762
FXUS61 KPBZ 270738
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
338 AM EDT TUE MAY 27 2025
SYNOPSIS
RAIN WILL OVERSPREAD THE REGION THIS AFTERNOON INTO WEDNESDAY
WITH A WEAK LOW PRESSURE SYSTEM. ADDITIONAL RAIN CHANCES RETURN
FRIDAY INTO THE EARLY WEEKEND WITH THE NEXT LOW PRESSURE SYSTEM.
BELOW NORMAL TEMPERATURE ARE LIKELY TO PERSIST UNTIL THE START
OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- RAIN WILL OVERSPREAD THE REGION THIS AFTERNOON AND EVENING,
FAVORING LOCATIONS EAST OF I-79.
- SEASONABLY COOL TEMPERATURE PERSISTS.
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SHORTWAVE MOVEMENT AHEAD OF A NORTHERN CENTRAL PLAINS TROUGH
WILL ENCOURAGE GRADUAL TOP-DOWN MOISTENING OF THE ATMOSPHERE
OVER THE UPPER OHIO RIVER VALLEY AND EVENTUALLY THE NORTHWARD
SPREAD OF LIGHT TO OCCASIONALLY MODERATE RAIN THIS AFTERNOON
AND EVENING. DRY ATMOSPHERIC CONDITIONS PRIOR TO THIS MOIST
ADVECTION WILL INITIALLY LIMIT PRECIPITATION RATES AND EVEN
STALL THE TIMING OF PRECIPITATION ONSET (OR LIMIT INITIAL RAIN
TO SPRINKLES).
THE MOISTURE SURGE REMAINS NOTABLE AS PWAT VALUES RISE NEAR THE
75TH CLIMATOLOGICAL PERCENTILE, WHICH INCREASES FLOODING RISKS.
HOWEVER, MINIMAL INSTABILITY PLUS WEAK DRY DOWNSLOPING AND
LIMITED SURFACE LIFT WILL PRECLUDE RISKS FOR WIDESPREAD FLASH
FLOODING WHILE THE LACK OF OVERLY SATURATED GROUNDS SHOULD
FURTHER MITIGATE RISKS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- RAIN CONTINUES INTO WEDNESDAY NIGHT BEFORE TAPERING OFF.
- DRY WEATHER FAVORED THURSDAY.
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SCATTERED TO NUMEROUS RAIN SHOWERS WILL PERSIST THROUGH MUCH OF
THE DAY WEDNESDAY AS ADDITIONAL SHORTWAVE MOVEMENT FROM THE WEST
CONTINUES LARGE SCALE ASCENT WITHIN THE MOIST UPPER OHIO RIVER
VALLEY ENVIRONMENT. THE PASSAGE OF THE UPPER TROUGH WEDNESDAY
AFTERNOON/EVENING MAY LIFT THE WARM FRONT FAR ENOUGH NORTH TO
ALLOW BRIEF HEATING BEFORE THE NOMINAL COLD FRONT ARRIVES; IF
SO, A LINE OF SCATTERED THUNDERSTORMS FAVORING THE I-70 CORRIDOR
AND SOUTH MAY DEVELOP BUT IS UNLIKELY TO REACH SEVERE LEVELS
(AND WILL BE TOO PROGRESSIVE TO POSE FLASH FLOOD THREAT).
OVERALL, MODEL TRENDS HAVE SHIFTED THE EVENT TOTAL QPF AXIS SLIGHTLY
EAST IN PART TO THE DEVELOPMENT OF A COASTAL LOW AND SOME
INTRUSION OF DRIER AIR FROM THE WEST. THIS MEANS THE
PROBABILITIES FOR EXCEEDING 1" HAVE FALLEN FOR MOST LOCATIONS
AND IS GENERALLY LESS THAN 50% OUTSIDE OF NORTHERN WV INTO THE
LAUREL HIGHLANDS. IF A FLOODING THREAT WERE TO DEVELOP, THE
FOCUS IS ON THE WV HIGHER TERRAIN AND LAUREL HIGHLANDS WHERE
UPSLOPE FLOW WITH SURFACE EAST WINDS MAY RESULT IN PRECIPITATION
RATE ENHANCEMENTS. HREF MODELING SUGGESTS THESE AREAS HAVE A
10-30% PROBABILITY FOR SEEING MORE THAN 2", BUT IS MORE LIKELY
JUST EAST OF THE FORECAST AREA. THUS, NO FLOOD HIGHLIGHTS ARE
BEING MENTIONED AT THIS TIME.
