238
FXUS61 KPBZ 211759
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
159 PM EDT MON SEP 21 2026
WHAT HAS CHANGED
A LARGE PORTION OF THE FLOOD WATCH WAS EXTENDED THROUGH 8 AM
WEDNESDAY, AS POTENTIAL REMAINS FOR ANOTHER ROUND OR TWO OF
HEAVIER RAIN NEAR AND SOUTH/EAST OF PITTSBURGH THROUGH TUESDAY
NIGHT.
KEY MESSAGES
1) RAIN CHANCES CONTINUE MUCH OF THIS WEEK. LONGER DURATION
RAINFALL TOTALS COULD BE HIGH AND LEAD TO LOCALIZED FLOODING
AND/OR RIVER RISES INTO WEDNESDAY MORNING.
2) BELOW-NORMAL TEMPERATURES LINGER THROUGH MUCH OF THE WEEK.
DISCUSSION
KEY MESSAGE 1...
GENERALLY LIGHT RAIN CONTINUES NEAR/NORTH OF PITTSBURGH THIS
AFTERNOON IN A GENERAL OVERRUNNING PATTERN. A BIT HEAVIER
ACTIVITY IS FOCUSED SOUTH OF I-70 WHERE PRECIPITABLE WATER
VALUES REMAIN A BIT MORE ELEVATED, IN THE 1.6 TO 1.8 INCH RANGE.
RAIN RATES ARE MOSTLY BEING HELD IN CHECK BY THE NEAR TOTAL
LACK OF SBCAPE/MLCAPE NORTH OF THE MASON-DIXON LINE, AND MID-
LEVEL FLOW IS ALSO SUFFICIENT TO KEEP ANY HEAVIER SHOWERS MOVING
AT PRESENT. CAMS SUGGEST A BIT MORE FOCUSED RAIN NORTH OF
PITTSBURGH DURING THE LATE AFTERNOON/EVENING IN LOW-LEVEL
CONVERGENT FLOW. GIVEN THE LOWER PRECIPITABLE WATER IN THIS
AREA AND SPOTTIER NATURE OF THE HEAVY RAINFALL TOTALS IN THIS
AREA, NOT CURRENTLY EXPECTING THIS RAIN TO CAUSE A FLOODING
CONCERN, BUT THE AREA WILL BE MONITORED.
LATER THIS EVENING AND INTO THE OVERNIGHT PERIOD, A WAVE OF LOW
PRESSURE RIDING ALONG THE MAIN FRONTAL BOUNDARY JUST TO OUR
SOUTH WILL REINVIGORATE SHOWERS ESPECIALLY TO THE SOUTH AND EAST
OF PITTSBURGH IN THE HIGHER TERRAIN, AND PERHAPS EVEN A
THUNDERSTORM OR TWO IN NORTHERN WEST VIRGINIA WITH FUMES OF
MUCAPE. PRECIPITABLE WATER REMAINING ABOVE 1.5 INCHES AND DECENT
WARM-CLOUD DEPTHS OF 10-11KFT WILL CONTINUE TO SUPPORT EFFICIENT
RAIN RATES. WHILE A BRIEF LULL IS POSSIBLE LATE TONIGHT INTO
TUESDAY MORNING, ADDITIONAL ROUNDS OF SHOWERS ARE LIKELY RIGHT
ON THROUGH TUESDAY NIGHT AND INTO WEDNESDAY AT LEAST, AS AN
UPPER TROUGH SLOWLY DIGS TOWARD THE REGION FROM THE UPPER
MIDWEST AND POTENTIALLY CLOSES INTO AN UPPER LOW WEDNESDAY NIGHT
OR THURSDAY MORNING IN OUR GENERAL VICINITY.
24-HOUR HREF MEAN PRECIPITATION TOTALS FROM 8 PM TONIGHT THROUGH
8 PM TUESDAY GENERALLY RANGE FROM 1 TO 1.25 INCHES DOWN THE
SPINE OF THE RIDGES AND THROUGH MORGANTOWN. 90TH PERCENTILE
TOTALS ARE MOSTLY BETWEEN 1.5 AND 2.5 INCHES, WITH A FEW 3+
BULLSEYES ILLUSTRATING THE LOCALIZED HIGH RAINFALL POTENTIAL.
