Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 250038 AFDGYX Area Forecast Discussion National Weather Service Gray ME 738 PM EST Wed Feb 24 2021 .SYNOPSIS... Low pressure will race eastward along the Maine-Quebec border tonight bring accumulating snow to areas along the the border and scattered rain showers elsewhere. A cold front will cross the forecast area tonight with winds increasing later tonight and gusting around 30 MPH on Thursday. Another fast-moving weather system will move across the forecast area on Saturday bring rain and snow. Colder high pressure then builds in early next week. && .NEAR TERM /TONIGHT/... 730PM UPDATE... First wave of light precipitation is crossing the area currently, although few observations so far have reported anything at ground level. Surface low remains to the northwest along the NY/Ontario border. Still expecting the most significant precipitation to skirt the northern border of NH and ME tonight where a few inches of snow is possible. Elsewhere another round of light rain showers is possible this evening before the cold front moves across tonight. ORIGINAL DISCUSSION... A short wave trough and attendant SFC low pressure center located over Lake Huron as of this Wednesday afternoon will race eastward along or near our border with Quebec tonight. As such, much of the forcing for ascent will be north of our CWA. However, locations near the Canadian Border such as Coburn Gore northeastward to near Jackman should pick up at least a few inches of snow tonight. South of that area, the rest of the forecast area will largely be warm sectored overnight allowing for mostly dry weather and relatively mild overnight temperatures. The exception will be a fast-moving line of rain showers (currently located from KPIT northeastward to eastern Lake Ontario) that will affect the rest of the forecast area this evening. If we had more moisture, there might be a few thunderstorms. However, will leave them out of the forecast due to lack of instability. A cold front sweeps across the forecast area late tonight with gusty winds. Temperatures south of the mountains will be pretty warm overnight due to being warm sectored with a strong low level jet in place. Most locations will remain in the upper 30s to lower 40s unless localized decoupling takes place. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... Strong CAA will occur on Thursday in the wake of the cold front. Temperatures will be 5 to 10 degrees colder than today, with a decent wind chill. Westerly winds will gust around 30 MPH for much of the day with some gusts around 35 MPH possible with good mixing expected. We should remain short of wind advisory criteria outside of some localized instances. Upslope snow in the mountains in the morning will wane as the day progresses. High pressure gradually builds in from the west Thursday night with gradually diminishing winds and fair weather. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Overview: A series of short-waves will move through New England beginning late Saturday through early to mid next week bringing multiple chances for both rain and snow to northern New England. Rain will be the predominant precipitation type in most locations but the mountains will likely be just cold enough for at least minor snow accumulations. A temperature roller coaster is expected with daily high temperatures both above and below average, although above average will be more frequent. Impacts: Minimal. Some locally icy spots will be possible each morning as daytime temperatures rise well above freezing allowing for melting of snow and ice before refreezing at night. Rain and snow late Saturday afternoon and night may result in locally slick travel conditions, especially across the north. High pressure will be centered to our south and west on Friday morning before moving northeastward off the Southern New England coast by Friday evening. This will result in a mostly sunny but cool day with high temperatures ranging from the middle 20s across the north to the 30s across southern NH and southwestern ME. A few locations near the Massachusetts state line may approach the 40 degree mark. Despite northwest winds resulting in upslope flow there will be enough subsidence over the area that even the mountains should stay dry and mostly sunny. Clouds will increase overnight on Friday and into Saturday morning as high pressure moves well off to our east and an area of low pressure associated with a frontal system advances northeastward towards New England. WAA may result in a brief period of light snow or flurries across the region during the morning hours, especially across southwestern NH, as indicated by the latest model guidance. As this weak system continues to advance northward southerly winds at the surface will allow temperatures to climb into the middle 30s across the north to the middle 40s in southern NH. Initially, 850 mb temperatures on Saturday morning and early afternoon will still be cold enough to sill support a few wet snowflakes to reach the surface even where surface temperatures are well above freezing but during the evening warmer air aloft will result in a changeover to all rain for most areas outside of the mountains. Some snow accumulations will be possible across the mountains and far north, but even in these areas rain may still mix in at times. Model ensemble means are in good agreement with generally bringing in between a quarter to locally a half inch of total QPF, with the highest amounts likely closer to the coast. There remains some disagreements in ensemble guidance in potential snow accumulations as the GFS ensembles are generally warmer than the ECMWF but on average expecting a coating to a half inch of snow for the coastal plain and foothills before the changeover to rain while the far north and mountains may receive several inches of snow. This system will rapidly move to the north and east of the area by Sunday morning as high pressure builds to our west. Skies will be partly cloudy with unseasonably warm high temperatures ranging from near 40 across the north to the lower 50s across southern NH. Another system may bring rain and snow on Monday as a relatively weak disturbance drops south out of Canada. The CMC ensembles are the most bullish on this potential as it develops a secondary low along or just offshore, which enhances precipitation chances. Due to this system still being several days out and a lack in ensemble agreement chance PoPs were used in this forecast package. Temperatures will still be mild though into the 40s and therefore rain would be the favored precipitation type. A cold front will then cross through New England on Monday afternoon or night pushing this system out of the area as much colder air filters in behind it. High pressure will then move in for Tuesday and and Wednesday with temperatures at or below average. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... Short Term...VFR conditions with a few pockets of MVFR cigs are expected tonight for most areas except in the mountains where lower conditions are expected in snow or mixed precipitation. LLWS will be present at most terminals tonight as a southwesterly low level jet of up to 50 kt moves overhead. VFR conditions are expected Thursday outside of the mountains. Westerly wind gusts 25 to 30 kt are expected Thursday which will diminish Thursday night. Long Term...VFR conditions expected on Friday for all terminals with west winds becoming southwesterly during the evening at between 10-15 kts. Patchy light snow on Saturday morning may result in MVFR conditions for some, especially across southwestern terminals. Widespread MVFR/IFR conditions possible Saturday afternoon and night as rain and mountain snow overspreads the region. VFR conditions will return by Sunday morning. && .MARINE... Short Term...Gales continue for the outer waters with small crafts in the bays tonight and Thursday. Confidence in gales is high. Winds and waves gradually subside Thursday night as high pressure pushes eastward toward the region. Long Term...Winds and seas should remain just below SCA criteria on Friday with northwest winds gusting to around 20 kts, especially early. SCA conditions are likely beginning Saturday afternoon through Saturday night as strong WAA allows southerly winds to gust between 25-30 kts and seas build to 4-7 feet. Winds decrease on Sunday to less than 25 kts but seas will remain elevated at 4-6 feet. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 7 PM EST Thursday for ANZ151-153. Gale Warning until 7 PM EST Thursday for ANZ150-152-154. && $$ NEAR TERM UPDATE...Ekster SHORT TERM...Ekster LONG TERM...Tubbs AVIATION...Ekster/Tubbs MARINE...Ekster/Tubbs is the U.S. government's official web portal to all federal, state and local government web resources and services.