The Homestead Ski Area Snow Report

792 FXUS61 KPBZ 170621 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 221 AM EDT Fri Jul 17 2026 .WHAT HAS CHANGED... Decreased confidence in severe convection tonight with smoke becoming too thick to allow for convection. Will need to be on the lookout for isolated instances of very dense fog come morning in river valleys given smoke concentrations. && .KEY MESSAGES... 1) Smoke, and visibility obstructions persist through tomorrow. 2) More widespread storm chances, along with severe and flooding risks, return on Saturday. && .DISCUSSION... KEY MESSAGE 1... With surface and deep layer column flow orienting more northwest to southeast on Friday, ground-level wildfire smoke from fires originating in southern Ontario and northern Minnesota will arrive to our area. Upstream observations show the worst of the visibility dipping down to as low as half a mile with general prevailing conditions between 1-2 miles. In addition, air quality is greatly degraded. Another concern, is the river valleys where there would be just enough moisture combined with the smoke to make visibility down to zero in some cases. This will mainly be an issue during the morning hours. The thickest ground- level concentration will arrive late Thursday into Friday. In coordination with OH, PA, and WV Departments of Environmental Protection, Air Quality Alerts are in place for Thursday and Friday. Refer to your state`s department for more information. The arrival of the next weather system should be enough to scour out the lingering smoke over the area. This should be the case by Sunday morning. KEY MESSAGE 2... The next concern will arrive Friday night and continue to impact the region through Saturday. The upper level pattern will continue to maintain a ridge - trough pattern aloft with northwest flow into the Upper Ohio Valley. Instability in the region remains contingent on potential convective development over the lower Midwest on Friday. Current CAMs suggest convection will develop over northern IL, IN, and OH along a boundary of differential heating influenced by the extent of wildfire smoke. The uncertainty in the factors surrounding this convection has led to disagreement between ensemble members on the impact to the convective environment on Saturday. The deciding factor will be the persistence of cloud cover from Fridays convection into the day Saturday. CAMs continue to dissipate convection Friday night rather quickly. Even so, in the latest run where NBM pop forecasts needed additional adjustment. With the wildfire smoke and potential early day convection, it will most certainly take a boundary with ample forcing to realize the instability available through the day on Saturday. While all hazards are on the table, wind and flash flooding look to be the primary threats. Current model soundings for Saturday show plentiful deep layer moisture and a favorable warm rain layer through 400mb, meaning hail development is less favorable. PW values near 2 across most models indicate high confidence in heavy rainfall production in sustained updrafts. Elevated dew points resulting in low LCLs pose a non-zero tornado threat, but low-level shear is relatively weak which could be a limiting factor. SPC has outlined the area in a slight risk for severe weather and WPC has outlined the area in a marginal risk for excessive rainfall for Saturday. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... The region will be under the influence of high pressure for one more day. Dry conditions will persist in most cases through 00Z. Northwest flow aloft will continue to bring in smoke from Canadian wildfires. This will cause surface visibility to drop to 1 to 2 miles at some places through the day. This is expected to persist through the day. The next disturbance will begin to impact the area in the 03Z to 06Z timeframe for ZZV as a PROB30 was used for showers and thunderstorms. Winds are expected to remain light and variable. Outlook... Restrictions are likely late Friday night into Saturday night with an initial warm front, then a crossing cold front. Showers and thunderstorms are likely, and some storms could be severe later Saturday. VFR returns Sunday and Monday under high pressure, with restrictions possible in showers and thunderstorms with a Tuesday cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Air Quality Alert until midnight EDT tonight for PAZ007>009- 013>016-020>022-029-031-073>078. OH...Air Quality Alert until midnight EDT tonight for OHZ039>041- 048>050-057>059-068-069. WV...Air Quality Alert until midnight EDT tonight for WVZ001>004- 012-021-509>514. && $$ DISCUSSION...Shallenberger AVIATION...Shallenberger/MLB