Area Forecast Discussion
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000 FXUS61 KPBZ 171834 AAA AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 134 PM EST Sat Feb 17 2018 .SYNOPSIS... A quick moving system brings snow to most locations this afternoon and evening. Next week should be warm and wet. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Fast moving low pressure will interact with a northern stream shortwave trough and lift across the upper Ohio Valley this afternoon and evening. Warm advection and increasing moisture will support an increase in cloud cover, but also temperature ahead of the precipitation. Bufkit profiles suggest that, despite this, some wet-bulbing and lift will bring a rain/snow mix to the region this afternoon. Recent warm antecedent conditions should limit accumulation during the daylight hours, save for maybe in the terrain where some dynamic cooling/ese flow will hold surface temperatures down. Frontogenetical forcing will also support a period of enhanced QPF, but again, this will be during daylight hours. Made only minor adjustments to QPF and snow ratios based on the latest model guidance which does include some high res guidance. Some deformation band snows may linger along the spine of the Alleghenies through midnight which could actually bring some locations close to advisory, but this will be difficult to pin down until it starts to materialize. This is however, enough support to keep the current headlines as is - with near warning snows possible in the terrain which may be helped by some northwest/upslope flow through Sunday morning before subsidence builds.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... Deeper moisture departs to the east tonight. This yields a questionable moisture profile as the dendritic layer dries out, upslope flow remains, and precipitation is still probable to be falling. This may yield a period of freezing drizzle, however given the proximity of the lifting profile to the bottom of the dendritic layer, it would seem poorly formed flakes are more likely in the terrain than freezing drizzle at the moment. Dry weather Sunday and most of Sunday night, with the bulk of precipitation waiting until Monday to move into the area from the west. Temperatures will be on the rise through the period, with highs in the 40s on Sunday and 50s/60s on Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Upper level pattern should allow for the chance of precipitation to continue through much of the week. The warmest temperatures should occur on Tuesday before a cold front moves through on Wednesday, with locations from Pittsburgh south likely to reach 70 degrees ahead of the front. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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Low pressure will spread precipitation across the region this afternoon. While surface temperatures are starting above freezing in some places, dewpoints remain in the 20`s so evaporative cooling should start most locations as snow. Strayed little from the previous forecast which quickly deteriorates conditions to low MVFR/IFR by 21-00z as the snow spreads northward. Window is rather short for efficient snowfall but this should support the restrictions that are forecast. Conditions will improve rather quickly, at least in regard to visibility. Stratus should linger but lift toward daybreak tomorrow, with VFR anticipated by Sunday afternoon. ESE shifting to the wnw overnight as the low passes. Wind should generally be under 10kts. 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. The flood crest has made it to the Point at Pittsburgh, with this crest expected continue down the Ohio through the afternoon. Precipitation this afternoon/evening should not pose much of an issue beyond slowing the fall through Sunday. All points are forecast to be below flood stage by Sunday night.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES...
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MD...Winter Storm Warning until 4 AM EST Sunday for MDZ001. OH...None. PA...Winter Weather Advisory until 4 AM EST Sunday for PAZ074-076. WV...Winter Weather Advisory until 4 AM EST Sunday for WVZ510. Winter Storm Warning until 4 AM EST Sunday for WVZ512-514.
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&& $$

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