359
FXUS61 KPBZ 171132
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
732 AM EDT FRI JUL 17 2026
WHAT HAS CHANGED
UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE.
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 /12Z FRIDAY THROUGH TUESDAY/
DRY CONDITIONS PREVAIL THROUGH TODAY UNDER HIGH PRESSURE AS
VISIBILITIES CONTINUE TO HOVER IN THE LOW-END MVFR TO IFR RANGE
DUE TO SMOKE FROM CANADIAN WILDFIRES. SOME ISOLATED TO SCATTERED
SHOWERS OR DECAYING THUNDERSTORMS ARE FORECAST TO MOVE WEST TO
EAST ACROSS THE AREA OVERNIGHT BUT SHOULD BRING LITTLE IN TERMS
OF IMPACTS TO AREA TERMINALS. AN APPROACHING LOW PRESSURE SYSTEM
WILL SHIFT WINDS TO MORE SOUTH OR SOUTHWESTERLY, WHICH WILL
HELP ADVECT WILDFIRE SMOKE OUT OF THE AREA SATURDAY MORNING.
OUTLOOK...
SHOWERS AND THUNDERSTORMS ARE LIKELY ON SATURDAY, SOME OF WHICH
COULD BE SEVERE LATER IN THE AFTERNOON AND EVENING. 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...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...CERMAK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page