735
FXUS61 KPBZ 051308
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
908 AM EDT SUN JUL 5 2026
WHAT HAS CHANGED
REMOVED KEY MESSAGE FOR DENSE FOG THIS MORNING.
KEY MESSAGES
1) THUNDERSTORMS, FAVORING AFTERNOON/EVENING PERIODS, REMAIN
LIKELY THROUGH MONDAY WHILE POSING A DECREASING DAMAGING WIND
THREAT BUT STEADY LOCALIZED FLOODING RISK.
2) ENSEMBLES TRENDING TOWARD A FAIRLY ACTIVE WEEK FEATURING
LIMITED "DRY" PERIODS BUT WITH LOW HAZARD PROBABILITIES.
DISCUSSION
KEY MESSAGE 1...
THE UPPER OHIO RIVER VALLEY IS EXPECTED TO REMAIN IN THE
SEASONABLY MOIST (PWATS AROUND 90TH-95TH PERCENTILE) LIGHT
SOUTHWEST FLOW AHEAD OF A SAGGING UPPER TROUGH SITTING TO THE
WEST TODAY INTO MONDAY. THIS PATTERN OFFERS SLIGHTLY IMPROVED
JET SUPPORT/LIFT, CREATING HIGHER CONFIDENCE IN THUNDERSTORM
DEVELOPMENT FAVORING THE AFTERNOON/EVENING HOURS THOUGH WEAK
SURFACE LIFT (AND POTENTIAL RELIANCE ON PRIOR CONVECTIVE OUTFLOW
BOUNDARIES) LENDS TO MORE VARIABILITY IN STORM POSITIONING AND
PROGRESSION.
FOR TODAY:
ENOUGH SURFACE HEATING COMBINED WITH MOISTURE THERMAL PROFILES
RESULTS IN SBCAPE VALUES RISING BETWEEN 1200-2000 J/KG WHILE
WEAK SHEAR SITS NEAR 20-25KTS, ENOUGH TO RISE THE (LOW)
POTENTIAL FOR LARGE HAIL. LESS AMOUNTS OF DRY AIR ALOFT DOES
LOWER THE DAMAGING WIND THREAT BUT THAT REMAINS A POSSIBILITY
ESPECIALLY IN WET DOWNBURSTS. THESE VARIABLES BEST ALIGN
SOUTHEAST OF PITTSBURGH WHERE THE SLIGHT SEVERE OUTLOOK IS
POSITIONED, BUT ANY AREA THAT MAXIMIZES SURFACE
HEATING/DESTABILIZATION COULD EXPERIENCE SIMILAR SEVERE RISKS.
ADDING TO THIS, WARM THERMAL PROFILES AND FAIRLY WEAK STEERING
FLOW PROVIDE FUEL TO A LOCALIZED FLASH FLOODING THREAT THAT WAS
ALREADY PRESENTED BY THE HIGHER CAPE/HIGH PWAT ENVIRONMENT
CAPABLE OF HIGH RAINFALL RATES. DUE TO THE LACK OF SURFACE
FORCING AND WEAK SHEAR, IT IS VERY DIFFICULT TO PINPOINT ANY ONE
AREA/REGION MORE LIKELY TO EXPERIENCE FLASH FLOODING AND THOSE
INSTANCES MAY STILL BE FAIRLY ISOLATED (VERSUS WIDESPREAD), THUS
NO FLOOD WATCH WILL BE ISSUED AT THIS TIME.
FOR MONDAY:
BROADLY SPEAKING, THERE IS LITTLE TO ADD TO THE DISCUSSION
BEYOND COPYING WHAT WAS SAID FOR TODAY AS HI-RES GUIDANCE TRENDS
MAINTAIN SIMILAR CAPE/SHEAR/PWAT PROFILES. POTENTIAL
DIFFERENTIATING FACTORS...POTENTIAL FOR EXTRA CLOUD COVER TO
LIMIT HEATING AND REDUCING BUOYANCY DEVELOPMENT (MAINTAIN THE
FLOOD THREAT BUT FURTHER ERODING WIND/HAIL THREATS)...AND/OR
SUBTLE MID-LEVEL RIDGING WORKING AROUND THE UPPER TROUGH THAT
OFFERS ENOUGH SUBSIDENCE TO DISPLACE CONVECTIVE ACTIVITY TO THE
NORTH/EAST. LIKE TODAY, HI-RES MODELING FAVORS AREAS SOUTHEAST
OF PITTSBURGH TO MAXIMIZE THE ENVIRONMENTAL PARAMETERS TO REACH
THOSE SEVERE/FLOOD RISKS BUT CONFIDENCE IS LOW ON THIS OCCURING.
