681
FXUS61 KPBZ 210239 AAA
AFDPBZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
1039 PM EDT WED MAY 20 2026
WHAT HAS CHANGED
THUNDERSTORM THREAT HAS DIMINISHED ACROSS NRN WV. CONFIDENCE
CONTINUES TO INCREASE FOR A WET MEMORIAL DAY WEEKEND.
KEY MESSAGES
1) POST FRONTAL RAIN TONIGHT
2) CONFIDENCE IN SOAKING RAINFALL DURING THE MEMORIAL DAY
WEEKEND CONTINUES TO INCREASE
DISCUSSION
KEY MESSAGE 1...
A SHORTWAVE TRACKING NORTH OF AN EXITING COLD FRONT WILL RESULT
IN AREAS OF LIGHT RAIN ACROSS THE REGION TONIGHT. INSTABILITY
ACROSS NRN WV HAS DIMINISHED BEHIND THE FRONT, SO REMOVED THE
MENTION OF THUNDER FROM THE FORECAST. LOWS TONIGHT ARE EXPECTED
TO BE CLOSER TO AVERAGE FOR THIS TIME OF THE YEAR.
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 /02Z THURSDAY THROUGH MONDAY/
THE COLD FRONT HAS NEARLY EXITED THE AREA TO THE SOUTH TO START
THE TAF PERIOD, WITH THE ONLY LINGERING CONVECTIVE SHOWERS
OCCURRING OVER PORTIONS OF NORTHERN WV NEAR THE HIGHER TERRAIN.
FARTHER NORTH, LIGHT STRATIFORM RAIN AND DRIZZLE LINGERS FOR THE
NEXT FEW HOURS BEFORE DISSIPATING AND SHIFTING SOUTH AS WELL.
CEILINGS ARE PREDOMINANTLY MVFR ACROSS MUCH OF THE AREA, WITH
THE EXCEPTIONS BEING VFR NORTH OF I-80 (FKL/DUJ) AND IFR IN
NORTHERN WV AT MGW. THESE GENERALLY REMAIN UNCHANGED OVER THE
NEXT FEW HOURS.
GRADUAL IMPROVEMENT TO HIGHER-END MVFR AND THEN VFR IS EXPECTED
AT BVI, ZZV, AND PIT/AGC BY EARLY THURSDAY MORNING AS LOW
CEILINGS SHIFT SOUTH WITH THE FRONT. THE FRONT IS FORECAST TO
STALL ACROSS CENTRAL OR NORTHERN WV, ALLOWING MVFR CEILINGS TO
CONTINUE GENERALLY ALONG AND SOUTH OF THE I-70 CORRIDOR INTO
THURSDAY. IMPROVEMENT TO VFR IS MOST LIKELY AT HLG BY LATE
THURSDAY MORNING, BUT LBE AND MGW MAY REMAIN SOCKED IN UNTIL
LATER IN THE DAY OR POTENTIALLY EVEN THROUGH THE 24-HOUR TAF.
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...WM/CL/LUPO
AVIATION...CERMAK/HEFFERAN
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