547
FXUS61 KPBZ 270608
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
208 AM EDT TUE MAY 27 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 TODAY/
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 /TONIGHT 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 /06Z TUESDAY THROUGH SATURDAY/
LOW PRESSURE IN WEST TENNESSEE SHOULD TRACK ACROSS KENTUCKY
TODAY AND INTO SOUTHERN OHIO TONIGHT. WARM ADVECTION AHEAD OF
THIS SYSTEM IS ALREADY SPREADING THICK HIGH CLOUDS INTO THE
AREA, AND VFR CEILINGS SHOULD GRADUALLY LOWER DURING THE DAY.
INCREASING PRESSURE GRADIENT WILL ALLOW FOR SOUTHEAST WINDS
GUSTING TO 20 TO PERHAPS 25 KNOTS THIS AFTERNOON.
EXPECT RAIN TO ARRIVE IN THE SOUTHERN TAF SITES LIKE ZZV AND MGW
AROUND 18Z, AND THEN SPREAD TO THE I-70 CORRIDOR BY 00Z. WET
BULB COOLING SHOULD ALLOW STRATUS TO FORM WITHIN A FEW HOURS OF
RAIN ONSET WITH MVFR AND EVENTUALLY IFR CEILING AND VISIBILITY
RESTRICTIONS DEVELOPING. BECAUSE OF THE EXTENT OF DRY AIR ALONG
I-80, THERE WILL BE A DELAY UNTIL LATER EVENING OF THE RAIN AND
ASSOCIATED RESTRICTIONS REACHING THE NORTHERN AIRPORTS LIKE FKL
AND DUJ.
A SOUTH TO SOUTHEAST 850 MB WIND MAXIMUM TONIGHT OF 30-40 KNOTS
MAY RESULT IN LOW LEVEL WIND SHEAR ESPECIALLY FOR THE PIT AGC MGW
AND LBE AREAS.
IFR CONDITIONS ARE LIKELY BY LATE TONIGHT ACROSS THE AREA.
OUTLOOK...
LOW PRESSURE SHOULD MOVE BY WEDNESDAY AFTERNOON AND SOMEWHAT
DRIER AIR WITH WESTERLY FLOW IS EXPECTED TO SHUT OFF SHOWERS AND
CEILINGS AND VISIBILITIES SHOULD BECOME VFR WITH POSSIBLE
EXCEPTION OF THE FKL AND DUJ SITES WHICH MAY STAY MVFR CEILINGS.
WIND GUSTS OF 20 TO 25 KNOTS ARE POSSIBLE.
AN UPPER TROUGH SHOULD BE OVERHEAD THURSDAY THROUGH SATURDAY
WITH COOLER AND UNSETTLED WEATHER CREATING OCCASIONAL MVFR
RESTRICTIONS IN SHOWERS. THERE WILL BE LARGE PERIODS OF VFR
OUTSIDE OF THESE SHOWERS WHICH WILL BE MOST COMMON IN THE
DAYTIME WITH DIURNAL HEATING. WIND GUSTS OF 25 TO 30 KNOTS ARE
POSSIBLE FROM THE NORTHWEST ON SATURDAY AS REINFORCING COLD AIR
ARRIVES.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...AK
SHORT TERM...HEFFERAN
LONG TERM...HEFFERAN
AVIATION...CRAVEN
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