KEY MESSAGE 2...
THE SAGGING TROUGH SLOWLY SHIFTS EAST THE REGION THROUGH THE
LATTER PORTION OF THE WEEK, ACTING TO LIMIT AIRMASS CHANGES TO
ESCAPE THE DAILY POTENTIAL FOR DIURNALLY DRIVEN THUNDERSTORMS.
FAVORED AREAS ARE MORE LIKELY TO BE DICTATED BY THE SUBTLE AREAS
OF JET-INDUCED LIFT/SINK AROUND THE TROUGH AS WELL AS RESIDUAL
STORM OUTFLOWS BECAUSE SURFACE FRONTOGENESIS AND WIND IS
EXPECTED TO REMAIN FAIRLY NON- EXISTENT. THERE IS VARIANCE IN
HOW QUICKLY THE UPPER TROUGH BECOMES POSITIONED TO THE EAST,
MEANING VARIANCE ON WHEN THE "LULL" PERIOD MAY OCCUR. QUICKER
SOLUTIONS OFFER LOWER POPS BY WEDNESDAY AFTERNOON AND
TEMPERATURE CLIMBING A FEW DEGREES ABOVE NORMAL; SLOWER
SOLUTIONS RESULT IN A CONTINUATION OF "CHANCE" OR SO POPS FOR
WEDNESDAY AS TEMPERATURE SITS NEAR AVERAGE.
OF HIGHER CONFIDENCE IS THAT A MORE PROGRESSIVE UPPER TROUGH IS
FAVORED TO CROSS THURSDAY INTO FRIDAY AND CONTINUE THE BROKEN
RECORD OF SHOWER/THUNDERSTORM CHANCES.
THOUGH ENVIRONMENTS ARE SUBJECT TO CHANGE WITHIN THE SUMMER
SEASON, INITIAL OUTLOOKS AND GUIDANCE SUGGESTS MOST OF THE
PERIODS OFFER LIMITED SEVERE/FLOOD RISKS TO MONITOR.
AVIATION /13Z SUNDAY THROUGH THURSDAY/
EXPECT A FEW INSTANCES OF MVFR/IFR AND BELOW THROUGH 14Z THIS
MORNING FOR SOME TERMINALS. WINDS ARE EXPECTED TO BE LIGHT AND
VARIABLE OUTSIDE OF THUNDERSTORMS.
VFR (SAVE FOR A BRIEF MVFR CU PERIOD AFTER HEATING INITIATES) IS
LIKELY AFTER 15Z BEFORE DIURNALLY DRIVEN THUNDERSTORMS DEVELOP
BETWEEN 18Z-00Z. WEAK SURFACE FORCING AND LIMITED UPPER SUPPORT
CREATES UNCERTAINTIES IN TIMING AND COVERAGE OF CONVECTION, SO
EXPECT AFTERNOON AMENDMENTS TO ADJUST FOR THE LATEST
ANALYSIS/TRENDS. ANY THUNDERSTORM WILL BE CAPABLE OF PRODUCING
GUSTY, ERRATIC WINDS AND QUICKLY DROP VISIBILITIES TO 2 MILES OR
LESS.
THE MOIST ENVIRONMENT WITH SOME CLEARING PORTENDS TO POTENTIAL
STRATUS/FOG DEVELOPMENT AT THE END/AFTER THE TAF PERIOD BUT
SIMILAR POTENTIAL FOR BOUNCY AND AREAL VARIABILITY IN
CONDITIONS.
FOR TONIGHT, DENSE FOG IS EXPECTED AGAIN WITH SITES DROPPING
DOWN TO FIELD MINS IN SOME CASES. AFTER ANOTHER DAY OF WARM AND
MUGGY CONDITIONS WITH SCATTERED SHOWERS AND THUNDERSTORMS,
ANOTHER NIGHT OF IMPACTS TO VIS AND CIGS ARE EXPECTED.
OUTLOOK...
MORNING FOG AND STRATUS RESTRICTIONS GIVING WAY TO MVFR/VFR CU
AND DIURNALLY DRIVEN THUNDERSTORMS CAN BE EXPECTED THROUGH
WEDNESDAY AS THE UPPER TROUGH DRIVING THE WEATHER SLOWLY SHIFTS
EAST.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER/MCMULLEN
AVIATION...SHALLENBERGER
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