Area Forecast Discussion
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000 FXUS61 KPBZ 210523 AAC AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 123 AM EDT Fri Oct 21 2016 .SYNOPSIS... A crossing cold front and large upper level system, will generate more rain today. Much cooler weather will follow for the weekend. && .NEAR TERM /THROUGH TODAY/... For the overnight, will be tracking a series of shortwaves moving northeastward in the tight southwest flow aloft. The late night energy will help to push the cold front and its associated low pressure further east. By 12z the entire system will begin to cross the ridge counties, pushing the axis of heavier rain into Central Pennsylvania. Using a blend of hires data and current radar and satellite trends, have update the PoPs overnight, timing the movement of higher probability with the front. Temperatures have also been updated. The surface system will weaken this morning as it drifts east of my forecast area. Behind the exiting front, strong cold air advection will ensue, and the main upper level trough axis will move over my Ohio counties early this afternoon. This will keep in the chance for showers throughout the day and provide steady or slowly falling temperatures. Additionally, surface winds will increase with gusts of 20 to 25mph possible this afternoon. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... the trough axis will pass to the east of the area late this evening, and the colder air will continue to advect in. Will need to keep in the chance for precipitation overnight with the cold air advection and a saturated low level. However, as inversion heights lower, expect any showers to become more spotty and light. Cold advection in northwest flow, will keep in shower chances Saturday, but this too will drift eastward as the large upper level low swings northeastward toward New England. Latest hires nam run is actually showing a lake enhanced band developing Saturday morning, which will drift eastward throughout the day. This looks reasonable considering the cold air aloft and the lack of directional shear between the winds in the mid and lower levels. Will shift PoPs eastward in correlation with the timing of the possible band. Locations in the ridge counties, especially on the peaks, could see a few snow showers mix in Saturday morning. Building high pressure will bring and end to any lingering showers over the northeast Saturday evening. Dry Sunday, with a decrease in cloud cover as warm air advection gets underway. Temperatures will recover on Sunday to near seasonal averages. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A fast moving shortwave is progged for an early week passage, with most of the shower chances remaining north of PIT. Ridging is progged thereafter through mid week before another trough advances out of the Midwest by late week. Temperatures should average a few degrees below seasonal levels through the period. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... All sites should gradually transition to IFR as low level moisture increases and cold advection gradually begins. This will occur as thunderstorm chances increasingly become confined to the SE portions of the area. Guidance continues IFR conditions at all sites through Friday, however there is a chance that as wind gusts increase that a few sites may pop to MVFR for a time during the afternoon. Fries .OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/... Periodic restrictions are expected into Sunday as an upper trough crosses the area. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch until noon EDT today FOR MDZ001. OH...Flash Flood Watch until noon EDT today FOR OHZ039>041-048>050- 057>059-068-069. PA...Flash Flood Watch until noon EDT today FOR PAZ007>009-013>016- 020>023-029-031-073>076. WV...Flash Flood Watch until noon EDT today FOR WVZ001>004-012-021- 509>514. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.