Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 161005 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 605 AM EDT Fri Mar 16 2018 .SYNOPSIS... An arctic cold front will cross northern Maine late this afternoon and will push off the Downeast coast late this evening. An unseasonably cold air mass is expected across northern New England this weekend. High pressure will build toward the region Sunday. && .NEAR TERM /THROUGH TONIGHT/...
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6:05 am update: No significant changes to the forecast. Some minor adjustments to the hourly forecast elements based on the 6 am observations and the latest satellite, radar, and near term model trends. Previous discussion: A cold upper low is dropping south from the Canadian Archipelago and will move across the eastern Hudson Bay today and into northern Maine by 12Z Sat. 500H heights are expected to drop below 500 dam by early Saturday morning. At the surface, an arctic cold front will move into northern Maine late this afternoon or early this evening and sweep off the Downeast coast by late evening. Arctic air will pour into the region on a gusty northwest wind. The combination of strong mid March solar heating, increasing low to mid level instability, and some moisture with the approaching front will generate scattered snow showers. The best chance of snow showers will be across the northern half of the CWA with more downslope flow toward the coast. There is the potential across northern and central area for a heavier snow squall or two during the afternoon and early evening. The BTV snow squall parameter is not all that enthusiastic with values below 1. Until there is higher confidence will hold off on any special weather statements, but this will need to be watched closely during the day. The wind is going to be strong enough to produce at least some patchy blowing snow, especially across the Crown and will add some to the forecast for later this morning into early evening. Temperatures today will see some recovery ahead of the front, and will be seasonable. Temperatures tonight will drop back into the single digits north to near 20 along the coast. A gusty wind will drive wind chills below zero after midnight across the north with zero to 10 above wind chills along the coast. It will feel more like January than mid March by daybreak Saturday.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY/... The model guidance is in good agreement through the short term period of the forecast. Wrap around precipitation will continue around a broad area of lower heights over the Gulf of St Lawrence extending back across western Maine. Snowshower activity will diminish through the day Saturday. High pressure ridge build south from Hudson Bay will build east into Maine early evening Saturday. A weak frontal boundary will move through on Sunday bringing a chance for a few snowshowers. Otherwise the high pressure ridge will dominate the weather through period. Loaded a blend of the GFS/NAM/ECMWF to smooth out the minor differences in the models. Used NAWAVE4 for seas in the coastal waters. Loaded windgust by factor tool add to winds 20% over land, 28% for the coastal waters. Used QPF from POP for QPF. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... The extended models are in good agreement at the start of the period. A Canadian high pressure ridge will be build across the region at the start of the period. The ridge will dominate the weather through Wednesday evening. A low exiting along the coast of Virginia Tuesday evening. The GFS/GEM move the low northeast to the east of Cape Cod Wednesday evening. The associated frontal boundary will move into the Downeast coast early Thursday morning. By Thursday morning the models are no longer in agreement. The GEM moves the low rapidly NE into the Gulf of St lawrence. The GFS move the low to SW Nova Scotia, the EC has the low SE of Cape Cod and not threat to Maine at this time. At this time the GFS seems to be the consensus solution. Thursday evening the low tracks east along the south coast of Nova Scotia. This continues into Friday morning the low will continue moving east and clearing the eastern coast of Nova Scotia and moving into the maritimes. High pressure will dominate the weather the end of the period. Loaded a blend to smooth out the differences in the models. Used NAWAVE4 for seas in the coastal waters. Loaded windgust by factor tool add to winds 20% over land, 28% for the coastal waters. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... NEAR TERM: MVFR to at times low end VFR at the northern terminals today. Brief reductions to LIFR/IFR this afternoon and early evening in snow showers. A heavier snow squall is possible this afternoon with gusty wind and reduced visibility. There will be some patchy blowing snow at the northern terminals today. Conditons to improve to VFR tonight. At the Downeast terminals, predominately VFR for the next 24 hours. SHORT TERM: VFR with periods of MVFR in snowshowers through the early Saturday in isolated snowshower across northern and western Maine. Higher pressure will start building into Maine Friday clearing out the snowshowers and cloud cover Saturday afternoon. && .MARINE... NEAR TERM: A small craft advisory will remain in effect through tonight for gusty northwest wind. Light freezing spray is expected to develop toward daybreak Saturday. SHORT TERM: A Small Craft Advisory will likely be needed through the period. Winds and or Seas will be above SCA criteria through the period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ050>052. && $$ Near Term...CB Short Term...Norton Long Term...Norton Aviation...CB/Norton Marine...CB/Norton is the U.S. government's official web portal to all federal, state and local government web resources and services.