Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 091530 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1030 AM EST Sat Dec 9 2017 .SYNOPSIS... Low pressure will strengthen south of Cape Cod today and track south of Nova Scotia late tonight. The low will lift north through the Maritimes on Sunday. Another low pressure system will track through the Gulf of Maine by mid-week. && .NEAR TERM /THROUGH SUNDAY/... 1000 AM Update: Chgs this update included slowing down the onset tmg of snfl by about an hr or two based on later arrival of snfl to Nrn mid Atlc and SE New Eng states this morn. Otherwise we increased Cld cvr across the N based on latest sat imagery. Lastly, we updated fcst hrly temps/dwpts across the Rgn based on latest sfc obs with fcst highs across Downeast areas lowered a deg or two given little or no additional sunshine factor and the potential of evaporational cooling with snfl onset this aftn. Orgnl Disc: Low pres is currently sitting south of the NC coast. S/wv shearing out of the southeast U.S. is expected to phase with wv currently dropping thru the upr Midwest. This wl help intensify low to the south of Cape Cod nr the benchmark by 00z tonight. Expect that pcpn wl mv from south to north beginning arnd 15z this mrng with coastal areas experiencing categorical pops by 18z. May see light snow to start off with along the immediate coast bfr mixing with or changing to rain in the aftn as blyr warms. The most lkly area for this to occur is near Eastport where temps are currently in the m/u 30s as of 08z. Elsewhere along the coast, with the exception of the outer islands, locations look to be blo frzg at this hr. Depending on how much temps are able to warm this mrng, pcpn could vry easily be all snow. For this reason hv issued Winter Wx Advisory for coastal Hancock County where the higher terrain further inland may pick up 3- 5 inches thru Sunday morning. Elsewhere, models have rmnd fairly similar to prior runs with the exception of the 00z GFS. The GFS had a fairly noticeable shift to the east with the latest EC shifting east by a very negligible amnt. Either way, thinking is that coastal wl track just to the south of Nova Scotia with widespread 3-6 inches acrs the CWA. Hv issued Winter Wx Advisory for all but coastal Washington, northern Somerset and northeast Aroostook. Interior Downeast and Bangor region look to see accumulating snowfall around 19z while northern areas around 22z this afternoon. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... The model guidance is in good agreement through the near term period of the forecast. A low pressure system will be exiting the region over the Canadian Maritimes. An upper level low will be center over Northern Quebec, with a trough extending south to the eastern Great Lakes. By Monday morning the trough will move east to the Gulf of Maine. The ECMWF show a low along the Downeast coast, the GFS/GEM shows deepen of the trough which could also support a low along the coast of Maine. A new low will form in the upper Midwest, and by the end of the period Monday evening move east to Lake Michigan. Loaded a blend of the GFS/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 /WEDNESDAY THROUGH FRIDAY/... The extended models are in good agreement at the start of the period. Monday evening a weak ridge of higher pressure will build into the area ahead of the next system Tuesday morning. A low moving across the Great Lakes will be over Lake Ontario, with a frontal system extending east across New Jersey into the north Atlantic. The cold front interacting with the warmer waters along the Atlantic coast is expected to form a secondary low on the Front near Cape Cod. This low will track into southeastern Maine Tuesday evening. Wednesday morning the models diverge a bit on their solutions. The GFS moves the low to northern Maine, with an upper level low digging south to NE New York. The ECMWF move the low east to the mouth of the St Lawrence, also showing the upper low digging south into central New York. The GEM shows a broad area of lower pressure extending from Northern Maine to the mouth of the St Lawrence, and the upper low centered over Vermont. So the average position would be the GFS. By Wednesday evening the upper low will move east across Maine. Thursday morning northern Maine will remain under wrap around precipitation as the upper low continues to move east. A new low will form over the Great Lakes Thursday morning. The GFS and ECMWF have this low tracking east into the North Atlantic near Cape Cod Friday morning. Again the models diverge on solution, the GFS deepens the low and tracks it east to the Bay of Fundy. The ECMWF move it rapidly east to the south coast of Newfoundland. Higher pressure will ridge in for Friday evening through Saturday afternoon. Another low will track east across southern Canada bringing a warm front into Maine Saturday evening, with the associated cold front moving into NW Maine by the end of the period. Loaded a blend to smooth out the differences in the models, however the solution leans more towards the GFS solution. Used NAWAVE4 for seas in the coastal waters. Used windgust by factor tool. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: VFR for all terminals this morning with southern terminals lowering to MVFR after 18z. Expect IFR in light snow after 21z thru end of TAF valid time at BGR and BHB. Further north, VFR expected until 22z at HUL and 00z for terminals to the north. Expect IFR in -sn at all terminals after 00z tonight. SHORT TERM: A weak ridge of higher pressure will build into Maine. VFR conditions for BGR and BHB. MVFR conditions at HUL, PQI, CAR, and FVE at the start of the period. A trough will move through Maine Monday morning bring all sites to lower MVFR conditions in scattered snowshowers. The trough will move east of the area early Monday afternoon, conditions will improve to VFR. VFR conditions will give way to IFR conditions as a cold front move into the area early Tuesday morning, Conditons will begin to improve south to north Tuesday evening as the low and cold front clears the area. VFR conditions in BGR and BHB, MVFR conditions at all other sites. Conditions will fall back into IFR conditions as the upper low moves through Maine Wednesday morning through the end of the period. && .MARINE... NEAR TERM: SCA conditions will develop this evening as low pressure tracks through the Gulf of Maine. Seas will increase above 5 feet after midnight as southerly swell builds in. SHORT TERM: A Small Craft Advisory will likely be in effect through the short term portion of the forecast for winds and seas. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 5 PM this afternoon to 10 AM EST Sunday for MEZ002-004>006-010-011-031-032. Winter Weather Advisory from 2 PM this afternoon to 7 AM EST Sunday for MEZ015>017-029. MARINE...Small Craft Advisory from 7 PM this evening to 8 PM EST Sunday for ANZ050>052. && $$ Near Term...VJN Short Term...Norton Long Term...Norton Aviation...VJN/Norton Marine...VJN/Norton

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