Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 190514 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1214 AM EST Mon Feb 19 2018 .SYNOPSIS... High pressure will crest south of the area tonight then move to the east on Monday. A frontal boundary will form across the region Monday night into Tuesday as warm high pressure remains to our southeast and cold high pressure builds to our north. && .NEAR TERM /THROUGH MONDAY/... 12:14 am update: Strong low level inversions early this morning with a midnight temperature of +7F at Northern Maine Regional Airport at Presque Isle (valley) and 19F at the northern Aroostook Regional Airport at Frenchville (hilltop). Similar temperature differences are noted at valley versus hilltop locations across the CWA. The only adjustment at this time was to lower the overnight lows across mainly of the broad valleys. Previous discussion... Low pressure that brought snow to portions of down east Maine this morning continues to quickly move east out into the open atlantic. Drier air was moving in behind the system with clearing skies this evening as high pressure builds across to our south. The high will move off the southern New England coast late tonight with a light southwest return flow developing toward morning. This will also bring an increase in high and mid clouds toward daybreak Monday. Lows tonight will range from the mid to upper teens north and lower 20s downeast. High pressure continues to move east of New England on Monday with milder air continuing to move across the region on southwest winds. Along with the milder air will come an increase in moisture during Monday with increasing clouds especially Monday afternoon but the bulk of the daylight hours will remain precipitation free. Highs on Monday will range from the mid to upper 30s north and low to mid 40s central and downeast. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Warmer air on the back side of a high pressure system to our southeast will be pushing up into the area Monday night as high pressure builds into northern Quebec. A moist frontal boundary will be forming in the convergence between these two highs, across our area, Monday night into Tuesday. Some rain is likely across the region late Monday night into Tuesday and the rain may mix with a bit of sleet, freezing rain or snow over the far north where temps will be close to freezing and some cooler air will push into the low levels. The frontal boundary will remain stalled across the area Tuesday night with occasional rain produced by convergence along this front. Low pressure tracking north of the Great Lakes on Wednesday will then lift the front north as a warm front on Wednesday. Some of the warmest air so far this year will push north into the region on Wednesday as skies remain mostly cloudy and some rain showers continue over central and northern spots. Temperatures may approach 60 Downeast and 50 over parts of the north on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Low pressure passing to our north will slide to the east Wednesday night pulling a cold front across the region. This will bring some showers, mainly across the Downeast area overnight Wednesday night. Seasonably cold weather will follow with partial clearing on Thursday as high pressure builds in from the west. High pressure will build over the area Thursday night bringing a clear and cold night. The high will crest over the region on Friday with a sunny, tranquil and cool day. A return flow behind the high will bring moisture, clouds and warming temperatures on Saturday as low pressure lifts to our west. Another low may approach Sunday to bring a chance of rain Downeast and rain or snow over the north. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... NEAR TERM: VFR conditions through Monday. Winds will become light and variable overnight and then turn to the southwest during Monday. SHORT TERM: IFR conditions are likely Monday night into Tuesday as warm, moist air produces low clouds and some fog. IFR conditions in low clouds will likely persist Tuesday night into Wednesday, with a possible improvement to MVFR Downeast around midday Wednesday. Conditions will likely be IFR Downeast and IFR improving to MVFR then VFR across the north Wednesday night as a cold front pushes through. Conditions should then return to VFR everywhere on Thursday and be VFR in high pressure on Friday. && .MARINE... NEAR TERM: Winds/seas will continue to trend down this evening and remain below SCA levels through tonight. Southwest flow will bring increasing winds and seas beginning Monday afternoon and an SCA has already been issued for Monday through Monday. SHORT TERM: A SCA will likely be needed for southwesterly winds gusting up to 30 kt early Monday night. Winds should decrease below SCA late Monday night into Tuesday. Winds may then approach SCA again on Wednesday, but should diminish again Wednesday night into Thursday as a cold front pushes across the waters. Winds should be light on Friday as high pressure crests over the waters. && .CLIMATE... ...N. Amer. Arctic Potential and Impact over Nrn and Ern ME... It`s interesting to note that tdy is the last day of ami values near 100 (pristine arctic air mass rating) ovr far Nrn Manitoba prov Can with respective NAai and NDAai values of 40%/30%, with the areal cvrg and core values of this air mass xpctd to modify as it lifts ene into Nrn QB and then off the Nrn Labrador coast ovr the next 1-2 days. Overall NAT values will cont arnd +0.5 durg this tm then begin to gradually modify to negative values by next week. Although the overall initial NAT value is around +0.5, substantial differences exist between NATw and NATe index (indices derived from source rgn sectorized AO and ptns of the TNH and EP-NP teleconnection patterns, respectfully) with NATw around +2 and NATe -1 both accompanying a strong PNA- pattern. Overall modification of arctic residency ovr Nrn N. Amer. by next week will occur as TNH and AO/NAO all chg signs from positive to negative and PNA becomes more neutral, resulting in long fetch mid-trop Erly anomalous flow from the far N Atlc to overtake much of the NAe and even ern ptns of the NAw source Rgns. The ovrall affect for Nrn/Ern ME will be after several rn...mixed precip and sn events this week, drier conditions may arrive by next week with any arctic air mass intrusions of only low to mdt residence and relatively brief occurrences (http:/ and http:/ VNouhan.pdf). && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 10 AM Monday to 5 AM EST Tuesday for ANZ050>052. && $$ Near Term...CB/VJN Short Term...Bloomer Long Term...Bloomer Aviation...CB/VJN/Bloomer Marine...CB/VJN/Bloomer Climate...VJN is the U.S. government's official web portal to all federal, state and local government web resources and services.