Area Forecast Discussion
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000 FXUS61 KPBZ 261926 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 326 PM EDT Wed Oct 26 2016 .SYNOPSIS... Low pressure will bring rain to the region tonight and Thursday. Dry and cool weather returns for Friday. Warmer but unsettled weather is anticipated for the weekend. && .NEAR TERM /THROUGH THURSDAY/... Band of pre-warm frontal precipitation is now lifting across the CWA. The dry low levels are allowing for some sleet (including here at the office) due to wet-bulb effect in the dry lower levels. Have added this possibility to the grids for more areas for the afternoon. Models are in good agreement with tracking low pressure across southern Michigan and Lakes Erie/Ontario through Thursday. Overall moisture with the system is not excessive...with PWATs around 1.1 inches around the 90th percentile. Support for lift looks good though with the approaching warm front plus coupled jets at 250 mb. This setup looks best over the northern counties, where the highest categorical PoPs have been placed. Steady rain likely begins here after 06Z. There is a north/south gradient in precip chances, bottoming out in the chance category near the Mason-Dixon line, where rain may not show up in earnest until near sunrise. A few snowflakes may mix with the rain in the far northeast counties tonight for a time, with wet-bulb effect plus southeast damming flow playing a role for a bit. We expect a non-diurnal temperature curve overnight with warming values past midnight, so this snow would likely not last long. Rain will be ongoing Thursday morning as the surface low passes. Cold frontal passage occurs on Thursday afternoon, which will sweep the steady rain off to the east. Some lake-enhanced showers will linger behind the boundary for a few hours, but will be decreasing in coverage through the afternoon as moisture decreases and inversion heights lower. High temperatures will end up near climatologic norms. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... Cold advection behind the departing low pressure will be brief, but shower chances should continue through Thursday night. Some snow may mix in as well, especially north of I-80 and in the high terrain. High pressure will settle over the Ohio Valley for Friday with lingering cloud cover to likely hold temperatures down a little. With the progressive upper level pattern, another system is expected to approach late on Saturday with chances for showers increasing by the afternoon. Warm advection ahead of this system should allow for temperatures 5-10 degrees above seasonal averages. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The models are in relatively good agreement for the start of the long term, with another shortwave expected to cross along a slow moving boundary over the Ohio Valley on Sunday. After this time, the models evolve the next low pressure system over the northern Plain/Canadian border differently, so a blend of model guidance was used. Overall, expect temperatures to remain at or just slightly above seasonal averages through the period. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... Conditions are expected to remain VFR into the evening hours with high-based ceilings and spotty light precipitation. Pockets of sleet are possible at the terminals this afternoon. ESE winds will strengthen with time as a low pressure system approaches. Ceilings will fall with time, with MVFR conditions developing by morning at most locations. Areas north of Pittsburgh will likely see IFR by sunrise as the steadiest precipitation moves in. These restrictions will persist through the end of the TAF. .OUTLOOK /WEDNESDAY THROUGH SUNDAY/... Restrictions may continue into Thursday evening, before VFR returns by Friday. More restrictions are possible this weekend with another front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.