531
FXUS61 KPBZ 101720
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
120 PM EDT WED JUN 10 2026
WHAT HAS CHANGED
IMPROVED TIMING AND AREAL FOCUS FOR STORMS AND SEVERE CHANCES
THROUGH THURSDAY MORNING, OTHERWISE PRIOR MESSAGING AND ITS
DEGREES OF UNCERTAINTY REMAIN.
KEY MESSAGES
1) POTENTIAL FOR SEVERE WEATHER EXISTS TODAY THROUGH FRIDAY,
BUT LARGE UNCERTAINTY EXISTS IN TIMING/COVERAGE/THREATS
2) LOW PROBABILITY FLASH FLOODING CONCERNS EXISTS THROUGH FRIDAY
DUE TO WARM, MOIST ENVIRONMENT
3) ABOVE-AVERAGE TEMPERATURE WITH POTENTIAL FOR RECORD HIGH
MINIMUMS POSSIBLE THROUGH FRIDAY, PENDING STORM OUTCOMES
DISCUSSION
KEY MESSAGE 1...
THE REGION WILL REMAIN WITHIN A WARM, HUMID ENVIRONMENT THROUGH
PORTIONS OF FRIDAY CONDUCIVE TO CONVECTIVE ACTIVITY BEFORE A
MORE WELL-DEFINED FRONT AND UPPER TROUGH CROSS BY FRIDAY EVENING
THAT PROVIDE AT LEAST A BRIEF PERIOD OF MORE SEASONABLE AND DRY
WEATHER.
FOR TODAY, LATEST MESOANALYSIS SHOWS A CLEAR EXITING OF A MID-
LEVEL SHORTWAVE TROUGH AND AXIS OF ENHANCED PWATS AS OF 17Z
WHILE SATELLITE-NOTED DRY AIR ARRIVES IN ITS WAKE AMID SHORTWAVE
RIDGING. CONFIDENCE IS HIGHER AT THE MOMENT THAT THESE FEATURES,
DRY MID-LEVEL AIR AND RIDGE SUBSIDENCE, WILL SUPPRESS CONVECTIVE
ACTIVITY FOR A LARGE PORTION OF THE AFTERNOON. THEREAFTER, HI-
RES MODEL GUIDANCE NOTES A CORRIDOR OF SURFACE TEMP/DEWPOINT
CONVERGENCE NEAR CLE THAT IS THE MOST LIKELY AREA FOR
THUNDERSTORM DEVELOPMENT BETWEEN 6PM-10PM, WITH THESE STORMS
MOVING SOUTHEAST (BEFORE WEAKENING) DURING THE LATE NIGHT HOURS.
THE HIGHLIGHTED MARGINAL RISK BY SPC REMAINS CONDITIONAL ON
THESE OR ANY OTHER THUNDERSTORMS DEVELOPING PRIOR TO MIDNIGHT, WHICH
REMAINS ON THE LOWER END OF PROBABILITIES; IF THEY DO FORM
WITHIN THE PROPER EVENING WINDOW, THE RISK FOR DAMAGING WIND AND
HEAVY RAIN RISES DUE TO SBCAPE VALUES APPROACHING 2000 J/KG,
DCAPE VALUES AROUND 1000 J/KG, AND WEAKER SHEAR.
THURSDAY'S OUTLOOK SHOWS SIMILAR TO HIGHER SEVERE POTENTIAL DUE
TO MAINTENANCE OF HIGH SBCAPE/DCAPE VALUES BUT CONFIDENCE IS
SIGNIFICANTLY LOWER IN STORM DEVELOPMENT/COVERAGE/TIMING. LIKE
TODAY, THESE FACETS WILL BE PREDICATED ON STORM EVOLUTION
OVERNIGHT PLUS ANY INFLUENCES FROM WESTERN GREAT LAKE ACTIVITY
THAT MAY OR MAY NOT PROVIDE SOURCES OF LIFT/CONVERGENCE TO HELP
THE INITIATION PROCESS.
FRIDAY FEATURES A MORE WELL DEFINED MID-LEVEL SHORTWAVE AND
SURFACE FRONTAL BOUNDARY THAT OFFERS A LIFTING MECHANISM, BUT
MODEL GUIDANCE REMAINS SPREAD ON TIMING DIFFERENCES THAT COULD
RESULT IN MORE BULLISH PRECIPITATION/SEVERE CHANCES (AFTERNOON
PASSAGE) OR MORE BEARISH PRECIPITATION/SEVERE CHANCES (OVERNIGHT
TO MID MORNING FRIDAY PASSAGE). EARLY HINTS FROM THE MOST RECENT
HI-RES MODELING SEEM TO LEAN TOWARD THE LATTER IDEAL, MEANING
OVERALL PRECIPITATION CHANCES AND ASSOCIATED SEVERE RISKS TREND
LOWER WHILE FAVORING AREAS EAST OF PITTSBURGH.
KEY MESSAGE 2...
