Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 080118 AFDGYX Area Forecast Discussion National Weather Service Gray ME 818 PM EST Sun Mar 7 2021 .SYNOPSIS... Cool and fair weather continues tonight as high pressure builds in from the west. A warming trend will start Monday into the second half of the week. Much of the week will be precipitation free with the exception of isolated mountain snow showers Monday night and rain showers towards the end of the week as a front approaches. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Update... Clear skies continue across the forecast area per latest satellite imagery. With easing winds and very dry air in place for the overnight hours, the instinct is to lower temperatures due to radiational cooling, especially across the north. However, satellite imagery does show some low and mid level moisture over Quebec Province moving southeast this evening. Latest HREF guidance does bring a period of cloudiness across northern and eastern zones after midnight. This would reduce the rate of cooling in some areas. Because of the discussion above, have allowed for clear skies through the late evening hours, but have added clouds to the forecast after midnight. Have lowered the wind forecast for the near term portion of the forecast and left forecast mins as is. Prev Disc... Beautiful day across northern New England, with satellite showing only a few stray clouds over the Gulf of Maine. The strong March sun has allowed temperatures to climb above freezing in the south even as the temperatures aloft remain relatively cool. That cold pool aloft will remain overhead through tonight, and the clear skies should allow for some good radiational cooling. Have pushed low temperatures to the bottom quarter of the range, with a few below zero spots expected across the northern valleys. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday will see the start of what will become a week long warming trend. The cold air aloft will pull out to the east with moderating temperatures. Highs will again reach above freezing, this time with the thawing temperatures pushing northwards into the foothills. With the sun have leaned warm on the highs. A weak wave will pass to the north of us late Monday afternoon. While most of the precip looks to stay in southern Quebec the mountains of Maine may eek out a few snow showers from this, and have increased both pop and cloud cover overnight in support of this. That cloud cover and the warming temperatures will significantly moderate the overnight lows, pulling them back into the teens north to mid 20s south. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Overview...The warming trend begins in earnest on Tuesday with temperatures looking to peak on Wednesday and Thursday. While we will not be setting any records, temperatures will be some 10-20 degrees above normal for mid-week. Significant precipitation continues to look elusive in the long term, but a frontal system could bring isolated to scattered showers to the region toward the latter part of next week along with a return to near-normal temperatures. Impacts...Minimal. The warm temperatures mid-week in southern areas, especially southern NH, could lead to some ice movement on rivers and that could ultimately lead to ice jams. Forecast Details...A shortwave is expected to brush northern portions of the region Monday night into Tuesday morning while crossing through Quebec. However, not expecting any significant impacts from this system other than isolated to scattered snow showers in the mountains and foothills with very light accumulations possible. The big story in the long term is the warm temperatures expected for mid-week. From Tuesday through Thursday, surface high pressure builds over the eastern U.S. while mid-upper level ridging also builds into New England. This setup will allow deep southwest flow to develop and funnel warmer air into the region. Parts of southern NH and southwestern ME should reach 50 degrees on Tuesday, but Wednesday and Thursday look like the warmest days as the high shifts east and the southwest flow really gets going. Highs on Wednesday are expected to range from the upper 40s to upper 50s, and Thursday generally looks to be about 5 or so degrees warmer than Wednesday....which gives much of southern NH a real shot at reaching 60 degrees. The only impact this taste of spring may have is on area rivers, especially in southern NH; there could be some ice movement that could ultimately lead to ice jams. A final note on temperatures for this period concerns Tuesday night as the high crests over New England; did go a bit lower than NBM here, blending in some cooler guidance for what could ultimately be favorable radiational cooling conditions. By Thursday morning, the high should be holding firm off the Atlantic coast and a developing frontal system looks to approach from the west. This could be our next chance for significant precipitation, but it continues to look like isolated to scattered showers at best for late Thursday night into Friday. High temperatures on Friday will be interesting depending on the timing of the frontal passage; some areas could still reach the lower to mid 50s. A cooler air mass arrives in the wake of the front, bringing down high temperatures closer to normal for Saturday. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Short Term...VFR as far as the eye can see with cold clear high pressure over the region. That high will shift eastwards overnight and by Monday evening a weak wave passing to the north through Quebec may bring brief periods of MVFR in SHSN to the mountains. Long Term...Widespread VFR conditions expected through Thursday. Could see a few snow showers at HIE Tuesday morning with associated MVFR/IFR conditions possible. Light northwesterly winds on Tuesday will become light and southerly on Wednesday and a little stronger but more southwesterly on Thursday. A frontal system could bring showers Thursday night into Friday morning with winds shifting to westerly behind the front. && .MARINE... Short Term...It`s been quite a while since we had a prolonged stretch without at least SCA on the waters, but that`s what`s ahead. High pressure well crest across the region tonight with southerly slow slowly moving in to start next weeks warming trend. Long Term...Broad high pressure dominates the waters through Wednesday,keeping winds and seas below SCA criteria. Southerly winds increase on Wednesday as high pressure slides east and increase again and become more southwesterly on Thursday as a frontal system approaches from the west and impinges on the high. Marginal SCA conditions look likely from Wednesday night through Friday night, especially over the outer waters, with a return to quieter conditions on Saturday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ Cannon

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