Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 280717 AFDGYX Area Forecast Discussion National Weather Service Gray ME 317 AM EDT Wed Sep 28 2016 .SYNOPSIS...
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Canadian high pressure will continue to build into the region from the north today through Thursday. The high will remain parked to our north while low pressure over the midwest drifts slowly north and east. Moisture from this system may spread into southern areas Friday. The best chance of rain will be this weekend when a large upper level low pressure system over the Great Lakes lifts to the north, and may spread rain into New England.
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&& .NEAR TERM /THROUGH TODAY/...
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A rather strong Canadian ridge of high pressure will continue to build south into the region today. It now appears drier air will filter into the northeast flow today so not expecting any drizzle or fog to develop as earlier thought. Some early morning valley fog still possible though but unrelated to the maritime northeast flow. Temps will be a little below seasonal with highs around 60 based on a blend of models.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
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Tonight and Thursday more of the same with the large blocking Canadian ridge of high pressure anchored to the north and in control pumping a dry and persistently cool northeast flow. All models agree on keeping it dry through Thursday as the shield of precipitation will remain well south. Temps to remain cool.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Chance of high impact weather: Minimal. Dominant feature affect our weather at 500 mb b over the long range period will be closed low meandering around the Midwestern CONUS, and associated downstream ridging over New England. Actually, 00Z GS and Euro are in somewhat better agreement than previous models runs as to timing, although Euro is a about 12-24 hours slower in lifting the low northward and then getting caught up in tough extending from low south of Greenland. DEspite the better agreement, this is not a high confidence forecast, as the closed low will be separated from the flow and surrounded by ridging, and troughing that models are suggesting starts to move it along is not all that impressive. Models are trending to keep things mostly dry through Friday at this point, with some moisture working up in the weak SW flow aloft/ We will be stuck in that areas through the weekend and perhaps into Monday, and for this reason have chance pops in the forecast for most of the CWA in this timeframe. It is unlikely every period will see SHRA, but for now depending on what happens with the closed low have to include a chance. Also, there will be lots of clouds, given the moist S flow aloft and the low-mid lvls E-NE flow. Still could see clearer periods as dry air will be able to be pulled in from the NE at times, for this reason, have undercut Superblend sky a little to call it mostly cloudy rather than overcast. The other thing will be air aloft will be above normal, around 10C, through at least Monday /or whenever the cooler air in the closed low eventually moves through/, and temps overall should end up around normal for highs and above normal for overnight lows. Periods when the flow shifts onshore may be a few degrees cooler, but the water temps not that far off climo normals at this point. Overall highs will be in the 60s most days, and overnight lows will range from the mid 40s to low 50s. The middle to end of next week will all depend on how things shake out prior to that time, but could see a dry period around the middle of the week, with slightly cooler temps, but not significantly below normal.
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&& .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
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Short Term/through Thursday/...Variable conditions today through Thursday with VFR conditions over central and mountain areas with mainly MVFR conditions over southernmost areas. Some overnight and early morning valley fog til 13z will allow for lcl IFR conditions. Long Term...Will have to watch for low clouds through the extended period, and maybe a few SHRA. Best chc for flight restrictions would be Fri night through Sunday, but this is a low confidence forecast.
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&& .MARINE...
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Short Term /through Thursday/...Strengthening Northeast flow will bring SCA conditions outside the bays through Thursday. Long Term...Expect persistent NE flow Friday through the weekend. Winds will, for the most part, remain below SCA, but expect seas to build to 5-7 feet, especially south of Casco Bay.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...Small Craft Advisory until 9 PM EDT Thursday for ANZ150-152- 154.
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&& $$

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