565
FXUS61 KPBZ 221801
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
201 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...
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 /18Z SUNDAY THROUGH FRIDAY/
VFR CONDITIONS ARE IN PLACE AS OF 18Z, WITH MAINLY MID AND HIGH
CLOUDS AT THIS MOMENT IN ADVANCE OF A COLD FRONT, WHICH CROSSES
DURING THE LATE AFTERNOON AND THE EVENING. SOUTHWEST WIND GUSTS
OF UP TO 25 KNOTS SHOULD CONTINUE IN ADVANCE.
CONVECTIVE INITIATION IS TRENDING SLOWER NOW, WITH THE FIRST
SHOWERS AND THUNDERSTORM MORE LIKELY TO APPEAR AFTER 20Z. MORE
WIDESPREAD ACTIVITY IS FORECAST TO DEVELOP AHEAD OF THE
BOUNDARY FROM 22Z ON AS IT SINKS THROUGH THE REGION. ALL
TERMINALS ARE EXPECTED TO BE IMPACTED TO SOME DEGREE. HAVE USED
2 HOUR TEMPO GROUPS TO TRY THE MOST LIKELY TIME OF ARRIVAL.
STORMS WILL BE STRONG TO PERHAPS SEVERE IN SOME CASES. DUE TO
DRY LOW-LEVEL AIR, CEILINGS WITH THE MAIN LINE OF STORMS SHOULD
REMAIN VFR. HOWEVER, EXPECT IFR TO PERHAPS BRIEF LIFR
VISIBILITY IN DOWNPOURS. VARIABLE WIND GUSTS TO 40 KNOTS OR SO
ARE POSSIBLE AT ANY TERMINAL, BUT ARE A LITTLE LESS SO AT
FKL/DUJ, AND THUS THESE GUSTS HAVE NOT BEEN INCLUDED IN THE
TEMPO GROUPS AT THOSE TERMINALS. DO NOT BE SURPRISED IF HAIL IS
OBSERVED AT ONE OR TWO AREA AIRPORTS - AND IT COULD BE FAIRLY
LARGE.
BEHIND THE FRONT THIS EVENING, CEILINGS SHOULD CRASH
THROUGH LOW MVFR TO IFR IN MOST CASES AS LOW-LEVEL MOISTURE
LINGERS. A WIND SHIFT TO NORTHWEST WILL OCCUR BEHIND THE BOUNDARY,
WITH SOME GUSTS OF 15 TO 20 KNOTS LINGERING. A FEW
THUNDERSTORMS MAY LINGER IN THE POST-FRONTAL ENVIRONMENT, BUT
LIGHT RAIN/DRIZZLE AND LOW CEILINGS SHOULD DOMINATE THROUGH MOST
OF THE NIGHT. MOST OF THE PRECIPITATION SHOULD END LATE TONIGHT
OR NEAR SUNRISE. SLOW IMPROVEMENT BACK TO MVFR CEILINGS IS
FORECAST TOWARDS THE TAIL END OF THE TAF PERIOD.
OUTLOOK...
MOSTLY VFR RETURNS MONDAY AFTERNOON THROUGH WEDNESDAY UNDER
BUILDING HIGH PRESSURE. THE NEXT NOTABLE CHANCE OF RESTRICTIONS
MAY ARRIVE BY THURSDAY WITH THE NEXT COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...MILCAREK
AVIATION...CL
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