628
FXUS61 KPBZ 211107
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
707 AM EDT MON APR 21 2025
SYNOPSIS
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS MORNING AS
A WARM FRONT LIFTS NORTH ACROSS THE REGION. MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS ARE EXPECTED LATER TODAY WITH THE
APPROACH AND PASSAGE OF A COLD FRONT. DRY WEATHER THEN RETURNS
THROUGH MID WEEK UNDER HIGH PRESSURE.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:
- SCATTERED SHOWERS/THUNDERSTORMS EARLY THIS MORNING WITH A WARM
FRONT
- COLD FRONT BRINGS MORE WIDESPREAD SHOWERS/STORMS LATER TODAY
- MARGINAL RISK FOR SEVERE STORMS THIS AFTERNOON
-------------------------------------------------------------------
SURFACE LOW PRESSURE WAS CENTERED ACROSS SOUTHERN WI, WITH A
WARM FRONT EXTENDING SEWD ACROSS CENTRAL OH AND NRN WV . A COLD
FRONT TRAILED SOUTH OF THE LOW TO THE MISSISSIPPI VALLEY
REGION. THE WARM FRONT WILL CONTINUE TO LIFT NORTH ACROSS THE
UPPER OHIO VALLEY REGION EARLY THIS MORNING, WITH SCATTERED
SHOWERS AND THUNDERSTORMS. SHOWERS WERE DEVELOPING ON THE
LEADING EDGE OF A SECONDARY LOW LEVEL JET ASSOCIATED WITH THE
WARM FRONT. WEAK ELEVATED INSTABILITY COULD ALSO RESULT IN A FEW
THUNDERSTORMS DEVELOPING THROUGH THE MORNING.
THE WARM FRONT SHOULD LIFT NORTH OF THE REGION LATER THIS
MORNING, AS A PREFRONTAL TROUGH DEVELOPS AHEAD OF THE
APPROACHING COLD FRONT. SOME DESTABILIZATION IS EXPECTED AFTER
THE PASSAGE OF THE WARM FRONT, AND BEFORE THE ARRIVAL OF THE
PREFRONTAL TROUGH LATE THIS MORNING INTO THE AFTERNOON. IN
GENERAL, 500-750 J/KG OF MU CAPE IS PROGGED IN MOST OF THE CAMS
THIS AFTERNOON AND EARLY EVENING, WITH 40-50KT OF 0-6KM SHEAR,
ENHANCED BY A MID LEVEL JET. A FEW STORMS COULD BE SEVERE, BOTH
WITH THE PREFRONTAL TROUGH FROM EARLY TO MID AFTERNOON, AND WITH
ANY POTENTIAL REDEVELOPMENT ALONG THE SURFACE COLD FRONT LATER
THIS AFTERNOON AND EARLY EVENING. THE MAIN LIMITING FACTOR IN
SEVERE STORM DEVELOPMENT WILL BE THE AMOUNT OF INSTABILITY THAT
DEVELOPS, DEPENDING ON HOW THE FORECAST CONDITIONS EVOLVE
THROUGH THE DAY.
THE STORM PREDICTION CENTER HAS INCLUDED MUCH OF OUR REGION IN A
MARGINAL RISK FOR SEVERE STORMS. THE MAIN HAZARD IS EXPECTED TO
BE THE POTENTIAL FOR DAMAGING WIND GUSTS WITH INCREASING FLOW
ALOFT, THOUGH ISOLATED EMBEDDED QLCS TORNADOES ARE POSSIBLE AS
0-3KM HELICITY INCREASES WITH A VEERING WIND PROFILE.
HIGH TEMPERATURES ARE EXPECTED TO BE 10 TO 15 DEGREES ABOVE
AVERAGE WITH THE AREA IN THE WARM SECTOR.
SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/
KEY MESSAGES:
- SHOWERS/STORMS END THIS EVENING WITH THE PASSAGE OF A COLD
FRONT
- DRY WEATHER THEN RETURNS THROUGH WEDNESDAY NIGHT
-------------------------------------------------------------------
THE PREFRONTAL TROUGH IS EXPECTED TO BE JUST EAST OF THE AREA
EARLY THIS EVENING, AS THE SURFACE COLD FRONT CROSSES THE
REGION. A POTENTIAL FOR STRONG TO SEVERE STORMS WILL CONTINUE
UNTIL FROPA, THOUGH THIS WILL DEPEND ON THE AMOUNT OF
INSTABILITY ABLE TO OCCUR BEHIND THE PREFRONTAL TROUGH. SHOWER
AND THUNDERSTORM CHANCES WILL END AFTER FROPA, WITH DRY WEATHER
RETURNING THE REMAINDER OF THE NIGHT.
SURFACE HIGH PRESSURE WILL SLIDE EAST ACROSS THE UPPER OHIO
VALLEY REGION LATER TONIGHT THROUGH WEDNESDAY NIGHT UNDER ZONAL
FLOW ALOFT, MAINTAINING DRY WEATHER THROUGH WEDNESDAY NIGHT.
