Area Forecast Discussion
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000 FXUS61 KPBZ 281552 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1152 AM EDT Sun May 28 2017 .SYNOPSIS... Crossing low pressure will result in areawide showers and thunderstorms this afternoon and tonight. && .NEAR TERM /THROUGH TONIGHT/... Elected to issue a Flash Flood Watch for the southeastern CWA until 02Z, as low-level convergence may combine with terrain to create a few rounds of showers and thunderstorms with heavy rainfall, across an area with lower FFG. Have adjusted PoPs to follow with radar/hi-res model trends. Previous discussion... A small cluster of storms has already formed ahead of the warm front in southeast Ohio. Expecting further formation ahead of the slowly advancing boundary later this morning and this afternoon, with the best focus across northern and eastern sections of the CWA, especially since this region will likely see the best destabilization. Surface-based CAPE values of between 1000 and 2000 J/kg look possible, and with 35-40 knots of shear as well, some scattered severe storms still appear possible. Will also need to monitor rainfall rates, as localized storm training could produce locally heavy totals. The lowest FFG values reside from Allegheny/Westmoreland counties south into northern West Virginia. Cannot rule out isolated high water issues, but not sufficiently concerned to hoist a flash flood watch yet. Will continue to monitor. Shower and thunderstorm chances will continue into tonight as low pressure tracks to our northwest, dragging a cold front across. Coverage will decrease to scattered showers behind the boundary. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... Dry conditions are largely expected on Monday with building high pressure, however, isolated showers cannot be ruled out across northern zones as an upper trough remains over the forecast area and a shortwave brushes by to the north. && .LONG TERM /TUESDAY THROUGH SATURDAY/... The upper trough will remain the dominant feature through the end of the week with no major changes to the longwave pattern. This will result in periodic shower chances as shortwaves propagate within the flow. Temperatures will average near to a few degrees below seasonal levels. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... MVFR to LIFR fog/stratus have persisted for two hours after sunrise, but should soon lift as mixing and surface heating begin. A shortwave is expected to cross the area this aftn pulling a warm front north, resulting in scattered thunderstorms. Maintained a VCTS mention until timing can be refined further. More storms developing ahead of an approaching cold front should continue through the evening with MVFR and local IFR restrictions. .Outlook... Restrictions are possible Tue/Wed with an upper trough. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch until 10 PM EDT this evening for MDZ001. OH...None. PA...Flash Flood Watch until 10 PM EDT this evening for PAZ021-029- 031-073>076. WV...Flash Flood Watch until 10 PM EDT this evening for WVZ021- 509>514. && $$

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