Area Forecast Discussion
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000 FXUS61 KPBZ 192222 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 622 PM EDT Mon Jun 19 2017 .SYNOPSIS... An upper trough will maintain daily chances for showers and thunderstorms and cooler conditions through midweek. && .NEAR TERM /THROUGH TUESDAY/...
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Showers and isolated thunderstorms are moving into our northern and western zones as a shortwave trough moves through the broad upper-level trough. Colder temperatures aloft and speed shear are aiding spotty thunderstorm development as lapse rates steepen. Some of these thunderstorms could have gusty winds accompanying them. Any convection should really weaken with the loss of heating tonight, with PoPs diminishing toward midnight. Tuesday should generally be a repeat of today, although with lower chance PoPs until the next shortwave approaches late. There are timing differences amongst the model guidance with this wave, so nothing more than low chance PoPs, with a focus closer to the upper trough. Temperatures will remain close to or just below seasonal values.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Upper trough will remain situated across the Great Lakes through Wednesday before departing to the east and being replaced by weak upper ridging/nearly zonal flow for Thursday. Again, models continue to time the shortwave passage differently Tuesday night/Wednesday with the GFS suggesting a boundary will hang up across the region and help for invitation Wed afternoon, while the NAM pushes the boundary and precipitation chances south of the forecast area. With low confidence, will keep no more than slight chance PoPs in the forecast at this time. Models generally agree in rising heights and dry conditions on Thursday with temperatures moderating to near or above seasonal averages. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... The progressive flow will make any long term forecast difficult, and the models resolve the evolution of a potential tropical system differently. With this in consideration, have opted to stay close to a blend of guidance which keep conditions mostly dry until late Thursday. After this time, deeper moisture will support higher PoPs and warming temperatures until an upper level trough deepens over the central CONUS late. && .AVIATION /22Z MONDAY THROUGH SATURDAY/...
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Scattered showers with isolated thunderstorms through about 03z, mainly for northern ports of FKL/DUJ. After sunset VFR conditions will slowly give way to a moist boundary layer and development of MVFR stratocu across the north. For now, opted to keep all airports no lower than MVFR, however would not be surprised to see FKL and DUJ drop below 1KFT CIGS between 09Z-13Z. Stratocu will break into a scattered cu field Tuesday as mixing commences. Winds will generally be from the west around 10kts with some gusts 15-20kts possible this evening. .Outlook... Brief restrictions are possible through mid week as an upper trough slides over the region.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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