403
FXUS61 KPBZ 201238
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
838 AM EDT SAT JUN 20 2026
WHAT HAS CHANGED
SCATTERED SHOWERS AND STORMS ARE NOW MOST LIKELY TO OCCUR NORTH
OF PITTSBURGH TODAY, WITH MORE ISOLATED ACTIVITY NEAR AND SOUTH
OF THE CITY. NO MAJOR CHANGES TO THE REST OF THE FORECAST. HIGH
CONFIDENCE IN A SOAKING RAINFALL SUNDAY NIGHT INTO MONDAY
REMAINS.
KEY MESSAGES
1) SCATTERED SHOWERS AND STORMS SATURDAY AFTERNOON
2) MORE WIDESPREAD RAIN CHANCES RETURN SUNDAY NIGHT AND MONDAY.
THERE IS HIGH CONFIDENCE IN A SOAKING RAINFALL, BUT LOW
CONFIDENCE IN THE THREAT OF FLOODING.
DISCUSSION
KEY MESSAGE 1...
TROUGHING LINGERS OVER THE GREAT LAKES/NORTHEAST CONUS TODAY,
WITH A WEAK SHORTWAVE MOVING THROUGH THE WESTERLY MID-LEVEL
FLOW. THIS DISTURBANCE SHOULD WORK WITH A MODEST INCREASE IN
MOISTURE (UP TO 0.8-0.9 INCH PRECIPITABLE WATER) TO SPARK
SCATTERED AFTERNOON SHOWERS AND POTENTIALLY A FEW THUNDERSTORMS,
GENERALLY BETWEEN 17Z AND 00Z. COVERAGE WILL LIKELY BE HIGHER TO
THE NORTH OF PITTSBURGH GIVEN THE SHORTWAVE TRACK AND HREF/CAMS
SUPPORT. MOISTURE PROFILES STILL APPEAR A BIT SHALLOW TO SUPPORT
TALL UPDRAFTS, WITH STORM TOPS LIKELY STRUGGLING TO GET TOO HIGH
ABOVE THE -10C TO -15C RANGE. THIS SHOULD LIMIT THUNDERSTORM
COVERAGE A BIT. SURFACE-BASED CAPE IS MOST LIKELY TO BUILD INTO
THE 500 TO 750 J/KG RANGE THIS AFTERNOON, AND COULD WORK WITH
40-50 KNOTS OF 0-6KM SHEAR TO SUPPORT SOME STORM ORGANIZATION.
IT WOULD LIKELY TAKE CAPE HIGHER THAN THAT (ROUGHLY A 30 PERCENT
CHANCE OF EXCEEDING 750 J/KG) TO SUPPORT A MODEST SEVERE RISK,
WHICH WOULD BE LIMITED TO MARGINAL STRONG TO DAMAGING GUSTS IN
THE WORST CASE.
ANY ACTIVITY WILL END BY SUNSET WITH THE DEPARTURE OF THE
SHORTWAVE AND THE LOSS OF SURFACE HEATING. DRY WEATHER WOULD
THEN FOLLOW FOR SATURDAY NIGHT AND SUNDAY WITH SURFACE HIGH
PRESSURE AND MID-LEVEL RIDGING CROSSING THE OHIO VALLEY.
KEY MESSAGE 2...
THE MID-LEVEL RIDGE AXIS REACHES THE CWA AROUND 00Z MONDAY,
AFTER WHICH MOISTURE SURGES NORTHEASTWARD INTO OUR REGION AHEAD
OF A SURFACE LOW WHICH WILL BE RIDING UP THE OHIO VALLEY.
PRECIPITABLE WATER LIKELY SURGES INTO THE 1.7 TO 1.8 INCH RANGE
BY MONDAY, WHICH REACHES THE 90TH TO 95TH PERCENTILE OF
CLIMATOLOGY. THIS, COUPLED WITH AN EAST-WEST ORIENTED WARM
FRONT ACROSS THE REGION, SUGGESTS ROUNDS OF MODERATE TO HEAVY
SHOWERS AND THUNDERSTORMS ARE LIKELY DURING THE SUNDAY NIGHT TO
MONDAY PERIOD.
