Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 190510 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1210 AM EST Thu Jan 19 2017 .SYNOPSIS... Low pressure south of the Gulf of Maine will track out to sea tonight. An upper level disturbance approaching from Canada will cross the area late tonight into Thursday morning. High pressure will build into the region on Friday and remain across the area into early next week. && .NEAR TERM /THROUGH THURSDAY/...
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12:10 AM Update...A shortwave visible on water vapor satellite pictures is moving across Quebec and is causing diffluent flow aloft across the area early this morning. Snow is developing across northern Maine, and there will be a relatively quick shot of snow overnight that will wind down by around 12Z across most of the CWA with the exception of the eastern zones where some areas of light snow will linger into Thu morning. The ongoing forecast has a very good handle on the situation with only very minor tweaks based on the midnight observations and the latest radar and near term model trends. Previous discussion... Orgnl Disc: The low which brought some light snow Downeast will slide out to sea well south of Nova Scotia tonight. A separate upper level wave will approach from the northwest tonight bringing a period of snow late tonight into early Thursday morning. The snow will be produced as a function of divergence aloft and some surface convergence ahead of the shortwave. Starting times will be around midnight over the north and a few hours after midnight Downeast. Snow will gradually taper off early Thursday morning. Amounts will range from around 3 inches north to an inch or less Downeast. The sky will remain mostly cloudy on Thursday with highs a few degrees above normal as high pressure builds in from the west.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... The models are in good agreement through the period. A high pressure ridge builds into Maine from the west as an Upper level low over eastern Quebec continues to move away from the area. A low move through northern Quebec with a trough extending south to northern Maine early Saturday morning may product a few snowshowers across the crown of Maine Saturday morning, otherwise high pressure will dominate the weather through the period. Loaded a blend of the GFS/GEM/NAM/ECMWF to smooth out the minor differences in the models. Loaded NAWAVE4 for seas in the coastal waters. Loaded windgust by factor tool. For QPF used GFS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The extended models are in good general agreement at the start of the long term. A high pressure ridge over the area will begin to build to the east of the area as a low over Lake Superior and a low moving north along the Atlantic coast begin to put pressure on the western edge of the ridge. By Monday morning the frontal system associated with the lows will move into southwest Maine. By early Tuesday morning the warm front moves to Downeast Maine. By Tuesday morning the models start to diverge a bit, with the ECMWF moving the low to eastern Lake Huron and a secondary low over Portland, The GFS shows the low remaining over Virginia Beach. Both models show an occluded frontal boundary over Maine. Tuesday evening the GFS shows signs of secondary development over Portland, the ECMWF moves its low east to the Bay of Fundy. Both models continue to show the occluded frontal boundary over Maine. Wednesday morning both models show the main front east of Maine with northern Maine remaining in wrap around precipitation. The GFS builds a ridge in for the remainder of the period, while the ECMWF maintains the wrap around precipitation through the end of the period. Loaded a blend to smooth out the minor differences in the models. Loaded NAWAVE4 for seas in the coastal waters. Loaded windgust by factor tool. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR conditions this evening will lower to IFR from north to south in snow late tonight. IFR conditions on Thursday will improve to MVFR around midday across the region as snow tapers off and some clouds remain. SHORT TERM: VFR conditions all all sites through the period. FVE and CAR may see a few snowshowers Saturday and again Sunday adding HUL to the chance snowshowers. These snowshowers will bring vsby and cigs down to lower MVFR, but these snowshowers should be brief and vsby and cigs will return to VFR quickly after the shower passes. && .MARINE... NEAR TERM: An SCA will remain up early this evening for the offshore waters for wind gusts above 25 kt and seas over 5 ft. Winds and seas should diminish and subside overnight. SHORT TERM: High pressure will dominate the weather for the coastal waters, winds and seas below SCA criteria through through the period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/VJN Short Term...Norton Long Term...Norton Aviation...CB/VJN/Norton Marine...CB/VJN/Norton

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