Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 201350 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 950 AM EDT Thu Jul 20 2017 .SYNOPSIS... Weak high pressure will build across the region today. A stronger cold front will approach Thursday night and cross the area Friday. Canadian high pressure will build over the region on Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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950 am update... Latest surface analysis shows a weak cold front was situated along the down east Maine coast. The front is weak and today will still be another warm and muggy day with dew points in the 60s. The concern this afternoon will be possibility of some isolated convection in association with an approaching short wave from Quebec. SB Capes by late this afternoon are forecast to reach close to 1000J by late afternoon on GFS and even higher on the NAM. 0 to 6 km shear values are expected to be around 30 kt, so there is some support if a few cells did get going. Did notice that the new SPC day 1 outlook extended the marginal risk area across much of southwest Maine but just clips the southwest corner of southern Penobscot county. Will not include any enhanced wording at this time but will monitor for later updates. The main changes with this update was to add isolated thunder across the entire area and increased pops just a bit. Rest of the forecast seems on track. previous discussion Weak high pressure will build across the region today then move of to the east into the Gulf of Maine Tonight. A cold front will then approach from the northwest late tonight.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... Cdfnt wl be poised to enter the state Fri mrng. A few showers may be occurring acrs the North Woods shortly aft daybreak and as front drops thru CWA drg the day expect a line of showers to occur along bndry. Instability increases aft 15z therefore a line of showers and tstms looks to dvlp fm about a Caribou-Jackman live and drop south fm there. NAM looks to be up to it`s usual tricks of overblowing CAPEs ahd of front (1500 J/kg) while GFS looks to be more reasonable (800 J/kg). With frzg levels expected to be ~13kft and bulk shear values lagging bhnd bndry, feel the threat for strong storms is low and wl not include enhanced wording in attm. Temps ahd of front wl be in the u70s under mocldy skies while interior Downeast zones warm into the m80s. Coastal area wl rmn in the l/m70s due to onshore flow ahd of front. A secondary cold front wl mv thru the state Fri night with cooler and drier air in its wake. High pressure wl be building out of Canada into the northeast into the first half of the weekend. Sunny skies wl be on tap for Saturday with warmest temps expected acrs the south. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Ridging wl be building ovr the intermountain west which means troffiness acrs the east. Sfc high pressure wl keep most of the CWA dry thru Sun tho lopres tracking along a stalled frontal bndry may skirt close enuf to bring showers into srn zones drg the aftn. Another wv of low pressure wl mv acrs on Monday altho med range guidance begins to show disparity regarding timing and extent of nwrd reach of qpf. By Mon ngt/Tue timeframe 1025mb high pressure (latest EC) is in contrast to 1008mb sfc low (GFS) riding up along the coast and hv gone with Superblend thru end of the pd, which gives chc showers thru Tue night. Overall throughout the long term expect blo normal temps as low H5 heights encompass the northeast. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... NEAR TERM: MVFR/IFR conditions are expected at KBHB this morning, otherwise VFR conditions are expected through Friday. SHORT TERM: VFR expected thru the weekend. && .MARINE... NEAR TERM: Have used the NAM to initialize the wind grids. Will reduce the wind speed from the NAM by 15 percent due to relatively cold sea surface temperatures creating a low level inversion. For across the coastal waters will dissipate later in the morning. For waves: Observations from 44027 showing the primary wave system southerly 1-2 feet/6-7 seconds. This is expected to be the primary wave group through Friday. There is also a secondary southeasterly long period swell system (1 foot/11 seconds) which is expected to persist for the next several days. Wind wave will remain below 1 foot through Friday. Will use the Nearshore Wave Prediction System to initialize wave heights, however will lower by 1 foot to adjust for bias. SHORT TERM: Winds and seas will remain below SCA levels thru the weekend. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Duda/Mignone Short Term...Farrar Long Term...Farrar Aviation...Duda/Mignone/Farrar Marine...Duda/Mignone/Farrar

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