Area Forecast Discussion
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000 FXUS61 KPBZ 210537 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 137 AM EDT THU JUL 21 2016 .SYNOPSIS... Hot and dry weather is expected tomorrow. Hot and humid weather with periodic thunderstorm chances are expected Friday though the weekend. && .NEAR TERM /THROUGH TODAY/... High pressure will continue to settle in overhead tonight. Very low dewpoints in place should allow for strong radiational cooling to continue with a readily apparent urban heat island remaining fairly strongly around Pittsburgh. This will allow lows to drop into the 50s on a widespread basis tonight due to dewpoints largely in the mid 40s to lower 50s. Likewise with dry air in place in the morning and a surface high with its accompanying subsidence shifting to the east during the day, abundant sunshine into the dry boundary layer and dry soils below will be exceedingly efficient in raising temperatures due to the fact that little incoming radiation will be going into latent heating. Additionally, boundary layer flow will turn to the southwest after 18z, which while not likely a long enough duration to bring dewpoints up very much will be enough to increase vertical mixing. This will result in highs jumping toward and into the 90s on a fairly widespread basis by afternoon. Fries && .SHORT TERM /TONIGHT THROUGH SATURDAY/... A shortwave is progged to approach and cross the region late Thursday night through Friday in northwest flow aloft, resulting in scattered showers and thunderstorms with it`s passage. Instability and shear parameters appear sufficient for a few strong storms, and the SPC marginal risk over the area seems reasonable. Will hold off on an HWO mention for now with uncertainty in the details. Upper ridging is progged to build in across the region from the central CONUS Saturday, with areas north of I 70 expected to stay capped. Diurnally driven instability/thunderstorms are possible to the south, though the ridging should limit the potential. Building heat and humidity is also expected through the weekend, with many locations reaching 90 or above, with heat indices in the mid to upper 90s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The ridge is expected to remain across the region through the rest of the weekend, though sufficient instability could result in diurnally driven thunderstorms. The ridge should break down by early next week with better shower/thunderstorm chances associated with a crossing shortwave/surface front. Ridging is progged to redevelop by mid week. Hot and humid conditions should diminish by early next week, though temperatures should still remain a few degrees above seasonal levels. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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VFR conditions and light winds are expected through the TAF period. Not much fog is expected as crossover temperatures should not be achieved in most cases. Some clouds will begin to invade from the north after 00Z as a disturbance approaches. A shower or thunderstorm cannot be ruled out at FKL or DUJ by 06Z but chances are too low to include in this issuance. .OUTLOOK /WEDNESDAY THROUGH MONDAY/... Scattered restrictions in thunderstorms are possible Friday through Monday.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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