Area Forecast Discussion
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572 FXUS61 KPBZ 281328 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 928 AM EDT THU JUL 28 2016 .SYNOPSIS... A series of crossing disturbances will keep showers in the forecast through the weekend with humid conditions. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Mid morning update to adjust POPs toward current radar trends, as well as hourly temperatures. No other changes and previous discussion follows. Area of rain continues to track north-northeast in response to an area of H2 ageostrophic divergence. Atmospheric column is saturated with PWATS pushing 2.0" and warm cloud depths nearing 10KFT. Storm motion vectors correlate well with the recent HRRR experimental and track the area of rain towards the baroclinic zone located along I-70. Increased pops to account for a several hour period of rainfall south of the Mason Dixon line. Given recent run of dry weather flash flood guidance remains high. It will likely take over two inches in a 1-2 hour time frame to start causing high water issues. Lower amounts are needed in our urban areas. Given stability in place and overall coverage of thunderstorms predicted, elected not to hoist any flood headlines. If we see places, especially northern WV get repeated rounds then we may need a short fuse flash flood watch. After the morning rain moves through and a little break before the next shot at isentropic upglided generated QPF, we will re-evaluate. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... Models continue to struggle with the placement and amount of the heaviest rainfall tonight. Some of the ops models appear to have convective feedback problems this evening and overnight as the surface low moves to the east and the trailing upper level trough swings through. It still looks that the best chance for heavier rainfall will be confined to the locations near the Mason- Dixon line this evening and possibly into early Friday morning. Additionally, convection coverage and strength remains in question due to all the cloud cover and rain prior to the passage of the low and aforementioned trough. The upper level system will exit the forecasting area Friday morning, decreasing POPs northwest to southeast across the region. Multiple shortwaves will cross the region Friday night and Saturday, keeping in shower and thunderstorm chances through the period. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A series of shortwaves moving through the weak trough over the eastern CONUS will support periodic rain chances and seasonal temperatures into Monday. A weak bubble of surface high pressure looks to bring warm temperatures with little chance for showers Tuesday and Wednesday. A modified Superblend was used for much of the extended period. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... A slug of rain will move east northeast through the morning hours with the greatest impact at MGW where MVFR/IFR weather is forecast /mostly this evening/. This terminal has the highest confidence of all. For the remainder of the airports, confidence falls to medium where questions arise how far north will the rain shield get? Either way, possibility exists for scattered showers and perhaps a thunderstorm through the evening. IFR clouds should develop overnight due to rainfall today and increased low level moisture and light winds along the boundary. For now, included sub 1KFT cigs for PIT and MGW. The other terminals, MVFR stratocu was introduced. .OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/... Brief sub VFR restrictions are possible in showers and thunderstorms through Monday, however given duration and coverage nothing more than a CB or VCTS/ VCSH expected at this time. && .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.