043
FXUS61 KPBZ 012354
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
754 PM EDT SAT AUG 1 2026
WHAT HAS CHANGED
CONFIDENCE OF RAINFALL AMOUNTS EXCEEDING MORE THAN TWO OR THREE
INCHES HAS INCREASED, THUS INCREASING THE POTENTIAL FOR HIGH
WATER SOMEWHERE SUNDAY AFTERNOON. NO OTHER SIGNIFICANT CHANGES
THIS FORECAST CYCLE.
KEY MESSAGES
1) POTENTIAL FOR HIGH WATER AND ISOLATED SEVERE STORMS SUNDAY
2) UNSETTLED WEATHER FOR MOST OF NEXT WEEK, BUT NO WASHOUTS
DISCUSSION
KEY MESSAGE 1...
NOT A LOT OF CHANGE IN THE FORECAST EVOLUTION FOR SUNDAY WITH
THE LATEST MODEL SUITE. IT APPEARS THAT FLASH FLOODING WOULD GET
THE NOD OVER SEVERE WEATHER IF YOU HAD TO PUT THE THREATS IN
ORDER.
FLASH FLOODING:
A PLUME OF HIGH PWATS (IN EXCESS OF 2.00") WILL OVERSPREAD MOST
OF THE REGION SUNDAY WITH HIGH CONFIDENCE. MEANWHILE, THE
VERTICALLY STACKED CYCLONE ALLOWS SOUTHERLY WIND FLOW TO BECOME
PARALLEL TO THE BAROCLINIC ZONE, SETTING THE STAGE FOR TRAINING.
HREF 95TH PERCENTILE PRECIP FEATURES POCKETS OF OVER 4" ACROSS
PARTS OF NORTHWEST PA, WHILE LPMM HAS SEVERAL POCKETS OF 3". WE
CAN'T TAKE THE LOCATIONS LOCK STEP, BUT THIS DOES HIGHLIGHT THE
POTENTIAL TO SEE A 10-20 YEAR RAINFALL RETURN INTERVAL.
PROBABILITY OF 3" OR MORE OF RAIN IN 24H FROM THE HREF WITH A
25-KM NEIGHBORHOOD RADIUS FEATURES SEVERAL RELATIVE MAXIMA,
INCLUDING ALONG AN AXIS FROM YNG-FKL (WHERE EXCEEDANCE PROBS OF
60-70% ARE NOTED) AND FROM MGW-AOO (WHERE 60-80% EXCEEDANCE
PROBS ARE NOTED). ALL THIS SAID, WE MAY NEED TO HOIST A SHORT-
FUSE FLOOD WATCH AS THIS EVENT UNFOLDS. THE AREA OF MOST CONCERN
WOULD BE NORTHWESTERN PA GIVEN PAINTBALL PLOTS OF HIGHEST QPF.
THERE WILL BE UPPER-LEVEL SUPPORT THROUGH AGEOSTROPHIC WIND
DIVERGENCE AT H2 THANKS TO FAVORABLE JET LOCATION. IT WILL BE AN
EFFICIENT RAIN PROCESS WITH WARM CLOUD DEPTHS OVER 11-12KFT.
INTERESTINGLY ENOUGH, THE PROBABILITY OF 1" PER HOUR RAIN RATES
ARE LOW, WHICH SUGGESTS REPEATED ROUNDS OF STORMS COULD LEAD TO
STREAMS COMING OUT OF THEIR BANKS AND/OR ROAD CLOSURES. WITH
THE DRY RUN RECENTLY, FLASH FLOOD GUIDANCE FOR THREE HOURS IS
RUNNING AROUND 2.00" WHILE THE URBAN GUIDANCE OF 0.75" IN ONE
HOUR REMAINS THE SAME.
SEVERE THUNDERSTORMS:
THE TRENDS CONTINUES TOWARD A LESS-FAVORABLE SHEAR PROFILE FOR
POTENTIAL WEAK TORNADOES GIVEN STRAIGHT-LINE HODOGRAPHS AND SRH
VALUES. FRIDAY IT WAS BECAUSE OF A VEER-BACK-VEER SETUP AND
SUNDAY WILL REFLECT WEAKER SPEED SHEAR. NONETHELESS, A DAMAGING
WIND THREAT DOES EXIST GIVEN 30-35 KNOTS OF DEEP-LAYER SHEAR AND
MLCAPE AROUND 1000 J/KG. THE COVERAGE/INTENSITY OF STORMS
DEPENDS ON HOW MUCH DIURNAL HEATING WE OBSERVE TOMORROW. LOOKING
UPSTREAM OVER PARTS OF IND AD KY WHERE THE DRY SLOT IS ALLOWING
FOR BREAKS IN THE CLOUDS, EXTRAPOLATION BRINGS THAT ACROSS
EASTERN OHIO AND POSSIBLY INTO NORTHERN WV AND WESTERN PA SUNDAY
AFTERNOON. THIS WOULD CREATE SUFFICIENT HEATING TO FIRE OFF
STORMS THAT COULD KNOCK DOWN TREES AND WIRES. THE WAY THE CAMS
ARE PLAYING THINGS, I COULD SEE A SCENARIO WHERE THE SEVERE
THUNDERSTORM POTENTIAL RESIDES OVER OUR OHIO COUNTIES AND THE
EXCESSIVE RAIN THREAT STAYS IN NORTHWEST PA. EITHER WAY, THERE
WILL BE A BREAK BETWEEN SHOWERS OVERNIGHT AND THE STORMS SUNDAY
AFTERNOON. THE LONGER THE BREAK AND MORE SUNSHINE WE SEE, THE
HIGHER CHANCE OF STORMS, SOME OF WHICH COULD BE SEVERE.
