


Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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-- Discussion containing changed information from previous version are highlighted. --496 FXUS61 KPBZ 090934 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 534 AM EDT Wed Jul 9 2025 .SYNOPSIS... A surface front will meander across the region through the week and into the weekend, maintaining daily shower and thunderstorm chances. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... KEY MESSAGES: - Stalled boundary along the PA/WV border keeps most convection south of Pittsburgh today. - Daytime highs top out just above normal. --------------------------------------------------------------- Latest surface analysis shows a pseudo-stationary boundary parked along the PA/WV border, which will serve as the focal point for any convective development today once instability increases with diurnal heating. Increased mid and upper level cloud coverage will persist through the period with increased moisture advection ahead of an approaching mid-level shortwave. The cloud coverage that has increased over the course of the night has mitigated any widespread fog development this morning, and do not anticipate the need for any advisories at this time. Models, analogs, and machine learning guidance are all in agreement with minimal strong/severe potential with any convection today. T his would be limited to portions of northern West Virginia, where there is better instability/stronger updraft potential, and potential for localized heavy rainfall, but the overall threat is low. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... KEY MESSAGES: - Better coverage of scattered storms Thursday as boundary lifts back north. - Slightly above normal temperatures continue. ---------------------------------------------------------------- Convection fades this evening, with the overnight period largely dry across the region. On Thursday, a crossing shortwave trough will push the aforementioned boundary north again as a warm front, resulting in slightly more diurnal convective coverage. Relatively weak CAPE profiles and relatively low shear suggest a minimal severe threat. Latest MSU-CLP and CIPs guidance does not hint at much potential at all for severe convection or flooding in the period. && .LONG TERM /FRIDAY THROUGH TUESDAY/...-- Changed Discussion --KEY MESSAGES: - Stalled boundary lingers into the weekend at least with continued daily rain chances, currently highest Sunday. - Low rain chances next week as pattern uncertainty increases. - Continued near to above-normal temperature. ------------------------------------------------------------------- On Friday, a wave of low pressure along the boundary may push it further south, keeping higher diurnal shower/storm chances across our southern zones. Precipitable water remains elevated near and south of the boundary, so locally heavy rainfall will remain possible. Mainly diurnal shower and storm chances continue into the weekend, with the best chance for more widespread coverage on Sunday as surface low pressure transitions over the northern Great Lakes and the associated cold front crosses the region. There is some uncertainty in timing of FROPA, so with that, NBM 10th to 90th percentile spreads continue to exceed 10 degrees for most of the region, with possible max values ranging from around 80 to the lower 90s. Severe/flooding potential is non- zero, but on the low end at this time based off latest models, analogs, and machine learning guidance. Uncertainty them propagates into next week. Elevated 500mb heights and zonal flow aloft are most likely, keeping temperatures near to above normal, but differences in disturbances in that flow require low-end PoPs for both Monday and Tuesday.-- End Changed Discussion --&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... There is still some uncertainty regarding the areal coverage and degree of intensity for fog formation this morning. Factors favoring fog include enough boundary layer moisture, very light wind, and a period of clearer skies fostering strong radiational cooling. Factors that could limit fog include the influx of mid-high level clouds overnight ahead of the next shortwave and its timing to disrupt cooling processes. Cloud cover has remained over eastern Ohio, allowing for some radiative cooling to occur over western PA and parts of northern WV. This has resulted in the development of river valley fog. The following terminals have a higher likelihood of observing fog: FKL, DUJ, LBE, and MGW. There is a moderate chance for PIT/AGC since the river valley fog development has been slower and cloud cover will reach this area sooner than the eastern terminals. There is a lower probability for fog at BVI/HLG since these terminals will soon have cloud cover. Diurnal heating/mixing will erode any fog/low stratus by 14z, with VFR expected the rest of the day. Shortwave movement is likely to be displaced too far north/south to generate precipitation, however, there is a low probability (30%) for a shower between 18z-00z at ZZV and MGW. Following sunset, the probability for a rain shower decreases. Outlook... A weakly forced but warm/humid environment is favored through the end of the week that will allow for intermittent periods of showers/thunderstorms; confidence is likely to be lower on timing various rounds of precipitation as well as the resultant cig/vis impact they could have during the morning hours. More significant upper level and surface boundary movement appears to arrive over the weekend that will create a more focused and better timed period for convection and restriction development. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...88 NEAR TERM...88 SHORT TERM...88 LONG TERM...88 AVIATION...Frazier/Lupo