159
FXUS61 KPBZ 251756
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
156 PM EDT FRI APR 25 2025
SYNOPSIS
A COLD FRONT WILL BRING SHOWERS AND STORMS TO THE
REGION TODAY, CONTINUING INTO SATURDAY MORNING. BRIEF COOL DOWN ON
SATURDAY AND SUNDAY, BEFORE ABOVE NORMAL TEMPERATURES RETURN NEXT
WEEK. THE POTENTIAL FOR ACTIVE WEATHER RETURNS NEXT TUESDAY.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- SHOWERS AND STORMS TODAY AHEAD OF A COLD FRONT
- TRAINING SHOWERS AND STORMS CAN LEAD TO HEAVY RAIN CONCERNS
- TEMPERATURES REMAIN ABOVE NORMAL
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SHOWERS ASSOCIATED WITH OUR FIRST UPPER WAVE ARE FLEEING THE REGION
EAST AND THE BREAK BETWEEN OUR TWO UPPER WAVES IS EVIDENT IN THE
SEVERAL HUNDRED MILE GAP BETWEEN DEPARTING SHOWERS AND THOSE ON
THEIR WAY IN. THERE IS EVIDENCE OF SLIGHT CLEARING IN BETWEEN THESE
TWO WAVES ON THE LATEST SATELLITE LOOPS. ANY SUCH CLEARING WILL
LIKELY HELP HEAT AND DESTABILIZE THE AIRMASS, GIVING A MORE
CONVECTIVE EDGE TO OUR SECOND ROUND OF SHOWERS KICKING OFF THIS
AFTERNOON/EVENING AND CONTINUING UNTIL THE COLD FRONT CLEARS THE
AREA SATURDAY MORNING.
A LACK OF DEEP-LAYER SHEAR AND INSTABILITY COMBINED WITH MESSY
HODOGRAPHS DO NOT SUPPORT ORGANIZED SEVERE WEATHER TODAY. THE
INSTABILITY WE DO ATTAIN MAY LEND ITSELF MORE TO A DOWNPOUR/HEAVY
RAIN THREAT INSTEAD. PWATS FROM THE MORNING SOUNDING WERE NEAR THE
90TH PERCENTILE AND RELATIVELY SLOW STORM MOTIONS COULD LEAD TO
TRAINING SHOWERS/THUNDERSTORMS BOOSTING LOCALIZED RAIN TOTALS.
EXPECTED RAINFALL TOTALS ARE LARGELY BETWEEN 0.75-1.25 INCHES BUT
PROBABILITY STREAKS OF >2 INCHES OF RAIN HIGHLIGHT THE POTENTIAL FOR
TRAINING. IT IS DIFFICULT TO PIN DOWN EXACTLY WHERE THESE HIGHER
TOTALS CAN BE FOUND BUT THERE IS A CONSISTENT SIGNAL FOR THEIR
POTENTIAL TO BE HIGHEST NORTH OF PITTSBURGH IN OUR I-80 COUNTIES.
NEIGHBORHOOD PROBABILITIES GIVE ISOLATED PARTS OF THESE COUNTIES 60-
70% CHANCE OF SEEING >2.00 INCHES OF RAIN AND 40-50% CHANCE OF
SEEING >2.50 INCHES OF RAIN. ANTECEDENT CONDITIONS LIKELY HELP US
LOWER OUR OVERALL RISK OF FLOODING BUT HIGH RAINFALL RATES IN
HEAVIER SHOWERS AND THE POTENTIAL FOR TRAINING STORMS MEAN THAT THE
RISK IS NOT ABSENT. OUR ENTIRE REGION IS IN A MARGINAL RISK OF
EXCESSIVE RAINFALL FROM WPC.
CLOUDS AND RAIN WILL KEEP A LID ON OUR TEMPERATURES TODAY BUT WE CAN
STILL EXPECT THEM TO BE 10 OR SO DEGREES ABOVE NORMAL. WITH
CONTINUED CLOUD COVERAGE AND RAIN, LOW TEMPERATURES OVERNIGHT ARE
EXPECTED TO BE COOLER THAN LAST NIGHT BUT STILL AROUND 10 DEGREES
ABOVE AVERAGE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
KEY MESSAGES:
- COOLER BUT DRY FOR THE WEEKEND
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SHOWERS ARE EXPECTED TO WIND DOWN FROM WEST TO EAST BY EARLY
SATURDAY MORNING AS OUR SECOND UPPER WAVE AND THE ASSOCIATED COLD
FRONT CLEAR THE REGION. COOLER AND DRIER AIR OVERSPREADS THE REGION
BEHIND THE FRONT. THE LONGWAVE TROUGH THAT BROUGHT RAIN TO THE
REGION IS FINALLY EXPECTED TO CROSS THE REGION SATURDAY. HIGH
TEMPERATURES ARE EXPECTED TO BE TRIMMED AND FALL JUST A FEW DEGREES
BELOW NORMAL, POTENTIALLY OUR FIRST BELOW AVERAGE HIGH SINCE APRIL
17TH. BREEZY CONDITIONS ARE POSSIBLE SATURDAY DUE TO COLD AIR
ADVECTION AND A TIGHTENED PRESSURE GRADIENT.
SURFACE HIGH PRESSURE FILTERS IN AND CONTINUES DRY WEATHER SUNDAY.
