891
FXUS61 KPBZ 101336
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
936 AM EDT MON AUG 10 2026
WHAT HAS CHANGED
INCREASED CONFIDENCE IN SEVERE LATE THIS MORNING WITH A CROSSING
LINE OF STORMS.
KEY MESSAGES
1) DAILY SHOWER AND THUNDERSTORM CHANCES RETURN TODAY AND
REMAIN IN THE FORECAST THROUGH AT LEAST THURSDAY WITH BOTH THE
POTENTIAL FOR STRONG/SEVERE STORMS AND HEAVY RAINFALL.
DISCUSSION
KEY MESSAGE 1...
A CONVECTIVE LINE IS EXPECTED TO PASS, MOSTLY NORTH OF
PITTSBURGH, WITH THE REMNANTS OF OVERNIGHT CONVECTION. IN THE
LAST FEW HOURS, CHANCES OF SEVERE ALONG THIS LINE HAVE
INCREASED AS STORMS HAVE RAMPED UP AND RECOUPLE IN A 30-35KT
0-3KM SHEAR. THE PRIMARY THREATS WITH THIS WILL BE DAMAGING
WINDS, UP TO 60-70MPH, WITH A LOW-END TORNADO THREAT, MORE
LIKELY IS STORMS TAKE A DIVE SOUTHEAST. IN THE LAST HOUR, THIS
CONVECTION HAS DEVELOPED UPSCALE ON THE SOUTHEAST SIDE FOR THE
PASSING MCV, WHICH HAS PROMPTED THE ISSUANCE OF A SEVERE
THUNDERSTORM WATCH ACROSS MOST OF THE AREA (SAVE PARTS OF
NORTHERN WEST VIRGINIA.
AFTER A BRIEF BREAK LATER THIS MORNING, ADDITIONAL CONVECTION
MAY ARRIVE BY MIDDAY/EARLY AFTERNOON, LIKELY THE CONTINUATION OF
ACTIVITY CURRENTLY NEAR THE SOUTHERN END OF LAKE MICHIGAN.
ALTHOUGH, EARLY CONVECTION MAY COMPLICATE THESE CHANCES. ANOTHER
ROUND IS THEN POSSIBLE AFTER SUNSET WITH A SHORTWAVE PASSAGE.
WHILE EXACT TIMING AND EVOLUTION OF AFTERNOON/EVENING CONVECTION
REMAINS IN QUESTION, THERE IS STILL A DECENT LEVEL OF
CONFIDENCE IN THE PRESENCE OF AN ENVIRONMENT CONDUCIVE FOR
SEVERE STORMS. MODEL SOUNDINGS SUGGEST MEAN-LAYER CAPE VALUES
WILL BE IN THE 1500 TO 2000 J/KG RANGE DURING THE PEAK HEATING
PERIOD, WITH DEEP-LAYER SHEAR ON THE ORDER OF 25 TO 35 KNOTS.
THIS WILL SUPPORT ORGANIZED CONVECTION WITH MAINLY A DAMAGING
WIND THREAT, BOTH FROM COLD POOL CONSOLIDATION AND DOWNBURST
POTENTIAL (DCAPE OF AROUND 1000 J/KG). SOME AT LEAST TRANSIENT
SUPERCELL STRUCTURES/ROTATING STORMS ARE ALSO POSSIBLE, THUS THE
THREAT FOR A TORNADO OR TWO CANNOT BE IGNORED.
FOR TUESDAY (AND POTENTIALLY WEDNESDAY AS WELL), THE MAIN THREAT
CORRIDOR SHIFTS SOUTH A BIT, WITH THE BEST POTENTIAL FOR SEVERE
STORMS MAINLY SOUTH OF I-70 (MATCHING SPC'S DAY 2 SLIGHT RISK
AREA). THIS IS WHERE RICHER INSTABILITY WILL RESIDE DURING THE
AFTERNOON AND EVENING. AGAIN, DAMAGING WINDS APPEAR TO BE THE
PRIMARY THREAT, AS THIS MAY BE THE MORE FAVORED REGION FOR
CONVECTIVE COMPLEX PASSAGE. THE MORE CONCENTRATED WIND DAMAGE
THREAT AREA LIKELY REMAINS JUST TO THE SOUTH OF OUR REGION, BUT
COULD CLIP PORTIONS OF AT LEAST EASTERN OHIO.
