Area Forecast Discussion
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000 FXUS61 KPBZ 190548 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1248 AM EST Sun Nov 19 2017 .SYNOPSIS... A strong cold front will cross tonight bringing strong winds and a changeover to snow showers by early Sunday morning. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Cold front currently draped along a line running from Clarion to just east of Pittsburgh...extending SSW beyond the Mason/Dixon line. Observed gusts have in general been around 35-40mph on average with a few isolated higher gusts. Wheeling saw the highest gusts at 11:22PM when 51mph was observed by the ASOS. Expect more of the same along the front as it progresses east. Will let the Flood watch expire for Ohio counties as they are now behind the front and additional precipitation amounts should be on the light side. Will let the watch PA counties continue for another couple hours...although most reports of roadway flooding are likely due to poor drainage based off of actual observed rainfall totals and rates. Wind advisory will continue for the ridges where more widespread gusts of >=46mph are more likely with frontal passage during the next couple hours. Previous discussion follows... Rain with the front will continua tonight. Current timing of precip with the boundary looks good, so minimal change was needed. There may still be a rumble of thunder but overall, coverage has diminished. Will maintain the flood watch as is for now, until precip with the front crosses. Boundary is rather progressive but some isolated issues may still arise as upwards of 2 inches of rain was reported along the watch area. Still expecting a period of strong winds with the front as it crosses and behind with as lapse rates steepen. While pressure rises are rather impressive, many of the obs upstream have not reported gusts to advisory levels. This and some of the newest hi res guidance keep gusts below thresholds outside the terrain. Thus, will hold off on any wind advisory, but it will still be gusty overnight. Changeover to snow is expected overnight as cold air returns to the region. Warm and saturated ground will limit accumulation at first, with rather low snow ratios but this should improve as the core of the coldest air approaches later Sunday. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/... Northwesterly flow will continue scattered snow showers and keep temperatures in the 30s through the day. Highest PoPs remain the snow belt north of I-80 and in the mountains of PA/WV/MD where lake enhancement/upslope is anticipated. Still thinking 2-4 is reasonable, though some higher amounts may be possible. Best window for accumulating snow in the terrain looks to be as the second shortwave dives through the trough tomorrow afternoon, deepening the saturation layer through the snow growth zone, but this only lasts for a short period of time. With this in mind, have opted not to issue a winter weather advisory at this time though consideration will be given on future shifts. Building ridge of high pressure and backing flow should end chances for showers by Monday morning, with dry conditions expected through Tuesday. Some warming is expected under an upper ridge, which should get us closer to seasonal values by Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Minimal change was needed in the extended. The majority of the week will be dry with seasonal temperatures outside of a weak wave progged to pass to the north midweek. Have kept slight chances in for locations north of I80 on Wednesday. Next system is progged for late in the period, with broad troughing in place. Model guidance differs, so opted to stay near a blend of guidance. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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Gusty WNW wind and MVFR/local IFR conditions are expected through most of the day with broad upper troughing behind an exiting strong cold front. Rain showers should taper off by sunrise, though scattered snow showers are expected mainly N and E of PIT with cold NW flow and lake/terrain enhancement. A shortwave rotating through the main trough should increase the coverage of snow showers/flurries. Ports N of I 80 have the best chance at seeing brief IFR vsby restrictions. .Outlook... Cig restrictions should continue Sun night in cold NW flow. Restriction potential returns with a Tue cold front and subsequent upper troughing through mid week.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES...
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MD...Wind Advisory until 10 AM EST this morning for MDZ001. OH...None. PA...Flood Watch until 3 AM EST early this morning for PAZ007>009- 013>016-020>023-029-073-074. Wind Advisory until 10 AM EST this morning for PAZ074-076. WV...Wind Advisory until 10 AM EST this morning for WVZ510>514.
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&& $$

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