856
FXUS61 KPBZ 071627
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1227 PM EDT MON JUL 7 2025
SYNOPSIS
SHOWERS AND STORMS TODAY COULD PROVIDE LOCALIZED CHANCES OF SEVERE
WEATHER AND FLASH FLOODING, WITH FLASH FLOOD POTENTIAL
LINGERING NEAR AND SOUTH OF THE I-70 CORRIDOR TUESDAY AND
WEDNESDAY. THE LATE-WEEK AND WEEKEND OUTLOOK FAVORS WARM AND WET
CONDITIONS.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- HEAT INDICES PUSHING 100F FOR VALLEYS AND URBAN AREAS THIS AFTERNOON.
- SHOWERS AND STORMS TONIGHT CARRY A SEVERE WIND AND FLASH
FLOODING RISK THIS AFTERNOON/EVENING.
---------------------------------------------------------------
WARM AND MOIST SOUTHWEST FLOW CONTINUES TO STREAM IN FOR THE
AFTERNOON HOURS AHEAD OF THE NEXT DISTURBANCE. A BIT OF THIS IS
EVIDENCED IN SPC MESO-ANALYSIS SHOWING 925MB TO 850MB MOISTURE
TRANSPORT WITH PWATS OF UP TO 1.8" TO 2" AHEAD OF THE TROUGH PASSAGE.
THIS MOISTURE, COMBINED WITH HIGH TEMPERATURE PUSHING THE MIDDLE 80S
TO LOWER 90S (WARMEST FOR VALLEY AND URBAN AREAS; COOLEST FOR HIGH
TERRAIN AND NORTH OF I-80), WILL SPELL CONTINUED HEAT CONCERNS FOR
THIS AFTERNOON, WITH MODERATE TO MAJOR HEAR RISK. FORECAST HEAT
INDICES MAY APPROACH 100F FOR VALLEY AND URBAN AREAS, BUT BECAUSE
COUNTY AVERAGE WILL LIKELY BE BELOW ADVISORY CRITERIA OF 100F, NO
HEAT HEADLINES WERE RAISED FOR TODAY.
HEAT WILL BE INTERRUPTED IN THE AFTERNOON TO EVENING WITH A SLOW
MOVING COLD FRONT COMING DOWN FROM THE NORTH. MEAN BOUNDARY LAYER
FLOW WILL GENERALLY BE IN THE 20KS TO 30KTS RANGE AS THE FRONT SWINGS
THROUGH. BECAUSE OF AFOREMENTIONED MOISTURE, THE FIRST THREAT TODAY
WILL BE FLOODING. HREF QPF MAXIMA TEND TO INDICATE RAINFALL RATES OF
UP TO 2"/HR WILL BE POSSIBLE IN STORMS ALONG THE FRONT, WITH VERY
LOCALIZED BOUTS OF 2" TO 3" OF RAIN, MOST LIKELY FOR THE I-80
CORRIDOR AND EASTERN OHIO, BUT POSSIBLE ANYWHERE. WITH MOST OF REGION
FORECAST WITH 1.5" TO 2.5" 1HR FFGS AND 2" TO 3" 3HR FFGS, FLASH
FLOODING WILL BE POSSIBLE IN 1) AREAS WITH THE HEAVIEST RAIN RATES
AND 2) AREAS WHERE STORMS MOVE OVER MULTIPLE TIMES, THOUGH UPPER FLOW
MAY HELP WITH REDUCED TRAINING POTENTIAL UNTIL THE FRONT SLOWS IT
PROGRESSION IN THE EVENING/EARLY OVERNIGHT. WPC MAINTAINS A
SLIGHT (OR 2/4 RISK) OF FLASH FLOODING.
