821
FXUS61 KPBZ 301446
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1046 AM EDT FRI MAY 30 2025
SYNOPSIS
SHOWERS AND THUNDERSTORMS ARE EXPECTED BY THIS AFTERNOON,
LINGERING INTO THE OVERNIGHT. HEAVY RAIN IS POSSIBLE FOR SOME,
ESPECIALLY IN THE WV AND PA RIDGES. DRIER WEATHER RETURNS
SATURDAY AFTERNOON THROUGH EARLY NEXT WEEK AS TEMPERATURES WARM.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- WIDESPREAD RAINFALL RETURNS TODAY
- HEAVY RAIN IS POSSIBLE SOUTH OF PITTSBURGH WHERE THERE IS A
SLIGHT RISK OF EXCESSIVE RAINFALL
- A FLOOD WATCH IS IN EFFECT FOR PRESTON/TUCKER COUNTY
- MARGINAL RISK FOR SEVERE STORMS ACROSS NORTHERN WV THIS
AFTERNOON
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MCS CONTINUES TO TRACK ACROSS OHIO/KENTUCKY/WEST VIRGINIA THIS
MORNING, WITH LIGHT RAIN BEGINNING TO ARRIVE IN EASTERN OHIO.
GENERALLY LIGHT TO MODERATE SHOWERS WITH OCCASIONAL THUNDER ARE
EXPECTED NORTH OF PITTSBURGH TODAY AS THE MCS TRACKS EAST. AREAS
SOUTH OF PITTSBURGH AND ESPECIALLY SOUTH OF THE PA BORDER SHOULD
EXPECT HIGHER RAINFALL RATES WITH PERIODS OF HEAVY RAIN. RAINFALL
RATES OF 0.5-1.0 INCHES HAVE BEEN NOTED OVER THE LAST 3 HOURS
IN AREAS TO OUR WEST. GIVEN ANTECEDENT WET CONDITIONS OVER
PORTIONS OF NORTHERN WV, AND EXPECTED RAINFALL TOTALS NEAR OR
EXCEEDING 1", A SLIGHT RISK FOR EXCESSIVE RAINFALL IS
HIGHLIGHTED FOR THE REGION. PROBABILITIES FOR EXCESSIVE RAINFALL
ARE HIGHEST ACROSS PRESTON AND TUCKER COUNTIES (WV), WHERE THE
LIKELIHOOD OF 2" THROUGH SATURDAY IS 30-40%. THIS AREA ALREADY
HAS SATURATED SOILS FROM PREVIOUS RAINFALL, SO A FLOOD WATCH WAS
ISSUED FOR THIS EVENING THROUGH EARLY SATURDAY.
THERE REMAINS SOME CONCERN ABOUT ISOLATED SEVERE STORMS THIS
AFTERNOON/EVENING AS LOW PRESSURE CROSSES THE AREA. GIVEN THE
TRACK OF LOW PRESSURE, THIS THREAT SHOULD REMAIN GENERALLY SOUTH
OF I-70 AND LIKELY SOUTH OF THE MASON-DIXON. DAMAGING WIND IS
THE MOST LIKELY HAZARD WITH ANY STRONG-TO-SEVERE STORMS, BUT
WIND PROFILES/HODOGRAPHS IN PROXIMITY TO THE LOW SUGGEST THE
POSSIBILITY FOR ISOLATED TORNADOES AS WELL. SPC HAS HIGHLIGHTED
THE AREA ROUGHLY SOUTH OF I-70 IN A MARGINAL RISK FOR SEVERE.
SIGNIFICANT RAIN AND ANY SEVERE THREAT ACROSS THE SOUTH WILL END
DURING THE EVENING HOURS, BUT A NORTHERN DIGGING TROUGH WILL
BRING ANOTHER ROUND OF SHOWERS THROUGHOUT THE FORECAST AREA
MAINLY AFTER MIDNIGHT AS COLD ADVECTION AND NORTHWEST UPSLOPE
FLOW BEGINS. LOW TEMPERATURES WILL DROP INTO THE 50S OVERNIGHT
AS SHOWERS LINGER.
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 /14Z 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...RACKLEY
NEAR TERM...RACKLEY
SHORT TERM...CRAVEN
LONG TERM...CRAVEN
AVIATION...FRAZIER
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