Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 141540 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1040 AM EST Tue Nov 14 2017 .SYNOPSIS... High pressure builds in from the northwest today and Wednesday, keeping conditions cool. The next storm system will drag a cold front through the area on Thursday, with mainly rain and some mountain snow expected. Cold high pressure builds in again for Friday before the next system arrives this weekend. && .NEAR TERM /THROUGH TONIGHT/...
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Update...There is a broad area of subsidence in the low level NE flow across parts of Wrn ME at this time. With the clouds it is thinning in some areas and clearing in others as this subsidence slowly drifts SWwd. I have adjusted sky cover to match these satellite trends...but otherwise forecast remains on track. ORIGINAL DISCUSSION... Surface high pressure builds in from the northwest today while upper level low pressure tracks overhead. This low is rather broad and does not have much lift or moisture with it, so mainly just expect some cloud cover through the day. Lingering trough axis in southwest New Hampshire will keep a bit of light snow falling there for a few more hours this morning. Temperatures will be cool, but not quite as cold as yesterday, generally topping out in the low 40s.
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&& .SHORT TERM /WEDNESDAY/... Central axis of high pressure moves into the northern part of the area overnight tonight with calm winds and decreasing cloud cover. Should have a good shot at some good radiational cooling conditions especially in the north and east tonight where temperatures will fall into the low 20s or upper teens in the coldest spots. Cloud cover may linger longest in the southwest where temperatures may only bottom out in the mid to upper 20s. High pressure continues to slowly slide east on Wednesday with temperatures making an ever so gradual rise... into the low to mid 40s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Once again, the main emphasis in the extended forecast will be two centered around Thursday and the other over the weekend. The first system will arrive later Wednesday night as a strong and amplifying short wave trough approaches from the Great Lakes. The degree of amplification will have ramifications on the forecast because it looks likely secondary SFC low pressure will form just off the coast on Thursday. The track and degree of amplification of the short wave trough will determine how close the secondary low forms to the coastline which in turn will determine how much precipitation gets thrown back onto land. As of the 00z model suite, the NAM is the most aggressive deterministic solution as far as precipitation amounts on the coastal plain. The ECMWF delays significant amplification and results in a more eastward track. Either way, the sub-850mb portion of the column looks too warm for significant snow even if heavy precipitation does get thrown a good ways westward. We will have to watch this however, as the western edge of the precip shield (wherever it may be) could get cold enough for a change to snow. At this time, took a blend of the available guidance which allows for some light mixed precip at the start later Wed night into early Thurs which then changes to rain in many areas. The system looks to depart overnight Thursday night. As the low departs, gusty NW winds are expected late Thursday night and during the day on Friday. High pressure moves in Friday and Friday night before the next short wave trough begins to impinge on the region from the west. This system looks to be taking a more southerly track than advertised yesterday, so more of a mix could be in the cards for the interior late Saturday and Saturday night. However, warm air still looks to win out for most of the CWA, resulting in rain for the bulk of the event. Will continue to watch for significant trends as we are still quite a distance away from the event. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... Short Term...Dry air pushing in from the north should erode the low level cloud cover from north to south this morning. By tonight expect conditions to become mostly clear, with VFR expected to continue through Wednesday. Long Term...VFR conditions are expected for much of Wednesday night before lowering to MVFR then IFR late Wednesday night through Thursday as low pressure moves across the region. Some mixed precipitation will be possible across the interior at the start later Wed night. Otherwise, VFR returns Thursday night and Friday, and likely lasts through at least midday Saturday. && .MARINE... Short Term...Northeast winds are at their peak this morning and should stay just below the 25KT criteria for Small Craft Advisory. Wave heights will be at their highest in the western Gulf of Maine where they will be generally 4 FT to possibly as high as 5 FT. Long Term...Northwesterly gale force gusts look possible Thursday night into Friday in the wake of low pressure. These are likely to subside as high pressure moves in Friday afternoon and night. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro is the U.S. government's official web portal to all federal, state and local government web resources and services.