Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 191623 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1223 PM EDT Wed Apr 19 2017 .SYNOPSIS... Cool onshore flow will persist today. Weak low pressure tracks across Quebec this afternoon and tonight and drags a cold front across the region tonight. Weak high pressure builds in Thursday, and brings slightly warmer temperatures. Low pressure will move out of southern Ontario on Thursday night and spread precipitation across the region on Friday. Weak high pressure will build in for late Saturday into Sunday before another disturbance arrives on Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1222 PM...Minor ESTF update to reflect current satellite trend and the 16z mesonet in near term grids. Prev Disc... 935 AM...GOES imagery shows clouds arriving from the west with low clouds beginning to move onshore in the onshore flow. We`ll see a mix of clouds today with showers currently on NWS Doppler Radar Mosaic over upstate New York arriving in the Connecticut Valley and International border area by late today. For this ESTF update...I adjusted near term grids to reflect the current mesonet as well as satellite trends. Prev Disc... 705 AM...Forecast in good shape. Update reflects a few changes to forecast based on current conditions. Coastal stratus seems to be holding so far, but cirrus and mid-lvl clouds thick enough to still call things mostly cloudy in many spots. Onshore flow increases today in advance of sfc cold front approaching from the west. This will keep the wx on the cloudy and cool side today. Exceptions will be areas west and north of the mtns where some sun will be possible this morning, and perhaps parts of interior srn NH which could see flow shift more SW than SE later today and cold see a little sun this afternoon. Highs will be in the mid-upper 40s, except in the CT valley and srn NH where they will reach into the low to mid 50s. Showers could move into wrn zones late this afternoon.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... The cold front will move the region tonight, and will produce a period of showers, especially this evening. QPF continues to trend downward in the 00Z model runs, and will range from a tenth of an inch to a third of inch, higher amounts in the north. Higher elevations will see the SHRA change to SHSN. Lows will drop to the mid-upper 30s in the north to the low 40s in the south. AS usual, it remains questionable as to whether the front mixes to the surface before sunrise on the coastal plain, in which case some fog may develop. The 00z models also continue to trend to weak sfc ridging building in for Thursday, and the forecast trends a little warmer and little brighter, especially in the morning. Inland areas should get some breaks of sun, but the weak NW flow flow will be short lived and onshore flow will develop along the coast in the afternoon, with low clouds and fog working back in late. Any precip from the next system should hold off until Thu night. Highs will rise to around normal, generally from around 50 in the north, to around 60 in inland srn NH and SW ME. It will be cooler near the coast. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... The week will come to an end with some wet weather as a series of short waves move along the US Canadian border. The core of the cold air is locked up in Nunavut with a more zonal flow in place across southern Canada and the Northern United States. A wave just starting to move through British Columbia tonight will move eastwards and begin to cut off over southern Ontario early Friday morning. This will move through Southern Quebec Friday into Saturday morning bringing rain to the region. Rain will move into western NH by daybreak on Friday and spread across the entire forecast area by midday. Overall expect 0.5-1" of total precipitation with the highest amounts along the coast. Elevations above 4000ft may see some of this fall as snow but overall the warm lower layers should prevent any significant accumulation with just a few tenths expected. The rain will move out on Saturday morning allowing for weak high pressure to build in. By Sunday temperatures will climb back up with highs in the mid 50s ahead of another front moving through Sunday night into Monday. Monday morning features a tug of war between a weak cold front moving through Quebec and a elongated surface low tracking up the eastern seaboard. Currently the low is the out to sea looser with the northern portion of the forecast area feeling the effects of the Quebec front in the form of showers. Either way the week will start off cloudy with some unsettled weather. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... Short Term...Cigs will drop to MVFR this morning, and will persist there through the day. Should see lowering to IFR tonight in SHRA and some fog. Some improvement to MVFR or VFR possible Thu, especially inland. Long Term... A storm system will move in THursday night resulting in MVFR conditions deteriorating to IFR rain from west to east by daybreak. Rain will continue on and off through the day on Friday. Conditions will improve Saturday morning to overcast but VFR in the south and MVFR in showers in the north and mountains. && .MARINE... Short Term...S-SE flow increases today with SCA gusts developing this afternoon into tonight. Winds will veer to the SW this evening, and then weaken below SCA levels by early Thursday as they shift briefly N-NW Thu morning, before beginning to turn onshore again in the afternoon. Long Term... Easterly flow ahead of the low pressure will reach small craft criteria on Thursday night and remain through the day on Friday. Winds and seas will subside on Saturday returning to generally calm by Saturday night. && .FIRE WEATHER... Cool and moist onshore flow will persist through the end of the week. There will be showers late today and tonight and night more widespread rain expected Thursday night into Friday. && .HYDROLOGY... Flood warning continues for the Connecticut River at Dalton which has crested as is once again beginning to recede. THe Androscoggin and Kennebec have also crested and dropped back below flood stage. With snow water equivalent almost completely gone from all but the highest elevations expect the river flooding threat due to snow melt to be over in the next day or so. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ150>154.
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