Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 212237 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 637 PM EDT Tue Mar 21 2017 .SYNOPSIS... A arctic cold front from Central Canada will approach the region later tonight. Low pressure will develop and intensify over the Bay of Fundy along the front as it crosses into the Canadian Maritimes Wednesday. Strong high pressure will build across the region later Wednesday night into Thursday. && .NEAR TERM /THROUGH WEDNESDAY/... 615 pm Update...No major changes made this update. Radar returns showing between Katahdin and the coast appear to be almost entirely not reaching the ground, as both obs and webcams don`t show anything around the region. That said, will keep the Iso to Sct POPs in across the southern half of the CWA through 00z, with gradually increasing POPs overnight. Original Discussion... Latest model guidance from the 12z cycle is in pretty good agreement with the synoptic pattern evolution tngt thru Wed, in which an arctic cold front supported by a strengthening s/wv alf from Cntrl Can will approach the region ovrngt, then cross on Wed. Meanwhile, sfc low pres ovr S Cntrl QB will re-form near the mouth of the Bay of Fundy by Wed morn, then deepen over the Can Maritimes later Wed into Wed ngt. This scenario will allow a band of sn shwrs from QB alg the arctic front to evolve into a more organized area of steady snfl crossing Nrn and Ern ptns of the region very late tngt thru Wed. This snfl will also be accompanied by very strong NNW winds accompanying llvl cold advcn on the back side of the intensifying low by Wed aftn contg into the eve. So even though most lctns will be receiving less than sn adv snfl from this system, the concern is that powdery sn falling with strong winds and a rapidly falling temp environment will produce a thin ice layer due to initial sn melt then freeze, followed by blowing and drifting of powdery snow. the delineation of the wntr wx adv was based on total snfl accumulations of greater than 1.5 inches. Most models indicate the best snfl potential across Cntrl and SE Aroostook county where lclzd max snfl amts could reach 4 to 5 inches, but exactly where the best banding will occur is still a little uncertain attm. Blowing in drifting will intially greater impact E to W roadways with N winds late Wed morn into erly aftn, then begin to impact N to S roads late Wed aftn into eve as winds become more Wrly component. The residence of the arctic air mass which begins in the deep category over NE Ont prov modifies to mdt by late Wed aftn as some of the cold air is utilized in the baroclinic intensification of the secondary sfc low over the Can Maritimes. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... Snow showers move out for Wednesday night but cold air continues to filter in from the northwest. Wind will be slow to die down, and with temperatures around 0F later in the night in the north, wind chills will be around -20F in the north and may need a wind chill advisory. Quiet for Thursday and Thursday night with high pressure building in. Could be quite cold Thursday night except high clouds streaming in from the northwest may keep it from getting as cold as it could be. Next potential system moves in Friday. Looks fairly weak and would probably be a mix of precipitation types with a warmer airmass moving in. Overall, good model agreement through Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Forecast confidence decreases into the weekend. Most models bring the Arctic air back in early Saturday with the front stalling out south of toward Southern New England, with precipitation possible along the front south of our area and us staying cold air dry into Monday. However, the possibility is there that the Arctic front could not make it that far south. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR conditions late this aftn and eve will begin to lower MVFR/IFR late tngt in snfl...then to LIFR and VLIFR in falling and blowing sn across Nrn TAF sites with MVFR/IFR ovr Downeast sites. SHORT TERM: MVFR improving to VFR Wednesday night as the system moves out and blowing snow diminishes. VFR Thursday and Thursday night. A weak system for Friday could bring MVFR/IFR conditions. && .MARINE... NEAR TERM: No chgs in the GLW slated to begin across all of our waters late Wed morn...contg thru the remainder of the day Wed. Fzg spray will begin to become an issue later Wed aft when colder air begins to advect ovr the water but should be lgt until later Wed eve. Kept close to WW3 wv guidance for fcst wv hts thru the near term. SHORT TERM: Freezing spray advisory issued for Wednesday night with unseasonably cold air and strong gale force northwest winds over the waters. Conditions gradually improve from gale Wednesday night to below small craft Thursday night. Small crafts likely with next system Friday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 7 AM to 10 PM EDT Wednesday for MEZ002-005-006-011-017-032. Winter Weather Advisory from 4 AM to 6 PM EDT Wednesday for MEZ001-003-004-010. Wind Advisory from 2 PM Wednesday to 2 AM EDT Thursday for MEZ029-030. MARINE...Freezing Spray Advisory from 10 PM Wednesday to 11 AM EDT Thursday for ANZ050>052. Gale Warning from 11 AM Wednesday to 8 AM EDT Thursday for ANZ050>052. && $$ Near Term...Kredensor/VJN Short Term...Foisy Long Term...Foisy Aviation...Kredensor/VJN/Foisy Marine...Kredensor/VJN/Foisy is the U.S. government's official web portal to all federal, state and local government web resources and services.