467
FXUS61 KPBZ 301051
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
651 AM EDT FRI MAY 30 2025
SYNOPSIS
STRENGTHENING LOW PRESSURE SHOULD MOVE ACROSS WEST VIRGINIA AND
VIRGINIA TODAY, HEAVY RAIN EXPECTED. COOL WEATHER FOLLOWS ON
SATURDAY UNDER A TROUGH. A WARMING TREND IS EXPECTED NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- WIDESPREAD RAINFALL RETURNS TODAY ESPECIALLY PITTSBURGH ON
SOUTH
- THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN NORTHERN WV
- FLOOD WATCH ISSUED FOR PRESTON/TUCKER COUNTY
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7AM UPDATE: A MESOSCALE CONVECTIVE SYSTEM (MCS) IS CURRENTLY
TRACKING ACROSS SOUTHERN INDIANA, SOUTHERN OHIO, AND KENTUCKY
EARLY THIS MORNING. OVER THE LAST 3 HOURS, 1.50 TO 2 INCHES OF
RAINFALL HAS ACCUMULATE IN AREAS TO OUR WEST. WITH SATURATED
SOILS FROM A PREVIOUS EVENT IN WEST VIRGINIA, ISSUED A FLOOD
WATCH FOR PRESTON/TUCKER COUNTY. EXPECT RAPID RISES ALONG
SMALL STREAMS AND MAIN STEAM RIVERS LATE THIS EVENING AND INTO
EARLY SATURDAY MORNING.
PREVIOUS DISCUSSION:
120 METER HEIGHT FALL CENTER BLASTS ACROSS WEST VIRGINIA TODAY
ON ITS WAY TO NEW YORK CITY AREA LATE TONIGHT. THIS INDUCES
RATHER POTENT CYCLOGENESIS WITH SURFACE LOW DEEPENING ABOUT 20
MB IN 24 HOURS WHICH IS IMPRESSIVE FOR THE END OF MAY. HEIGHTS
AROUND PIT FALL 100 METERS TODAY AND ANOTHER 60 METERS TONIGHT
AS THE NORTHERN TROUGH DIGS DUE SOUTH OUT OF ONTARIO AND THE
GREAT LAKES.
RATHER COMPACT COMMA HEAD EXPECTED TO FORM NORTH OF THE SURFACE
LOW AND PRODUCES MAINLY OVER CENTRAL AND SOUTHERN AREAS AND
BRUSHES THE NORTHERN AREAS WITH RELATIVELY LIGHT PRECIPITATION
DURING THE DAY. HEAVIEST RAIN SHOULD BE OVER WEST VIRGINIA WHERE
0.50 TO 1.00" OF RAIN IS EXPECTED WITH LOCALLY 2-3" OVER
SOUTHERN PRESTON AND TUCKER COUNTIES. DECENT SPREAD IN HOW MUCH
CONVECTION AND HEAVY RAIN FALLS DOWN THERE. DISCUSSED ISSUING A
FLASH FLOOD WATCH GIVEN SOME OF THE CAM SOLUTIONS BUT THE
PROBABILITY APPEARS TO BE LESS THAN 50% BUT COULD CERTAINLY SEE
DAY SHIFT NEEDED TO PUT ONE OUT IF 00Z NAMNEST AND 05Z HRRR END
UP BEING CLOSER TO REALITY.
SIGNIFICANT RAIN IN SOUTH ENDS DURING THE EVENING BUT NORTHERN
DIGGING TROUGH WILL BRING ANOTHER ROUND OF SHOWERS THROUGHOUT
THE FORECAST AREA MAINLY AFTER MIDNIGHT AS COLD ADVECTION AND
NORTHWEST UPSLOPE FLOW BEGINS.
SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/
KEY MESSAGES:
- BLUSTERY AND COOL WEATHER WITH READINGS 10 TO 15F BELOW NORMAL
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500 MB HEIGHTS DROP TO ABOUT 5480 METERS SATURDAY AFTERNOON AS
NORTHERN TROUGH PASSES OVERHEAD, WHICH IS ABOUT 3 STANDARD
DEVIATIONS BELOW NORMAL AND QUITE IMPRESSIVE. NBM MEAN MAXT HAS
FINALLY CAUGHT UP AND IS GOING LOWER TO MIDDLE 60S FOR HIGHS
WHICH IS REASONABLE GIVEN THE STRENGTH OF THE LOW LEVEL COLD
ADVECTION.
WENT WITH NBM 90TH PERCENTILE WINDS AND WIND GUSTS ON SATURDAY
GIVEN DEEP MIXING AND MEAN WIND OF ABOUT 25-30 KNOTS IN THE
BOUNDARY LAYER. WINDS TEND TO OVERPERFORM GUIDANCE WITH STRONG
COLD ADVECTION SO TRYING TO ACCOUNT FOR THAT BIAS.
