Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 200118 AFDGYX Area Forecast Discussion National Weather Service Gray ME 918 PM EDT Wed Apr 19 2017 .SYNOPSIS... Weak low pressure will track across Quebec tonight pulling a cold front across the region. The front will stall across southern New England on Thursday as a weak area of high pressure builds by to our north. Low pressure will move out of southern Ontario Thursday night and spread precipitation across the region through Friday. Weak high pressure will build in for late Saturday into Sunday while low pressure passes to our south. High pressure builds in early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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9 pm Update: Precipitation widespread across the area...categorical pops cover this well. Heavier showers are mixing down colder air from aloft allowing surface temps to be colder than forecast, thus made temp adjustments based on mesonet data. Also with colder temps expanded areas of mixed ptype for the next few hours since some currently being observed mainly in the mountains. By midnight temps should slowly warm a few degrees as some waa occurs on the southerly flow in the lower levels. 455 pm Update: Quick update to increase pops the rest of the afternoon and evening across the area. Solid area of showers currently moving through NH and into western Maine. No other changes attm. Previous Discussion: At 18z...a freshening southeast flow around a 1038 millibar high over the maritimes and an advancing frontal system over the eastern Great Lakes. It was a seasonably cool day with onshore flow and clouds limiting highs to the 40s and lower 50s across the region. Shortwave impulse evident on GOES water vapor loop over the upper Great Lakes will race east along with associated 1012 millibar surface low vicinity of the Ottawa valley. NWS Doppler Radar mosaic showed an area of showers in advance of this disturbance entering western New England at moment with activity to cross the area tonight. The column is cold enough to support some snow and sleet tonight across the higher terrain near the international border where a few inches of accumulation will be possible.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... The front will be draped along the coast Thursday morning and move to our east and south during the day before stalling. High pressure will try to briefly nose into the area from the north and west during the day. However...along the coastal plain weak flow will likely result in an onshore flow with lingering moisture and low clouds for much of the day. Highs will be mainly in the 50s...with some lower 60s over southern interior New Hampshire as well as the lower Connecticut Valley. Mostly cloudy Thursday night in onshore flow with light overrunning precipitation developing overnight from west to east along with the potential for some light drizzle early along the coast in onshore flow. The column may be cold enough in the mountains and near the International Border for some wet snow or sleet across the higher terrain. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Much of the long term period looks cool and unsettled as Canadian high pressure continues to nose into the region at the SFC. A short wave trough will approach from the west Thursday night and allow for a light rain event as WAA occurs above the cool, stable boundary layer. The column may be cold enough for a few inches of wet snow in the western ME mountains at the highest elevations. The clouds and showers will be slow to move out on Saturday as another short wave trough moves in from the west. A southern stream system may affect southern zones with some showers Sunday, but right now it looks as though the bulk of the action will remain to our south. Strong Canadian high pressure will return for early next week with fair weather but still cool temperatures. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... Short Term /Through Thursday Night/...MVFR with lcl IFR tonight in -shra and fog with -shra/-shsn in the mtns. Areas of MVFR cigs lingering on Thu...with MVFR and LCL IFR Thu night in cigs...fog and developing -RA. Long Term...IFR conditions are expected Friday in low clouds and light rain. IFR to MVFR conditions continue to be expected Friday night into Saturday before improving Sunday and Monday. && .MARINE... Short Term /Through Thursday Night/...Expect Small Craft winds and seas tonight in advance of the cold front with lingering SCA seas possible outside the bays on Thu. Winds and seas will increase once again Thu night and may reach Small Craft by early Friday. Long Term...Small craft conditions are possible Friday as low pressure passes to our west. && .FIRE WEATHER... Cool and moist onshore flow will persist through the end of the week. There will be showers tonight with more widespread rain expected Thursday night into Friday. && .HYDROLOGY... && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ150>154. && $$

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