NBM PROBABILITIES OF 1.5 INCHES OF RAIN FOR THE 24-HOUR PERIOD
ENDING AT 00Z TUESDAY LIE IN THE 50 TO 80 PERCENT RANGE ACROSS
THE BULK OF THE FORECAST AREA, WITH 2 INCH PROBABILITIES FROM 35
TO 55 PERCENT. ASSUMING THAT THESE TOTALS ARE SPREAD OUT MAINLY
OVER A 12 TO 24 HOUR PERIOD, CURRENT SOIL MOISTURE/FLASH FLOOD
GUIDANCE VALUES SUGGEST THAT MOST AREAS SHOULD BE ABLE TO HANDLE
THIS RAINFALL WITHOUT SIGNIFICANT FLOODING ISSUES, EXCEPT
PERHAPS URBAN/POOR DRAINAGE LOCATIONS. ONCE THE EVENT FULLY
ENTERS THE REALM OF CAMS AND HREF/REFS PROGS, MESOSCALE DETAILS
MAY EMERGE THAT WOULD INDICATE AT LEAST A LOCALIZED HIGHER
THREAT AREA THAT POSSIBLY COULD REQUIRE A FLOOD WATCH - THIS
SEEMS MOST LIKELY TO THE SOUTH OF PITTSBURGH. UNTIL THEN,
CONFIDENCE IN WIDESPREAD IMPACTS REMAINS TOO LOW FOR ISSUANCE.
WILL CONTINUE HWO MENTION.
MACHINE LEARNING OUTPUT INDICATES SOME MODEST POTENTIAL FOR
SEVERE WEATHER, ALTHOUGH HIGHER RISKS REMAIN TO OUR SOUTH, WHERE
AVAILABLE BUOYANCY IS LIKELY TO BE GREATER.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
VFR IS FORECAST THROUGH MOST OF THE TAF PERIOD WITH RELATIVELY
HIGH CONFIDENCE WITH SCATTERED TO LOCALLY BROKEN CUMULUS BY
MIDDAY.
A WEAK SHORTWAVE PASSAGE SHOULD SUPPORT THE DEVELOPMENT OF
SCATTERED SHOWERS AND A FEW THUNDERSTORMS BETWEEN 17Z AND 00Z.
CLOUD TOPS WILL STRUGGLE TO COOL BELOW -10C TO -15C GIVEN
RELATIVELY WEAK BUOYANCY, SO ANY LIGHTNING ACTIVITY SHOULD
REMAIN FAIRLY ISOLATED. HIGHEST CONFIDENCE OF THIS, AS WELL AS
OVERALL PRECIPITATION COVERAGE, LIES AT FKL AND DUJ. TEMPOS FOR
TSRA WERE USED HERE, WHILE OTHER TERMINALS TO THE SOUTH KEEP A
PROB30 MENTION AND CONFIDENCE IN RAIN-INDUCED RESTRICTIONS
REMAINS LOW. ANY ACTIVITY SHOULD END BY SUNSET AS THE SHORTWAVE
DEPARTS, WITH A VFR EVENING.
LIGHT OVERNIGHT WIND WILL KICK UP BY THE LATE MORNING AS MIXING
COMMENCES, WITH SOME GUSTS OF AROUND 20 KNOTS OUT THE WEST
DURING THE AFTERNOON. LOCALIZED AREAS OF FOG OR LOWER STRATUS
MAY DEVELOP SUNDAY MORNING AS WINDS CALM AND CLOUDS CLEAR.
OUTLOOK...
PROBABILITIES FAVOR OVERNIGHT SUNDAY INTO MONDAY FOR WIDESPREAD
SHOWERS (LOW PROBABILITY THUNDERSTORMS) RESULTING IN MVFR/IFR
RESTRICTIONS AS A DEEPER TROUGH/SURFACE LOW COMBO TRAVELS
THROUGH THE OHIO RIVER VALLEY REGION.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CL
AVIATION...CL/LUPO
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