Area Forecast Discussion
Issued by NWS Caribou, ME

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152 FXUS61 KCAR 180407 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1207 AM EDT Wed Apr 18 2018 .SYNOPSIS... Low pressure will slowly move north of the region overnight then exit into the Maritimes Wednesday. A new low will develop to our south on Thursday then track toward Nova Scotia Thursday night. && .NEAR TERM /THROUGH WEDNESDAY/...
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12:07 am update: An upper low along the western Maine/Quebec border will slowly lift across northern Maine overnight. As it does, there will be enough moisture and weak disturbances to produce some showers, mainly across the northern half of the cwa. Most of the showers are currently in the form of rain, but as cooling continues aloft and near the surface they will transition to snow showers, mainly from Frenchville and Clayton Lake west to the Quebec border. Most areas will have little/no accumulation, but locally up to an inch is possible across the higher terrain. Only some minor tweaks to the ongoing forecast based on the latest observations, radar, and near term model trends. Previous Discussion... Low pressure will continue to slowly move away to the northeast tonight. An upper level low pressure system will bring showers to the north Wednesday. Another area of low pressure over the Midwest will move to the northeast tonight then across Southern New England Wednesday.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... Vertically stacked low wl be kicked into the Maritimes Wed night with cyclonic flow contg to result in sctd showers, mainly acrs the north. Wk sfc bndry wl slide thru CWA in the evng with drier air mvg in bhnd. Next system wl be mvg acrs the country drg the day Wed, moving into the northeast Thur morning. Precip wl gradually spread north and east drg the day Thu. Operational 12z GFS is faster than other guidance and just slightly faster than its ensemble means. Thus wl trend more twd delaying pops until aftn hours. This results in mostly lgt rain as temps are able to warm into the 40s up into the St. John Vly. As is typically the case in a Gulf system, lightest qpf amnts wl be acrs the far north. Cold air wl sink south late Thu night and turn rain over to lgt snow as sub-1000mb sfc low draws in cldr temps on nrly flow in wake of system. May possibly see 1-2 inches, mainly north of the Katahdin region, overnight with and additional 1/2 inch expected Fri mrng bfr mixing with and changing back over to rain showers. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Cyclonic flow conts early in the weekend with a chilly and dreary day expected Sat as northeast rmns under the influence of upr lvl trof. Temps wl cont to run blo normal on Sat with highs only in the lwr 40s acrs the north and m/u 40s for Downeast, with normal highs in the u40s across the north and lwr 50s Downeast. Upr lvl ridge wl be building twd CWA late in the weekend with clrg occurring Sat night allowing temps to dip into the 20s CWA-wide by Sun mrng. Temps wl moderate twd normal on Sun under prtly sunny skies and lgt winds. An extended pd of dry/fair wx is expected thru the middle of next week. Another frontal bndry wl be dropping south twd the area fm Canada on Wed. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: Generally expect MVFR/IFR conditions across northern areas overnight, with VFR/MVFR conditions Downeast. MVFR/IFR conditions will persist across the north and mountains early Wednesday, with MVFR conditions during the afternoon. Occasional MVFR conditions are possible early Wednesday Downeast, with VFR conditions during the afternoon. SHORT TERM: MVFR restrictions expected Wed night in low cigs and light rain/snow showers. Restrictions return from south to north Thu morning with potential MVFR rain in the afternoon diminishing to IFR Thur night as rain transitions to snow. Improvement to VFR Sat at all but far northern terminals where MVFR restrictions may linger in low-lvl stratus. && .MARINE... NEAR TERM: A Small Craft Advisory is in effect on the waters overnight into Wednesday morning. The Small Craft Advisory will likely need to be extended through Wednesday. Have used a 50/50 blend of the Nam and Gfs for sustained winds Wednesday. Waves: Primary wave system tonight will be the long period swell generated from the Gulf of Maine southward yesterday and last night. This wave system will continue to subside Wednesday however this will be a slow process since it originated from a long fetch. There will also be a secondary southwesterly wind wave system present tonight. Will use NWPS for wave grids. SHORT TERM: Seas will likely fall below SCA levels Thur morning with winds increasing ahead of sfc low Thur evng to aoa 25kts. && .HYDROLOGY... Rivers will be on the rise this week due to the combination of rain and snowmelt in the north, and rain in the south. Open water flooding appears unlikely. The main concern will be on the northern rivers like the Saint John, Aroostook, and Allagash Rivers which have weakening ice. The rising water levels may cause the ice to break up later this week and could lead to the potential for ice jams, and possible localized ice jam flooding. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 8 AM EDT Wednesday for ANZ050>052. && $$ Near Term...CB/Mignone Short Term...Farrar Long Term...Farrar Aviation...CB/Mignone/Farrar Marine...CB/Mignone/Farrar Hydrology...CB is the U.S. government's official web portal to all federal, state and local government web resources and services.