268
FXUS61 KPBZ 151703
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
103 PM EDT SAT AUG 15 2026
WHAT HAS CHANGED
A FLOOD WATCH HAS BEEN ISSUED FOR COUNTIES NEAR AND SOUTH OF
PITTSBURGH FROM 04Z SUNDAY TO 12Z MONDAY, AS CONFIDENCE HAS
INCREASED IN POTENTIALLY FLOODING RAIN. THERE IS ALSO SLIGHTLY
HIGHER CONFIDENCE IN THE POTENTIAL FOR SEVERE STORMS MAINLY
SOUTH OF I-70 SUNDAY AFTERNOON AND EVENING.
KEY MESSAGES
1) THE NEXT THUNDERSTORM CLUSTER IS FAVORED TO CROSS LATE
TONIGHT INTO SUNDAY MORNING, POSING MAINLY A FLASH FLOOD THREAT.
A FLOOD WATCH HAS BEEN ISSUED AS A RESULT.
2) UNCERTAINTY INCREASES SUNDAY, BUT FLASH FLOOD AND SEVERE
RISKS REMAIN WITH POTENTIAL RENEWED CONVECTION.
3) AFTER LINGERING RAIN CHANCES DISSIPATE MONDAY, THERE IS
FAIRLY HIGH CONFIDENCE IN DRY WEATHER UNTIL THE NEXT SYSTEM
ARRIVES WEDNESDAY/THURSDAY.
DISCUSSION
KEY MESSAGE 1...
CURRENT ACTIVITY OVER INDIANA/WESTERN OHIO IS EXPECTED TO
CONTINUE MORE OF A SOUTHEAST TRAJECTORY ALONG THE MIXED-LAYER
CAPE GRADIENT INTO SOUTHERN OHIO AND CENTRAL WEST VIRGINIA,
MAINLY AS RAIN SHOWERS WITH A LOW PROBABILITY FOR THUNDER.
PERHAPS, IF CLOUDS CLEAR SUFFICIENTLY, ENOUGH BUOYANCY COULD
DEVELOP IN MUSKINGUM/COSHOCTON COUNTIES AND VICINITY FOR A BRIEF
THREAT OF STRONG WIND GUSTS FROM A WET MICROBURST THIS
AFTERNOON, BUT CONFIDENCE IN SUCH A THREAT REMAINS LOW.
CAMS CONTINUE TO SUGGEST THAT THE NEXT CONVECTIVE COMPLEX
DEVELOPS IN WESTERN OHIO AROUND 00Z, ASSOCIATED WITH A MID-LEVEL
SHORTWAVE AND A STRENGTHENING LOW-LEVEL JET. THIS ACTIVITY
WOULD THEN ARRIVE IN OUR EASTERN OHIO COUNTIES AROUND 03Z OR SO
AND TRACK ACROSS THE REGION THROUGH SUNRISE. BY THAT POINT, LOW-
LEVEL BUOYANCY SHOULD BE MINIMAL, AND THUS SEVERE RISK SHOULD
BE A SECONDARY CONCERN TO THE FLASH FLOOD POTENTIAL.
VERY EFFICIENT RAINFALL PRODUCTION IS EXPECTED WITH ANY SUCH STORMS.
BEHIND A WARM FRONT, OVERALL MOISTURE LEVELS WILL SURGE, WITH
NBM/HREF SUGGESTING PRECIPITABLE WATER VALUES CLIMBING INTO THE
2 TO 2.25 INCH RANGE. THE HIGHER END OF THAT RANGE, IF ACTUALLY
OBSERVED BY OUR 12Z SOUNDING, COULD BE ONE OF THE HIGHEST SUCH
PWAT READINGS EVER RECORDED (SINCE 1952) AT THIS UPPER AIR SITE.
DEEP SATURATION AND IMPRESSIVELY HIGH WARM-CLOUD DEPTHS OF
AROUND 14KFT ARE ALSO NOTED, HIGHLIGHTING THE EXPECTED TROPICAL
AIRMASS. HREF PROGS SUGGEST MAXIMUM HOURLY RAINFALL RATES OF 1.5
TO 1.75 INCHES ARE POSSIBLE, WHICH WOULD EXCEED 1-HOUR FLASH
FLOOD GUIDANCE IN COUNTIES FROM PITTSBURGH ON SOUTH. CONSIDERING
THIS AND THE FAVORABLE ENVIRONMENT FOR EXCESSIVE RAIN, A FLOOD
WATCH HAS BEEN ISSUED FROM MIDNIGHT THROUGH 8AM MONDAY.
KEY MESSAGE 2...