500MB HEIGHTS FINALLY BEGIN TO RISE AS THE UPPER TROUGH KICKS
EASTWARD AND RIDGING BEGINS TO SLIDE IN FROM THE CENTRAL CONUS.
DESPITE THESE HEIGHT RISES, HIGH TEMPERATURES ARE NOT EXPECTED TO
RISE MUCH AND WE COULD END UP WITH TWO DAYS IN A ROW OF BELOW
AVERAGE HIGHS. LARGELY CLEAR SKIES AND LIGHT WINDS SUNDAY NIGHT
LIKELY LEAD TO EFFICIENT RADIATIONAL COOLING AND A CHILLY START TO
OUR NEXT WORK WEEK.
LONG TERM /MONDAY THROUGH THURSDAY/
KEY MESSAGES:
- ABOVE AVERAGE TEMPERATURES TO START NEXT WEEK
- ACTIVE WEATHER POSSIBLE MIDWEEK BUT DEPENDENT ON TROUGH SPEED
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CLUSTERED ENSEMBLES STILL DISAGREE ON EXACTLY HOW EAGER THAT
DEPARTING TROUGH IS TO MOVE EASTWARD INTO THE ATLANTIC. THERE IS A
SLIGHT SIGNAL TODAY FOR A POSSIBLY FASTER DEPARTURE LEADING TO AN
EARLIER ONSET OF RIDGING BUT THE EURO IS THE NOTABLE EXCEPTION.
DESPITE THE UNCERTAINTY ON SPEED, IT REMAINS HIGHLY LIKELY THAT
HEIGHTS RISE ON MONDAY AND TEMPERATURES BOUNCE BACK ABOVE NORMAL.
CLUSTERED ENSEMBLES SHUNT THE RIDGE EASTWARD ON TUESDAY, RAISING
TEMPERATURES ONCE AGAIN, AS AN UPPER WAVE TRAVERSES THE CENTRAL
CONUS. THIS WAVE BRINGS POTENTIAL FOR ACTIVE WEATHER AND POSSIBLE
SEVERE THREATS NEXT WEEK BUT THE PICTURE OF ITS ARRIVAL IS FAR FROM
CLEAR. CLUSTERED ENSEMBLES STILL HAVE THE BASE OF THIS TROUGH IN THE
FOUR CORNERS REGION BY TUESDAY. FROM THERE, THEY PAINT A DISJOINTED
PICTURE OF THE WAVE BECOMING UNPHASED, WITH THE BASE OUT WEST AND
REMAINDER RIDING THROUGH THE GREAT LAKES AND FLATTENING THE EASTERN
CONUS RIDGE. THE PICTURE BECOMES EVEN MUDDIER BY WEDNESDAY, WITH
SIGNALS FOR A POSSIBLY WEAKER AND SLOWER WAVE BECOMING EQUALLY AS
LIKELY.
AS IT STANDS NOW IT SEEMS LIKELY THAT POPS WILL RETURN TUESDAY INTO
TUESDAY NIGHT, BUT THIS AND THE EVOLUTION OF THE LONG-RANGE FORECAST
LARGELY REMAIN CLOUDED BY THE UNCERTAINTY IN THE AMPLITUDE, SPEED
AND EVOLUTION OF THE WAVE PACKET.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
SHOWERS ACROSS THE REGION SHOULD DIMINISH IN COVERAGE DURING
THE AFTERNOON AS A WEAK SHORTWAVE RIDGE TRANSITIONS ACROSS THE
REGION. COVERAGE THEN INCREASES THIS EVENING WITH A CROSSING
SHORTWAVE WITH A FEW ELEVATED THUNDERSTORMS POSSIBLE. MVFR
RESTRICTIONS WILL BECOME MORE WIDESPREAD THIS EVENING, AND THEN
EVENTUALLY IFR OVERNIGHT. LATEST GUIDANCE SHOWS IFR CIG
PROBABILITIES RANGING FROM 80 TO 100% BY SATURDAY MORNING, WHICH
SHOULD GRADUALLY IMPROVE TO MVFR LATER IN THE AFTERNOON/EARLY
EVENING WITH DRY AIR ADVECTION OUT OF THE NORTHWEST.
OUTLOOK...
VFR CONFIDENTLY RETURNS SUNDAY AS HIGH PRESSURE BUILDS. HIGH
PRESSURE REMAINS DOMINANT THROUGH MONDAY WITH LOW RESTRICTION
POTENTIAL. THE NEXT WIDESPREAD RESTRICTION CHANCE APPEARS TO BE
TUESDAY INTO WEDNESDAY WITH RAIN AND FRONTAL PASSAGE.
OUTLOOK...
GRADUAL CIG IMPROVEMENT IS EXPECTED SATURDAY MORNING AND
AFTERNOON WITH DRY AIR ADVECTION FROM THE NORTHWEST. VFR
CONFIDENTLY RETURNS FOR ALL BY EARLY SUNDAY AS HIGH PRESSURE
BUILDS. HIGH PRESSURE REMAINS DOMINANT THROUGH MONDAY WITH LOW
RESTRICTION POTENTIAL. THE NEXT WIDESPREAD RESTRICTION CHANCE
APPEARS TO BE TUESDAY INTO WEDNESDAY WITH RAIN AND FRONTAL
PASSAGE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...22/AK
NEAR TERM...AK
SHORT TERM...AK
LONG TERM...AK
AVIATION...88
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