THE THIRD THREAT WILL BE DAMAGING WINDS IN SEVERE STORMS. THE 12Z
SOUNDING HAS SHOWN ~400 J/KG MLCAPE AND ~15KTS OF SFC TO 6KM MEAN
WIND, BUT SOME ATMOSPHERIC MODULATION IF FORECAST BEFORE THE FRONT
DROPS DOWN INTO THE AREA. THE FIRST INGREDIENT WILL BE ~1200
J/KG FORECAST DCAPE DEVELOPING FROM DRY AIR ALOFT AHEAD OF THE
FRONT, THE SECOND WILL BE AN UPTICK IN SHEAR TO UP TO 20KTS TO
30KTS, AND THE THIRD WILL BE THE DEVELOPMENT OF DAYTIME
INSTABILITY OF UP TO 3000 TO 4000 SBCAPE, AND UP TO 2000 J/KG
MLCAPE. THE MAIN UNCERTAINTY WILL BE HOW THE FRONT TRACKS
RESPECTIVE TO THE DCAPE MAXIMA. AS EXPECTED, THE FRONT WILL BE
ON THE DCAPE GRADIENT; THE MOST FAVORABLE ENVIRONMENT FOR
DOWNBURSTS WILL BE PRE-FRONTAL, ALTHOUGH THE CHANCE OF STORMS
DEVELOPING AHEAD OF THE MAIN AXIS WILL BE LOW. CLOSER TO THE
FRONT, THE ENVIRONMENT MAY BE MORE MARGINAL, CONDITIONAL ON DRY
AIR ALOFT AND MATURE UPDRAFT DEVELOPMENT.
STORMS ARE EXPECTED TO CONTINUE INTO THE EARLY OVERNIGHT PERIOD IN
FORECAST LONG, SKINNY CAPE, BUT STORMS SHOULD GENERALLY FOLLOW A
TREND OF WEAKENING AFTER SUNSET, THOUGH FLASH FLOODING RISK MAY
PERSIST INTO THE OVERNIGHT BEFORE PROFILES AND STABILIZE SOME AND
RAINFALL RATES DECREASE BEFORE DAYBREAK. GIVEN DAYTIME RAINS,
HIGH HUMIDITY, AND CALM WINDS, LOW CEILINGS AND PATCHY FOG ARE
POSSIBLE WITH LOWS ONLY BOTTOMING OUT IN THE LOW 70S FOR SOME
SOUTH OF I-80.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
KEY MESSAGES:
- THE STALLED FRONTAL BOUNDARY WILL CONTINUE TO ALLOW FOR MORE
FLOODING CHANCES TUESDAY AND WEDNESDAY.
----------------------------------------------------------------
THE FRONT WILL SAG AROUND AND SOUTH OF THE I-70 CORRIDOR INTO TUESDAY
AND WEDNESDAY, PROVIDING DAILY CHANCES OF RAIN AND FLOODING.
UNFORTUNATELY, PWATS WILL GENERALLY REMAIN ABOVE THE 90TH PERCENTILE
(IN THE 1.75" TO 2" RANGE), PARTICULARLY NEAR AND SOUTH OF THE
BOUNDARY. WITH FORECAST WEAK WESTERLY FLOW ALONG AN EAST-WEST
BOUNDARY IN HIGH PWATS, MORE EFFICIENT RAIN RATES OF UP TO 2" APPEAR
TO CONTINUE TO BE POSSIBLE WITH TRAINING POTENTIAL. THIS WILL KEEP
FLASH FLOODING RISK MOSTLY SOUTH OF PITTSBURGH AND INTO NORTHWEST WV
AND SOUTHEAST OHIO THROUGH TUESDAY AND WEDNESDAY. WPC MAINTAINS
A MARGINAL (OR 1/4 RISK) OF FLASH FLOODING.
THE POST-FRONTAL ENVIRONMENT TUESDAY WITH SOME CLOUD COVER FOR MUCH
OF THE AREA WILL KEEP TEMPERATURES CLOSER TO NORMAL DURING THE DAY
TUESDAY WITH ABOVE AVERAGE LOWS OVERNIGHT IN BOUNTIFUL MOISTURE.
TEMPERATURES MAY CLIMB A DEGREE OR TWO HIGHER INTO WEDNESDAY WITH A
RETURN TO SOME WEAK SOUTHWESTERLY FLOW. WHILE NOT OUTLOOKED FOR
SEVERE AT THIS TIME, CSU MLP AND CIPS SHOW LOW PROBABILITY DAMAGING
WIND POTENTIAL FOR NORTHERN WEST VIRGINIA TUESDAY AND
WEDNESDAY.
LONG TERM /THURSDAY THROUGH SUNDAY/
KEY MESSAGES:
- STALLED BOUNDARY PLAGUES THE AREA WITH DAILY PRECIP CHANCES
THROUGH THE END OF THE WEEK.
