Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
393 FXUS61 KPBZ 141058 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 658 AM EDT Mon Sep 14 2026 .WHAT HAS CHANGED... Confidence in later arrival time of the next rain chance by midweek is a bit higher. No other significant changes. && .KEY MESSAGES... 1) Dry weather is expected into Tuesday night. Cooler temperatures today and tonight, then a warmup Tuesday. 2) Warm and humid conditions return Wednesday and Thursday, along with rain chances. && .DISCUSSION... KEY MESSAGE 1... A few isolated showers remain along the windshift/leading edge of drier air, which is currently working into the ridges. The main shortwave trough axis rotates through this morning, which will be followed by 500mb ridging through Tuesday. Isolated patches of fog are possible this morning due to the moist ground, but decreasing dewpoints and lingering light mixing may tend to limit this somewhat. Crossing surface high pressure will then provide dry weather today into at least Tuesday evening. Lingering lower heights aloft will support high temperatures some 5 to 8 degrees below normal today. With the surface high overhead tonight, a clear and seasonably cool night is forecast, with lows in the 40s expected in the ridges and north of US-422. Temperatures climb back above normal Tuesday in 850mb warm advection behind the departing high. KEY MESSAGE 2... The next chance of precipitation now appears a bit more likely to hold off until late Tuesday night or Wednesday morning, as the next shortwave trough skirts the northern Great Lakes. Ensemble clusters show some agreement in keeping elevated, quasi-zonal 500mb heights over the Ohio Valley. This may help to hang an associated surface front closer to the shores of the eastern Great Lakes into Thursday before it potentially gets a southward push. Machine-learning guidance continues to suggest lower-end severe and flooding threats. The high heights should also keep temperatures above normal, and with low-level southwest flow pushing dewpoints well into the 60s to around 70, an increase in heat stress is possible. Probabilistic HeatRisk guidance shows 50-90% chances for Moderate (level 2 of 4) or higher near and south of Pittsburgh Wednesday, and CWA- wide on Thursday. Temperatures may then cool slightly Friday behind the front. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Surface high pressure and dry northerly winds will erode lingering low VFR/high MVFR stratus southeast of Pittsburgh this morning. The rest of the day features few to mostly scattered Cu between 2-5kft with northerly winds that could occasionally gust to around 15kts. There is a non-zero probability for river valley steam fog near dawn Tuesday due to lighter wind and starker water/air temperature differences but locations of impact will be hard to predict. Outlook... Outside of morning valley fog, VFR is expected into Tuesday night under high pressure. Shower and thunderstorm chances increase from N-S late Wednesday into late Thursday with the approach and passage of a cold front. VFR should return Friday as the front exits and high pressure builds in. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ DISCUSSION...CL AVIATION...Frazier