Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 231443 AFDGYX Area Forecast Discussion National Weather Service Gray ME 943 AM EST Fri Feb 23 2018 .SYNOPSIS... High pressure will exit into the Canadian Maritimes early today. A weak weather system will approach New England this afternoon and evening followed by high pressure late tonight and Saturday. Another weather system will bring mixed precipitation for Sunday and Sunday night. Fair weather returns for early next week as high pressure slowly builds over the Mid Atlantic region. Yet another complex weather system will pass south of New England Wednesday and Thursday. && .NEAR TERM /TODAY/...
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945AM UPDATE... Not a terribly high confidence forecast for precipitation type today. Generally it looks like precipitation starts as light snow before temperatures aloft begin to warm and change things to rain or freezing rain. Ground temperatures are expected to warm to near or above freezing for many areas as the precipitation arrives, which would end the freezing rain chances. However there is a chance that some areas stay below freezing, especially in the foothills of western Maine, thus will continue the advisory. 645AM UPDATE... Minor ESTF tweaks to temps otherwise no changes to previous forecast package at this time. The clear skies over the region this morning will be quickly giving way to the upstream clouds racing east from New York shown nicely on the satellite imagery. Timing looks on target. ORIGINAL DISCUSSION... A weak and fast moving short wave will move rapidly northeast spreading light WAA overunning mixed precipitation into the region during the afternoon. Over southern and coastal areas the precipitation will be all rain while well inland and in the mountains a mix of light snow sleet and some freezing rain is expected. The reason for the Winter Weather Advisory this afternoon into the evening is due to some areas of light freezing rain to occur which will make for slippery travel conditions. QPF with this system will be very light.
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&& .SHORT TERM /TONIGHT AND SATURDAY/... The WAA overunning mixed precipitation will continue through the evening before coming to an end by midnight. Any snow accumulations in the mountains or foothills will be no more than an inch or two since very little QPF will be associated with this system. After midnight the system quickly exits to the east followed by high pressure and fair weather. Downsloping winds on Saturday will allow temps to reach into the upper 40s to lower 50s over southern and coastal areas of ME/NH. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Low pressure will intensify Saturday night, before crossing over the western Great Lakes Sunday. Warm air will attempt to surge ahead of this system aloft and into New England late in the weekend as a dry and cold area of high pressure gradually exits to the Canadian Maritimes. Evaporational cooling will allow the precipitation to begin as snow in all areas before warm air advection overwhelms the atmospheric column over southernmost portions of the forecast area. Precipitation is expected to initially change to a mix over southern areas before potentially ending as a mix over central areas per latest forecast soundings. All models within the 00Z model suite in good agreement that a weak wave of low pressure will form along the southern New England coastline Sunday evening before crossing through the Gulf of Maine Sunday evening. This will effectively shut off any warm air advection as the precipitation comes to an end. High pressure will then gradually build towards the Mid Atlantic region on Monday and Tuesday. As the surface ridge finally shifts east on Thursday, yet another area of low pressure will approach the region from the Ohio River Valley. This system will likely be shunted south of New England late in the week. After a chilly start to the long range forecast, expect temperatures to climb to slightly above normal levels for much of next week. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... Short Term...VFR conditions will lower to MVFR later today and then IFR/MVFR this evening in light rain along the coast and mixed precipitation well inland. Conditions will quickly return to VFR by Sat morning. Long Term...VFR conditions will continue through Saturday evening. This will be followed by lowering ceilings and visibilities to IFR to LIFR conditions by Sunday in mixed precipitation. VFR conditions are expected Monday and Tuesday. && .MARINE... Short Term...Winds and seas will increase to SCA conditions over the outer waters tonight. Winds and seas will subside toward Sat morning. Long Term...SCAs are likely Sunday through Tuesday. SCA conditions may redevelop with low pressure passing south of the waters on Thursday. Otherwise, conditions are expected to be below SCA criteria. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 2 PM this afternoon to 10 PM EST this evening for MEZ007>009-012>014. NH...Winter Weather Advisory from 2 PM this afternoon to 10 PM EST this evening for NHZ001>006-009. MARINE...Small Craft Advisory from 6 PM this evening to 5 AM EST Saturday for ANZ150-152-154. && $$ NEAR TERM UPDATE...Kimble SHORT TERM...Marine LONG TERM...Cannon

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