Area Forecast Discussion
Issued by NWS Portland, ME

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938 FXUS61 KGYX 230033 AFDGYX Area Forecast Discussion National Weather Service Gray ME 733 PM EST Thu Feb 22 2018 .SYNOPSIS... High pressure will build across the area tonight through early Friday. A weak weather systems will move through the region Friday afternoon and evening followed by high pressure for Saturday. Another weather system will bring a mixture of precipitation for Sunday. Fair weather returns for early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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700 PM Update... Area of snow has pushed south of the forecast area early this evening and skies are clearing from northwest to southeast. Very dry airmass over central and northern zones will push into southern zones through midnight and patchty fog in southern New Hampshire should dry up as this drier air works south. Expect good radiational cooling overnight with lows in the single number north and teens south. Have adjusted pops and wx grids to reflect current and expected conditions. Aside from a few temp/td/rh tweaks no other changes planned to current forecast. Prev disc... Area of snow along the northern edge of precipitation shield associated with a broad wave moving through southern New England will continue to bring some light snow to the southern part of the forecast area this evening. Still expecting accumulations of an inch or less for the most part with this coming to an end fairly quickly this evening. High pressure building in from the west will move into northern Maine tonight. This should set up a pretty good radiational cooling night, especially in the northern part of the area where single digit lows are forecast. In the south a fresh snow cover could wreak havoc on overnight lows but for now have indicated teens and low 20s.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... As high pressure moves east on Friday it will set up a southeast flow around it in advance of the next approaching system. This next wave brings another round of precipitation arriving in the afternoon, this time affecting just about the entire forecast area. Think this will initially start as snow, but could see a transition to freezing rain as temperatures aloft warm behind the warm front and rain in areas that warm above freezing. Southeast flow in the lowest levels could initiate damming in interior southwest Maine keeping temperatures down there, but confidence is not very high. If temperatures get colder than expected tonight, this could be a factor which encourages low level damming and could enhance the freezing rain threat Friday into Friday night. Confidence currently not high enough for an advisory, but one may eventually be needed. This precipitation will move out overnight Friday night with high pressure building in again from the west. && .LONG TERM /SATURDAY THROUGH THURSDAY/... High pressure will provide for a mostly sunny day across the region for Saturday. Models are not in good agreement for temperatures on Saturday with the GFS showing some rather mild readings. Have compromised with highs ranging from the lower 40s north to the lower 50s south. The high moves overhead Saturday night leading to good radiational cooling. Precipitation will spread northeastward across the region Sunday morning, initially starting as snow but likely transitioning to rain or a mix during the day. There remains quite a bit of uncertainty in the forecast precipitation type during the day Sunday. Models all show warming aloft from morning to late evening from south to north. At the same time, the surface high will provide a source of colder air feeding into the system near the surface. Surface temps across much of the region will likely remain in the low to mid 30s for much of the day. The precipitation will start as snow all areas with advisory snowfall amounts possible in inland areas. Although some freezing rain is possible, the recent warm temperatures combined with late February sun should help to keep the impact of any freezing rain to a minimum. The precipitation comes to an end Sunday night with another relatively mild day for Monday with temperatures mainly in the 40s. Mainly fair weather is expected for Tuesday through Thursday with a slight cooling trend and the only precipitation being some mountain snow showers. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... Short Term...After the snow moves out of southern areas this evening, we should see conditions go VFR for all areas. Another round of precipitation is expected Friday afternoon into Friday night. This may start as snow before changing to freezing rain or rain depending on temperatures. IFR conditions seem likely during this period, but improve after midnight. Long Term...VFR conditions Saturday. IFR to LIFR conditions Sunday in mixed precipitation, followed by VFR conditions Monday and Tuesday. && .MARINE... Short Term...High pressure crosses the waters tonight with a return southeast flow tomorrow until a cold front moves through early Saturday morning. Generally expecting winds to stay below advisory levels, but a few gusts to 25 KT here or there would not be out of the question mainly Friday night with the cold front. Long Term...SCAs likely Sunday into Tuesday, otherwise conditions expected to be below SCA criteria.. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.