Area Forecast Discussion
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000 FXUS61 KPBZ 180545 AAC AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 1245 AM EST Sun Feb 18 2018 .SYNOPSIS...
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Snow will taper off early this morning and temperatures will moderate during the day. The start of the work week will be warm and wet.
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&& .NEAR TERM /THROUGH TODAY/...
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For the overnight. First, will cancel the advisory near the Mason-Dixon line, but only in the low lands. Accumulating snow is over there and temperatures have risen above freezing at most locations. Next, will have to deal with rather impressive shortwave trough which will quickly swing through late tonight, swinging east of the area around 5am. This will keep in the chance for snow showers across the northern half of the area through the period. There are some indications that a weak lake band could develop behind the exiting shortwave as winds swing around to the northwest. However, inversion levels drop quickly behind the wave, well below the snow growth zone, and temperatures aloft are not impressively cold. Will indicate the threat of the band in the late night PoPs. Shortwave will quickly exit the east coast this morning and zonal flow aloft will setup behind it. The colder air aloft over my area will slowly erode this morning, lingering over the higher elevations until late morning. Will need to keep in PoPs in the highest elevation through a portion of the morning hours, as the risk for orographic snow showers continues. Clouds will stubbornly hang on over the eastern half of the area with the slowly exiting cold pool aloft and its accompanying northwest flow. Clouds will erode from west to east, but it may take until late in the afternoon for all of the cloud cover to dissipate over the eastern half of the region. Temperatures will moderate today.
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&& .SHORT TERM /TONIGHT THROUGH TUESDAY/...
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Continued the idea of slowing the onset of precipitation late tonight and Monday morning, as the intrusion of upper level lift is slowed and weakened by some minor ridging aloft. Rain will overspread the entire area Monday morning, moving northward along the surface warm front and rising upper level heights. By Monday evening, most of the area should be well into the warm sector and upper level heights will continue to slowly increase Monday night. This will require me to remove PoPs for much of the region Monday evening, with the exception of the far north, which will lie in close enough proximity to the surface boundary that a passing shower cannot be ruled out. By late Monday night, the warm sector will have spread across the entire region and the upper level ridge will have settled in, allowing for a dry forecast. Mainly dry forecast will continue through most of Tuesday with ridging aloft taking hold. A passing shower is possible across the north Tuesday morning, as a weak shortwave rides over top of the ridge, but only chance PoPs were indicated for this feature. Temperatures will push well above normal both Monday and Tuesday.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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While the GFS and ECMWF have wavered on the timing for the cold front passage over the last few days, there is general consensus that this will happen late Wednesday into Thursday morning. This will bring the best chance for rain, but also an end to the very warm temperatures. The front will linger to the southeast, keeping a chance of showers in the forecast. Even after the cold front passes, temperatures should still remain above normal.
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&& .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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IFR/MVFR restrictions through most of the morning hours. Snow and patchy fog will provide visibility restrictions through dawn. Snow will be mainly from PIT and ports northward. By midday, surface flow backing to the south will push drier air in and scatter out the cloud deck from south to north. VFR is expected for the latter part of the current TAF period. OUTLOOK...VFR prevails until Monday afternoon when precip with a lifting warm front clips the region.
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&& .HYDROLOGY...
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Flooding continues on the Upper Monongahela, Ohio, and at Stillwater Creek. Precipitation tonight should not pose much of an issue beyond slowing the fall today. All points are forecast to be below flood stage tonight.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES...
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MD...Winter Storm Warning until 4 AM EST early this morning for MDZ001. OH...None. PA...Winter Weather Advisory until 4 AM EST early this morning for PAZ016-022-023-074. Winter Storm Warning until 4 AM EST early this morning for PAZ076. WV...Winter Storm Warning until 4 AM EST early this morning for WVZ510-512-514.
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