CONFIDENCE IN WHAT FOLLOWS FOR SUNDAY AND SUNDAY NIGHT DROPS
OFF, AS EVENTS WILL DEPEND ON THE MESOSCALE SETUP LEFT BEHIND BY
THE OVERNIGHT COMPLEX, MOST NOTABLY HOW MUCH CLEARING/SUBSEQUENT
DESTABILIZATION CAN OCCUR. WHILE SOME STABLE AIR SHOULD LIMIT
COVERAGE AND INTENSITY OF CONVECTION AT LEAST INTO EARLY
AFTERNOON, SOME CAMS DO SUGGEST DEVELOPMENT OF SUFFICIENT
MLCAPE TO REFIRE CONVECTION DURING THE LATE AFTERNOON AND
EVENING, PARTICULARLY SOUTH OF PITTSBURGH IN THE SPC DAY 2
SLIGHT RISK AREA. HERE, A POCKET OF 25-30 KNOTS OF 0-6KM SHEAR
COULD PROVIDE ENOUGH STORM ORGANIZATION FOR A DAMAGING WIND
POTENTIAL, WHILE STRETCHED LOW-LEVEL HODOGRAPHS AND SUFFICIENT
0-1KM SRH SUGGEST A LOWER-END TORNADO THREAT FOR ESE-MOVING
STORMS. MACHINE-LEARNING GUIDANCE DOES SUPPORT THESE
ASSERTIONS. ALSO, THE SAME FAVORABLE HEAVY-RAINFALL INGREDIENTS
FROM THE PREVIOUS NIGHT WILL CONTINUE, EXTENDING THE FLASH
FLOOD THREAT INTO SUNDAY NIGHT.
KEY MESSAGE 3...
DIURNAL STABILIZATION SHOULD BEGIN TO LIMIT CONVECTIVE COVERAGE
AND INTENSITY LATE SUNDAY EVENING, WITH A FEW SHOWERS LINGERING
INTO MONDAY WITH ONE LAST SHORTWAVE. BY THIS POINT, PWAT WILL
BE DROPPING OFF THANKS TO DEVELOPING DRIER NW FLOW, WHICH SHOULD
HELP TO TAPER THE HEAVY RAINFALL THREAT. HIGH PRESSURE BUILDING
IN FROM THE GREAT LAKES SHOULD END PRECIPITATION BY MONDAY
EVENING. DRY WEATHER IS THEN FAVORED UNTIL WEDNESDAY, WHEN THE
NEXT FRONT COULD POTENTIALLY ARRIVE, ALTHOUGH THIS TIMING COULD
CHANGE.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
VFR IS EXPECTED THROUGH THIS EVENING UNDER SHORTWAVE RIDGING,
THOUGH SCATTERED CUMULUS AND INCREASING MID LEVEL CLOUDS ARE
EXPECTED AHEAD OF AN APPROACHING SHORTWAVE TROUGH. A WARM FRONT
WILL APPROACH AND CROSS THE REGION TONIGHT INTO SUNDAY MORNING,
WITH SHOWERS, EMBEDDED THUNDERSTORMS, AND MVFR TO IFR
RESTRICTIONS EXPECTED. ELEVATED INSTABILITY AND A LOW LEVEL JET
SHOULD MAINTAIN STORMS OVERNIGHT INTO SUNDAY MORNING. ZZV AND
MGW HAVE A HIGHER POTENTIAL OF SEEING THUNDERSTORMS TONIGHT, SO
INCLUDED A TEMPO MENTION FOR THUNDER THERE. MAINTAINED A PROB30
FOR MOST OTHER AIRPORTS WITH A SOMEWHAT LOWER CHANCE OF THUNDER.
IFR RESTRICTIONS ARE EXPECTED SUNDAY MORNING WITH ADDITIONAL
SHOWERS/EMBEDDED THUNDERSTORMS AS THE WARM FRONT MOVES
NORTHEAST ACROSS THE AREA. AFTERNOON THUNDERSTORMS ARE LIKELY
ON SUNDAY AS A COLD FRONT APPROACHES, MAINLY AFTER 18Z. INCLUDED
A TEMPO MENTION IN THE 30HR PIT TAF BEGINNING AT 20Z.
OUTLOOK...
OCCASIONAL RESTRICTIONS IN SHOWERS/THUNDERSTORMS ARE EXPECTED
SUNDAY AFTERNOON AND EVENING WITH THE APPROACHING COLD FRONT. A
FEW SHOWERS AND RESTRICTIONS COULD CONTINUE MONDAY AS THE COLD
FRONT COMPLETES ITS PASSAGE. GENERAL VFR IS THEN EXPECTED
THROUGH TUESDAY UNDER HIGH PRESSURE. RESTRICTIONS AND
SHOWER/THUNDERSTORM CHANCES RETURN LATER WEDNESDAY INTO EARLY
THURSDAY WITH THE APPROACH AND PASSAGE OF A COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH MONDAY MORNING
FOR PAZ020-021-029-031-073>076.
OH...FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH MONDAY MORNING
FOR OHZ039>041-048>050-057>059-068-069.
WV...FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH MONDAY MORNING
FOR WVZ001>004-012-021-509>514.
DISCUSSION...CL
AVIATION...WM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page