Area Forecast Discussion
Issued by NWS Caribou, ME

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745 FXUS61 KCAR 221104 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 604 AM EST Wed Nov 22 2017 .SYNOPSIS... A cold front will cross the region this afternoon and evening as an area of low pressure passes to the east of the area tonight. High pressure will cross the region Thursday. A cold front will cross the area Friday. && .NEAR TERM /THROUGH TONIGHT/... 6:04 am update...High clouds continue to stream across the CWA early this morning. Lower clouds will follow later this morning with rain to develop from the southwest later this morning and into the afternoon. Will need to keep an eye on convection off the NJ coast, and a very isolated thunderstorm can`t be ruled out in Washington County this afternoon, but the chance is fairly low. Only minor tweaks to the ongoing forecast based on the latest satellite, radar, observations, and near term models. Previous discussion... An upper trough across the Great Lakes early this morning will push east into western New England late this afternoon, and will sweep off into the Canadian Maritimes tonight. Low pressure off the SC coast early this morning races northeast and deepens today and will be near Halifax late this evening, and into the northern Gulf of Saint Lawrence by 12Z Thursday. A cold front will push into western Maine early this afternoon, and will sweep across the remainder of the CWA this evening. A moderately colder air mass will spread back into the region tonight. Rain associated with the the low to our south will overspread the Downeast Region by late morning to midday with the heaviest rain across Washington County where rainfall totals of around 1.5" are expected. A few showers of rain or snow are possible this morning in northwest Maine ahead of the cold front. Rain with the southern low will work north across most of the CWA this afternoon. Much lighter QPF is expected across northern and western portions of the CWA on the order of around a quarter of an inch north of the Katahdin Region. Colder air sweeps in as the precipitation ends this evening, and will likely produce a short period of mixed rain and snow followed by a period of snow for a couple of hours across northern areas. a quick in or so of snow many accumulate, and as temps fall it could turn icy later in the evening. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... Thxgvg day will be fair and seasonably cold with a brisk NW wind. Late in the day, clds will increase from the W ahead of a clipper s/wv movg ESE from Cntrl Can. Thu ngt into Fri morn will then be msly cldy with lmtd chcs of sn shwrs across the NW as the s/wv crosses the Rgn. Following the passage of this system, slightly colder modified arctic air will move into the Rgn Fri with below avg hi temps. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Another s/wv complex from Cntrl Can will bring increasing cldnss to the Rgn Fri ngt with a chc of rn/sn shwrs on Sat as temps moderate. Blended long range models show higher PoPs just to our E later Sat into Sat ngt as a s/wv from the SE states swings NE toward the Ern Maritimes. Will have to watch whether any s/wv energy from Cntrl Can merges with this system ovr the next day or two, but for now the majority of the guidance including the latest 00z ECMWF keeps these systems separate. Colder air with the passage of the upper trof axis will mean more in the way of sn shwrs for Sun with ptly to msly cldy skies and seasonably cold conditions for erly next week with msly ocnl Nrn sn shwrs/flurries. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: Conditions will lower to IFR and LIFR today from south to north as rain overspreads the region. The rain may end as a period of wet snow at the northern terminals this evening. Conditions will improve to VFR tonight at the Downeast terminals, and to MVFR at the northern terminals late in the evening and to VFR overnight. SHORT TO LONG TERM: Mainly MVFR clgs with bkn-ovc SC for Nrn TAF sites and VFR conditions Downeast sites with brief MVFR vsbys in rn/sn shwrs mainly across the N Fri and again Sat and Sat ngt. && .MARINE... NEAR TERM: A small craft advisory remains in effect for the coastal waters through tonight. There will be a bit of a lull in the wind today and the seas will subside, but they are still running 7 to 8 feet at Jonesport and the Eastern Maine Shelf as of 5 am. The seas will likely subside to around 5 ft later this morning, but the wind will increase again tonight. On the intra- coastal waters a small craft advisory was issued for tonight as the wind will increase as low pressure begins to pull away from the waters. SHORT TO LONG TERM: Winds and wvs will be at or below marginal SCA conditions across our waters. Kept close to a WW3/NWPS model blend for fcst wv hts throughout these ptns of the fcst. && .CLIMATE... ...Arctic Air Mass Potential... Latest long range models indicate the N. Amer. Arctic transition index (NAT - a non-teleconnection arctic variability index formed by combining EP- NP and TNH teleconnection indices) will slowly moderate from values just abv zero to negative values just below zero ovr the next week. This potentially will reduce the magnitude of arctic air masses breaking loose from a deep arctic air mass over NW N.Amer that have been sliding ESE thru Cntrl Can grazing Nrn Nrn New Eng. Even ovr NW N. Amer., max arctic air mass indices will moderate from the mid 60s to mid 40s by next Wed as deep arctic air moderates and contracts ENE toward the Can Inuit territory. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 7 PM this evening to 7 AM EST Thursday for ANZ052. Small Craft Advisory until 7 AM EST Thursday for ANZ050-051. && $$ Near Term...CB Short Term...VJN Long Term...VJN Aviation...CB/VJN Marine...CB/VJN Climate...VJN

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