AFTER A BRIEF COOL DOWN ON TUESDAY BEHIND THE COLD FRONT,
TEMPERATURES WILL RETURN TO READINGS AROUND 10 DEGREES ABOVE
AVERAGE BY WEDNESDAY.
LONG TERM /THURSDAY THROUGH SUNDAY/
KEY MESSAGES:
- INCREASING SHOWER CHANCES THROUGH LATE WEEK INTO SATURDAY
- DRY WEATHER RETURNS FOR THE END OF THE WEEKEND
-------------------------------------------------------------------
MODEL ENSEMBLES INDICATE ZONAL FLOW ALOFT EARLY IN THE PERIOD
WILL BECOME MORE AMPLIFIED BY LATE WEEK. A TROUGH IS EXPECTED TO
DEVELOP ACROSS THE CENTRAL CONUS ON THURSDAY. INCREASING
MOISTURE AND WARM ADVECTION AHEAD OF THIS TROUGH SHOULD RETURN
SHOWER CHANCES TO THE AREA LATE THURSDAY AND THURSDAY NIGHT. THE
TROUGH, AND ITS ASSOCIATED SURFACE COLD FRONT, IS EXPECTED TO
TRACK ACROSS THE UPPER OHIO VALLEY REGION FRIDAY AND FRIDAY
NIGHT, WITH THE HIGHEST CHANCES FOR SHOWERS AND POSSIBLE
THUNDERSTORMS. THE TROUGH AND FRONT SHOULD EXIT THE REGION EARLY
SATURDAY, WITH SHOWERS ENDING FROM W-E.
RIDGING, BETWEEN THE EXITING TROUGH TO THE EAST, AND A
DEVELOPING WESTERN CONUS TROUGH, SHOULD RETURN DRY WEATHER TO
THE REGION SATURDAY NIGHT AND SUNDAY AS IT BUILDS ACROSS THE
UPPER OHIO VALLEY REGION. ABOVE AVERAGE TEMPERATURES ARE
EXPECTED TO RETURN TO SEASONABLE LEVELS AFTER THE PASSAGE OF THE
TROUGH.
AVIATION /12Z MONDAY THROUGH FRIDAY/
PASSAGE OF AN EARLY MORNING WARM FRONT WILL LEAVE AREA TERMINALS
WITHIN THE WARM SECTOR OF AN APPROACHING SURFACE LOW, RESULTING
IN WIND VEERING TO THE S AS IT SLOWLY INCREASES AS WELL AS ABOVE
5KFT CIG HEIGHTS.
A BROKEN LINE OF SHOWERS WITH EMBEDDED THUNDERSTORMS IS EXPECTED
TO TRAVERSE THE REGION BETWEEN 15Z-00Z TODAY AHEAD OF THE
CROSSING COLD FRONT. HI-RES MODELS REMAIN A BIT MUDDLED ON
WHETHER CONVECTION ALONG THE PRE-FRONTAL TROUGH (PASSING BTWN
15Z-21Z) OR ALONG THE COLD FRONT (APPROXIMATELY 2-3 HOURS AFTER
THE INITIAL TROUGH) WILL FEATURE THE MOST INTENSE CONVECTIVE
ACTIVITY. THE LIKELY LIMITED INSTABILITY FOR EITHER LINE
SUGGESTS RAINFALL INTENSITY WILL BE LOW (LIMITING THE DEGREE OF
VSBY DROPS) AND WIND GUSTS BETWEEN 30-50KT LIKELY WILL BE
ISOLATED (TOO LOW OF PROBABILITY FOR TAF MENTION).
PASSAGE OF THE UPPER SHORTWAVE AXIS AND SURFACE COLD FRONT WILL
SEE A QUICK END TO CONVECTIVE ACTIVITY IN THE REGION. WEAK COLD
ADVECTION AND SLOWLY VEERING WIND PROFILES SUGGEST THE PRESENCE
OF STRATOCU HOVERING JUST ABOVE 3KFT, THOUGH WEAK CONVERGENCE
ALONG THE HIGHER TERRAIN OFFERS GREATER PROBABILITY FOR MVFR
CIGS (DUJ/LBE/MGW).
OUTLOOK...
HIGH PRESSURE AND WEAK RIDGING ALOFT WILL FAVOR VFR AND ERODING
STRATOCU TUESDAY, WHICH SHOULD PERSIST THROUGH MUCH OF THE
DAYTIME HOURS THURSDAY.
WEAK SHORTWAVE MOVEMENT WITHING SOUTHWESTERLY FLOW IS EXPECTED
TO INCREASE SHOWER AND THUNDERSTORM CHANCES LATE THURSDAY INTO
THE EARLY WEEKEND WHERE CONVECTIVE ACTIVITY BECOMES THE MAIN
DRIVER FOR TERMINAL RESTRICTIONS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...FRAZIER
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