781
FXUS61 KPBZ 192356
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
756 PM EDT SAT APR 19 2025
SYNOPSIS
SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING AHEAD OF A
COLD FRONT. A FEW STORMS COULD BE STRONG TO SEVERE BEFORE 8PM.
GENERALLY DRY WEATHER RETURNS SUNDAY AS THE FRONT MOVES SOUTH,
AND HIGH PRESSURE BRIEFLY BUILDS IN.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
KEY MESSAGES:
- SHOWERS AND THUNDERSTORMS CHANCES CONTINUE THROUGH LATE
EVENING
- STORMS COULD BE STRONG TO SEVERE, HAIL AND DAMAGING WIND
WOULD BE THE MAIN THREAT
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MESOSCALE UPDATE...
CONDITIONS REMAIN FAVORABLE MAINLY FOR DAMAGING WIND GUSTS NEAR
AND SOUTH OF I 70 EARLY THIS EVENING AS A COLD FRONT TRACKS
ACROSS THE REGION. THE LATEST DATA FROM THE 00Z RAOB LAUNCH,
ACARS DATA, AND CAM PROGGED SOUNDINGS INDICATE STRONG FLOW/SHEAR
ALOFT, WITH DRY AIR IN THE MID LEVELS. AS THE STRONGEST CORE OF
THE STORMS REACH THIS DRY AIR, WIND DAMAGE HAS BEEN REPORTED.
THIS SHOULD CONTINUE OVER THE NEXT COUPLE OF HOURS UNTIL
INSTABILITY BEGINS TO WANE, AND THE FRONT SINKS FURTHER SOUTH.
ML CAPE IS AROUND 500 J/KG NEAR AND SOUTH OF THE FRONT, WITH
60-75KT OF EFFECTIVE SHEAR. THESE CONDITIONS SHOULD GRADUALLY
SHIFT SOUTHWARD WITH THE FRONT THIS EVENING.
PREVIOUS DISCUSSION...
STRONG TO SEVERE STORMS ARE CURRENTLY ONGOING THIS AFTERNOON,
AHEAD OF A COLD FRONT. THE FRONTAL BOUNDARY IS CURRENTLY
SITUATED NEAR TOLEDO, OH AND STRETCHES SOUTHWEST INTO THE
MISSISSIPPI RIVER VALLEY.
AS THE RIDGE SLOWLY BREAKS DOWN AND MID TO UPPER-LVL WINDS
SHIFT FROM THE WEST, DEW POINTS WILL CONTINUE TO INCREASE.
THEREFORE, OUR CHANCES OF INSTABILITY INCREASE AS WELL WITH
TEMPERATURES IN THE UPPER-70S TO LOW-80S. WITH EFFECTIVE WIND
SHEAR RANGING BETWEEN 55KTS-65KTS, OUR PROBABILITY OF STRONG TO
SEVERE STORMS REMAIN ELEVATED THROUGH LATE EVENING. IF
CONDITIONS PERMIT, SEVERE STORMS COULD CREATE DAMAGING WIND AND
QUARTER SIZED HAIL. DESPITE STRONG WIND SHEAR ALOFT, CEILINGS
MAY BE CONSIDERED TOO HIGH FOR A TORNADO THREAT TO PROMOTE
STRETCHING WITH ROTATING UPDRAFTS. HODOGRAPHS ARE ALSO DEPICTING
A STRAIGHT LINE WIND THREAT.
THE PROBABILITY OF A FAVORABLE SEVERE STORM ENVIRONMENT WILL
LIKELY DECREASE FROM NORTH TO SOUTH BETWEEN 7PM TO 9PM WITH THE
LOSS OF DIURNAL HEATING AND THE PASSAGE OF A COLD FRONT.
DEPENDING ON THE POSITION OF THE COLD FRONT BY MIDNIGHT, THERE
IS ALSO THE CHANCE OF BREAKING HIMIN TEMPERATURES AT CLIMATE
SITES.
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
KEY MESSAGES:
- LINGERING SHOWERS BETWEEN MIDNIGHT TO 5AM SOUTH OF I-70 SUNDAY
- DRY CONDITIONS LATE MORNING SUNDAY THROUGH LATE EVENING
- WARM FRONT WILL RETURN THE POTENTIAL FOR SHOWERS AND STORMS
AFTER MIDNIGHT MONDAY
- STRONG TO SEVERE STORMS POTENTIAL SUNDAY AFTERNOON/EVENING
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AS THE COLD FRONT STALLS SOUTH OF I-70 AFTER MIDNIGHT ON SUNDAY,
THERE MAY BE SOME LINGERING SHOWERS IN THE VICINITY OF THE
LAUREL HIGHLANDS.
