467
FXUS61 KPBZ 201740
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
140 PM EDT WED MAY 20 2026
WHAT HAS CHANGED
LOCALIZED AREAS OF HEAVY RAIN POSSIBLE IN NORTHERN WEST
VIRGINIA THIS AFTERNOON AND EVENING. CONFIDENCE CONTINUES TO
INCREASE FOR A WET MEMORIAL DAY WEEKEND.
KEY MESSAGES
1) POTENTIAL FOR ISOLATED THUNDERSTORMS IN NORTHERN WV THROUGH
LATE AFTERNOON. HIGH PRECIPITATION POSSIBLE IN NORTHERN WEST
VIRGINIA, HOWEVER, FLOODING POTENTIAL IS A LOW
2) CONFIDENCE IN SOAKING RAINFALL DURING THE MEMORIAL DAY
WEEKEND CONTINUES TO INCREASE
DISCUSSION
KEY MESSAGE 1...
ONGOING RAIN AND CLOUD COVER LENDS SOME UNCERTAINTY TO THE AMOUNT OF
DESTABILIZATION THAT WILL BE ABLE TO OCCUR OVER OUR SOUTHEASTERN
COUNTIES THIS AFTERNOON. EVEN THOUGH GUIDANCE IS SUGGESTING MODERATE
INSTABILITY, THERE IS WEAK 0-6KM WHICH WILL LIMIT STORM
ORGANIZATION. STILL, THERE MAY BE A RELATIVELY BRIEF WINDOW DURING
THE MID-TO-LATE AFTERNOON FOR TALL STORMS TO TAKE ADVANTAGE OF
MARGINAL DCAPE TO PRODUCE ISOLATED STRONG TO DAMAGING GUSTS. IF
THERE IS HAIL, IT IS LIKELY TO BE SMALL. MOST LIKELY AREA FOR ANY
SEVERE WEATHER WILL BE TUCKER AND SOUTHERN PRESTON COUNTIES. THE
PASSAGE OF THE FRONT SHOULD END ANY SEVERE THREAT BY 00Z.
SOME VERY LOCALIZED INSTANCES OF HEAVY RAINFALL ARE ALSO POSSIBLE
WITH THESE STORMS. CLOUD-LAYER FLOW WILL BE LARGELY PARALLEL TO THE
FRONT, WHICH COULD ENCOURAGE STORM TRAINING. ALSO, EXPECTED
PRECIPITABLE WATER VALUES OF 1.5 TO 1.6 INCHES IS AT THE VERY TOP OF
CLIMATOLOGY. HREF/REFS MAX PRECIP POTENTIAL SUGGEST LOCALIZED 1.5-
1.7 INCH TOTALS ARE NOT OUT OF THE QUESTION IN NORTHERN WEST
VIRGINIA. STILL, 3-HOUR FFG VALUES ARE GENERALLY BETWEEN 1.75 - 2.5
INCHES IN THIS AREA, AND THUS ANYTHING MORE THAN AN ISOLATED WATER
ISSUE OR TWO IS NOT EXPECTED.
KEY MESSAGE 2...
THE FRONT MAY WAVER NEAR THE SOUTHERN REACHES OF THE CWA THROUGH
THURSDAY NIGHT, KEEPING OCCASIONAL RAIN CHANCES IN THE FORECAST,
ESPECIALLY SOUTH OF I-70. THE ENVIRONMENT FAVORABLE FOR STRONG
CONVECTION AND HEAVY RAINFALL WILL HAVE DEPARTED THOUGH, AND NO
MAJOR IMPACT FROM THIS ACTIVITY IS EXPECTED.
MEMORIAL DAY WEEKEND CONTINUES TO LOOK QUITE WET OVERALL. SURFACE
LOW PRESSURE LIFTS NORTHEASTWARD INTO THE LOWER OHIO VALLEY TO OUR
WEST FRIDAY INTO SATURDAY, BRINGING A BOUNDARY NORTH AS A WARM FRONT
PUSHES A BROAD INVERTED TROUGH INTO OUR REGION. THIS SHOULD RETURN
ANOMALOUSLY HIGH PRECIPITABLE WATER VALUES BACK NORTH, ACCOMPANIED
BY BROAD ISENTROPIC LIFT. ALSO DURING THIS TIME, SURFACE HIGH
PRESSURE IS FORECAST TO BE CENTERED OVER THE UPPER GREAT LAKES AND
NEW ENGLAND STATES. THIS SETUP IS SIMILAR TO PAST EVENTS THAT HAVE
GENERATED 2+ INCHES OF RAINFALL ACROSS THE LOCAL AREA, THOUGH IT
SHOULD BE NOTED THAT MINOR DEVIATIONS (E.G., EAST-WEST POSITIONING
OF THE LOW OR STRENGTH OF THE RIDGE) COULD RESULT IN THE AXIS OF
HEAVIEST RAINFALL SHIFTING AROUND (OR AWAY FROM) THE LOCAL AREA.