IN ADDITION TO SEVERE THREATS, THERE REMAINS THE RISK OF FLASH
FLOODING. GIVEN PRECIPITABLE WATER VALUES LIFTING BACK INTO THE
1.6 TO 1.7 INCH RANGE (90TH TO 95TH PERCENTILE IN THE
CLIMATOLOGY), AS WELL AS THE POTENTIAL FOR MULTIPLE THUNDERSTORM
COMPLEXES, WPC CONTINUES TO HIGHLIGHT OUR REGION IN A SLIGHT
(LEVEL 2 OF 4) RISK FOR EXCESSIVE RAIN FOR TODAY INTO TUESDAY
NIGHT, WITH THE MAIN HEAVY RAIN THREAT AREA SHIFTING SOUTH OF
THE MASON-DIXON LINE BY WEDNESDAY. 48-HOUR NBM MEAN
PRECIPITATION TOTALS ARE IN THE 1.5 TO 2.5 INCH RANGE GENERALLY
SOUTH OF US-422, WITH 90TH PERCENTILE TOTALS IN THE SAME AREA OF
3 TO 4 INCHES. GIVEN THE STILL RELATIVELY MOIST SOIL ACROSS THE
REGION, SUCH RAINFALL TOTALS COULD CREATE AT LEAST ISOLATED
FLASH FLOODING ISSUES IN THE HEAVIER CONVECTION. STILL, WITH THE
UNCERTAINTY IN TIMING AND LOCATION OF THE GREATEST POTENTIAL,
WILL HOLD OFF ON THE ISSUANCE OF A FLOOD WATCH AT THIS TIME.
BY THURSDAY, BOTH HEAVY RAIN AND SEVERE WEATHER THREATS SHOULD
BEGIN TO SUBSIDE AS A STRONGER GREAT LAKES SHORTWAVE PUSHES A
BOUNDARY ACROSS THE AREA, LEADING TO LESS THREATENING WEATHER.
AVIATION /13Z MONDAY THROUGH FRIDAY/
VFR IS GENERALLY FAVORED OUTSIDE OF CONVECTIVE PERIODS, THOUGH
DIURNAL HEATING/MIXING BETWEEN 13Z-18Z MONDAY MAY YIELD BRIEF
MVFR CU.
TIMING OF FUTURE THUNDERSTORM COMPLEXES REMAINS TRICKY TODAY.
TWO GENERAL ROUNDS ARE FORESEEN DURING THE TAF PERIOD: ONE FROM
14Z TO 20Z, ASSOCIATED WITH CURRENT SOUTHERN GREAT LAKES STORMS,
AND ANOTHER MAINLY AFTER 00Z WITH A SHORTWAVE PASSAGE. THESE
DETAILS ARE SUBJECT TO CHANGE AS THE MESOSCALE ENVIRONMENT
EVOLVES. IN ANY CASE, STORMS WILL BE CAPABLE OF BRIEF IFR TO
LIFR VISIBILITY AS WELL AS GUSTY WIND - PERHAPS TO BETWEEN 40
AND 50 KNOTS PEAK IN THE STRONGEST STORMS, AND EVEN HAIL IS A
POSSIBILITY. SUCH WINDS ARE MORE LIKELY WITH THE DAYTIME
ACTIVITY AS OPPOSED TO THE EVENING STORMS. THE CURRENT TAFS
REPRESENT BEST GUESS TIMING BASED ON LATEST AVAILABLE DATA BUT
IS OF LOW CONFIDENCE.
FOLLOWING THIS EVENING'S STORMS, WE EXPECTED A BRIEF PERIOD
WITHOUT PRECIPITATION. DUE TO MOISTURE TRAPPED AT THE SURFACE,
SOME FOG IS POSSIBLE. BY THE MORNING, ANOTHER AREA OF RAIN IS
FORECAST TO MOVE THROUGH MAINLY EASTERN OHIO (SLIGHTLY EXTENDING
INTO WESTERN PA).
OUTLOOK... ACTIVE WEATHER THROUGH MUCH OF THE WEEK WITH VARYING
ROUNDS OF SHOWERS AND THUNDERSTORMS. TIMING OF STORMS FOR A
GIVEN DAY IS LIKELY TO BE OF LOWER CONFIDENCE AND DEPENDENT ON
UPSTREAM STORM PROGRESSION. MOST RESTRICTIONS DURING THIS PERIOD
WILL BE TIED TO STORM ACTIVITY AND/OR MORNING FOG/STRATUS
RESULTANT OF RAIN PLUS OVERNIGHT CLEARING.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CL/MILCAREK
AVIATION...CL/LUPO
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