DRY WEATHER IS EXPECTED AFTER SUNRISE ON SUNDAY AS RIDGING
RETURNS. ABOVE-AVERAGE TEMPERATURES ARE LIKELY WITH DEEP
SOUTHWEST FLOW SUNDAY AFTERNOON.
THE PROBABILITY OF SHOWERS AND THUNDERSTORMS INCREASE AFTER
MIDNIGHT ON MONDAY WITH THE PASSAGE OF A WARM FRONT. WITH
ELEVATED INSTABILITY RANGING BETWEEN 300J/KG TO 700J/KG AND
30-40KTS OF SHEAR, THERE COULD BE A FEW STORMS THAT PRODUCE
HAIL EARLY MONDAY MORNING BEFORE SUNRISE.
AS THE COLD FRONT PROGRESSES MONDAY EVENING, ADDITIONAL SHOWERS
AND STORMS ARE LIKELY MONDAY AFTERNOON. STRONG SHEAR AND
INSTABILITY COULD CREATE STRONG TO SEVERE STORMS IN THE LATE
EVENING. THIS TIME PERIOD WILL NEED TO BE MONITORED OVER THE
NEXT 24 HOURS FOR POTENTIAL IMPACTS.
LONG TERM /TUESDAY THROUGH SATURDAY/
KEY MESSAGES:
- SEASONABLY WARM WEATHER CONTINUES
- PRECIPITATION CHANCES DEPENDENT ON SHORTWAVE MOVEMENT AND
RIDGE LOCATION
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THERE REMAINS STRONG AGREEMENT ON LONG RANGE ENSEMBLE MODELS ON
BRIEF RIDGING WITHIN QUASI-ZONAL FLOW TUESDAY THAT WILL PROVIDE
DRY WEATHER AND MAINTAIN THE RECENT TREND OF ABOVE NORMAL
TEMPERATURE.
THOSE TRENDS MAY CONTINUE WEDNESDAY AS THE OVERALL 500MB PATTERN
IS LIKELY TO EXHIBIT LITTLE CHANGE, BUT EMBEDDED 500MB SHORTWAVES
AND MOVEMENT WITHIN THE 850-700MB LEVEL COULD OFFER LOW
PROBABILITY PRECIPITATION CHANCES TO NORTHWEST PA. A FEW GLOBAL
MODELS HINT AT POTENTIAL FOR UPPER MIDWEST CONVECTION DECAYING
AS IT REACHES THIS AREA DUE TO WEAK SHORTWAVE MOVEMENT. MENTION
OF RAIN WILL REMAIN JUST IN THIS TEXT FOR NOW.
THE LATE WEEK INTO EARLY NEXT WEEK PERIOD WILL BE DRIVEN BY THE
GRADUAL DEVELOPMENT OF A NOTABLE RIDGE AXIS AND WHERE THE
CORRESPONDING TROUGH SITS. A CENTRAL PLAINS RIDGE AXIS MAY OFFER
A DRIER PERIOD (OUTSIDE OF A TRANSITION PRECIPITATION DAY) WITH
TEMPERATURE TRENDING DOWN TOWARD OR POTENTIALLY EVEN BELOW THE
SEASONAL AVERAGE. A SOUTHEAST CONUS RIDGE MAY OFFER MORE
PERIODIC PRECIPITATION CHANCES WITH SHORTWAVE MOVEMENT OVER THE
RIDGE TOP, BUT A HIGH LIKELIHOOD FOR MAINTAINING ABOVE NORMAL
TEMPERATURE.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
A COLD FRONT IS EXPECTED TO SLOWLY CREEP SOUTHEAST THROUGH THE
NIGHT. THE SHOWERS AND THUNDERSTORMS WILL COME TO AN END BY 02Z
IN MOST CASES. A FEW SHOWERS ARE POSSIBLE OVERNIGHT BUT OVERALL,
EXPECTED TO SEE SOME MVFR/IFR CIGS THROUGH THE OVERNIGHT AND
THROUGH DAWN. VFR CONDITIONS ARE EXPECTED THROUGH THE DAY ON
SUNDAY WITH LIGHT NORTHWEST WINDS EXPECTED THROUGH THE DAY WITH
LINGERING LOW VFR CLOUD COVER.
OUTLOOK...
A PASSING WARM FRONT EARLY MONDAY MAY CREATE ISOLATED
RESTRICTIONS AND THUNDERSTORMS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...WM/HEFFERAN
SHORT TERM...HEFFERAN
LONG TERM...FRAZIER
AVIATION...SHALLENBERGER
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