Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 251608 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1208 PM EDT Sun Oct 25 2020 .SYNOPSIS... High pressure will build across the region today, then exit across the Maritimes tonight. Low pressure will approach later Monday, then cross the region Monday night. High pressure will cross the region Tuesday through Wednesday. A cold front will cross the region Thursday. High pressure approaches the region Friday and Saturday. && .NEAR TERM /THROUGH TONIGHT/... Update... High pressure will build toward the forecast area this afternoon with partly/mostly sunny skies. North/northwest winds will gust up to 20 to 25 mph. High temperatures will range from the upper 30s to lower 40s north, to the mid to upper 40s Downeast. Have updated the forecast to adjust for current conditions along with afternoon temperatures and clouds. The Small Craft Advisory for the intracoastal waters has been allowed to expire with this update. Previous Discussion... High wl be over the state by 00z tonight with winds going near calm. This wl allow temps to rapidly drop with sunset under clr skies. Mid-high clds wl begin to spill in fm the west and likely keep temps from dropping after 06z acrs the west. Because of the timing of clds min temps wl drop into in the upr-teens in the deeper vlys over the north. However, if clds are not as quick to move in cannot rule out the possibility of lower temps. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... High pressure will be sliding east of New Brunswick Monday morning. In the low levels, east winds will push dry air into Downeast while a surge of moisture aloft arrives from the SW. It will take some time for the column to fully saturate and for precip to reach the surface, so have trended back arrival time by a couple hours Mon morning. Once precip overspreads the area Monday afternoon, temperature profiles will support all rain across Downeast and the coast up into the Penobscot and Bangor Region. It isnt as simple further north. A mix of frozen precip will greet the Central Highlands and North Woods Mon afternoon. The forecast mix of rain/snow/sleet/fzra will largely depend on local elevation, as well as how much cold air remains in the NW shadow of the Longfellow Mtns. The highest summits will be in for a glaze of ice early as temperatures begin well below freezing and profiles above 6000 suggest enough warm air to melt precip. Warm air below 800mb makes a push into the region later in the afternoon, allowing a changeover to all rain until the trough swings through after midnight and temps again fall below freezing. Some remaining snow showers will be possible, but precip will be tapering off into early Tues morning. Up in the St. John Valley and far North Woods, a mix of rain and snow will be the predominant precip type, with enough consistent snow possible for light accumulations of around an inch along the NB border. Temperatures will support mainly rain in eastern Aroostook. Without much terrain to dam up cool air from southeasterly flow, warm temperatures should flush in Monday morning. It will be a cold rain, with temps struggling to make it past 40. Remaining rain showers will mix with snow showers late Mon night as temperatures fall behind the front. GEM and ECMWF guidance suggest low pressure strengthening in the Gulf of Maine, which would position parts of Interior Downeast in a bit of a embedded deformation zone and thus some enhanced convergence/lift. This may lead to increased rainfall rates, however have kept QPF on the lighter side given the PWATs only approaching 1 inch (still above 75% average). Some elevated instability arrives along the coast where a nocturnal rumble of thunder is possible over the coastal waters. Precip will taper quickly Tuesday morning as cool, dry air is introduced behind the front from the NW. Clouds will linger with moisture still in the low levels. High temperatures will be similar to Monday, topping out in the mid 40s Downeast, and upper 30s in the North Woods. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Temperatures will remain on the cool side in the long term as Maine remains in a cooler air mass. Dominant high pressure moves overhead Wednesday with dry conditions expected amid the provided subsidence. How this high exits (and trough enters from the west) will help play a role where a potential large storm system tracks into the East Coast late week. Guidance has shown this system for a number of runs now, but kept the bulk of precip suppressed well to our south, only making it as far north as southern New England. Decided to keep slight chance PoPs in much of Downeast for this time period as some trends bring the northern fringe of QPF into southern and eastern Maine. The potential exists for a lot of moisture to be with this system, as it could contain remnants of Zeta in addition to strong southerly moisture advection. Remains plenty of time to assess this system and refine the forecast over the coming days. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... NEAR TERM: Generally expect VFR conditions across the region this afternoon through tonight. However, local MVFR ceilings are possible through early afternoon. North/northwest winds will gust up to around 20 knots. SHORT TERM: Monday...VFR early then lowering to MVFR/IFR with developing rain. A rain/snow/sleet mix possible across northwest areas. Monday night...IFR/LIFR early, improving to VFR/MVFR late. A mix of rain/sleet/snow early, transitioning to snow showers overnight north. Rain early, transitioning to rain showers overnight Downeast. Wind shifting SE to NW. Tuesday...Generally VFR. MVFR possible early Downeast. Tuesday night...MVFR possible Downeast , otherwise, VFR. Wednesday through Wednesday night...Generally VFR. MVFR possible late Wednesday night north with a chance of rain/snow showers. Thursday...VFR/MVFR. A chance of rain showers Downeast. && .MARINE... NEAR TERM: The Small Craft Advisory for the intracoastal waters has been allowed to expire with this update. A Small Craft Advisory remains in effect for the remainder of the waters through 4 PM. Conditions will be below small craft advisory levels on all the waters tonight. SHORT TERM: Conditions below SCA with waves generally 3 to 4 ft Monday and Tuesday, becoming 2 to 3 ft through Wednesday night. Patchy fog may form Monday afternoon, with a rumble of thunder possible in the evening and overnight. Winds shift SE to NW Monday night, gusting to around 20 kt. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ050- 051. && $$ Near Term...Norcross/Farrar Short Term...Cornwell Long Term...Cornwell Aviation...Norcross/Cornwell Marine...Norcross/Cornwell

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