Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 261535 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1135 AM EDT Tue Mar 26 2024 .SYNOPSIS...
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High pressure exits across the Maritimes today. A warm front crosses the region tonight through Wednesday. Low pressure will approach Thursday, cross the Gulf of Maine Friday, then exit across the Maritimes Saturday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Update... High pressure exiting across the Gulf of Saint Lawrence will still ridge across the region today. At the same time, an inverted trof will extend north toward the Gulf of Maine from low pressure located well to the south. Moisture will expand north along the inverted trof. However, drier air with retreating high pressure will slow the advancement of rain across northern areas this afternoon. Generally expect precipitation in the form of rain this afternoon. However, pockets of light freezing rain or patchy freezing drizzle are possible dependent on how rapidly precipitation expands north. Otherwise, expect increasing clouds across northern areas this afternoon with cloudy skies Downeast. High temperatures today will range from the upper 30s to around 40 north, with mid to upper 30s Downeast. Have updated to adjust for current conditions along with expected afternoon temperatures, clouds and precipitation chances/types. Previous Discussion... The inverted trof will push moisture northward into the region today and into tonight. By tonight, rain will spread across the entire region. With temps and dew points cooling towards freezing in the higher terrain, freezing rain will return, especially in the North Woods. Some areas in central and southern Aroostook and northern Penobscot could cool enough to see freezing rain as well, but only a glaze is expected. Due to the warmer temps, rainfall, snowpack, and calm winds, patchy to areas of fog are expected across the area throughout the night.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Strong warm advection will occur with 850mb temps moving towards 10C by Wednesday morning. This will set up a steep low level inversion that will persist through Thursday night. The CAD will slowly release its grip on the area by Wednesday morning. Temperatures will remain above freezing for the most part Wednesday through Friday. While there is some uncertainty in how much rain falls Wednesday and Wednesday night, dense low level moisture should be able to at least squeeze out light rain and drizzle as the remnants of a weakening occluded front moves over the area and stalls. Fog will also become a threat Wednesday through Thursday night as dew points surge into the 40s over the cold, snow-covered terrain. The ridge in the Atlantic will not budge Wednesday into Wednesday night while the occluded front remains stalled over the area. The upper flow become more meridional as the upper ridge gains amplitude east of the area. Increasing baroclincity develops Wednesday night into Thursday with steadily increasing PoPs. Low pressure is expected to be drawn northward along the old occluded frontal boundary along the Eastern Seaboard Thursday into Thursday night. This southern stream low will phase with an upper trough moving out of the Great Lakes region. The amount of deep moisture from the Gulf of Mexico/Caribbean being pulled northward spurs concern for significant rainfall. PWs may rise towards 1.5 inches on the coast by Thursday...a very high reading for March. There are still uncertainties on the track and evolution of the low...which will depend on the blocking high in the Atlantic, but the trend with the latest guidance has been to the west. This means more rain. If the ridge is displaced a bit further east, the heaviest precip will fall in the Canadian Maritimes. The best chance for heavy rain currently appears to be Downeast where we conservatively expect over 3 inches of rainfall by the weekend at this point. The warm and wet week could yield significant river rises by late week if the westward trend observed in recent guidance solidifies. Guidance indicates a negatively-tilted trough may develop Thursday night with a rapidly deepening surface low moving from the Delmarva coast due northward towards the Gulf of Maine. Thus, the greatest lift and rainfall will occur late Thursday and Thursday night. Small stream and urban flooding are a concern by Thursday night given the combination of snowmelt and rainfall. && .LONG TERM /FRIDAY THROUGH MONDAY/... The expectation is that strong lift persists over the area Friday as the negatively-tilted trough quickly cuts off aloft and the surface low continues to rapidly deepen as it tracks towards the Bay of Fundy and the Canadian Maritimes. As this process occurs, attention turns to snow. The CWA will be the cold side of the low with accumulating snow possible as early as Friday and probable by Friday night. Accumulation amounts and distributions will again depend on the low track. The max rainfall scenario is also the max snowfall scenario. If the low tracks further east in the Maritimes, a glancing blow of snow results Friday night towards the eastern border of the state. The expectation that this low does materialize and quickly becomes a closed low in the Maritimes leads to a forecast for strong northwest winds on Saturday with some snow shower activity in the north. Decreasing PoPs and clouds are anticipated by Saturday afternoon as high pressure slowly builds eastward into the area. Temperatures will trend back to normal readings for late March. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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NEAR TERM: Across northern areas, expect VFR/MVFR this afternoon with a chance of rain. Across Downeast areas, MVFR/IFR this afternoon with increasing rain chances. Local freezing rain or patchy freezing drizzle possible through early afternoon. IFR/LIFR regionwide tonight with rain and fog. Pockets of freezing rain or patchy freezing drizzle also possible across northern areas. East/northeast winds 10 to 15 knots with gusts up to 20 knots today, then 5 to 10 knots tonight. Low level wind shear later this afternoon into tonight. SHORT TERM: Wednesday...IFR due to cigs/fog/drizzle. Light south winds. Wednesday night and Thursday...IFR tempo LIFR due to cigs/fog/drizzle. Light and variable winds. Thursday night...IFR due to cigs/rain. Winds becoming NW 5 to 10 kt. Friday...IFR cigs/vis in rain. NW winds 10 to 15 kt. Friday night...IFR vis due to snow north of GNR and HUL. MVFR tempo IFR due to rain/cigs for BGR and BHB. Northwest winds 15 to 25 kt. Saturday...IFR in morning north of HUL due vis in snow. MVFR in the afternoon due to cigs. MVFR in the morning for BGR and BHB, becoming VFR in afternoon. NW winds 15 to 30 kt.
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&& .MARINE...
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NEAR TERM: A Small Craft Advisory remains in effect for all the waters this afternoon through tonight. However, a few wind gusts could approach gale force this afternoon. Increasing rain chances today. Rain and patchy fog tonight. SHORT TERM: Small Craft Advisories have been extended into Wednesday due to seas. Fog is likely to take hold Wednesday into Friday morning. Winds may be sufficient for another Small Craft Advisory by Friday morning. Gales are a threat Friday night into Saturday as strong northwesterlies develop.
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&& .HYDROLOGY... Heavy snow in the past week combined with warm and rainy conditions this week offers a chance of rivers rising towards action stage or greater by late this week. Of particular interest will be the Piscataquis River. Uncertainty remains in how much rain falls later this week with a slow moving low pressure system moving up the Eastern Seaboard. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 2 PM this afternoon to 8 AM EDT Wednesday for MEZ001-003-004-010. MARINE...Small Craft Advisory until 8 PM EDT Wednesday for ANZ050>052. && $$ Near Term...Norcross/LaFlash Short Term...MCW Long Term...MCW Aviation...Norcross/MCW Marine...Norcross/MCW Hydrology...MCW

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