... Short Term...VFR conditions expected thru Sat night for most locations. Cannot totally rule out some CT River Valley fog tonight and again Sat night...but confidence is not high enough to include in the TAF at LEB at this time. Long Term...VFR prevails through the day Sunday, with ceilings thickening and lowering Sunday night. Monday sees generally MVFR conditions with showers. Some brief IFR restrictions can`t be ruled out if heavier rain materializes. Wind gusts 20-30kts are likely as well, especially at coastal terminals. Some fog may develop after around 06Z Tuesday as rain tapers off and skies clear a bit. Some improvement may be seen for a period on Tuesday, but another system swings in Tuesday night so it will likely be brief. && .MARINE... Short Term...SCA conditions continue outside the bays today...but winds and seas continue to diminish. Current SCA looks pretty good on timing...but south of Cape Elizabeth some lingering seas near 5 ft are possible into tonight. Long Term...Seas build back to around 5ft Sunday night as a low pressure system approaches the waters. Wind gusts will also increase Sunday night with Monday featuring frequent gusts 25-30kts. Winds calm below 25kts Monday night, with seas slower to subside and likely not falling below 5ft until late in the day Tuesday. An SCA may be needed in the mid-week timeframe as another system passes through. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150- 152-154. && $$ NEAR/SHORT TERM...Legro LONG TERM...Baron