Area Forecast Discussion
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000 FXUS61 KPBZ 251150 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 750 AM EDT Thu May 25 2017 .SYNOPSIS... Slow moving low pressure will keep rain in the forecast through early Friday. Rain chances return for part of the weekend with another area of low pressure. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Adjustments to hourly trends for the pre dawn update. Previous...Ascent and deep layer moisture ahead of approaching low pressure should maintain the showers across the area this morning. The ascent/moisture is progged to shift N of the area by this afternoon as the low drifts across OH to Wrn PA. Scattered showers are expected through the rest of the day however with the close proximity of the low. Minimal instability is progged by afternoon, so maintained the isolated thunder mention in the forecast. The best, but still marginal, shear and instability is progged E of the area. Temperatures are expected to average around 5 degrees below the seasonal levels. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... Another area of ascent and deep layer moisture is progged to track across the region tonight as the low begins to drift E of the area, with increasing POPs for showers. A few showers could continue through Fri morning until the low exits the E coast and shortwave ridging builds in. The next approaching shortwave and surface warm front is progged for Fri night/Sat as surface low pressure tracks NE from the Srn Plains, resulting in shower chances increasing. Model progged instability is sufficient S of I 80 for thunderstorm chances also. The low is progged to track across the lower Great Lakes Sunday, dragging a cold front across the region. Maintained likely POPs for showers/tstms with it`s approach and passage. After below average readings Friday, temperatures should return to near or above average levels by the weekend. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... Upper troughing is progged across the NE CONUS through most of the period. Individual shortwaves rotating through the trough should maintain periodic shower chances, with the Memorial Day holiday progged to see the least activity at this time. Temperatures should average within a few degrees of the seasonal levels. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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As of 8am, southern edge of precipitation is about to move from south to north across ZZV/MGW, with much of the widespread rain having already moved north and allowing for more of a transition to scattered showers during the morning. Atlantic moisture fetch should then be briefly cut off as low level flow turns SW. This should shunt low level saturation progressively NEward, allowing for MVFR then VFR conditions to return to most sites with scattered showers still about as the upper low settles overhead. However, as it moves NEward this evening, low level moisture will quickly wrap back in and trend cigs decidedly downward overnight. Fries/Green .Outlook... Showers continue through much of the period with episodic restrictions.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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