Area Forecast Discussion
Issued by NWS Caribou, ME

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628 FXUS61 KCAR 161208 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 708 AM EST Sat Dec 16 2017 .SYNOPSIS... An upper level disturbance will cross the region today. High pressure will begin to build east tonight and Sunday. && .NEAR TERM /THROUGH TONIGHT/... 625 AM... Skies were mainly cloudy at this hour with temperatures ranging from the single digits above zero across the far north and lower to mid teens down east. The ocean low continues to pull east of the Gulf of Maine early today. Light snow that was falling along the down east coast will continue to diminish as the low continues to move away. Otherwise, any lingering flurries across the remainder of the region will gradually diminish as well. Still expecting partial clearing later today. previous discussion An upper disturbance crossing the region today will bring mainly cloudy skies and isolated snow showers or flurries to the region this morning. In addition, low pressure will move well east of the gulf of Maine this morning, bringing a little light snow to the down east coast. Any light snow down east early this morning will quickly taper off by mid day, as the low continues to pull off to the east. Any snow accumulation across the region this morning will be less than an inch. Otherwise, mainly cloudy skies this morning will gradually give way to partial clearing by late afternoon. High temperatures will once again be below normal today, with highs ranging from the mid to upper teens north and low to mid 20s down east. High pressure will slowly build east toward the region tonight with mainly clear to partly cloudy skies expected. With the high still well off to our west there should still be a bit of a northwest wind to inhibit much in the way of radiational cooling. However, lows tonight will still be very cold, with a few sub zero readings expected across the far north. Couldn`t rule out marginal wind chill advisory criteria across the far northwest for a few hours tonight. Otherwise, lows tonight across central and down east areas will generally range from 5 to 10 above. && .SHORT TERM /SUNDAY THROUGH MONDAY/... Artic Air will Msly Hold Thru Most of the Short Term... Sun will be msly sunny brisk and cold with llvl cold advcn weakening by late aftn. With the apch and passage of the sfc hi ovr the rgn Sun eve into the ovrngt hrs, winds should become lgt and vrbl. This will allow for some radiational cooling with some arctic sfc base invsn potential particularly ovr Nrn Vlys before hi/mid cldnss crosses into the FA from the W late Sun ngt, which will result in temps lvlng off and even slowly rising by erly Mon morn. Clds will thicken spcly ovr the Cntrl and Srn ptns of the FA Mon morn with a chc of lgt sn ovr these areas thru Mon aftn as a weak s/wv crosses from Cntrl QB, with somewhat lesser cld cvr ovr Nrn third. Any lgt sn ovr the Cntrl/Downeast areas will move E of the Rgn Mon eve with minimal sn accumulations of less than an inch, leaving ptly to msly cldy skies and not as cold air later Mon ngt, not allowing for as cold of ovrngt lows. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 00z Models indicate two more progressive s/wvs movg across the FA from Cntrl Can Tue and Tue ngt, with lgt sn Tue aftn/eve msly for Nrn ptns of the Rgn and sn shwrs late Tue ngt into Wed morn. Downeast and Cntrl ptns of the FA may become mild enough later Tue aftn into Tue eve for a mix of lgt rn/sn or even all lgt rn as sfc winds become S ahead of a warm occluded front. Max snfl accumulations will be msly in the 1 to 2 inch range across the far N. Mdtly strong llvl cold advcn will occur behind the second s/wv later Wed into Wed ngt with brisk NW winds as arctic air from Cntrl Can with mdt residence advects back ovr the Rgn with cold conditions, with potentially colder hi temps then what we show for Thu under ptly cldy to msly clr skies. After msly clr and lgt winds Thu eve, clds will be back on the increase for late Thu ngt and Fri morn ahead of a more sig sfc low and associated s/wv from the upper great lks, with this system potentially resulting in greater warm advcn/ovrrng precip, msly in the form of sn across the N and Cntrl areas with sn chgng to a rn/sn mix or even rn ovr Downeast areas Fri eve into Fri ngt as temps greatly moderate under the influence of S winds ahead of the sfc low. Went with max likely PoPs msly across th N. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: Mainly VFR conditions can be expected across the region through tonight outside of any brief IFR/MVFR in light snow early this morning. SHORT TO LONG TERM: Msly VFR conditions Sun and Sun ngt with MVFR clgs and vsbys likely on Mon spcly Downeast sites in very lgt sn. VFR conditions Mon ngt will likely transition to MVFR Downeast sites in mixed precip and IFR Nrn TAF on Tue sites in sn...transitioning to MVFR clgs Nrn TAF sites with sct sn shwrs/VFR clgs Downeast sites Tue ngt and Wed. && .MARINE... NEAR TERM: Winds/seas will remain below small craft advisory levels through early afternoon. Winds will begin to increase a bit by late afternoon and early this evening in the wake of the departing ocean low. There could be frequent gusts up to 25 kt during that time frame, mainly across the outer waters, where a small craft advisory has been issued for late this afternoon and into this evening. Visibility will be reduced to 1 to 3 nm at times this morning in light snow. SHORT TO LONG TERM: Intially no hdlns anticipated, then winds and wvs increase to SCA range later Tue into Wed. Went with a blend of 00z WW3/NWPS wv guidance for fcst wv hts this fcst update. && .CLIMATE...
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...Arctic Potential Discussion.... NAT will decrease ovr the next few days as the LW pattern intially flattens ovr N. Amer. This will result in a temporary retreat of the arctic front into Nrn/Cntrl Can erly to mid next week. Aftwrds, NAT will increase late next week into the following week with the TNH+ teleconnection being the main contributor. The resultant 500mb anomalous NE component of flow will then impinge on the Can Rockies Divide resulting in a high residence arctic air mass and rapid arctic sfc anticyclogensis ovr W. Cntrl Can with ami(s) potentially reaching 85 to 90 and corresponding Arctic Area Index (Aai) reaching about 45 to 50 percent and the Deep Arctic Area Index (DAai) about 15 to 20 percent by Christmas day. Most of the residence gain durg this tm will be ovr the N. Amer arctic source rgns, with little or no transarctic infusion from Siberia despite an impressive full latitude 500mb ridge msly just west of N. Amer. and blocking N of AK. The long ENE-WSW axis of the arctic air mass will likely result in episodic mdt winter wx precip events for Nrn/Ern ME beginning next weekend and continuing into Christmas week punctuated by brief incursions of deep to potentially bitter cold arctic air masses into our region with the main entry axis of the airmass core into the Nrn Plains...Upper Midwest and Upper Great Lakes regions.
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&& .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 11 PM EST this evening for ANZ050-051.
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&& $$ Near Term...Duda Short Term...VJN Long Term...VJN Aviation...Duda/VJN Marine...Duda/VJN

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