193
FXUS61 KPBZ 262336
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
736 PM EDT MON MAY 26 2025
SYNOPSIS
RAIN CHANCES RETURN LATE TUESDAY INTO WEDNESDAY WITH A PASSING
LOW PRESSURE SYSTEM OVER THE OHIO RIVER VALLEY. SEASONABLE
TEMPERATURES ARE EXPECTED MID-WEEK.
NEAR TERM /THROUGH TUESDAY/
KEY MESSAGES:
- DRY AND QUIET WEATHER THROUGH TONIGHT
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EVENING UPDATE: FAIR WEATHER CU ARE EXPECTED TO BEGIN TO DISSIPATE
SHORTLY WITH THE LOSS OF SFC HEATING. HIGH CLOUDS ARE EXPECTED TO
BEGIN TO FILTER IN QUICKLY AFTER SUNSET DEVELOPING A HIGH OVERCAST
TONIGHT AHEAD OF OUR APPROACHING SYSTEM. STOUT CLOUD COVER WILL LEAD
TO A WARMER NIGHT TONIGHT THAN LAST WHEN RADIATIONAL COOLING WAS FAR
MORE EFFICIENT.
VERY FEW TWEAKS MADE TO THE PREVIOUS FORECAST PACKAGE. THERE HAS
BEEN A NOTABLE TREND TOWARDS AN EARLIER ARRIVAL TIME OF RAIN OVER
THE LAST 24 HOURS AND THAT CONTINUED WITH THE 19Z NBM. I HAVE MOVED
TOWARDS THIS BUT KEPT CHANCES LOW UNTIL THE MIDDAY HOURS. LATEST
ACARS SOUNDINGS INDICATE A RELATIVELY DRY SFC LAYER UP TO 800 AND
EARLY RAIN WILL STRUGGLE TO FIGHT THROUGH THIS DRY AIR.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
KEY MESSAGES:
- RAIN RETURNS LATE TUESDAY EVENING INTO WEDNESDAY
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BY DAYBREAK ON TUESDAY, HIGH-RESOLUTION MODELS SHOW HIGH
CONFIDENCE IN DRY CONDITIONS ACROSS THE REGION, SUPPORTED BY
SUFFICIENT MID-LEVEL DRY AIR. MODEL SOUNDINGS INDICATE
INCREASING MOISTURE BETWEEN 200MB AND 500MB, LEADING TO
DEVELOPMENT OF HIGH CLOUD COVER.
THE PROBABILITY OF MEASURABLE RAINFALL INCREASES ACROSS
PORTIONS OF COUNTY WARNING AREA BETWEEN 4PM TO 7PM TUESDAY, AS A
NEW LOW PRESSURE SYSTEM OVER THE SOUTHEAST ADVANCES INTO THE
OHIO RIVER VALLEY. NORTHERN WEST VIRGINIA IS EXPECTED TO BE THE
FIRS AREA TO BE IMPACTED BY RAIN. HOWEVER, IF PRECIPITATION
BEGINS IN THE EARLY AFTERNOON, IT WILL LIKELY BE VERY LIGHT DUE
TO LOOMING DRY AIR IN THE BOUNDARY LAYER.
AS THE CENTER OF THE LOW APPROACHES SOUTHERN OHIO EARLY
WEDNESDAY MORNING, THERE IS POTENTIAL FOR WIND GUSTS BETWEEN 30
TO 35MPH DUE TO DOWNSLOPING ACROSS THE TERRAIN OF PENNSYLVANIA
AND WEST VIRGINIA. THIS SCENARIO IS MORE LIKELY IF LOW-LEVEL
WINDS (BETWEEN 925MB TO 850MB) REMAIN ORIENTED PERPENDICULAR TO
THE RIDGE AXIS FROM THE SOUTHEAST. HOWEVER, CONFIDENCE REMAINS
LOW THAT GUSTS WILL EXCEED 47MPH, MAKING THE ISSUANCE OF A WIND
ADVISORY UNLIKELY AT THIS TIME.
IF MODERATE TO HEAVY RAINFALL OCCURS, IT WILL MOST LIKELY TAKE
PLACE EARLY WEDNESDAY MORNING, DRIVEN BY STRONG WARM ADVECTION
FROM THE SOUTHEAST. PRECIPITABLE WATER (PWAT) VALUES ARE
EXPECTED TO RANGE FROM 1.00 TO 1.25 INCHES--APPROXIMATELY 1 TO
1.5 STANDARD DEVIATIONS ABOVE AVERAGE. FORECAST RAINFALL TOTALS
BETWEEN 8PM TUESDAY TO 8PM WEDNESDAY ARE EXPECTED TO RANGE FROM
0.4 TO 1.0 INCHES, WITH HIGHER AMOUNTS LIKELY ALONG THE RIDGES
DUE TO UPSLOPE ENHANCEMENT. LOCALIZED HIGHER TOTALS CANNOT BE
RULED OUT, PARTICULARLY IF THUNDERSTORMS DEVELOP WEDNESDAY
AFTERNOON OR EVENING.
