Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 022339 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 639 PM EST Fri Dec 2 2016 .SYNOPSIS... an elongated area of low pressure over eastern Canada will gradually slide well offshore by Saturday night. This system will provide clouds and a few rain and snow showers through Saturday. The most persistent clouds and snow shower activity, along with a few inches of snow accumulation, will be confined to the higher terrain of western Maine and Northern New Hampshire. A ridge of high pressure will slowly build into the region by Sunday, before retreating offshore Sunday night. A weak weather disturbance may bring a few snow showers to the region Monday. Otherwise, cold high pressure will settle in for the start of the new work week. A snow and rain mixture may enter the region late in the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Update...S/wv trof is well defined on IR satellite imagery this evening...as a swirl of clouds drops Swd out of Quebec. The leading edge of the trof has picked up a lot of the shower activity and lake enhancement...and is pushing that S and E thru New England. It could be briefly squally type snow shower activity in the higher elevations of the notches before warmer air temps turn that into more rain showers as they near the coast. BTV snow squall parameter is quite high in the area...so if temps were just a couple of degrees cooler it could have been a nice brief heavy snow event. Given the forecast for more unstable flow over the mtns I see no reason why the showers will not continue towards the coast either. So I have adjusted PoP to reflect at least a small chance that measurable precip makes it to near coast communities by later this evening. Previous discussion...At 19z...a 1000 millibar low was over Quebec with a second center near Prince Edward Island. A surface trough extended from the Quebec low through the eastern Great Lakes. GOES water vapor imagery showed a shortwave impulse along the Quebec/Ontario border riding southeastward towards the forecast area. With daytime heating and the approaching shortwave cloud cover has expanded to include the entire forecast area at moment. Not surprisingly...NWS Doppler radar mosaic shows echoes increasing in coverage to our north and west ahead of the surface trough and associated shortwave. We warmed into the 40s and lower 50s today...or a good ten degrees above average for early December. For tonight...mostly cloudy skies with a few rain and snow showers as the shortwave and surface trough cross the area. As the colder air arrives the precipitation will transition to snow. The most widespread precipitation will be found across the higher terrain in upslope flow enhanced by the passing shortwave. We should see a coating to as much as three inches of snow by dawn over the high terrain. Lows tonight should range from the upper 20s to mid 30s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... On Saturday...a west-east surface trough will linger across the area while one last weak impulse crosses the area. Cold cyclonic flow will generate considerable clouds while upslope flow produces some additional light snow accumulations across the mountains and foothills. High temperatures will range from the 30s in the mountains to the lower 40s over southern New Hampshire and along the coastal plain. However...a blustery westerly wind will make it feel considerably cooler. Some lingering clouds from northern New Hampshire into adjacent western Maine with the exiting upper trough and upslope flow...with mainly clear skies elsewhere as the surface ridge inches its way into Northern New England. Lows should be mainly in the 20s...with a few teens over some northern mountain valleys. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Fairly quiet extended forecast shaping up for the end of the weekend and early next week. High pressure will build in from the west on Sunday. Expect lingering clouds in the morning to give way to mostly sunny skies in the afternoon. High temps will only reach the mid 20s to lower 30s north and mid to upper 30s south. High pressure will crest over the region Sunday night. After a mostly clear evening high clouds will push in from the southwest ahead of a weak warm front. Lows will range through the teens north and lower to mid 20s south. Warm front will gradually dissipate over the region on Monday. Expect variable cloudiness during the day with just a chance of a stray flurry or snow shower. Highs will range from the mid 20s to lower 30s north and mid to upper 30s south. Surface high pressure will build over the northeast Monday night. Expect decreasing clouds overnight with lows in the mid teens to lower 20s north and lower to to mid 20s south. High pressure will gradually drift off to the northeast on Tuesday as a occluded front approaches from the southwest. After a mostly sunny morning high clouds will push into the region in the afternoon. Highs Tuesday will top out in the mid 20s to lower 30s north and mid to upper 30s south. Clouds will thicken Tuesday night and will likely see light snow developing after midnight in western zones. Could pick up an inch or two in southern and central New Hampshire by daybreak Wednesday. Lows overnight will range from the mid teens to lower 20s north and lower to mid 20s south. Occasional light snow will continue on Wednesday as the occluded front lifts northeast through the region. Will see some additional light accumulations of another inch or two...mainly across western Maine. Coastal areas will see boundary layer temps warm enough for a mix of rain and snow. Highs in the north will range from the mid 20s to mid 30s and mid 30s to near 40 south. Occlusion will push east of the region Wednesday evening as a shallow ridge of high pressure builds in from the west. Looking for clearing downwind of the mountains and variable clouds in the north. Lows will generally range through the 20s. High pressure will shift east on Thursday as a deep upper trough settles into the northeast. Will see increasing clouds with perhaps a few flurries in western zones by late in the day. Highs will range through 30s north and upper 30s to lower 40s south. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... Short Term /through Saturday night/...Areas of MVFR through 23z Sat mainly in Mtn shsn. Some lcl mvfr cigs psb Sat night in the mtn...otherwise VFR expected. NW sfc wind on Sat will gust to 25 kt. Long Term... VFR Sunday through Monday morning. Areas of mvfr/ifr ceilings Monday afternoon. VFR Monday night and Tuesday. IFR/LIFR ceilings/vsby Wednesday. && .MARINE... Short Term /through Saturday night/...Winds and seas build tonight ahead of the approaching surface trough with SCA conditions expected outside the bays. I`ve extended the current SCA through Saturday AM. The current SCA will likely be extended into Saturday night outside the bays. There could be a brief surge in winds over the bays with a period of gusts to SCA threshold on Saturday. So, the current SCA headline may need to be expanded to include the bays on Saturday. Long Term... SCA`s likely early Sunday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 7 AM EST Saturday for ANZ150-152- 154. && $$ NEAR TERM...Legro

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