Area Forecast Discussion
Issued by NWS Caribou, ME

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610 FXUS61 KCAR 220222 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1022 PM EDT Thu Sep 21 2017 .SYNOPSIS... Tropical Storm Jose will remain southeast of Cape Cod and will slowly weaken through this weekend while High pressure both at the surface and upper atmosphere builds across the region from the west. && .NEAR TERM /THROUGH FRIDAY/...
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10pm Thursday Update... No changes needed other than to copy in current temperatures, dewpoints, and wind. Quiet night. Temperatures falling fast central/northern areas due to light winds, mostly clear skies, and dry air. Slower cooling down this evening near the coast thanks to somewhat thicker clouds and a bit of a breeze. Previous Discussion... Strong high pressure will persist over the region tonight into Friday then weaken later in the day Friday. Some clouds from Jose are possible along coastal areas tonight into Friday but not rain is expected from the storm. The north will remain mostly clear Tonight and Friday. A High Surf Advisory in effect through Friday afternoon for the coast. More on this in the Tides/Coastal Flooding section below.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... Unseasonably warm conditions expected this weekend... What`s left of any hi cldnss from slowly weakening and departing Maria in the open Atlc SE of Cape Cod will dissipate Fri ngt into Sat morn. Otherwise, xpct, msly clr skies and lgt winds Fri ngt. Cannot rule out late ngt patchy fog for parts of the area, but milder ovrngt lows compared to tngt and antecedent dry ground conditions will be lmtg factors, so we so not show any fog in our fcst grids for Fri ngt attm. Sat will be msly sunny and sig warmer with msly lgt west winds as high pres alf conts to build, xcpt aftn sea breeze for Downeast areas. A weak s/wv movg E across Cntrl QB could bring some hi cldnss to Nrn ptns of the FA late Sat ngt and Sun morn. Otherwise, most model guidance shows an additional surge of warmer and somewhat more humid air movg into the Rgn from the W by Sun aftn. The only lmtg factor to area wide record hi temps Sun aftn may be the amt of sunshine across NE ptns of the Rgn which will be in the NE quadrant of a very large and unseasonably strong upper ridge. If the 12z GFS model and supporting ensm run is correct, however, the hi temp fcst of lower 80s for low trrn lctns N will be conservative by 3 to 5 deg F. Other models like the 12z ECMWF show a delay of the arrival of the warmest air until nearly eve, and the 12z CanGem model, interestingly enough shows a back door cold front sliding across the Rgn on Sun. Given past trends of CPC guidance regarding the strength of the upper hi, we have discounted the 12z CanGem model attm. Sun ngt will be mostly clear to partly cloudy and quite mild for this tm of season. && .LONG TERM /MONDAY THROUGH THURSDAY/... Mon will cont to be ptly to msly sunny and unseasonably warm across the Rgn, with most models advertising a back door cold front beginning to move Swrd into Nrn ME from Ern QB by aftn. Subsequently, Hi temps may be a little cooler across the far N. We tried to split the difference with the tmg of the cold front passage from the faster GFS and slightly slower ECMWF. Both models bring the front to near the Downeast coast by Tue morn. With little in the way of frontal cnvrg and very stable lapse rates alf, we do not xpct much in the way of shwrs with this feature, with only some cldnss. Additional s/wvs will continue to flatten the NE U.S. upper ridge and will bring the Rgn better shwr chcs from late Wed thru Thu with perhaps appreciable rnfl amts for the Rgn Wed ngt into Thu. Hi and low temps Tue thru Thu will be cooler, but still sig abv seasonal norms with ovrngt lows Thu ngt behind a strongercold front closer to seasonal avgs. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... NEAR TERM: Generally VFR next 24 hours. One exception is right along the coast where an MVFR ceiling should develop Friday morning. Other exception is patchy shallow valley fog from KHUL north late tonight. SHORT TO LONG TERM: Mainly VFR xpctd area wide from Fri ngt through Tue with perhaps a pd of MVFR cldnss across Nrn most TAF sites late Mon ngt into Tue morn. && .MARINE... NEAR TERM: Have used the NAM to initialize the wind grids, however there is still a strong inversion resulting from the relatively cold sea surface temperature. Therefore have reduced the wind speeds from the NAM by 20 percent to adjust for high bias. For Waves: Currently long period swell from Jose (7-8 feet/12 seconds) is still entering the Gulf of Maine. This wave system will subside tonight into Friday but due to additional waves being generated by the weakening storm the process will be slow. A secondary northeasterly wind wave system has also developed across the Gulf of Maine but this wave group will also subside tonight as high pressure builds down from the north. Will use the Nearshore Wave Prediction System (NWPS) to initialize the wave grids but will lower model wave heights by 1 foot to adjust for high bias resulting from cold sea surface temperature. SHORT TO LONG TERM: SCA seas from long pd swell from slowly weakening Jose will still be continuing Fri ngt into Sat. Following this, there may be a break in from SCA conditions Sun and Mon before wv hts increase back into the SCA range by midweek from long distance swell radiating from Maria as it tracks well SE of our waters. Kept close to WW3 wv guidance for fcst wv hts. Wv pds will be exceptionally long, ranging from 12 to 16 sec, with the longest pd swells erly next week from Maria. && .TIDES/COASTAL FLOODING... Currently long period swell from Jose which is running at 12 seconds/7-8 feet continues to enter the Gulf of Maine. Waves are expected to to slowly subside Tonight and Friday. Have extended the high surf advisory into Friday afternoon. Concern is that long period waves high impact in the surf zone, and can run up much higher on the shore than shorter period waves resulting in the danger of spectators being washed into the ocean. Dangerous Rip Currents are also expected. Some minor beach erosion is possible. However, runup, splashover, flooding due to storm surge are not expected. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...High Surf Advisory until 6 PM EDT Friday for MEZ029-030. MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ050>052. && $$ Near Term...Foisy/Mignone Short Term...VJN Long Term...VJN Aviation...Foisy/Mignone/VJN Marine...Foisy/Mignone/VJN Tides/Coastal Flooding...Mignone is the U.S. government's official web portal to all federal, state and local government web resources and services.