Area Forecast Discussion
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000 FXUS61 KPBZ 181949 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 249 PM EST Mon Dec 18 2017 .SYNOPSIS... Warmer, but damp weather can be expected early this week followed by cooler temperatures on Wednesday. The next chance for widespread measurable precipitation will be later Friday and into the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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Drizzle is possible through the evening as a weak wave passes over the moisture locked in by an inversion. Generally kept PoPs low but a bit of an upslope component is expected as the wind shifts more westerly aloft. Will keep highest chance values here. Otherwise, low level moisture and clouds will remain locked in place. Temperatures will be able to warm even with modest mixing and will likely stay elevated, with minimal diurnal range, overnight.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/... Zonal flow will be maintained with weak forcing. Overcast skies will persist, however, periods of light precipitation should end by Tuesday afternoon as the depth of the saturated layer decreases. Warm southwesterly surface flow will continue the upward trend in temperatures until a weak boundary drops south across the forecast area Tuesday night and flow shifts to the northwest...resulting in cooler temperatures on Wednesday. Stable conditions should result in little more than continued cloud coverage. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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More amplified pattern is expected through the weekend as a system ejects into the Plains. Strong warm advection will lend to temperatures between 10 and 15 degrees above average until a cold front approaches, but the timing is several days different between the models. This obviously has an impact on whether we will see rain or snow by the end of the weekend. Adjustments in the extended were largely based on superblend and ensemble guidance.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/...
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High confidence forecast of IFR cigs and drizzle through at least this evening, if not longer. Weather patten remains constant with abundant low level moisture trapped underneath inversion socking clouds in place through most of Tuesday. Would not be surprised if cigs teeter around 1KFT IFR/MVFR threshold tonight before slowly returning to MVFR /015/ by mid to late morning Tuesday. Most guidance has stratus lifting tonight which seems odd, however looking at upstream observations, MVFR cigs are out in Indiana and western Kentucky so its possible especially after 3Z in the west then 6Z in mountains. Winds will be from the southwest between 8-11kt. Gusts near 20kts are possible after 15Z Tuesday. .Outlook... No widespread IFR weather is forecast.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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