MACHINE LEARNING IS MOSTLY IN LINE WITH SPC WITH NADOCAST
PUTTING A 15% CHANCE OF SEVERE WIND OVER WESTERN PA AND THE
NORTHERN WV PANHANDLE. DEPENDING ON THE HOW MUCH WE CLEAR OUT
AND HOW LONG GOES A LONG WAY TO PUTTING THE PIECES OF THIS
ATMOSPHERIC PUZZLE TOGETHER.
KEY MESSAGE 2...
THE SLOW-MOVING UPPER-LEVEL LOW FINALLY KICKS OUT OF HERE MID
WEEK, HOWEVER BROAD TROUGHING OVER THE GREAT LAKES QUICKLY
ESTABLISHES. THIS SPELLS A FORECAST WITH A CONTINUED CHANCE OF
SHOWERS AND THUNDERSTORMS EVERY DAY NEXT WEEK. THE TIME WINDOW
WHEN THEY ARE MOST LIKELY TO HAPPEN IS DURING PEAK HEATING
HOURS. AS STATED IN THE KEY MESSAGES ABOVE, NO ALL-DAY RAINS
ARE FORECAST, AND SOME LOCATIONS MAY NOT SEE A DROP ALL WEEK.
THERE WILL BE PERIODS OF SUNSHINE AS WELL, SO DON'T PUT AWAY THE
SUNGLASSES JUST BECAUSE YOU SEE A CHANCE OF RAIN IN THE
FORECAST.
TEMPERATURES WILL BE ABOVE AVERAGE ALL WEEK AS HUMIDITY RETURNS.
DAYTIME HIGHS WILL BE WIDESPREAD IN THE 80S WITH SOME
COMMUNITIES HITTING 90F IN WEST VIRGINIA AND EASTERN OHIO.
OVERNIGHT LOWS WON'T GET BELOW 65 UNLESS YOU RESIDE NORTH OF I80
OR IN THE MOUNTAINS OF SOUTHWESTERN PA AND NORTHERN WV. AS OF
NOW, NO ORGANIZED SEVERE WEATHER IS EXPECTED.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THE FORECAST FOR THE NEXT 24 HOURS HAS GAINED A SLIGHT BIT OF
CLARITY LATELY.
ONGOING LIGHT RAIN SHOWERS FROM HIGH-BASED CLOUDS ARE CONTINUING
TO WEAKEN AND ERODE, WHICH WILL PRESERVE VFR CONDITIONS AT ALL
SITES THRU THE NEXT SEVERAL HOURS.
DEEPER CONVECTIVE ELEMENTS ARE LIKELY TO DEVELOP LATE TONIGHT AS
WARM ADVECTION OVERSPREADS THE UPPER OH VALLEY. THIS CONVECTION
WILL BLOSSOM AFTER 04Z NEAR ZZV, AND IN THE 06-12Z PERIOD AT
MOST OTHER TERMINALS. TSRA REMAINS LESS CERTAIN, BUT WARM-RAIN
PROCESSES WILL SUPPORT LIGHT-OCCASIONALLY MODERATE RAIN RATES
FROM EPISODIC SHOWERS DURING THIS TIME.
SEVERAL WAVES OF RAIN MAY AFFECT TERMINALS ALONG AN AXIS FROM
MGW-AGC/LBE-DUJ DURING SUN MORNING, BUT AN EVENTUAL BREAK IN
SHOWERS IS APPEARING INCREASINGLY LIKELY FOR AT LEAST A FEW
HOURS MID-/LATE-MORNING TO VERY EARLY AFTERNOON.
INCREASINGLY VIGOROUS STORMS ARE POSSIBLE AT MOST TERMINALS
DURING SUN AFTERNOON, ALTHOUGH PRECISE TIMING AT THE MOMENT IS
STILL UNCLEAR, AND DEPENDENT ON DEGREE OF HEATING IN THE WAKE OF
MORNING SHOWERS. THE TAFS REFLECT THE BEST GUESS AT TIMING THE
AFTERNOON STORM POTENTIAL, BUT LIKELY WILL BE BETTER REFINED AS
THE TIME NEARS.
ALTHOUGH IT IS BEYOND THE TAF PERIOD, OVERNIGHT FOG WITH VSBY
RESTRICTIONS SEEMS LIKELY IN THE WAKE OF SUN AFTERNOON STORMS,
AS IS TYPICAL FOLLOWING HEAVY RAIN.
OUTLOOK...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE,
ESPECIALLY DURING THE AFTERNOON AND EVENING, THROUGH MID-WEEK
AS AN UPPER TROUGH LINGERS ACROSS THE UPPER OHIO VALLEY REGION.
IN ADDITION, EARLY MORNING FOG AND STRATUS WILL BE POSSIBLE
WITH LOW-LEVEL MOISTURE IN PLACE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...KRAMAR/MCMULLEN
AVIATION...KRAMAR/MLB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page