NEVERTHELESS, THE NBM CONTINUES ILLUSTRATE A 55%-75% CHANCE FOR AT
LEAST AN INCH OF 24-HR RAINFALL ACCUMULATION FRIDAY INTO SATURDAY
(NORTH OF PITTSBURGH), AND A 15%-30% CHANCE FOR 2+ INCHES.
A SECOND WAVE OF RAIN IS THEN FORECAST SUNDAY INTO MONDAY THOUGH
THAT ONE APPEARS A BIT MORE PROGRESSIVE IN NATURE THANKS TO A
POTENTIAL GREAT LAKES SHORTWAVE THAT HAS SOME FORWARD MOMENTUM. NBM
PROBABILITIES FOR AN INCH TOP OUT IN THE 20%-25% RANGE BETWEEN 12Z
SUNDAY AND 12Z MONDAY. WHEN LOOKING AT THE TOTAL 72-HOUR PERIOD FROM
12Z FRIDAY TO 12Z MONDAY, THE NBM HAS A 40%-60% CHANCE FOR 2 INCHES
OR MORE OF RAIN ACROSS THE MAJORITY OF THE FORECAST AREA.
EXTENDED MACHINE-LEARNING GUIDANCE SUGGESTS SEVERE WEATHER CHANCES
REMAIN QUITE LOW THROUGH THE WEEKEND, SO THAT ASPECT IS OF LESSER
CONCERN. HOWEVER, MMEFS RIVER GUIDANCE DOES SUGGEST SOME POTENTIAL
IMPACT ON AREA RIVERS BY EARLY NEXT WEEK IN HIGHER-END PRECIPITATION
SCENARIOS, WITH A NUMBER OF FORECAST POINTS ON THE LARGER RIVERS
POTENTIALLY REACHING ACTION STAGE. THIS ALSO SUGGESTS THAT FLOODING
ISSUES ON SMALLER STREAMS AND CREEKS MAY BECOME AN ISSUE IN TIME. IT
IS TOO EARLY TO DISCUSS SPECIFICS AND FORECAST DETAILS ARE YET TO BE
SOLIDIFIED, BUT THIS SIGNAL WILL WARRANT MONITORING.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO
THE LATE AFTERNOON WITH THE PASSAGE OF A COLD FRONT. EXPECTED
MVFR TO IFR CIGS AND VIS WITH PASSING LIGHT TO MODERATE SHOWERS.
THE POTENTIAL FOR SEVERE STORMS NEAR A TERMINAL HAS DECREASED
SINCE THE LATE FORECAST UPDATE.
A WIND SHIFT TO THE NW, AND EVENTUALLY N, IS ALSO EXPECTED
AFTER THE PASSAGE OF THE FRONT. SOME IMPROVEMENT BACK TO MVFR IS
EXPECTED BY EVENING, THOUGH A CROSSING WAVE ALONG THE FRONT
COULD SPREAD A FEW MORE SHOWERS ACROSS THE REGION.
RESTRICTIONS WILL LIKELY CONTINUE INTO TONIGHT WITH A STALLED
FRONTAL BOUNDARY. VFR SHOULD RETURN TO MOST AIRPORTS ON
THURSDAY AS HIGH PRESSURE BRIEFLY BUILDS IN FROM THE N, THOUGH
MGW/LBE COULD SEE RESTRICTIONS CONTINUE THROUGH LATE MORNING.
OUTLOOK...
WIDESPREAD RESTRICTIONS IN RAIN ARE EXPECTED TO OVERSPREAD THE
REGION FROM S-N FRIDAY INTO SATURDAY WITH A WARM FRONT. SOME
IMPROVEMENT IS POSSIBLE SUNDAY UNTIL A COLD FRONT APPROACHES
LATER IN THE DAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CL/LUPO
AVIATION...HEFFERAN
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