005
FXUS61 KPBZ 222331
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
731 PM EDT SUN MAR 22 2026
WHAT HAS CHANGED
CONFIDENCE IN OCCURRENCE AND TIMING OF SEVERE STORMS REMAIN
SIMILAR TO THE PRIOR UPDATE. MESOSCALE GUIDANCE MAY SLIGHTLY
FAVOR THE HIGHEST CHANCE OF HAIL/WIND IMPACTS IN WESTERN
PENNSYLVANIA.
KEY MESSAGES
1) SEVERE THUNDERSTORMS EXPECTED LATE TODAY. PRIMARY THREAT
REMAINS HAIL (1.5" TO 2.5" POSSIBLE), AND DAMAGING WIND (UP TO
60MPH). MOST LIKELY TIMING FOR IMPACTS IS 3PM TO 10PM. RAIN AND
MARGINAL EXCESSIVE RAINFALL CONCERNS INCREASE OVERNIGHT.
2) QUIET WEATHER THROUGH THURSDAY. STORM CHANCES INCREASE LATE
THURSDAY INTO EARLY FRIDAY.
DISCUSSION
KEY MESSAGE 1...
.. 430 PM UPDATE ..
INITIAL CONVECTION HAS STRUGGLED TO DEVELOP DEEPLY WITH SLIGHT
CAPPING AT AROUND 500MB AS EVIDENCED BY THE 18Z SOUNDING. THIS
HAS PRECLUDED WIDESPREAD SEVERE THUS FAR, THROUGH WE CONTINUE TO
EXPECT INSTANCES TO BECOME MORE NUMEROUS INTO THIS EVENING AS
WET-BULBING FROM CONVECTION SATURATES AND DESTABILIZES THE MID-
LEVELS. THIS HAS PROMPTED THE ISSUANCE/CONTINUATION OF SEVERE
THUNDERSTORM WATCH #72.
WHILE HIGH-END HAIL MAIN BE CURTAILED BY A FAILURE TO SEE MANY
DISCRETE SUPERCELLS, LARGE HAIL REMAINS POSSIBLE (1" TO 2")
WITHIN SOME STORMS BOTH ALONG AND BEHIND THE COLD FRONT.
ALTHOUGH, AREAS BEHIND THE COLD FRONT MAY NOT SEE AS MUCH OF A
WIND THREAT WITH STABILIZATION AT THE LOW LEVELS. WIND AND HAIL
THREATS EXIST IN TANDEM AHEAD OF THE FRONT.
.. PREVIOUS DISCUSSION ..
THE ENVIRONMENT TODAY REMAINS PRIMED FOR SEVERE WEATHER AREA-
WIDE. THE MAIN UNCERTAINTY WILL BE THE COVERAGE OF STORMS, TIED
TO UNCERTAINTIES IN INITIATION WITH PLENTIFUL LOW-LEVEL DRY
AIR.
FIRST, WE WILL ADDRESS THE ENVIRONMENT. THE 12Z SOUNDING SHOWED
A RATHER ATYPICAL SETUP FOR THE NORTHEAST. DRY AIR NEAR THE
SURFACE HAS ALLOWED FOR A RATHER DEEP MIXED LAYER UP TO 600MB.
THIS IS COMMONLY REFERRED TO AS AN INVERTED-V SETUP. +6 HR. SPC
RAP MESOANALYSIS SUGGESTS THAT WITH DIURNAL HEATING INTO THE
DAY TODAY, SOME DECENT INSTABILITY GENERATION REMAINS POSSIBLE
(1000+ J/KG MLCAPE, 1500 TO 2000 J/KG SB/MU CAPE), THOUGH WE WILL
HAVE TO MONITOR CIRRUS BLOW-OFF FROM INITIAL DEVELOPMENT AS A
MODE OF POTENTIALLY LIMITING ADDITIONAL INSTABILITY GENERATION.
SHEAR IS BOUNTIFUL, WITH EFFECTIVE/SFC-6KM VALUES REACHING OR
EVEN EXCEEDING 60 KTS. GIVEN THIS SETUP, ONE WOULD EXPECT THE
POTENTIAL TO ACHIEVE STRONG STORMS. SUPERCELL COMPOSITES POKE
ABOVE 4, WITH NO INHIBITION. GIVEN THESE ENVIRONMENTAL
INGREDIENTS, THE PRIMARY RISK EARLY WILL BE HAIL, WHICH WILL
TRANSITION MORE TO WIND LATER TONIGHT.
INITIAL DEVELOPMENT IS STILL FAVORED ALONG A COLD FRONT BETWEEN
THE 2PM TO 5PM HOURS IN NORTHWEST PA, GIVEN THE FORECAST PUSH OF
DEWPOINTS BACK INTO THE 50S. IF DEWPOINTS DO NOT INCREASE AS
FORECAST, INITIATION MAY BE CHALLENGED INITIALLY. GIVEN THAT
MID- LEVEL FLOW IS MOSTLY BOUNDARY PERPENDICULAR, THESE CELLS
MAY REMAIN DISCRETE INITIALLY. GIVEN THE ENVIRONMENT, HIGH-
BASED SUPERCELLS ARE POSSIBLE. WHILE TRADITIONALLY, SUPERCELLS
ARE FAVORABLE FOR TORNADOES, HIGH-BASED STORMS WOULD NOT WITH
INITIAL CLOUD BASES AS HIGH AS 5KFT TO 10KFT. AS MENTIONED
ABOVE, THE INITIAL THREAT WOULD BE LARGE HAIL (1.5" TO 2.5"
POSSIBLE), THOUGH WIND IS ALSO POSSIBLE GIVEN THE 60KTS OF SHEAR
AND UP TO 600 TO 800 DCAPE.
