Area Forecast Discussion
Issued by NWS Caribou, ME

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515 FXUS61 KCAR 230423 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1223 AM EDT Wed May 23 2018 .SYNOPSIS... High pressure will remain south of the region overnight. Low pressure with a cold front will cross the region Wednesday. Canadian high pressure will then build southeast behind the front Wednesday night into Thursday morning. A strong warm front will approach the region from the west late Thursday into Thursday night. && .NEAR TERM /THROUGH TODAY/...
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1215 AM Update... Adjusted POPs overnight to blend the previous forecast with recent HRRR runs through 12z, as that model seems to be handling the precip coverage better so far tonight. Did make a few further tweaks to that blend through 06z to reflect current precip areas and movement. Otherwise, just minor updates to temps and dewpoints for current conditions and trends. Original Discussion... A cold front to the north of the state will push into far northern ME and the St. John Valley after midnight. Some showers are expected to accompany the front as it starts to sink down across the state. The front will continue to cross the rest of northern and central ME Wednesday morning before pushing off the down east coast by afternoon. Some showers are expected as the front crosses the region. Have maintained the chance of thunder across portions of the upper Penobscot Valley and interior downeast for Wednesday afternoon owing to the later timing of the front there. SB CAPEs are generally less than 500J but there is plenty of 0-6km shear present. Did add a mention of gusty winds in any thunder tomorrow across the upper Penobscot Valley and interior downeast. However, overall the threat looks to be limited. Highs on Wednesday will be in the low to mid 50s north and in the low to mid 60 downeast.
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&& .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... Continued WNW Fast Flow Regime Aloft Pattern with Frequent Progressive Cold Frontal Passages. Showers from the prev cold frontal passage Wed aftn will have moves SE of our FA by erly Wed eve, with weak cool advcn contg into the ovrngt hrs and the sfc hi settling ovr the rgn from the W late Wed ngt to allow for lgt winds and radiational cooling. This will allow for another ngt of potential frost hdlns for msly NE ptns of the FA, with widespread frost likely ovr far NW ME where the frost/freeze hdlns season begins June 1st. Frost will rapidly melt shortly aft sunrise Thu as temps quickly rebound with the strong late May sun. Sunshine Thu morn will give way to increasing cldnss Thu aftn as a warm front apchs from the W. Shwrs will be likely across the N and E ptns of the FA very late Thu aftn thru the ovrngt and Fri erly morn hrs as the warm front slowly moves into our rgn. The final psn of this front on Fri appears to be problematic with the longer range models, with tdys 12z dtmnstc GFS and CanGem bringing the front as far N as the ST John vly, and the 12z ECMWF bringing it only as far N as Cntrl ptns of the FA. Subsequently, warmest aftn hi temps Fri were weighted toward the SW where highs ovr 80 deg F are likely with high temps ovr the NE held in the lower to mid 70s. Another fast movg s/wv alf from S cntrl Can will bring a chc of msly late aftn and eve shwrs and possible tstms Fri, with max CAPEs progged to be arnd 500J/kg. Another mdtly strong cold front will then sweep swrd behind the s/wv as it tracks ESE south of Nova Scotia by Sat morn. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Behind the cold front Sat looks to be cooler and drier with msly fair skies. Longer range models cont to have varying solutions with regard to the frontal cldnss and shwrs possibly movg back into the SWRN hlf of the FA late Sat ngt into Sun, where we will show chc PoPs, but there is enough fcst confidence to keep shwr mention out of the NE hlf for now durg this tm frame. Long range models are in fair agreement regarding another s/wv from Cntrl Can to bring a chc of shwrs to most of the rgn late Mon ngt into Tue where we kept max PoPs in the low chc cat. Temps as a whole durg this ptn of the fcst will remain near avg as a whole with individual days ranging up and down across the avg. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR this evening will give way to developing MVFR in showers overnight and possibly even IFR for a time, especially at KBGR/KBHB. SHORT TO LONG TERM: VFR xpctd all TAF sites, xcpt brief MVFR clgs and vsbys possible with any heavier shwrs late Thu ngt and again Fri aftn into Fri eve. && .MARINE... NEAR TERM: Winds and seas will remain below SCA levels through tonight. SHORT TO LONG TERM: Initially no hdlns then winds and seas increasing to possible SCA conditions in a WSW fetch beginning late Thu ngt and possibly contg into Fri ngt. Went with about 80 to 85 percent of WW3 guidance with fcst primary wv pds ranging from 5 to 8 sec. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hewitt/Kredensor Short Term...VJN Long Term...VJN Aviation...Hewitt/Kredensor/VJN Marine...Hewitt/Kredensor/VJN is the U.S. government's official web portal to all federal, state and local government web resources and services.