763
FXUS61 KPBZ 271858
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
258 PM 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 TEMPERATURES 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.
- GUSTY CONDITIONS WITH DOWNSLOPING ACROSS THE RIDGES.
- SEASONABLY COOL TEMPERATURE PERSISTS.
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THE INITIAL WAVE OF RAIN CONTINUES TO SLOWLY LIFT NORTHWARDS
THIS AFTERNOON WITH LOW-LEVEL WARM/MOIST ADVECTION AHEAD OF WEAK
SFC LOW PRESSURE. DESPITE HEALTHY RADAR RETURNS SOUTH OF
PITTSBURGH, A DRY SURFACE LAYER HAS PREVENTED MORE THAN LIGHT
SPRINKLES FROM REACHING THE GROUND IN MOST CASES. PIT ACARS
SOUNDINGS STILL SHOW A SIGNIFICANT DRY LAYER BELOW 700MB. TOP-
DOWN MOISTENING THROUGH THE REMAINDER OF THE AFTERNOON WILL
GRADUALLY ALLOW THE NORTHWARD SPREAD OF LIGHT TO OCCASIONALLY
MODERATE RAIN. LATEST CAMS KEEP MOST RAIN SOUTH OF I-80 THROUGH
AROUND 09Z, WHEN A SECOND SURGE BEGINS TO MORE RAPIDLY SPREAD
NORTHWARDS AS SFC LOW PRESSURE LIFTS NORTH.
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. CHANCES THROUGH TONIGHT FOR >1" EXCEED
50% ONLY IN PRESTON AND TUCKER COUNTIES, WEST VIRGINIA.
SOUTHEASTERLY FLOW WILL RAMP UP THIS EVENING INTO WEDNESDAY.
DOWNSLOPING ACROSS THE RIDGES WILL LEAD TO NEAR-ADVISORY LEVEL
GUSTS ACROSS THE RIDGES AND IMMEDIATELY DOWNSTREAM. HREF
PROBABILITIES OF >45MPH GUSTS EXCEED 80% IN A FEW POCKETS OF
WESTMORELAND COUNTY.
WITH OVERCAST SKIES AND INCOMING RAINFALL, HIGH TEMPERATURES
WILL RUN A FEW DEGREES COOLER THAN AVERAGE, ESPECIALLY ACROSS
SOUTHERN PORTIONS OF THE AREA. OVERNIGHT LOWS WILL RUN A DEGREE
OR TWO BELOW AVERAGE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- RAIN CONTINUES INTO WEDNESDAY NIGHT BEFORE TAPERING OFF.
- MOSTLY DRY WEATHER FAVORED THURSDAY.
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ADDITIONAL SHORTWAVES ABOUT THE LARGE CENTRAL CONUS TROUGH WILL
SUPPORT THE PERSISTENCE OF SCATTERED TO NUMEROUS SHOWERS
THROUGH MUCH OF WEDNESDAY. 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). GUSTY CONDITIONS WITH DOWNSLOPING ACROSS THE RIDGES
WILL DIMINISH WEDNESDAY AFTERNOON.
LATEST GUIDANCE CONTINUES TO TREND SLIGHTLY EAST WITH THE AXIS
OF HEAVIEST RAINFALL, AND STORM TOTALS HAVE SLIGHTLY DECREASED
AS A RESULT. PROBABILITIES FOR >1" TUESDAY AFTERNOON THROUGH
WEDNESDAY NIGHT REMAIN HIGHEST (>50%) ACROSS WEST VIRGINIA AND
IN THE LAURELS, WITH AREAS OVER 80% ACROSS PRESTON AND TUCKER
COUNTIES. FORECAST TOTALS GENERALLY RUN FROM 0.50" TO 0.75"
ELSEWHERE, WITH <0.5" NORTH OF I-80. 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 HAS BACKED OFF
THE PROBABILITIES OF 2" IN THIS AREA, THOUGH MAINTAINS A SMALL
AREA OF 30-50% FOR FAR EASTERN TUCKER COUNTY (DOLLY SODS).
