Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270246 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1046 PM EDT Fri May 26 2017 .SYNOPSIS... Low pressure in the Gulf of Maine will continue northeast into the maritimes tonight. Weak high pressure will build over the area on Saturday and will shift offshore on Sunday...allowing a window of dry weather. The next system over the eastern Great Lakes will lift north into Quebec Sunday night and will drag a front toward the region on Monday bringing rain showers. That front will slowly cross the area late Monday night and Tuesday with unsettled weather. && .NEAR TERM /THROUGH SATURDAY/... Update... No changes to this package, except to issue Coastal Flood Advisories for PWM and points south (see coastal flood section below). Have updated the grids based on current conditions and latest set of mesoscale models. Low level wind flow has backed to the northwest over much of New Hampshire, allowing for slightly drier conditions over the Granite State. Otherwise, north- northeasterly surface winds continue to bring moisture into the region around the periphery of the slowly departing area of low pressure which continues to exit through the Gulf of Maine. Have made minor adjustments to temperatures and dew points. Also will continue the threat of drizzle along and near the coastline and have upped pops over the region based on latest radar imagery. Showers should gradually diminish as we move through the night. Patchy fog is possible in most areas overnight, especially in Maine. Prev Disc... A cool, damp cyclonic flow continues through tonight as the center of low pressure in the Gulf of Maine exits into the Maritimes. Clouds and a few random lingering showers expected through the evening. With lower levels near saturation some patchy drizzle and fog may occur in areas along and near the coast. Temps will only drop a few degs into the mid-upper 40s overnight. Used a blend of models for overnight lows. && .SHORT TERM /SATURDAY NIGHT/... A lack of ventilation Saturday with weak high pressure over the area will make for slow clearing to occur since there will be lingering low level moisture. At least it will be a dry day! Temps will recover into the 60s in the afternoon as partly sunny conditions eventually develop in the afternoon. Saturday night the weak high pres remains over the area with dry conditions. Overnight lows once again in the 40s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... The 500 mb pattern continues to remain dominated by moderate to strong blocking across the nrn hemisphere, especially poleward of about 50N. The trend for for NE CONUS will be sit at the equatorward end of a trough, although some weak ridging will be possible at times as well, especially mid to late week. What this means for sensible weather is that temps will trend toward around normal, but there will be some threats for showers at times as weak waves move around the base of the trough to our north. So, maybe not great weather, but better than we have had for a large part of May. It continue to look like we will squeeze a decent day out of Sunday as weak 500mb ridging moves over the region and helps support sfc high. May see more clouds clip the NE zones, but overall partly to mostly sunny skies and highs coming close to normal. 70-75 inland, and in the 60s along the coast, as sea breeze develops. Closed 500mb low begins shift SE from Ontario Sun night into Monday, with decent wave rotation around the base, and this will bring in good threat for showers late Sunday night into Monday. Monday, therefore is not expected to be a great day withe numerous showers and a cool onshore flow, producing highs only in the mid-upper 50s on the coast and 60-65 inland. The upper level low begins to wobble NE out of the gReat Lakes Mon night and Tue, and should see a decrease in precip Mon night into early Tue, but another wave will rotate around the system by later Tue, and the htreat for showers will increase. Overall, the system aloft will be filling and flow aloft will be shifting W-SW which should at least allow some warmer air and some sunny breaks by Tue way from the coast, at least. Still showers will hold in the forecast on Tue with highs ranging from the low 60s in the eastern zones to near 70 in southern NH. As we move into Wed and the latter part of the week, the 500 mb low shifts slowly NNE, and although there will still be some wave rotating around it, and a threat of showers, the best chc chance of showers will begin northward, with more breaks of sun, and temps running close to normal, upper 60s in the mountains to mid 70s in southern NH. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Short Term...MVFR to IFR conditions at times in areas of low clouds and patchy precipitation and fog. During Saturday conditions improve to VFR and continue into Saturday night. Long Term...VFR Sunday into Sun evening, then MVFR to IFR possible Sun night into Mon night, with the best chance for the worst conditions along the coast. VFR, with tempo MVFR in showers Tuesday into Wed. && .MARINE... Short Term...Winds have diminished and have backed to the north and northwest. Not enough of an offshore flow to knock down the seas until later tonight so expect they will remain high through the night over the outer waters and will issue a SCA for hazardous seas into Saturday morning. During Saturday and Saturday night winds and seas will be light as we enter into a col zone. Long Term...For the most part winds/seas will remain below SCA conditions Sunday through Wed. && .TIDES/COASTAL FLOODING...
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The astronomical high tide in Portland is 12.0 feet MLLW in Portland at 12:22 am Saturday. A storm surge now appears will be between a half foot to close to a foot through high tide, bringing the storm tide possibly to around 12.75 feet or so. Flood stage is 12.0 feet. Have issued a coastal flood advisory for PWM and points south along the coast to the NH Seacoast for minor flooding and possibly minor splash- over.
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ME...Coastal Flood Advisory until 1 AM EDT Saturday for MEZ023-024. NH...Coastal Flood Advisory until 1 AM EDT Saturday for NHZ014. MARINE...Small Craft Advisory for hazardous seas until 8 AM EDT Saturday for ANZ152-154. Small Craft Advisory for hazardous seas until 2 PM EDT Saturday for ANZ150.
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&& $$ SYNOPSIS... NEAR TERM...Cannon SHORT TERM...Cannon LONG TERM... AVIATION... MARINE... TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.