Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 220238 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1038 PM EDT Tue Mar 21 2017 .SYNOPSIS... An arctic front will push south through the region late tonight, and produce a very cold and windy Wednesday. High pressure will build in from the west Wednesday night through Thursday. High pressure will shift east Thursday night. A warm front will approach from the southwest Friday followed by a cold front Friday night. High pressure will build south from Canada Saturday through Sunday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1040 PM Update...Just a few minor adjustments to the forecast based on latest trends in surface obs as well as satellite and radar data. 745 PM Update...Little change to the going forecast. Occasional snow continues in the higher terrain of the western ME Mountains and the Whites. Scattered rain/snow grain showers are also occurring from time to time further south. An arctic cold front continues to approach from the NW is expected to sweep across the region later tonight. A few squalls remain possible with the front. 6 PM Update...Have updated the forecast mainly in the PoP/Wx and temperature departments. Loosely organized snow banding is taking place across the western ME mountains, some of which is heavy based on some web cams. The HRRR continues a pretty narrow band of potentially mod-hvy snow through the evening, particularly across higher elevations of Franklin County. Have increased snow amounts to a few inches there. Otherwise, an arctic front is expected to move through later tonight - perhaps allowing for a band of snow squalls (mainly in the mountains). Previously... Some mid lvl WAA associated with weak low pressure form ahead of sfc cold front setting off a cluster of showers of rain and snow moving across nrn zones at this times. This should shift E in the next couple of hours, with a bit of a dry period. in the hours around sunset. The sharp edge to the arctic air will move through from late evening thru the pre-dawn. Scattered snow showers are a good bet in the mountains, with some squalls possible across the nrn zones. Models are stingy with bringing much in the way of snow showers with the front into srn half of NH or coastal plain of ME, but could see a few isolated SHSN after midnight in these areas. Temps will drop slowly through the evening, but once the cold front moves through the will begin to fall off quickly late with lows 15-20 in the N and around 30 in the south. Winds will also pick up fairly quickly behind the front, but strongest winds will be during the day Wednesday. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Strong CAA and gusty NW winds behind the front will allow for temps for temps drop through out the day, with highs early the day. Winds will pick up during the morning probably to around 20 mph with gusts around 40 mph at times, especially in the afternoon. Models keep gusts below wind adv criteria, but it gets close, so will have to watch for potential advisory in some spots. Temps will fall thru the teens and 20s during the afternoon, with wind chills in the single digits below zero in the mountains, and in the single digits above zero in the south, so it will be quite cold. The March sun will only go so far to counteract the strong CAA. Upslope snow showers will continue through the morning with some accums in the favored upslope areas and on the higher terrain. Winds will be slow diminish Wed evening and temps will continue fall through the night, with wind chills dropping blow zero everywhere and in the -10 to -20 range in the mountains. Lows will bottom out from around zero in the north to around 10 above on the coast and in srn NH. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Broad upper ridge will gradually replace a departing trough Thursday. Surface high pressure building in from the west will produce a mostly sunny day...although temperatures will remain well below normal. Highs will range through the 20s north and lower to mid 30s south. High pressure will shift offshore Thursday night and return flow will begin to bring warmer air back into the region. Expect high clouds to spill over the ridge as a broad area of over-running set up to the west. May see a few flurries or snow showers by daybreak but expect any precip to be light and spotty generally falling off a mid level deck. Lows will range from 5 to 15 north and will range through the teens south. Weak over-running precipitation will continue through the day Friday ahead of a cold front approaching from the west. Will likely see light snow mixing with or changing to rain in southern New Hampshire and southwest Maine as boundary layer temps warm through early afternoon. Models showing some differences in areal extent of this warming with the ECMWF remaining significantly colder. In any case QPF by the end of the day only amounts to a tenth of an inch or less so any impacts will be minimal. Temperatures will be fairly uniform across the region...ranging from the mid 30s north to the mid 40s south. Cold front will swing in from the west Friday night and will push south of the area by Saturday morning. Looking for lingering rain or snow showers to gradually end around midnight as the boundary moves through. looking for partial clearing after midnight as high pressure builds in from the north. Should see temperatures closer to normal overnight with lows from the mid 20s north to the mid 30s south. High pressure building south from Canada will produce a mostly skies Saturday. Not a lot in the way of cold air behind the front as it stalls just southwest of the area so highs top out above normal ranging from the mid 30s to lower 40s north and mid 40s to near 50 south. Models diverge at this point with the ECMWF lifting the front northward ahead of an approaching shortwave while the GFS parks it to the southwest of the area. Have pretty much gone with SB numbers for the remainder of the forecast and confidence quite low for days 6 through 8. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Short Term...Could see some periods of MVFR overnight in SHSN at KLEB, and especially KHIE, bit otherwise look for MVFR to persist through Wed night. Strong NW wind gusts, to around 35kt at times are expected on Wed, especially in the afternoon. Long Term...VFR Thursday through Thursday night. MVFR/IFR ceilings/vsby Friday and Friday night. VFR Saturday through Sunday. && .MARINE... Short Term...Gales are now effect for all zones Wed into Wed night, as strong NW flow moves in behind a cold front. With very cold air spilling in, have issue fz spray adv for Wed night. Wind should start to diminish a bit late Wed night. Long Term...SCA`s likely Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Freezing Spray Advisory from 7 PM Wednesday to 10 AM EDT Thursday for ANZ150>154. Gale Warning from 8 AM Wednesday to midnight EDT Wednesday night for ANZ153. Gale Warning from 8 AM Wednesday to 8 AM EDT Thursday for ANZ150>152-154. && $$ NEAR TERM...Ekster

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