THE UPPER SHORTWAVE TROUGH WILL EXIT THE REGION BY EARLY
THURSDAY MORNING, BRINGING QUASI-ZONAL FLOW TO THE AREA.
LINGERING MOISTURE AND ADDITIONAL WEAK WAVES THROUGH THIS FLOW
COULD PROMPT A FEW ISOLATED SHOWERS AND THUNDERSTORMS THURSDAY,
BUT MANY OF US SHOULD REMAIN DRY. POCKETS OF SUNSHINE AND HEIGHT
INCREASES WILL BOOST ARE TEMPERATURES BACK TO NEAR-AVERAGE AND
ROUGHLY 10 DEGREES WARMER THAN WEDNESDAY.
LONG TERM /FRIDAY THROUGH MONDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPERATURES CONTINUE THIS WEEKEND, WARMING NEXT
WEEK
- LIGHT RAIN CHANCES CONTINUE INTO THE WEEKEND
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SOME UNCERTAINTY REMAINS IN REGARDS TO PRECIPITATION CHANCES
FRIDAY INTO SATURDAY. ENSEMBLE GUIDANCE CONTINUES TO SHOW
DEEPER SHORTWAVE TROUGHING CROSSING OUT OF THE UPPER MIDWEST
LATE THURSDAY AND INTO THE OHIO VALLEY ON FRIDAY, EVENTUALLY
PHASING WITH THE BROAD UPPER TROUGH LATE FRIDAY. GREATEST
UNCERTAINTY IS TIED TO DEGREE OF PHASING/DEPTH OF THE TROUGH,
AND ULTIMATELY THE LOCATION OF DEVELOPING SURFACE LOW PRESSURE
SOUTH OF THE REGION ON FRIDAY, EVENTUALLY CROSSING INTO NEW
ENGLAND AND THE NORTHEAST ATLANTIC COAST. SOME SOLUTIONS (THOUGH
WITH INCREASINGLY LOWER MEMBERSHIP) KEEP MOST MOISTURE SOUTH OF
THE REGION, LIMITING RAINFALL FOR FRIDAY INTO SATURDAY AND
CLEARING SHOWERS EARLIER ON SATURDAY. GIVEN INCREASING ODDS,
HAVE CHANCE RAIN/THUNDER FOR MOST OF THE AREA DURING THIS
TIMEFRAME. ANY LINGERING SHOWERS SHOULD TAPER OFF EARLY SUNDAY
AS THE TROUGH SHIFTS NORTHEAST.
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 /18Z TUESDAY THROUGH SUNDAY/
LLOW 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...
RAIN IS GRADUALLY MAKING ITS WAY NORTHWARD INTO THE AREA THIS
AFTERNOON AS VFR CEILINGS LOWER IN RESPONSE TO THE MOISTENING
SUB-CLOUD LAYER. CEILING AND VISIBILITY RESTRICTIONS RETURN TO
THE ENTIRE AREA THIS EVENING THROUGH TONIGHT AS RAIN CONTINUES
TO ADVANCE NORTHWARD, WITH IFR SETTLING IN BY SUNRISE AND
RESTRICTIONS CONTINUING THROUGH THE REMAINDER OF THE PERIOD.
WIND GUSTS OF 20 TO 25 KNOTS REMAIN POSSIBLE AT AREA TERMINALS.
ANY SETTLING OF SURFACE WINDS THAT IS ABLE TO OCCUR OVERNIGHT
WILL BE ACCOMPANIED BY LLWS AS A 40-50 KNOT JET SETS UP.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...RACKLEY
NEAR TERM...RACKLEY
SHORT TERM...RACKLEY
LONG TERM...RACKLEY/FRAZIER
AVIATION...CERMAK
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