THE PROBABILITY OF 1"+ HOURLY RATES ON THE HREF THROUGH THE
PERIOD IS QUITE LOW, BUT THINK THIS MAY BE A BIT UNDERDONE,
ESPECIALLY INTO TUESDAY MORNING, GIVEN THE CONVERGENCE POTENTIAL
IN THE TERRAIN AND THE STILL-HIGH PWAT. MUCH OF THIS AREA IS
ALREADY QUITE WET, WITH 1-HOUR FLASH FLOOD GUIDANCE VALUES
AROUND OR JUST BELOW AN INCH. WHILE THE FLASH FLOODING THREAT
OVERALL MAY BE DECREASING ESPECIALLY AFTER TONIGHT,
OVERFLOW/AREAL FLOODING THREATS REMAIN. THUS, ELECTED TO EXTEND
A GOOD PORTION OF THE FLOOD WATCH THROUGH 12Z WEDNESDAY.
COUNTIES WEST OF PIT/HLG WERE ALLOWED TO DROP, AS THESE AREAS
ARE EXPECTED TO AVOID THE HIGHER RAIN RATES/OVERALL PRECIP
TOTALS.
SUPPORT FOR RAIN CONTINUES THROUGH WEDNESDAY AND INTO THURSDAY
AS THE UPPER LOW DEVELOPS, WITH HIGHER TOTALS BACKING A BIT INTO
EASTERN OHIO - 0.50" TO 1.0 MEAN 24 HOUR TOTALS THROUGH 8 PM
WEDNESDAY ACCORDING TO THE NBM. WE WON'T LOSE THE SUPPORT FOR
CONTINUED RAIN UNTIL LIKELY THURSDAY WHEN THE UPPER LOW EXITS
AND SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND ESTABLISHES
AND KICKS THE SURFACE BOUNDARY OUT. THERE IS STILL HOPE FOR A
DRIER PATTERN FOR FRIDAY AND NEXT WEEKEND.
KEY MESSAGE 2...
COOL TEMPERATURES ARE STILL FIGURED FOR MUCH OF THE WEEK. MUCH
OF SOUTHWEST PA/EASTERN OHIO NORTH OF THE SURFACE BOUNDARY HAS
SUNK INTO THE 50S TODAY, WHILE 60S ARE MAINTAINED SOUTH OF I-70.
GIVEN THE ABUNDANT CLOUD COVER AND STUBBORN EAST/NORTHEAST FLOW,
HIGHER RIDGE LOCATIONS MAY HAVE TROUBLE REACHING 60 DEGREES
TUESDAY THROUGH THURSDAY. LOWER AND MID 60S ARE STILL FIGURED
WEST OF THE TERRAIN, ALTHOUGH LOWER VALUES MAY AGAIN BE POSSIBLE
IN RAIN-COOLED AIR. MINIMUM TEMPERATURES WILL REMAIN FAIRLY
CLOSE TO NORMAL GIVEN ABUNDANT MOISTURE, BUT DAYTIME HIGHS ARE
STILL FIGURED TO RUN 10 DEGREES BELOW NORMAL THROUGH THURSDAY.
AVIATION /18Z MONDAY THROUGH SATURDAY/
SCATTERED RAIN SHOWERS LIKELY INTO THE EARLY EVENING WITH MVFR/IFR
CIGS/VIS EXPECTED DUE TO THE COPIOUS MOISTURE IN THE LOW-
LEVELS. FKL AND DUJ SHOULD SEE A LIGHT SHOWER BUT OTHERWISE
REMAIN VFR WITH A BKN TO OVC MID-LEVEL DECK. AN EASTERLY WIND
ESTABLISHES THIS AFTERNOON AROUND 10 KNOTS GUSTING TO 15-20
KNOTS AT TIMES.
ANOTHER PUSH OF RAIN AND EMBEDDED THUNDERSTORMS ARRIVES AFTER
SUNSET TONIGHT MAINLY FOR WESTERN PA AND NORTHERN WV. CEILINGS
WILL DROP REGION-WIDE AFTER MIDNIGHT. RESTRICTIONS WILL CONTINUE
INTO TUESDAY WITH ADDITIONAL CHANCES OF RAIN AND THE LINGERING
LOW-LEVEL MOISTURE.
OUTLOOK...
RESTRICTION CHANCES LINGERING THROUGH AT LEAST WEDNESDAY WITH
PLENTY OF MOISTURE AND ON-AND-OFF RAIN CHANCES.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR PAZ021-029-031-
073>076.
OH...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR OHZ059-068-069.
WV...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR WVZ002>004-012-021-
509>514.
DISCUSSION...CL
AVIATION...LUPO
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