Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 200732 AFDGYX Area Forecast Discussion National Weather Service Gray ME 332 AM EDT FRI MAY 20 2016 .SYNOPSIS...
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An area of high pressure will build in today before sliding offshore tonight. The high will bring sunshine and warmer temperatures to the area both today and Saturday. A cold front will drop south out of Canada and into northern New England Saturday night while low pressure moves northeastward off the New England coastline on Sunday. This system will likely bring some rain to the area later Saturday night and Sunday. Low pressure looks to linger around the region early next week with unsettled weather likely.
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&& .NEAR TERM /THROUGH TODAY/...
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at 06z...GOES imagery showed some lingering mid and high clouds over northern and eastern sections of the forecast area associated with the upper trough. For today...a few morning clouds over maine before the upper trough slides northeast otherwise a mostly sunny day as surface high pressure center builds to our south. High`s should be mainly in the 70s. The light synoptic flow should turn onshore along the coast by afternoon...with readings falling back into the 60s by late afternoon along the coast.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
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Mainly clear and cool tonight as the ridge crests across the forecast area with some late night valley fog and stratus. Lows should bottom out mostly in the mid 40s to lower 50s with some cooler readings in the mountain valleys. The ridge retreats offshore on Saturday with sunshine giving way to increasing clouds during the afternoon. High`s tomorrow should be within a degree or two of today`s across the forecast area. An approaching upper trough could introduce a few showers to western New Hampshire as well as the international border area towards evening.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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The main forecast challenge revolves around how far north a track low pressure to our south will take later Saturday night and Sunday. While Sunday doesn`t look like a great day no matter how one slices it with mean troughing in place, a nor`easter with a cold rain could potentially make Sunday a washout. The overall trend in the 00z guidance early this Friday morning has been for a more northerly track in the SFC low which puts at least southern and coastal zones in line for higher PoPs. Latest ensemble guidance continues to show substantial spread in the low track and resultant northward progress in the steady precipitation shield. Solutions vary from a widespread rain event for much of the CWA to more of a grazer for southeast zones. Based on the latest ensemble means along with latest trends in the 00z deterministic guidance, we have raised pops to low end likely for most areas. Did not want to go too crazy as spread still remains - with one of the possible scenarios still being out to sea or close to it. Western zones may not get into the action at least with the steadier precip shield associated with the frontogenetical forcing provided by developing mid level low pressure. However, with the upper trough digging in there should still be a good chance of showers. The best place to be on Sunday could very well be central ME and the foothills as that area may be spared the rain shield associated with the developing low and the showers associated with approaching upper troughing. In a nutshell, Sunday doesn`t look that great, but forecast confidence isn`t overly high right now due to uncertainties with the track of low pressure. Thereafter, it looks like our upper low will want to take up residence near or just south of New England Monday through Wednesday so unsettled weather may continue. Monday may be the better day as forcing for ascent may temporarily be shifted to our south.
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&& .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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Short Term /through Saturday/...lcl ifr in early morning valley stratus and fog today and Saturday morning...otw vfr expected. Long Term...MVFR to locally IFR conditions will be possible later Saturday night and Sunday in low clouds and rain associated with low pressure moving to the southeast of Cape Cod. How low conditions go will be determined by storm track and that is uncertain at this time. Lower conditions may continue through early next week with stubborn low pressure sticking around. The best day may be Monday when a long period of VFR conditions is possible.
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&& .MARINE...
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Short Term /through Saturday/...Winds and seas should remain below Small Craft threshold as high pressure builds by to the south of the waters. Long Term...Low pressure moves to the south of the waters Saturday night and Sunday. Small craft conditions look likely Sunday into Monday as a result. A period of marginal gales will be possible during that time depending on how strong low pressure gets and how far north it tracks.
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&& .FIRE WEATHER...
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High pressure builds across the area with dry weather, much warmer temperatures, and light winds today into Saturday. Minimum relative humidity values both days between 30 and 40 percent followed by good relative humidity at night. A coastal low may affect the area with wet weather later in the weekend and early next week.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ Schwibs/Ekster

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