Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 171648 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1248 PM EDT Mon Jul 17 2017 .SYNOPSIS... A stationary front will remain across northwestern Maine today and tonight. A cold front will approach later Wednesday then cross the region Thursday. && .NEAR TERM /THROUGH TONIGHT/...
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1245 PM update...Showers and thunderstorms are popping up already this afternoon, with the most robust activity in the Katahdin area. Have made some tweaks to PoPs, weather, sky, and temps to match current trends, but overall forecast remains unchanged. Previous discussion... South of the stationary front, a warm and humid air mass will produce varying degrees of fog early this morning. The denser fog will be in Hancock and Washington counties. Otherwise, patchy fog will be found further north. The fog will burn off early this morning. The coastal fog will retreat back over the ocean, but return again this evening. With dew points in the low to mid 60s and highs in the low to mid 80s, it will be somewhat uncomfortable by Maine standards. An onshore flow will keep the coast cooler in the upper 60s to 70s. In terms of convection, the bulk of the action will be north and west of a line from Dexter to Houlton and tend to retreat further north and west by late afternoon as the upper flow backs ahead of a closed upper low and the frontal boundary moves northwestward in response. This cut-off upper low will slowly drift from southern Ontario into southern Quebec later today while the Bermuda high actually strengthens over the area from the southeast. These events will create two outcomes. First, an increased southerly flow will advect fog and stratus northward earlier than the previous night and the stratus will reach all the way to northern Aroostook County by late tonight. Second, evening convection will focus towards the western border of the forecast area in a line from Greenville and Moosehead Lake region north towards Clayton Lake. Here, the stronger late afternoon storms will form with good SBCAPE due to colder air aloft...due to proximity to the closed upper low. These storms will also benefit from shear values that are at least approaching lower end favorable readings. The other concern there will be that the storms will be parallel to the flow with Corfidi vectors suggesting training storms. Otherwise, most of today`s thunderstorms will be of the pulse variety again with little shear for storm organization. Will maintain the enhanced wording for continuity, but the most appropriate place for the enhanced wording will be those far western zones late this afternoon. Due to the stratus covering most of the area and the warm, humid air mass...will only go with low 60s for tonight`s lows. The coast will be cooler with lows in the upper 50s.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... An upper level trof will cross the region Tuesday through early Tuesday night. Expect a chance of showers Tuesday morning, with a chance of showers/thunderstorms Tuesday afternoon into the evening. With the trof exiting to the east and the loss of diurnal heating, shower chances will then decrease overnight. A surface trof should cross the region Wednesday along with an approaching upper level disturbance. Will have a chance of showers/thunderstorms across northern areas Wednesday, mostly during the afternoon and evening with lesser chances Downeast. With high dewpoint air over the cold waters of the Gulf of Maine and light onshore winds expect areas of fog along the Downeast coast particularly during the overnight and morning hours Tuesday into Wednesday. The upper level disturbance will cross the region Wednesday night with a chance of showers mostly across northern areas. Temperatures will be at near normal, to slightly above normal, levels Tuesday/Wednesday. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A cold front will cross the region Thursday through early Friday with a chance of showers/thunderstorms. An upper level disturbance could cross the region later Friday keeping a chance of showers/thunderstorms into the evening. Surface high pressure will build across the region Saturday, though another upper level disturbance could bring a slight chance of showers. Low pressure should approach from the west later Sunday, though the exact timing of the low is still uncertain. The low will bring increasing shower chances or possibly a steadier rain. Near normal, to slightly above normal, level temperatures are expected Thursday with near normal level temperatures Friday through Sunday. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... NEAR TERM: Patchy fog will burn off early this morning. Fog near the coast will burn off by mid-morning. The fog will return towards the coast this evening and spread inland overnight...reaching BGR and possibly up towards HUL. The fog will be accompanied by IFR stratus that will move steadily northward all night and reach CAR and FVE by later in the night. The other concern for today and this evening will be thunderstorms that will mostly affect terminals north and west of a line from HUL towards BGR. Some locations such as GNR may have heavy and prolonged storms late this afternoon. SHORT TERM: Variable conditions could occur with any showers/thunderstorms Tuesday through Friday, with the better chances of thunderstorms during the afternoon and evening. Variable conditions could also occur with any low clouds and fog Tuesday into Thursday which will be most extensive overnight into the early morning hours particularly along the Downeast coast. && .MARINE... NEAR TERM: Fog will be widespread and dense at times through tonight. Winds will be light and seas will be 3 feet or less in a south to southeast swell. SHORT TERM: Winds/seas will remain below small craft advisory levels Tuesday through Wednesday night. Visibilities will be reduced in fog Tuesday into Wednesday night. Could also have a slight chance of showers Tuesday afternoon/Tuesday night, then again Wednesday night. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hastings/MCW Short Term...Norcross Long Term...Norcross Aviation...Hastings/MCW/Norcross Marine...Hastings/MCW/Norcross is the U.S. government's official web portal to all federal, state and local government web resources and services.