AS THE UPPER-LEVEL LOW ADVANCES NORTH, MID-LEVEL DRY AIR WILL
ADVANCE INTO THE REGION FROM THE SOUTHWEST. THE CHANCES OF
MODERATE TO HEAVY RAINFALL WILL DECREASE LATE WEDNESDAY EVENING
INTO EARLY THURSDAY.
LONG TERM /THURSDAY THROUGH MONDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPERATURES EXPECTED
- LIGHT RAIN CHANCES CONTINUE INTO THE WEEKEND
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AS A LOW-PRESSURE SYSTEM MERGES WITH A TROUGH OVER THE GREAT
LAKES AND STALLS MID-WEEK, THERE IS AN INCREASING LIKELIHOOD OF
RAIN DURING THE EXTENDED FORECAST PERIOD.
WITH PERSISTENT NORTHWEST FLOW, LINGERING CLOUD COVERAGE, AND
CONTINUED RAIN CHANCES, TEMPERATURES ARE ALSO EXPECTED TO REMAIN
BELOW AVERAGE AS WELL.
EXTENDED MODELS INDICATE A SHIFT IN THE SYNOPTIC PATTERN BY
SUNDAY, WITH THE TROUGH LIFTING NORTHWARD AND THE RIDGE AXIS
OVER THE CENTRAL CONUS GRADUALLY SHIFTING TOWARDS THE GREAT
LAKES. CONFIDENCE IS INCREASING THAT ABOVE AVERAGE TEMPERATURES
WILL RETURN BETWEEN JUNE 1ST AND JUNE 2ND.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
A HIGH-CONFIDENCE VFR FORECAST CONTINUES INTO TOMORROW MORNING.
THE REMAINING DIURNAL CUMULUS WILL DISSIPATE WITH THE LOSS OF
HEATING. CIRRUS COVERAGE WILL INCREASE FROM THE SOUTHWEST
TONIGHT AS UPPER-LEVEL MOISTURE INCREASES AHEAD OF DEVELOPING
LOW PRESSURE OVER THE TENNESSEE VALLEY. LIGHT WIND IS FORECAST
OVERNIGHT, WITH A VEER TO SOUTHEAST WITH TIME.
CLOUDS WILL BEGIN TO THICKEN AND LOWER AS THE SURFACE LOW LIFTS
INTO THE OHIO VALLEY TUESDAY MORNING. SOUTHEAST WIND WILL
INCREASE, WITH GUSTS BETWEEN 15 AND 20 KNOTS DEVELOPING, AS
LOW-LEVEL LAPSE RATES STEEPEN AND MIX DOWN INCREASING SOUTHEAST
FLOW ALOFT. LIGHT RAIN WILL SPREAD IN FROM THE SOUTH DURING THE
AFTERNOON, BUT WILL BE FIGHTING DRY AIR IN THE LOW LEVELS
INITIALLY, AND THUS IMPACTS ARE EXPECTED TO BE LOW INITIALLY.
SOME GUIDANCE WANTS TO BRING MVFR CEILINGS AS FAR NORTH AS
PIT/BVI/LBE BY 00Z WEDNESDAY, BUT GIVEN THE SOUTHEAST FLOW AND
HREF MVFR PROBABILITIES LESS THAN 10% BY THAT TIME AT ALL SITES
SAVE FOR ZZV, HAVE LIMITED SUCH RESTRICTIONS TO THAT TERMINAL
PRIOR TO 00Z. DO HAVE MVFR RESTRICTIONS DEVELOPING AT PIT BY THE
END OF THAT 30-HOUR TAF PERIOD. THUNDER IS NOT EXPECTED AT THIS
TIME GIVEN MINIMAL INSTABILITY.
OUTLOOK...
RAIN AND RESTRICTIONS WILL CONTINUE WITH PASSING LOW
PRESSURE INTO WEDNESDAY WITH INCREASING PROBABILITY FOR IFR
OVERNIGHT TUESDAY NIGHT INTO WEDNESDAY MORNING DURING THE PERIOD
OF LIKELY STEADIEST RAINFALL. A NOSE OF DRIER AIR FROM THE
SOUTHWEST WILL GRADUALLY ERODE CEILINGS WEDNESDAY EVENING WITH
VFR PROBABILITIES INCREASING TO 70+% WEST OF PIT BUT STILL
REMAINING ELEVATED AS HIGH AS 60-70% TO THE EAST.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...AK
SHORT TERM...HEFFERAN
LONG TERM...HEFFERAN
AVIATION...CL/MLB
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