Area Forecast Discussion (AFD)
Issued by Caribou, ME (CAR)
000 FXUS61 KCAR 191745 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1245 PM EST Tue Feb 19 2019 .SYNOPSIS... Canadian high pressure will build across the region today and crest over the area Wednesday then move east Wednesday night. Low pressure from the Great Lakes will approach late Wednesday night then cross the area Thursday. && .NEAR TERM /THROUGH TONIGHT/... 1220 pM Update: SC cld cvr has remained sct E of the mtns even as far N as Nern ME, so we trimmed back cld cvr ovr NE and Cntrl ptns of the FA. Isold sn flurries was kept for the far NW, closest to the St Lawrence vly where streamer moisture could enhance SC cld streets. Otherwise, we updated fcst hrly temps/dwpts into the late aftn hrs with hi temps raised only 1 deg F across the Rgn based on midday sfc obs trends. Orgnl Disc: The high will bring generally clear skies as there's very little low level moisture for cu and stratocu. The only exception could be the Saint John Valley where moisture advection from the St Lawrence and upslope could generate some clouds and even a flurry. While ingredients such as strong cold air advection, trajectory and upslope favor a flurry in the Saint John Valley. Wind chills are really the primary issue today with the Wind Chill Advisory in place for northern zones until 10 am. Subzero wind chills are expected for the entire area through much of the day. Highs today will again be far below normal with readings in the low teens north and upper teens to lower 20s in the southern half of the area. Winds are the challenge for tonight's forecast. If the winds went calm with the building ridge and cold air mass, readings less than minus 20F would be possible in Aroostook County. However, the ridge axis will stay west all night and maintain steady northwest winds. A deep low northwest of Newfoundland will help maintain a decent pressure gradient over the forecast area much of the night. Do not expect another round of Wind Chill Advisories for tonight, but it'll still be cold. Subzero readings are anticipated in northern zones and low single digits further south. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... High pressure will cross the region Wednesday with mostly/partly sunny skies. Low pressure tracking east from the Great Lakes will approach New England Wednesday night with a secondary low possibly starting to develop along the New England coast. Clouds will increase early Wednesday night, with snow developing overnight. The remnants of the primary low will cross the region Thursday, while the potential secondary low crosses the Gulf of Maine. Generally expect precipitation in the form of snow Thursday. However, dependent on the strength of the secondary low, enough warmer air could reach the Downeast coast to allow the snow to mix with rain there. However, a stronger secondary low across the Gulf of Maine would limit the amount of warm air and allow precipitation to remain mostly in the form of snow even along the Downeast coast. Generally expect total snow accumulations of 4 to 5 inches across much of the region through Thursday, though amounts along the Downeast coast will be dependent on the potential mix with rain. The low will exit across the Maritimes Thursday night with snow tapering to snow showers across the north and mountains with decreasing clouds Downeast. Temperatures will be at below normal levels Wednesday. Near normal level temperatures are expected Thursday. && .LONG TERM /FRIDAY THROUGH MONDAY/... High pressure should cross the region Friday into Saturday, with generally partly cloudy/mostly clear skies. Could also have a slight chance of snow showers across the north and mountains Saturday. Low pressure will approach from the Great Lakes Sunday, with a secondary low again possibly developing across the Gulf of Maine. The lows should cross the region Sunday night through early Monday, then exit across the Maritimes later Monday. Expect accumulating snow to develop across the region Sunday then persist through early Monday. Dependent on the strength and track of the potential secondary low, the snow could transition to a wintry mix Downeast later Sunday. The snow will taper to snow showers later Monday in the wake of the exiting low. Near normal, to slightly above normal, level temperatures are expected Friday through Monday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... NEAR TERM: VFR conditions with gusty NW winds are forecast. Some gusts to 25 kts can be expected north of HUL and GNR, especially at sites such as MLT, GNR and FVE. LLWS is forecast north of HUL early this morning with over 35 kts at 2000ft. A few afternoon snowshowers with tempo IFR vis cannot be ruled out at FVE, and possibly HUL. SHORT TERM: VFR conditions are expected Wednesday. Conditions will lower to MVFR/IFR levels Wednesday night. IFR/LIFR conditions are expected Thursday. Conditions will then improve to VFR/MVFR levels later Thursday night. Occasional MVFR conditions are possible across the north and mountains Friday, with VFR conditions Downeast. VFR conditions are expected across the entire region Saturday. && .MARINE... NEAR TERM: The Small Craft Advisory will remain in place through the forecast period. Mdt frzg spray with another adv will occur again later tngt ovr the waters. SHORT TERM: A Small Craft Advisory is in effect through Wednesday morning. Conditions should briefly fall below small craft advisory levels later Wednesday through early Wednesday night. Small craft advisory conditions are then expected later Wednesday night through Thursday night. Light freezing spray is expected Wednesday morning. Visibilities will lower in developing snow Wednesday night, with a snow/rain mix expected Thursday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until noon EST Wednesday for ANZ050>052. && $$ Near Term...VJN Short Term...Norcross Long Term...Norcross Aviation...VJN/Norcross Marine...VJN/Norcross