Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270128 AFDGYX Area Forecast Discussion National Weather Service Gray ME 928 PM EDT Mon Sep 26 2016 .SYNOPSIS... High pressure moves east tonight with a cold front arriving from the west. Along the front expect a period of showers arriving from west to east tonight into Tuesday morning. Conditions should dry out behind the front on Tuesday with temperatures a few degrees warmer. Low pressure developing along the offshore front will develop a northeasterly wind over Maine and New Hampshire Tuesday night, bringing clouds back in to the area. Several waves of low pressure will track northeast along the front through the western Atlantic, with an occasional chance of showers especially near the coast. The best chance of rain will be this weekend when the large upper level low pressure system over the Great Lakes lifts to the north, spreading rain into New England. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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930 PM Update...Have updated the timing of PoPs overnight a little bit (mainly a little slower due to the dry column in place as seen on our 00z sounding). Otherwise, no significant changes. 610 PM Update...Little change to the going forecast. Just a few minor adjustments to PoP and sky cover for the next few hours based on latest observational and mesoscale model data. The evening hours will feature increasing clouds but remain dry. Previously... Expect increasing clouds through the evening and a moistening southerly flow ahead of an approaching cold front. This front is currently over western Pennsylvania and New York pushing eastward. Areas of showers have been fairly widespread along the front in this area, and expect this trend to continue as the front moves eastward into New England tonight. There could be multiple different clusters of showers, with one moving to the north near the Canadian border and another moving in from southern New England, but expect the overall coverage of rain to be pretty high tonight even as total rainfall amounts remain less than half an inch. Best chance of rain generally occurs in a 2 to 4 hour window beginning in New Hampshire just after midnight and pushing through western Maine around sunrise. Temperatures tonight will not be nearly as cold as last night due to cloud cover and increasing low level moisture. In fact, temperatures will not follow their normal diurnal trend, with the lowest temperature occurring early in the evening for much of New Hampshire before temperatures rise as the front approaches. Attempted to place this trend into the hourly temperature forecast.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Cold front will still be making its way east through western Maine Tuesday morning, so showers will be ongoing there Tuesday morning. Should see clearing by around noon, with temperatures behind the front warming into the 60s or even low 70s. As the front moves offshore, low pressure strengthens along it, causing northeasterly winds to develop. This will send cool, moist air southwestward through Maine and into New Hampshire overnight. For the most part this will consist of cloud cover, but cannot rule out some drizzle as well. Models tend to overdo the QPF in such scenarios, but some light accumulation of drizzle is possible. Temperatures again stay warm due to cloud cover and moisture over the area with lows in the upper 40s to low 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Unsettled weather likely in the long term as models showing a stalled front to our east and a large cutoff low to our west through the period. This will result in an extended period of northeast winds that will keep the region cool and cloudy with sacttered showers. A couple of periods of steady rain are possible as the 500 ridge moves past us later in the week and then again late in the weekend or early next week when the upper low moves over us. The big question is how much rain will this system produce. It looks like the heaviest rain will remain to the south and west of the forecast area, closer to the closed upper low. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Short Term...Conditions deteriorate tonight around midnight in western New Hampshire as showers arrive from the west. This should spread eastward into western Maine in the early morning hours. Conditions could go IFR especially in heavier showers and along the coast where lower ceilings are likely. Front pushes to the east in the morning on Tuesday, helping bring VFR conditions back to the region from west to east. Could see some MVFR ceilings hang on north of the White Mountains through the afternoon. Tuesday night a northeast flow develops and sends a layer of low clouds and possible drizzle back to the west across Maine and into eastern New Hampshire. This could bring IFR conditions after 00Z Wednesday, with the western New Hampshire terminals HIE and LEB least likely to be impacted. Long Term...Expect VFR for most of Wednesday then mvfr moves in Wednesday night through much of the remainder of the period with some IFR likely in any fog/stratus that settles over the region at night. && .MARINE... Short Term...Although southerly flow does increase this evening and tonight, it should remain below advisory levels and will not persist long enough to cause wave heights to build too high. At this point advisory conditions are not expected, though gusts to 20KT and wave heights occasionally up to 5 FT in spots are possible. Front crosses the western Gulf of Maine Tuesday morning bringing light winds along and behind it. Long Term...Expect winds and seas to build to small craft criteria due to the persistant and strengthening northeast wind. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM UPDATE...Ekster SHORT TERM...Kimble LONG TERM...Hawley

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