850 MB TEMPERATURES FALL ABOUT 4C DURING THE DAY TO +2C BY
EVENING, WITH 500 MB TEMPS LOWERING TO -22C. DIURNALLY DRIVEN
SHOWERS ARE EXPECTED THROUGH EARLY AFTERNOON AND THEN SUBSIDENCE
AND DRYING SHOULD SHUT THINGS OFF LATER IN THE AFTERNOON AND
SATURDAY NIGHT SHOULD BE DRY AND COOL. 10TH PERCENTILE NBM MINT
DOES FALL INTO THE UPPER 30S IN THE I-80 CORRIDOR BUT MOST
LOCATIONS SHOULD STAY IN THE 40S SO FROST POTENTIAL APPEARS TO
BE LOW.
LONG TERM /SUNDAY THROUGH THURSDAY/
KEY MESSAGES:
- WARMING TEMPERATURES BEGIN SUNDAY AND CONTINUE THROUGH MIDWEEK
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QUITE A SWING IN TEMPERATURES IS EXPECTED AS RIDGING OVER THE
PLAINS HEADS INTO THE GREAT LAKES AND EVENTUALLY THE NORTHEAST
STATES. HEIGHTS RISE ABOUT 80 METERS ON SUNDAY AND THEN ANOTHER
100 METERS ON MONDAY BEFORE REACHING 5850-5880 METERS ON TUESDAY.
ENSEMBLE GUIDANCE SHOWS CONSISTENT WARMING THROUGH WEDNESDAY BUT
THEN UNCERTAINTY GROWS ON THE ARRIVAL OF THE NEXT TROUGH AND
ALSO THE EVOLUTION OF A POTENTIAL PESKY UPPER LOW ALONG THE
EASTERN SEABOARD. WOULD EXPECT QUIET WEATHER THROUGH WEDNESDAY
WITH A WARMING TREND LIKELY PUSHING US WELL INTO THE 80S TUESDAY
AND WEDNESDAY BEFORE UNCERTAINTY GROWS ABOUT THE LATE WEEK.
READINGS COULD EASILY BE 20F HIGHER BY TUESDAY AND WEDNESDAY
VERSUS WHAT WE SEE THIS WEEKEND, SO JUNE WILL ARRIVE WITH A
TASTE OF SUMMER.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
MOIST ADVECTION AHEAD OF AN INCOMING LOW PRESSURE SYSTEM SHOULD
GENERATE ENOUGH BKN/OVC MID-LEVEL CLOUD DECKS THROUGH THE
OVERNIGHT HOURS TO MAINTAIN VFR AND KEEP ANY FOG DEVELOPMENT
LOCALIZED (MGW/LBE/DUJ WOULD BE MOST LIKELY SITES TO SEE FOG IF
CLEARING REMAINS LONG ENOUGH).
NE MOVEMENT OF THE SHORTWAVE OUT OF THE OHIO RIVER VALLEY WILL
PROMOTE A SURGE OF RAIN SHOWERS TODAY, REACHING SE OH AROUND
14Z AND WESTERN PA AROUND 17Z. TRENDED FORECAST TOWARD HI-RES
MODEL MEAN LOW POSITIONING SLIGHTLY FARTHER SE AND KEEPING A
BULK OF THE RAIN/RESTRICTIONS TOWARDS NORTHERN WV AND THE LAUREL
HIGHLANDS. A COMBINATION OF CIG/VSBYS FALLS BETWEEN 16Z-00Z
SHOULD RESULT PERIODIC MVFR RESTRICTIONS AT TERMINALS, WITH A
LOWER PROBABILITY FOR IFR AT SITES LIKE MGW/LBE. LIGHTNING CAN'T
BE RULED OUT BUT MODELING SUGGESTS BETTER INSTABILITY WILL BE
SOUTH OF REGION.
AS TRANSITORY PERIOD IS LIKELY AS THE WAVE EXITS NEAR/SHORTLY
AFTER 00Z WHERE A MIX OF VFR/MVFR CONDITIONS DEVELOP WHILE
AWAITING ADDITIONAL WAVES IN NW OVERNIGHT. CONFIDENCE IN AREAL
COVERAGE OF MVFR/IFR STRATUS IS LOW FOR THIS PERIOD.
OUTLOOK...
SHORTWAVE MOVEMENT WITHIN NW FLOW AND STRONG COLD ADVECTION
ALOFT WILL SUPPORT SCATTERED SHOWERS AND EVEN THUNDERSTORMS
BETWEEN 06Z TO 18Z SATURDAY BEFORE SUBSIDENCE/DRY ADVECTION
DIMINISHES CHANCES. THE COLD AIR AND NOTABLE WIND SHIFT WILL
ALSO SUPPORT WIDESPREAD MVFR TO IFR SATURDAY MORNING IN THE
POST-FRONTAL ENVIRONMENT.
THERE IS HIGH CONFIDENCE (GREATER THAN 90% PROBABILITY) IN VFR
BY 00Z SUNDAY UNDER THE INFLUENCE OF HIGH PRESSURE AND DRY
ADVECTION. THESE CONDITIONS ARE LIKELY TO PERSIST UNDER RIDGE
BUILDING TO START THE NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...FLOOD WATCH FROM 4 PM EDT THIS AFTERNOON THROUGH LATE TONIGHT
FOR WVZ510>514.
SYNOPSIS...HEFFERAN
NEAR TERM...CRAVEN/HEFFERAN
SHORT TERM...CRAVEN
LONG TERM...CRAVEN
AVIATION...FRAZIER
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