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Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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491 FXUS61 KPBZ 141117 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 717 AM EDT Wed Aug 14 2024 .SYNOPSIS... Dry weather with slowly rising temperature is expected through Thursday. Precipitation chances will increase Friday as a front slowly crosses the region. A more active pattern is possible for the weekend. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Dry and comfortable with temperatures near normal. ------------------------------------------------------------------- The eastern trough, which has brought the quiet weather pattern to the region, will slowly shift eastward today. The trough is being displaced by an amplifying ridge that will build into the Midwest. With the shifting of the upper level waves, slow height rises are anticipated today. This will mean a continuation of the dry weather and warmer temperatures. We may not see as much CU develop this afternoon due to the warm air advection aloft. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... KEY MESSAGES: - Dry weather with slowly rising temperature expected Thursday. - Shower/storms chances increases Friday, but timing issues still remain. ------------------------------------------------------------------- Upper level height rises will continue on Thursday as the ridge axis moves into western Ohio during the afternoon. The rises will be somewhat shunted later Thursday as a shortwave trough will swing through the western Great Lakes and begin to flatten the eastward moving ridge. The biggest impact from the wave will be an increase in high clouds. Warmer air will continue to overspread the region, so temperatures will warm a few degrees above normal. Timing differences remain on the progression of the trough moving across the Midwest Friday morning and the corresponding surface front. Models are promoting a stacked system over the western Great Lakes Friday with a lobe of upper level energy swinging eastward on the southern side of the 500mb low. A warm front will press eastward with the energy aloft and cross the region sometime on Friday. Again, still seeing timing differences with the eastward progression. Latest model solutions are not showing a lot of instability or shear, and a slower progression would allow more cloud cover to spread across the region ahead of the rain. Temperatures aloft remain relatively warm, with model soundings showing a capped atmosphere for a time on Friday. Friday does look like a good shot at widespread rain, but there is still much to be resolved with the threat for convection. Temperatures will cool a bit on Friday with increased cloud cover and rain. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... KEY MESSAGES: - The threat for rain continues into Saturday with slow passage of a cold front. - Ensembles favor Great Lakes troughing into early next week that would maintain low probability, diurnally driven convection. ------------------------------------------------------------------- Ensemble synoptic pattern analysis shows relatively minor differences of the progression of an upper level trough towards the Great Lake region into early next week. Broadly speaking, this pattern will promote periodic shower and thunderstorm chances, low probability severe/flash flood threats, and near to slightly below average temperature. More convective development is possible Saturday as the upper trough positions just west of the area and both the pre-frontal trough and surface cold front swing through. Ensemble means hint at some marginal instability with dry air aloft leading to a low end wind threat Saturday afternoon, but confidence is still low on conditions all aligning properly. Sunday into Monday is likely to feature isolated to scattered diurnally driven convection with the backside of the trough remaining overhead. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... Surface high pressure will promote light NE wind and VFR conditions through the TAF period. Diurnal heating may spark a few to locally scattered CU this afternoon. Very localized river valley fog may develop between 06z-12z Thursday morning near FKL. .Outlook... High confidence exists for VFR through Thursday under the influence of high pressure. A slow moving upper level trough will promote periodic showers and thunderstorms with occasional restrictions Friday through Monday. Probabilities for restrictions peak Saturday morning with MVFR (40-70%) to localized IFR (20-50%) cigs. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...22/Frazier NEAR TERM...22 SHORT TERM...22 LONG TERM...22/Frazier AVIATION...Frazier