Area Forecast Discussion
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171 FXUS61 KPBZ 222341 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 741 PM EDT Sat Jul 22 2017 .SYNOPSIS... Warm and humid conditions will continue through the weekend with showers and storms expected through Sunday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Gradient in surface-based instability lies just to the south of the CWA, where a severe thunderstorm watch was issued in the past hour. Think that much of the wind/hail threat will remain there, although given some breaks in the clouds and the presence of multiple small-scale boundaries, we cannot rule out a few isolated strong to severe thunderstorms into this evening, mainly south of Pittsburgh. Most of the flood threat will remain south as well as storms train along that gradient. However, with high PWATs and a deep warm cloud layer, storms will be efficient rainfall producers. Isolated issues are possible if a location gets hit multiple times. Have adjusted PoPs to handle the cluster now approaching the Ohio River, taking it east over the next couple of hours. Have dragged likely PoPs back behind this line along our southern border, close to the main zone of action. Activity should slowly decrease in coverage through the night with loss of heating, but cannot rule out at least isolated storms all through the night. Temperatures will continue to run a few degrees above seasonal lows. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... The risk for showers and storms will continue on Sunday as a shortwave trough, diving across the Great lakes helps to push a boundary southward. Again, there is a chance for severe storms, with 1000j/kg CAPE and 40kts shear. It appears that there will be enough of a break in the activity Sat night/early Sunday to support better daytime heating, which may help support more organized convection. Again, the primary threat will be damaging wind. Activity wanes Sunday night with the loss of daytime heating, but again expect a muggy night with temps well into the 60s and lower 70s. Mid level trough sweeps through Monday afternoon so this will be the last round of showers/storms before a welcome break occurs. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Upper level ridge will shift eastward over the region on Tuesday, with rising heights leading to a gradual warming through Thursday. Deepening upper low over Hudson Bay will swing a boundary over the Great Lakes late week, returning better chances for showers/storms in northwest flow to end the week. Temperatures will generally be within 5 degrees of seasonal averages through the period, with lesser humidity Tuesday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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Most of the shower and thunderstorm activity has moved off to the east. Although a few scattered showers and storms remain possible this evening, the majority should see mostly VFR conditions through midnight. Given the recent rain and lingering low level moisture, low ceilings and fog are once again expected overnight. IFR will be fairly widespread, with LIFR possible at FKL and DUJ, and perhaps other terminals. Improvement back to VFR is expected by late morning, but another round of scattered showers and storms may provide brief restrictions during the afternoon. .OUTLOOK... Restrictions will continue through Monday, with VFR prevailing thereafter.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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