158
FXUS61 KPBZ 141720
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
120 PM EDT FRI AUG 14 2026
WHAT HAS CHANGED
THOUGH TIMING REMAINS FLUID, THERE APPEARS TO BE GREATER
CONFIDENCE IN WIND AND FLASH FLOOD RISKS MAXIMIZING LATE
SATURDAY INTO EARLY SUNDAY.
KEY MESSAGES
1) THE NEXT THUNDERSTORM CLUSTER IS FAVORED TO CROSS LATE
SATURDAY NIGHT INTO SUNDAY MORNING, POSING A FLASH FLOOD AND
LIMITED WIND THREAT.
2) VARYING STORM AND HAZARDOUS WEATHER RISKS FOR SUNDAY
AFTERNOON/EVENING.
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...
A THUNDERSTORM CLUSTER IS EXPECTED TO DEVELOP NEAR NORTHERN IL
TONIGHT INTO SATURDAY MORNING THAT WILL EVENTUALLY TRAVEL ESE
THROUGH THE LOWER GREAT LAKES IN CONJUNCTION WITH A MID-LEVEL
SHORTWAVE. 12Z GUIDANCE APPEARS TO BE COALESCING AROUND A LATE
SATURDAY NIGHT INTO SUNDAY MORNING TIMEFRAME FOR THIS SYSTEM IN
THE UPPER OHIO RIVER VALLEY, THOUGH VARIATIONS IN PATH RANGING
FROM SOUTHERN OH/CENTRAL WV TO NORTHEAST OH/NORTHWEST PA REMAIN.
ANY SEVERE RISKS ASSOCIATED WITH DAMAGING WIND RESIDE IN AN
EARLIER ARRIVAL (SAT AFTN/EVE) THAT SEES THE MCS DRIVING SE
THROUGH THE FAR EASTERN OH ZONES (MUSKINGUM/COSHOCTON COUNTIES)
ALONG THE CAPE GRADIENT. GIVEN WHERE LATEST TRENDS ARE HEADING,
THIS RISK APPEARS INCREASINGLY UNLIKELY, ESPECIALLY WITH A
POTENTIALLY STABLE ENVIRONMENT IN PLACE IF IT ARRIVES LATER IN
THE NIGHT. MORE LIKELY, THE HAZARDOUS WEATHER RISK WILL BE
FLASH FLOODING AS STRONG WARM/MOIST ADVECTION (WHICH IS
PARTIALLY RESPONSIBLE FOR ITS EASTWARD DRIVE) PUSHES PWAT VALUES
NEAR OR EVEN EXCEEDING THE 99TH PERCENTILE. COMBINED WITH WARM-
RAIN PROCESSES AND STRONG ASCENT, RAINFALL RATES OF 1-2" MAY BE
COMMON (AND POTENTIALLY EXCEEDED) THAT COULD RESULT IN FLASH
FLOODING, ESPECIALLY ON SATURATED GROUNDS. THE POTENTIAL LACK OF
NOTABLE ELEVATED BUOYANCY AND FASTER STORM MOTION (MORE ON THE
25-35KTS REALM) COULD LIMIT RAINFALL DURATION TO JUST STAY UNDER
FFG AMOUNTS. AS MENTIONED, FAVORED LOCATIONS AND TIMING REMAIN
VARIABLE ENOUGH TO PRECLUDE FLOOD WATCH AT THIS TIME, BUT COULD
BE NEEDED IF CONFIDENCE INCREASES.
KEY MESSAGE 2...
STABLE AIR DEVELOPS IN THE WAKE OF THE MORNING MCS SUNDAY THAT
COULD GENERALLY LAST MOST OF THE DAY AND LIMIT ANY ACTIVITY IN
THE AFTERNOON/EVENING TO SPOTTY, SUB-SEVERE COVERAGE.
HOWEVER, THERE REMAINS A LOW PROBABILITY THAT ENOUGH CLEARING
OCCURS IN THE WAKE FOR AFTERNOON DESTABILIZATION RESULTING IN
SBCAPE VALUES RISING TO 1000-1800 J/KG IN A 25-30KT SHEARED
ENVIRONMENT. IF THERE IS ENOUGH LIFT IN THE LINGERING NW FLOW, A
FEW INSTANCES OF SEVERE STORMS WITH DAMAGING WIND CAN'T BE RULED
OUT ALONG WITH NON-ZERO FLOOD RISKS WHERE RAIN PREVIOUSLY FELL.
KEY MESSAGE 3...
SCATTERED SHOWERS AND LOW PROBABILITY THUNDERSTORMS MAY LINGER
WITHIN THE INCREASINGLY STABILIZING ENVIRONMENT SUNDAY NIGHT
INTO MONDAY. HOWEVER, HIGH PRESSURE BUILDING IN FROM THE WEST
UNDER DRIER NW FLOW FAVORS A DRYING TREND IN STORM ACTIVITY BY
MONDAY EVENING THAT LASTS GENERALLY TIL WEDNESDAY.
THOUGH TIMING CAN CHANGE, THE NEXT SYSTEM FEATURING
SHOWER/THUNDERSTORM CHANCES FAVORS THE MID TO LATTER WEEK PERIOD
NEXT WEEK.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
PERIODS OF MVFR IN AND IMMEDIATELY BEHIND RAIN SHOWERS ARE
EXPECTED TO CONTINUE THIS AFTERNOON FOR MOST PORTS, SAVE PERHAPS
DUJ, FKL, AND BVI.
THIS RAIN WILL DEPART TO THE EAST THIS AFTERNOON WITH HIGH
CONFIDENCE IN CLEARING TO VFR LATE TODAY INTO EARLY TONIGHT. FOG
DEVELOPMENT IS FAVORED FOR AREAS THAT SEE THE HEAVIEST RAIN
TODAY (HLG, ZZV, MGW) OVERNIGHT AND FOR USUAL SUSPECTS
(DUJ/FKL). FOG IS GENERALLY LOW CONFIDENCE ELSEWHERE. FOG COULD
BE DENSE AT TIMES, MOST LIKELY DURING THE PRE-DAWN HOURS.
IMPROVEMENT TO VFR IS FORECAST INTO THE DAY SATURDAY.
OUTLOOK...
DRIER WEATHER IS FAVORED ON SATURDAY FOLLOWED BY THE NEXT
SYSTEM CROSSING THE REGION SATURDAY NIGHT INTO SUNDAY WITH MORE
SHOWERS, THUNDERSTORMS, AND RESTRICTION CHANCES.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER
AVIATION...MILCAREK
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