Area Forecast Discussion
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000 FXUS61 KPBZ 231802 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 159 PM EDT Tue Aug 23 2016 .SYNOPSIS... High pressure will provide dry weather through Wednesday before shower chances return early Thursday ahead of an approaching cold front. && .NEAR TERM /THROUGH TONIGHT/... High pressure is expected to maintain dry conditions with very little cloud coverage today. Highs are expected to reach slightly above normal. With very weak low level flow, the surface wind is expected to be light as the boundary layer mixes out. Another night of radiational cooling expected will result in similar conditions as this morning with temperatures lowering to near seasonal averages with high pressure in place. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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Ridging will continue to transition over the area through the period with the ridge axis progged to be east of the forecast area by Wednesday afternoon. Moisture is then forecast to increase via southwest flow ahead of a shortwave trough. Have added POPs late Wednesday as the first of a few shortwaves is forecast to progress faster than previously thought. Another passing shortwave with a surface cold front is expected to help initiate thunderstorms in the afternoon. While omega fields do not seem strong, marginal to moderate instability coupled with mostly unidirectional flow may help sustain some organized thunderstorms. Precipitation chances wane early Friday as the boundary shifts southeast. High pressure will slowly settle over region and help dissipate clouds by Friday evening.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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Surface high pressure and a building upper-level ridge should keep the weekend dry. 12z GFS brings in the early week system a little faster, spreading QPF across our northern counties by Sunday night. Sticking close to the Superblend, which keeps the bulk of the rain threat confined to Monday. Confidence thereafter lowers as guidance diverges with diagnosing amplification of upper-level flow pattern. As has been the general trend, temperatures will be a few degrees above normal through the period.
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&& .AVIATION /17Z TUESDAY THROUGH SATURDAY/...
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Surface high pressure centered just to our east will keep VFR conditions through the evening. Most terminals will stay VFR throughout, but some of the more favorable locations could again see pre-dawn fog development Wednesday morning. Surface flow will remain light and generally out of the south through the period. .OUTLOOK /WEDNESDAY THROUGH SATURDAY/... Restriction potential returns with the approach and passage of a cold front Thursday and Friday.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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