DESPITE FLUCTUATIONS IN MID-LEVEL MOISTURE CONTENT, AREA PWAT
VALUES WILL REMAIN IN THE 90TH AND HIGHER PERCENTILE RANGES
THROUGH FRIDAY WHILE THERMAL PROFILES REMAIN WARM. THESE FACTORS
ALONE CREATE NON-ZERO FLASH FLOOD RISKS AS THEY FAVOR WARM-RAIN
PROCESSES THAT RESULT IN HIGHER AND MORE EFFICIENT RAINFALL
RATES. ADD IN GENERALLY WEAKER MID-LEVEL FLOW (THOUGH STORM
MOTION QUICKENS FRIDAY), THE RISK FOR FLASH FLOODING EXISTS EACH
DAY.
HOWEVER, FAIRLY DRY SURFACES PLUS LOW CONFIDENCE IN STORM
COVERAGE/OCCURRENCE DAMPENS THE LIKELIHOOD OF FLASH FLOODING
ACTUALLY DEVELOPING FOR ANY OF THESE PERIODS. THE MOST LIKELY
OUTCOME IS MINIMAL FLOODING OCCURRENCES, WITH ISSUES ONLY
DEVELOPING IN POOR-DRAINAGE LOCATIONS THAT SEE PROLONGED 1-2"/HR
RATES OR AREAS THAT HAPPEN TO SEE MULTIPLE ROUNDS OF THESE
EFFICIENT RAINS IN A SHORT AMOUNT OF TIME.
KEY MESSAGE 3...
THE COMBINATION OF AREA DEW POINTS REMAINING IN THE UPPER 60S TO
LOWER 70S WHILE SEEING ENOUGH PERIODS OF SUNSHINE MEANS
INCREASED HEAT CONCERNS TODAY INTO FRIDAY MORNING, WITH IMPACTS
MORE ACUTELY IMPACTING HEAT-SENSITIVE POPULATIONS WITHIN URBAN
ENVIRONMENTS. THOUGH A BRIEF HOUR OF HEAT INDICES NEAR TO
MATCHING HEAT ADVISORY CRITERIA CAN'T BE RULED OUT, BUT ARE
UNLIKELY TO BE PROLONGED ENOUGH FOR HEADLINE ISSUANCE. EVEN
STILL THE LACK OF SIGNIFICANT OVERNIGHT COOLING CAN ACT TO
EXASPERATE ANY HEAT-RELATED IMPACTS UNTIL A COOLER AIRMASS
ARRIVES FRIDAY NIGHT INTO SATURDAY MORNING.
THE BIGGEST CAVEAT TO THIS HEAT POTENTIAL IS THAT CONVECTIVE
ACTIVITY COULD ACT TO LIMIT DIURNAL HEATING (OR FURTHER LIMIT
OVERNIGHT COOLING) IF IT RESULTS IN RAIN OVER A GIVEN LOCATION
AND/OR MAINTAINS THICKER CLOUD COVER THAN ANTICIPATED.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
IFR TO LOW MVFR CEILINGS THIS MORNING ARE EXPECTED TO IMPROVE TO
VFR LATER TODAY FROM WEST TO EAST AS A SHORT WAVE TROUGH MOVES
THROUGH. THIS DISTURBANCE IS TRIGGERING SCATTERED SHOWERS AND
THUNDERSTORMS WHICH MAY BRIEFLY LOWER VISIBILITIES IN THE
MORNING. DRIER AIR AND SUBSIDENCE ALOFT SHOULD END UP WITH
MAINLY DRY WEATHER THIS AFTERNOON AND EVENING.
WOULD EXPECT MAINLY MVFR CEILINGS TO RETURN LATER TONIGHT IN
MOIST ENVIRONMENT, WITH FKL AND DUJ LIKELY TO GO TO IFR AGAIN.
CONFIDENCE IN THUNDERSTORMS FOR TONIGHT AND THURSDAY IS LOW.
UNSTABLE AIRMASS WILL BE IN PLACE, BUT THERE IS A LOT OF
VARIABILITY IN HOW CLUSTERS OF THUNDERSTORMS WILL EVOLVE
UPSTREAM FROM MI TO IN AND IL ON BOTH TONIGHT AND THURSDAY AND
THAT WILL IMPACT WHAT HAPPENS IN THE UPPER OHIO RIVER VALLEY
AREA. PREDICTABILITY IN THESE PATTERNS IS USUALLY ONLY GOOD FOR
NEXT 6 TO 12 HOURS.
OUTLOOK...
A WARM, MOIST ENVIRONMENT WITH INTERMITTENT PASSING OF UPPER
SHORTWAVES FAVOR DAILY THUNDERSTORM CHANCES THROUGH THE REST OF
THE WEEK. RESTRICTIONS ARE LIKELY WITH ANY STORM WHILE EXCESSIVE
RAIN COULD CREATE CIG/VIS IMPACTS EVEN DURING NON-RAIN PERIODS,
LIKELY NEAR DAWN HOURS. CONFIDENCE REMAINS LOW IN TIMING AND
LOCATION OF THUNDERSTORMS EACH DAY GIVEN THE PATTERN. CHANCES
FOR STRONG/SEVERE THUNDERSTORMS WILL INCREASE EACH DAY WITH
POST-FRONTAL REPRIEVE ON SATURDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER
AVIATION...CRAVEN
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