Area Forecast Discussion
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000 FXUS61 KPBZ 191953 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 353 PM EDT Mon Jun 19 2017 .SYNOPSIS...
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An upper trough will maintain daily chances for showers and thunderstorms and cooler conditions through midweek.
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&& .NEAR TERM /THROUGH TUESDAY/...
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Few showers and storms are already developing closer to the lake shore and over western Ohio as the upper trough and cooler temperatures aloft advect over the southern Great Lakes. Expect this trend to continue as a shortwave pivots through the upper tough this evening. While there will be moderate levels of speed shear, unimpressive mid-level lapse rates and weak instability should limit strong/severe potential across the region. 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/...
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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.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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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.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/... MVFR cigs will lift to VFR as drier air works in from the west. With the passing of an upper level trough, scattered showers are possible especially for FKL and DUJ closer to the center of the disturbance. Confidence not high enough at any airport for prevailing conditions just VCSH at the aforementioned northern terminals between 22Z- 02Z. After sunset VFR conditions will slowly give way to a moist boundary layer and development of MVFR stratocu in the predawn hours. 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 by the end of the forecast. Winds will be light from the west around 5-8kts. .Outlook... Brief restrictions are possible through mid week as an upper trough slides over the region. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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