385
FXUS61 KPBZ 231747
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
147 PM EDT THU APR 23 2026
WHAT HAS CHANGED
THERE HAS BEEN A SLIGHT NORTHWARD TREND IN POTENTIAL FOR
ISOLATED SHOWERS/STORMS THIS AFTERNOON AND EVENING, WITH
SLIGHTLY HIGHER CHANCES IN PITTSBURGH. THE TREND WITH A FASTER
FRONTAL PASSAGE ON SATURDAY CONTINUES AS WELL.
KEY MESSAGES
1) ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS THIS
AFTERNOON/EVENING, MAINLY NEAR AND SOUTH OF PITTSBURGH.
2) INCREASING SHOWER AND THUNDERSTORM CHANCES FRIDAY INTO
SATURDAY
3) WIDESPREAD SHOWER AND THUNDERSTORM CHANCES AGAIN EARLY NEXT
WEEK
DISCUSSION
KEY MESSAGE 1...
A QUASI-STATIONARY BOUNDARY REMAINS HUNG UP JUST SOUTH OF I-80,
VISIBLE IN THE DEWPOINT FIELD (40S TO THE NORTH, 50S+ TO THE SOUTH).
ALTHOUGH THERE MAY BE A SLIGHT SOUTHWARD JOG TODAY, LITTLE OVERALL
MOVEMENT IS EXPECTED GIVEN THE NORTHWEST MID-LEVEL FLOW PARALLEL TO
THE FRONT. SOME MODEST INSTABILITY SHOULD BUILD SOUTH OF THE
BOUNDARY THIS AFTERNOON, TO THE TUNE OF 500-1000 J/KG OF SBCAPE VIA
HREF. THIS FIELD MATCHES WITH THE EARLIER IDEA OF A FAVORABLE ZONE
SOUTH OF A BVI/AGC/LBE LINE, AND THIS IDEA STILL SEEMS REASONABLE,
WITH WARM AIR ALOFT MORE LIKELY TO SUPPRESS DEVELOPMENT TO THE
NORTH. CAMS HAVE BEEN SHOWING A SLIGHT NORTHWARD TREND WITH THE
ZONE OF FAVORABLE DEVELOPMENT. THIS SEEMS REASONABLE GIVEN THE
BOUNDARY POSITION AND THE CAPE GRADIENT, AND THUS HAVE NUDGED
15+ POPS A BIT NORTHWARD, TO INCLUDE PITTSBURGH. SHEAR/LAPSE
RATES ARE STILL TOO WEAK TO SUPPORT ANY SEVERE THREAT, AND
PRECIPITABLE WATER VALUES REMAIN BELOW AN INCH, SUGGESTING THAT
EXCESSIVE RAINFALL SHOULD NOT BE AN ISSUE. STILL, BRIEF
DOWNPOURS AND SOME CLOUD-TO-GROUND LIGHTNING HITS REMAIN A
POSSIBILITY, AND CANNOT BE TOTALLY RULED OUT NEAR THE CITY OF
PITTSBURGH DURING THE EVENING. ANY ACTIVITY WILL FADE BY
MIDNIGHT AS INSTABILITY IS DIURNALLY LOST.
KEY MESSAGE 2...
THE STALLED SURFACE BOUNDARY SHOULD RETURN NORTH AS A WARM FRONT
THROUGH THE DAY ON FRIDAY, WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING ALONG AND AHEAD OF IT. BEST COVERAGE
APPEARS TO BE NORTH OF PITTSBURGH, WITH THE SURFACE BOUNDARY
PROVIDING A SOURCE OF LIFT. AN ISOLATED SHOWER/STORM CANNOT BE
TOTALLY RULED OUT IN THE WARM SECTOR, BUT CAPPING IS MORE LIKELY
TO THE SOUTH, LIMITING POTENTIAL COVERAGE. SEVERE RISK AGAIN
APPEARS LOW, SUPPORTED BY CSU/NCEP MACHINE LEARNING GUIDANCE.
A SHORTWAVE TROUGH, AND ASSOCIATED SURFACE LOW AND COLD FRONT,
ARE EXPECTED TO TRACK EAST ACROSS THE UPPER OHIO VALLEY REGION
FRIDAY NIGHT INTO SATURDAY, WITH SHOWERS AND ISOLATED EMBEDDED
THUNDERSTORMS EXPECTED. THE MODELS CONTINUE TO INDICATE A FASTER
FROPA OVERALL, TAKING IT EAST OF THE RIDGES SATURDAY MORNING.
HOWEVER, A LAGGING SHORTWAVE TROUGH AHEAD OF MIDDLE OHIO VALLEY
RIDGING COULD KEEP SOME SHOWER ACTIVITY GOING AT LEAST THROUGH THE
AFTERNOON HOURS, WITH ACTIVITY PULLING EAST BY SATURDAY NIGHT.
GENERALLY FOLLOWED NBM POP SUGGESTIONS FOR NOW, BUT A FASTER END TO
PRECIPITATION MAY BE NEEDED IF MODEL TRENDS CONTINUE.
KEY MESSAGE 3...
RIDGING SHOULD RETURN DRY WEATHER TO THE REGION SUNDAY INTO
MONDAY. MODEL ENSEMBLES INDICATE A SHORTWAVE TROUGH AND SURFACE
COLD FRONT RETURNING LATER MONDAY INTO TUESDAY, WITH SHOWERS AND
POSSIBLE THUNDERSTORMS RETURNING TO THE FORECAST, WITH AT LEAST
SOME POTENTIAL FOR STRONGER STORMS.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
THERE IS A SURFACE BOUNDARY CURRENTLY LOCATED ALONG THE MASON DIXON
LINE AND EXTENDING WEST TO MUSKINGUM COUNTY. THIS IS FORECAST TO
MOVE NORTHEAST THIS AFTERNOON. ENSEMBLES ARE INDICATING SOMEWHAT DRY
CONDITIONS (RELATIVE HUMIDITY BETWEEN 40%-50%) AND WEAK WIND SHEAR.
EVEN THOUGH THERE IS A BOUNDARY MOVING THROUGH THE AREA, IT WILL
ONLY PROVIDE WEAK FORCING.
OVERALL, THERE IS A LOW PROBABILITY THAT IT WILL PRODUCE SOME
POP-UP SHOWERS AND THUNDERSTORMS. AS A RESULT, THERE ARE NO
MENTION OF SHOWERS/STORMS IN THE TAFS. IF INSTABILITY WERE TO
OVER PERFORM THAN HLG, BVI, PIT, AND AGC WOULD BE THE BEST
LOCATIONS TO GET SHOWER ACTIVITY.
TONIGHT, WIND WILL REMAIN LIGHT AND VARIABLE. TOMORROW MORNING
AROUND SUNRISE, THERE IS A BRIEF CHANCE FOR SOME LOW-LEVEL WIND
SHEAR AT BVI, PIT, AND AGC. DURING THE DAY TOMORROW, VFR CONDITIONS
WILL PREVAIL AS WINDS WILL BE SOUTHWESTERLY AROUND 5-10 KNOTS.
OUTLOOK...
ANOTHER COLD FRONT BRINGS RAIN CHANCES AND RESTRICTIONS BACK TO
THE AREA LATE FRIDAY NIGHT INTO THE WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM/CL
AVIATION...LUPO
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