ONCE INITIATION HAS ESTABLISHED, THERE WILL LIKELY BE LITTLE TO
LIMIT A CONTINUED HAIL/WIND THREAT AS STORMS MATURE AND PERSIST
ACROSS THE CENTER OF THE FORECAST AREA. CAMS HAVE LATCHED ON TO
THE IDEA THAT THE BEST CHANCE OF STORMS WILL FALL ACROSS
SOUTHWEST PA AT THIS TIME (4PM TO 8PM) WITH THE BEST SHEAR
PUSHING THE BOUNDARY STRONGEST. FOR THE LATTER END OF THIS
PERIOD, THERE MAY BE SOME CONGEALING OF DISCRETE ELEMENTS AS
STORMS ARE EXPECTED TO SLOWLY TRANSITION TO MORE OF A WIND
THREAT AFTER SUNSET WHILST PUSHING INTO NORTHERN WEST VIRGINIA
(6PM TO 10PM), AS THE PRESENCE OF LINEAR, SHEAR-DRIVEN SEGMENTS
INCREASES.
OVERNIGHT, A MARGINAL RISK FOR EXCESSIVE RAINFALL PERSISTS, WITH
ANY FLOODING MOST LIKELY SOUTH OF PITTSBURGH AS CONVECTION
CONGEALS AND POTENTIALLY SLOWS, BECOMING MORE BOUNDARY-PARALLEL.
OHRFC FFG MAINTAINS 1" TO 1.5" PER HOUR RATES TO BE CONCERNING,
ALONG WITH 1.5" TO 2.0" IN 3HRS, WITH HREF MAX ALLUDING THESE
THRESHOLDS MAY BE ATTAINED IN ISOLATED INSTANCES, BUT WOULD BE
RELIANT ON MULTIPLE ROUND OF CONVECTION. SHOULD THE COLD FRONT
BE PROGRESSIVE ENOUGH, FLOODING WOULD LIKELY NOT OCCUR.
KEY MESSAGE 2...
BEHIND THE COLD FRONT, TEMPERATURES TUMBLE, WITH HIGHS AS MUCH
AS 10F TO 20F BELOW NORMAL MONDAY. WITH NORTHWEST FLOW OVER THE
LAKES AGAIN, WE WOULD NOT BE SURPRISED TO SEE LAKE EFFECT
SHOWERS (OR EVEN SNOW SHOWERS IN THE COLDEST SCENARIOS).
TEMPERATURES CLIMB WARMER AND BACK ABOVE NORMAL BY WEDNESDAY
WITH MOSTLY DRY CONDITIONS.
BY THURSDAY AFTERNOON, TEMPERATURES MAY BE AS WARM AS 10F TO
20F ABOVE NORMAL AGAIN WITH GUSTY DAYTIME WIND AND INCREASING
CHANCES OR RAIN AS THE NEXT SYSTEM APPROACHED FROM THE NORTHWEST
LATE-DAY. THIS MAY BRING THE NEXT CHANCE OF STORMS AND SEVERE,
ALTHOUGH THIS WILL LARGELY DEPEND ON ARRIVAL TIME (EARLIER
MEANS HIGHER CHANCES OF IMPACTS).
AVIATION /00Z MONDAY THROUGH FRIDAY/
SHOWERS AND THUNDERSTORMS CONTINUE TO AFFECT THE REGION WITH A
CROSSING COLD FRONT. SOME OF THE STORMS CONTINUE TO PRODUCE
LARGE HAIL (1 TO 1.75 INCH IN DIAMETER.) ANOTHER ROUND OF
SHOWERS AND THUNDERSTORMS ARE EXPECTED LATER THIS EVENING AS AN
UPPER LEVEL SHORTWAVE TRACKS ALONG THE FRONT. EXPECT MUCAPE TO
DECREASE THROUGH 10PM-MIDNIGHT, WITH THUNDERSTORMS
TRANSITIONING TO RAIN. MVFR IS EXPECTED IN THE RAIN LATE THIS
EVENING, WITH DETERIORATION TO IFR OVERNIGHT. RAIN SHOULD
GRADUALLY END LATE TONIGHT AS THE FRONT CONTINUES SOUTHWARD,
WITH A GRADUAL IMPROVEMENT BACK TO LOW MVFR CIGS.
VFR IS EXPECTED TO RETURN MONDAY EVENING AS HIGH PRESSURE BEGINS
TO BUILD ACROSS THE UPPER OHIO VALLEY REGION.
OUTLOOK...
VFR IS EXPECTED MONDAY NIGHT THROUGH WEDNESDAY NIGHT AS HIGH
PRESSURE TRACKS ACROSS THE UPPER OHIO VALLEY REGION. RESTRICTION
POTENTIAL RETURNS WITH A THURSDAY WARM FRONT, AND CONTINUES ON
FRIDAY WITH A CROSSING COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...MILCAREK
AVIATION...WM
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