Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 171439 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1039 AM EDT Tue Sep 17 2019 .SYNOPSIS... Canadian high pressure will build across the region through Wednesday night, then slowly settle south over the Gulf of Maine Thursday through Saturday. && .NEAR TERM /THROUGH TONIGHT/... 1020 AM Update: A large channel of clrg has opened up in the SC cld deck ovr N Cntrl areas late this morning in addition to SE ptns of the FA, both of which is experiencing a little more enhanced downslope from upstream highland areas ovr the Gaspe Peninsula and Nrn NB highlands, respectfully. A little band of shwrs ovr NB prov is movg SW toward Ern Downeast areas, but the trend should be toward weakening as they cross the Ern ME border, do for now will keep isold shwr mention ovr Downeast areas into the aftn. Otherwise, we will cont to show a slowly decreasing cld cvr trend from N to S across the FA this aftn into eve. lastly, fcst hrly temps/dwpts have been updated into the aftn from trends seen in latest sfc obs with no chgs to fcst aftn hi temps attm. Orgnl Disc: A surface trough and associated low-level moisture will continue to push southward today while colder and drier air arrives in northern zones this morning and sinks southward through tonight. The surface trough will maintain cloudy skies in the southern half of the forecast area and a few afternoon sprinkles towards Washington and Hancock counties. Hard to envision more than a hundredth of an inch anywhere with a modest unstable layer near 850mb yielding less than 50 J/kg of CAPE. The colder air working its way south will bring dew points dropping into the 30s and 850mb temps dropping towards 0C tonight. It`s the coldest air mass of the season to date. The 1028mb high will be dropping due south from northern Quebec. Skies will be clear to start the evening towards northern Aroostook County and the clearing will spread southward to the coast tonight. The existing Freeze Watch area continues to have the longest duration of clear skies and light winds and there`s a real threat of temperatures dropping as low as the mid to upper 20s in the normally colder spots of Aroostook, northern Penobscot and northern Piscataquis counties. Will continue the Freeze Watch to highlight the most vulnerable areas and let the day crew finalize the exact areas covered by advisories or warnings. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... High pressure will remain across the region Wednesday through Thursday night with mostly clear skies. Favorable conditions for radiational cooling will support the chance of frost across much of the forecast area Wednesday night, including Downeast areas. Sub-freezing temperatures are also possible, particularly across the normally colder locations of northern Maine. Temperatures will be at below normal levels Wednesday, with near normal level temperatures Thursday. && .LONG TERM /FRIDAY THROUGH MONDAY/... High pressure will remain across the region Friday into Sunday, with mostly clear/partly cloudy skies. A cold front will begin to approach later Sunday with increasing clouds in advance of the front. Could also have a slight chance of showers late, mostly across northwest portions of the forecast area. The cold front should then cross the region Monday with showers. Temperatures will be at above normal levels Friday through Monday. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... NEAR TERM: Prevailing condition will be VFR outside of some morning MVFR cigs possible from PQI southward to the coast. There`s also the risk of shallow patchy valley fog near sunrise Wednesday morning. SHORT TERM: Wednesday through Saturday...Generally VFR. However, variable conditions possible with any patchy valley fog Wednesday night. && .MARINE... NEAR TERM: A few northeasterly gusts may reach up to 20 kt this morning as colder air moves over the relatively warmer waters. Winds will tend to decrease later today into tonight and become more easterly. Seas will remain around 2 ft or less with a mix of locally wind-driven waves and a longer period south swell. SHORT TERM: Winds/seas will remain below small craft advisory levels Wednesday through Thursday night. Seas will then build to 5 to 8 feet in southeast swell Friday into Saturday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Freeze Watch from late tonight through Wednesday morning for MEZ001>006. MARINE...None. && $$ Near Term...VJN Short Term...Norcross Long Term...Norcross Aviation...VJN/Norcross Marine...VJN/Norcross is the U.S. government's official web portal to all federal, state and local government web resources and services.