FXUS61 KPBZ 080620 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 220 AM EDT Wed Jul 8 2026 .WHAT HAS CHANGED... The chances for showers and thunderstorms have decreased over the upcoming weekend. Otherwise no major changes to the latest forecast. && .KEY MESSAGES... 1) Morning fog, then mainly dry with limited convection potential today 2) Unsettled pattern through Friday, with lesser chances for showers/storms over the weekend && .DISCUSSION... KEY MESSAGE 1... Isolated showers continue early this morning along a boundary from Armstrong to Forest counties. These should gradually end with waning instability. Otherwise, with low level moisture in place, areas of fog and stratus are expected again early this morning. This should mix out after sunrise. Expect most of the day to be dry for much of the area today under flat ridging and capping warmth aloft. Surface convergence near a weakening surface boundary could result in isolated to scattered showers and thunderstorms, especially east of Pittsburgh. Precipitable water is progged to be lower than recent days, ranging from 1.2 to 1.4 inches east of Pittsburgh, though the flow aloft is weak. Expect any flood potential to be very low and localized. KEY MESSAGE 2... A shortwave trough is expected to advance out of the Midwest tonight, approaching and cross the Upper Ohio Valley region late tonight into Thursday. An increase in showers and thunderstorms is expected. The most numerous coverage is expected to be south of Pittsburgh, where the best moisture and upper level support is progged. Shear is expected to be around 20kt, with ML CAPE ranging from around 500 j/kg north of I-80, to around 1200 j/kg south of I-70. This should result in a limited potential for severe weather. Another, stronger shortwave is progged for a Friday passage. Maintained categorical POPs for showers and thunderstorms. Instability should be limited with existing cloud cover through the day, though precipitable water is expected to increase. Locally heavy rainfall will be possible. Current NBM probabilities of 1 inch of rain range from 35 to near 50 percent. A surface boundary is progged to set up across the Lower Ohio Valley on Saturday into Sunday. This will keep shower and thunderstorm chances in the forecast, with the highest POPs south of PIT. The overall severe weather and flood potential is expected to be low over the weekend. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... Expect conditions to deteriorate to IFR for most sites by early morning as fog and stratus develop with low level moisture in place. These conditions should gradually improve through the morning as mixing begins after sunrise. The CU rule and model soundings indicate a broken cumulus layer is likely through the day, though cigs heights should be in the VFR category. Convergence along a surface boundary could result in isolated to scattered showers and thunderstorms east of PIT this afternoon. Maintained a prob 30 mention for LBE, MGW and DUJ for this potential. Elsewhere, capping warmth aloft should preclude a TAF mention at this time. Expect partial clearing tonight, as convection wanes. Outlook... Patchy morning fog and stratus is possible again Thursday morning, with restrictions in scattered showers and thunderstorms developing from Thursday morning through the rest of the day. More widespread showers and possible thunderstorms are expected Friday with a crossing shortwave. Additional morning fog and stratus is possible through the weekend, with shower/thunderstorm potential mainly south of PIT. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ DISCUSSION...WM AVIATION...WM