Area Forecast Discussion
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888 FXUS61 KPBZ 301421 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1021 AM EDT Fri Sep 30 2016 .SYNOPSIS...
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Upper level low pressure will continue to produce bands of showers across the region into the weekend. Showers will be most numerous this afternoon and early tonight, becoming more scattered through the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Mid morning update to bring hourly temperatures and dew points in line, and raise max temperatures a degree or two outside of the ridges. Breaks in cloud cover looks to allow a bit more insolation this afternoon. Otherwise bands of showers and isolated thunderstorms continue to rotate around closed upper low over the Lower Ohio Valley, especially across eastern Ohio into the northern West Virginia panhandle into the afternoon. Tonight the upper level closed low and an associated occluded boundary will lift northward, with continued dry air entrainment behind it. This will push the bulk of the shower activity ahead of it. PoPs will thus decrease from the south with time, with most showers north of Pittsburgh by 12Z. Temperatures were nudged towards the lower side of the guidance envelope, with a model blend used with the previous forecast.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY/... The mature low pressure system that has plagued our area much of this week will linger through the weekend, bringing additional rain chances. By Saturday, the occluded front will have gradually lifted north spreading the best rain chances north of I-80. An expansive feed of dry air wrapping around the south and east of the low will push into our southern counties, resulting in a drying trend through the day. Model differences exist on the evolution and track of the low Sunday into Monday, but the overall trend is to push the track further south and slow it`s progress. This seems prudent, given the extreme northern trajectory of the upper-level jet stream, and the subsequent inability to capture the low and sweep it east. As a result of this slower southern solution, have introduced chance PoPs Sunday afternoon, mainly north of Pittsburgh, as low nears northern Ohio. Temperatures through the weekend will be slightly above normal. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Model consensus exists on the eventual departure of the low pressure system early next week and building a broad ridge through the Great Lakes by middle of next week. This will result in several days of dry weather. With little difference across model guidance, the Superblend was largely utilized in the extended. Temperatures will be back above normal for the first week of October. With the anomalously strong ridge in place, forecast temperatures were bumped a degree or two above the Superblend numbers. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/...
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Bands of showers continue to rotate around closed upper low over Kentucky. Most terminals will start out MVFR with IFR at KDUJ, with gradual improvement through the day to VFR outside of shower bands. Any thunder chance looks to be isolated with only a VCTS mention at KZZV due to proximity of colder air aloft. Winds will be east around 10 Kts with a few gusts to 20 Kts. Showers will consolidate more towards the occluded front this afternoon and advance northeastward tonight with the boundary. MVFR ceilings should accompany this activity. Ceilings late tonight are tricky, as models want to drop values to IFR or even worse, but suspect that this may be a bit pessimistic south of I-80. Elected to continue with MVFR for now. .OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/... Scattered restrictions can be expected into Monday as the upper level low lingers, then slowly lifts north of the region.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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