FXUS61 KPBZ 181125 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 725 AM EDT Sat Jul 18 2026 .WHAT HAS CHANGED... Severe storms expected today between 5pm and 10pm with a passing cold front; damaging winds the main threat. && .KEY MESSAGES... 1) Wildfire smoke expected to clear this morning 2) Isolated showers and storms this morning; damaging wind gusts this evening with a cold front 3) New low pressure system expected to return severe weather Tuesday && .DISCUSSION... KEY MESSAGE 1... Air quality will gradually improve early this morning as west/southwest winds develop and scattered showers and thunderstorms help disperse and wash out Canadian wildfire smoke. Visibility should steadily improve, with most of the smoke causing reduced visibility expected to clear between 10am and noon. KEY MESSAGE 2... A cold front, currently moving across central Wisconsin and northern Michigan, is expected to reach our region later this evening, generally moving through the region from 5pm and 10pm. As the front approaches, a squall line is expected to develop near Lake Erie and track south. Damaging straight-line winds will be the primary hazard. Secondary threats include quarter size hail, brief embedded tornadoes along the cold front, and locally heavy rainfall. The Storm Prediction Center has placed areas north of Interstate 70 in an Enhanced Risk (3/5) for severe weather, where the orientation of the wind shear relative to the front is most favorable for producing widespread damaging straight-line winds. Numerous communities could experience downed trees and scattered power outages this evening as the squall line moves through. Ahead of the approaching cold front, a few discrete thunderstorms may develop. If these storms produce updrafts that rapidly strengthen they could generate strong, ice-loaded downdrafts capable of producing severe wind gusts. The probability of thunderstorms is expected to decrease between 9pm and 11pm this evening as the cold front exits south into central West Virginia. Quiet and dry conditions are expected Sunday. KEY MESSAGE 3... Machine learning guidance has remained consistent in signaling that a low pressure system tracking across the Great Lakes on Tuesday will bring another threat of severe storms to the region. The Storm Prediction Center (SPC) has outlined the entire forecast domain in a 15% severe weather risk. Damaging wind gusts and tornadoes appear to the be the primary hazard as strong wind shear accompanies this large-scale system. In addition to the severe weather threat, there is also the potential for training showers and storms with a potential mesoscale convection system (MCS) across the Ohio River Valley. Rainfall totals could range between 1.5-2 inches in a short period of time and result in flash flooding. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Morning TSRA is fleeting eastward at this time and will bring VCTS conditions to DUJ and LBE between 12-13z before clearing out. IFR-MVFR VIS continues in smoke this morning. Although upper- level winds are beginning to clear smoke noticeably from the region, smoke trapped underneath our inversion layer will continue to be an issue until we remove the inversion and begin to mix closer to midday. VIS should gradually improve late this morning and then more readily by midday. VFR conditions with isolated showers and storms are expected between 16Z to 18Z due to broad ascent provided by an upper- level shortwave trough. Within these storms, vis could drop between 1SM to 3SM briefly. These storms could bring damaging wind gusts and carry a low end tornado risk. Between 20Z and 23Z the cold front is expected to advance south of Lake Erie and impact the northern terminals first. TEMPOS continue for strong wind gusts in heavy thunderstorms along the front. Outlook... Temporary visibility restrictions are possible Sunday morning before VFR returns Sunday and Monday under high pressure. Restrictions return in showers and thunderstorms on Tuesday with a cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...Air Quality Alert until midnight EDT tonight for WVZ001>004- 012-021-509>514. && $$ DISCUSSION...Hefferan AVIATION...Hefferan/AK