Area Forecast Discussion
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977 FXUS61 KPBZ 240129 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 929 PM EDT SAT JUL 23 2016 .SYNOPSIS... Hot and humid conditions will continue. The best chance for showers and thunderstorms will return on Monday with the passage of a weak cold front. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... With 9pm update, have continued isolated showers for the next hour or two as coverage of convection has dropped significantly over the last two hours. Although thunderstorms dropped from north to south almost all the way to the Mason-Dixon line, the original boundary is still evident looking at surface wind directions and spread of dewpoints. Dewpoints range from 57 at Franklin to 64 at Butler and 71 at Pittsburgh International Airport. Model guidance suggests that these drier dewpoints will never fully make it across the entire region before southerly flow returns ahead of the next front Sunday. But, this should be sufficient enough to provide a cooler night, for the northern half of the region, than previous nights. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Upper ridge will build eastward briefly on Sunday, with a weak shortwave crossing the lower Great lakes in advance of a front that is progged to cross on Monday. Anticipate that most of Sunday should remain dry, with warm and humid conditions continuing. 591dam heights build overhead, so again anticipate temperatures exceeding 90 although some high clouds may limit heating for the northwesternmost zones. At this time, with the uncertainty in cloud cover, have not expanded in time the heat advisory for Ohio but will continue to highlight the concern in the HWO. An upper-level trough and its associated front will approach from the west early Monday. Based the current model run timing, some precipitation may already be moving into the area Monday morning, which may limit the threat for any strong to severe storms despite instability and moderate shear. For now, agree with SPCs analysis of a Marginal Risk for the region. Ahead of the boundary, where we remain cloud free early, temperatures should still warm well into the 80`s and approach 90. Front will stall just south of the PA/MD border by Monday night and we will remain in zonal flow. This could lead to lingering chances of showers/storms, mainly along the terrain on Tuesday. While dewpoints will be lower, it should still be another day of mid-80 temperatures. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Zonal flow will be replaced by weak troughing over the eastern CONUS for the end of the week. With several shortwaves progged to pass in the upper level pattern, but differences in the deterministic models, have opted to stay close to a blend of guidance with near or slightly above normal temperatures forecast. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... Convection is largely over as instability wanes. Visibility restrictions are possible mainly KBVI and south where rainfall occurred earlier and drier air at the surface has not yet moved in out of the northeast. There will be a chance of thunderstorms Sunday afternoon as the boundary that currently runs roughly from KCLE to KLBE lifts north over the region as a warm front. .OUTLOOK /SUNDAY THROUGH THURSDAY/... Restrictions will be possible late Sunday and Monday with the approach and passage of a weak cold 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.