Area Forecast Discussion
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000 FXUS61 KPBZ 172028 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 328 PM EST Sat Feb 17 2018 .SYNOPSIS... A quick moving system brings snow to most locations this afternoon and evening. The beginning of next week should be warm and wet. && .NEAR TERM /THROUGH SUNDAY/... Low pressure will move across the southeastern United States quickly this afternoon and evening, moving offshore to the Atlantic. Precipitation will extend well to the northwest of this low into the region. Although many locations have warmed above freezing today, wetbulbing is quickly bringing temperatures back down. Even Morgantown, which was 38 degrees, dropped to 34 degrees in an hour as snow began. At this point, have removed all rain from the forecast and have gone entirely with snow. It appears that the heaviest precipitation will fall this afternoon with strong forcing moving through the region. A quick burst of snow could bring several inches of snow, especially in the ridges. Have not made any changes to advisories/warnings at this time, although intensity of snow has been heavier than expected at onset and cannot rule out the possibility that some additional counties may need advisories. The low will already be moving offshore by the evening hours, so intensity of snow should drop by that time. Most snow after midnight should be of the upslope variety. Once the low moves offshore by sunrise, a mostly sunny day is expected on Sunday. Sunday appears to be the only day in the forecast when sun will be prevalent. Temperatures will be near seasonal values. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Latest model runs slowed up arrival of precipitation from the inherited forecast, and it now appears that it will take until Monday for most locations to begin receiving rainfall. The rain will be in advance of a low pressure system moving into the Plains. The warm front will waver through the period, leaving most locations with only a chance of rain Monday night and Tuesday. Temperatures will be well above normal through this portion of the forecast, with temperatures in the 50s/60s on Monday and most locations reaching the 70s on Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... 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 Wednesday into Thursday. This will bring the greatest 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 slightly above normal. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... 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. && .HYDROLOGY... 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. && .PBZ WATCHES/WARNINGS/ADVISORIES... 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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