BY THURSDAY MORNING, THE UPPER TROUGH WILL HAVE SHIFTED TOWARDS
THE NEW ENGLAND REGION AS WEAK ZONAL TO SLIGHTLY RIDGING
DEVELOPS IN THE FORECAST AREA. LINGERING MOISTURE COMBINED
WITHIN SUBTLE WAVES WITHIN THIS FLOW COULD SPARK AN ISOLATED
AFTERNOON SHOWER/THUNDERSTORM THURSDAY, BUT OVERALL THE REGION
SHOULD BE DRY WITH GLIMPSES OF SUNSHINE. THE HEIGHT INCREASES
AND GREATER SUNSHINE WILL AID TEMPERATURE REBOUNDS FROM READINGS
AROUND 10 DEGREES BELOW AVERAGE WEDNESDAY TO NEAR AVERAGE
THURSDAY.
LONG TERM /FRIDAY THROUGH MONDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPERATURES EXPECTED
- LIGHT RAIN CHANCES CONTINUE INTO THE WEEKEND
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ENSEMBLE MODELS DEPICT THE GRADUAL EASTWARD TRANSITION OF A
SAGGING UPPER LEVEL TROUGH AXIS FROM THE CENTRAL PLAINS AS WELL
AS A DIVING LOBE OF ENERGY FROM EASTERN CANADA POTENTIALLY
COALESCING NEAR THE FORECAST REGION FRIDAY INTO SATURDAY. EXPECT
AN INCREASE IN PRECIPITATION CHANCES FRIDAY INTO SATURDAY
MORNING WITH SHOWERS SLOWLY TAPERING OFF THROUGH SUNDAY.
THE BIGGEST QUESTION AROUND THIS PERIOD SURROUNDS THE DEGREE OF
PHASING AND DEPTH OF THE RESULTANT TROUGH. NOT ONLY WILL THIS
DICTATE TIMING AND DURATION OF PRECIPITATION CHANCES, BUT WILL
GREATLY ALTER THE TEMPERATURE OUTLOOK. DEEPER/SLOWER TROUGH
OUTCOME WOULD MEAN PROLONGED PRECIPITATION CHANCES INTO SUNDAY
WITH TEMPERATURE WELL BELOW NORMAL (ON THE ORDER OF 10 TO 15
DEGREES BELOW THE AVERAGE). A MORE PROGRESSIVE AND LESS DEEP
TROUGH WOULD RETURN DRY CONDITIONS MORE QUICKLY SATURDAY EVENING
AND ALLOW TEMPERATURE TO HOVER NEAR/SLIGHTLY BELOW NORMAL
SATURDAY BEFORE WARMING SLIGHTLY ABOVE NORMAL SUNDAY. CURRENT
FORECAST IS A HEDGE TOWARD THE COLDER SOLUTION AND BETTER
MIRRORS RECENT ENSEMBLE TEMPERATURE TRENDS TOWARD A LOWER MEAN.
CONFIDENCE IS FAIRLY HIGH ON RAPID HEIGHT RISES OCCURRING SUNDAY
INTO MONDAY AS THE TROUGH SHIFTS EAST THAT WILL FOSTER RAPID
TEMPERATURE RISES TO NEAR/ABOVE NORMAL FOR THE NEXT WORK WEEK.
AVIATION /07Z 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...FRAZIER
NEAR TERM...FRAZIER
SHORT TERM...FRAZIER
LONG TERM...FRAZIER
AVIATION...CRAVEN
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