- ANOTHER SYSTEM FAVORED TO MOVE IN OVER THE WEEKEND.
-------------------------------------------------------------------
THE BOUNDARY REALLY STRUGGLES TO MOVE MUCH HEADED INTO THE MIDDLE OF
THE WEEK AS MID-LEVEL FLOW PARALLELS IT. LATEST ENSEMBLE CLUSTERS
KEEP IT WIGGLING ACROSS SOUTHWESTERN PENNSYLVANIA AND NORTHERN WEST
VIRGINIA. THIS IS GOING TO PROVIDE US WITH DAILY, DIURNALLY
DRIVEN RAIN CHANCES WITHIN THE PROXIMITY OF THE BOUNDARY AS
DAYTIME HEATING FIRES SHOWERS AND STORMS OFF OF IT. A RELIEF
FROM THE HIGHER PWAT AIR SEEMS UNLIKELY, SO ANY OF THESE SHOWERS
AND STORMS WILL BE CAPABLE OF LOCALLY HEAVY RAINFALL. THE
HIGHEST PRECIP PROBABILITIES WILL REMAIN MAINLY ALONG AND SOUTH
OF THE MASON DIXON LINE THOUGH LOWER END PROBABILITIES WILL
EXIST AS FAR NORTH AS PITTSBURGH.
DEVELOPING LOW PRESSURE WILL LIFT THE BOUNDARY BACK UP NORTH AS A
WARM FRONT THURSDAY AND FRIDAY. THIS WILL OVERSPREAD HIGHER PRECIP
CHANCES TO THE AREA BOTH DAYS AS ADDITIONAL WAVES OF LOW PRESSURE
RIDE ALONG THE FRONT. WE SHOULD FINALLY RID OUR AREA OF THAT
DISTURBANCE JUST IN TIME FOR ANOTHER ONE TO DEVELOP OUT OF THE
NORTHERN PLAINS AND KEEP THE UNSETTLED PATTERN THROUGH NEXT WEEKEND.
STILL SOME ENSEMBLE DISAGREEMENT ON HOW THAT EVOLVES, BUT NOT SEEING
TOO MUCH CONFIDENCE IN A DRY WEEKEND.
TEMPERATURES ARE FAVORED TO HOLD JUST ABOVE NORMAL THROUGH NEXT
WEEKEND, THOUGH WITH CLOUD COVER AND RAIN AROUND, THEY MAY PROVE TO
BE SLIGHTLY COOLER THAN CURRENTLY FORECAST IN SPOTS.
AVIATION /16Z MONDAY THROUGH FRIDAY/
VFR CONDITIONS WITH SOME MID TO HIGH LEVEL CLOUDS EXPECTED
THROUGH THIS MORNING. WILL THEN LIKELY SEE SOME CU POP AS LOWER
LEVELS BEGIN TO MIX AND WIND PICKS UP OUT OF THE SOUTHWEST.
OVERALL, WINDS WILL VEER MORE WESTERLY DURING THE AFTERNOON
AHEAD OF A SLOW-MOVING FRONT.
THE MENTIONED FRONT, WHICH WILL CROSS IN THE AFTERNOON TO
EVENING HOURS, WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS
THAT WILL BE CAPABLE OF BOTH HEAVY RAIN AND A DAMAGING WIND
RISK. EXACT LOCATION OF A HEAVIER STORM IS DIFFICULT TO PIN DOWN,
SO HAVE INCLUDED PROB30S WITH VIS REDUCTION AND INCLUSION OF
GUSTIER WIND FOR EACH SITE DURING THE MOST LIKELY TIMEFRAME.
OUTSIDE OF ANY SHOWERS AND STORMS, VFR IS LIKELY TO PREVAIL.
A REDUCTION TO IFR OR LOWER IS INCREASINGLY POSSIBLE IN A COLD
ADVECTION REGIME WITH LINGERING NEAR-SURFACE MOISTURE BEHIND
THE FRONT TUESDAY MORNING, ESPECIALLY IN AREAS THAT SEE
THUNDERSTORMS TODAY. HREF PROB OF IFR IS UP TO 60-80% MOSTLY
ONLY IN AREAS THAT IT THINKS WILL SEE PRECIP TODAY AND MUCH
LOWER ELSEWHERE, BUT IN REALITY THAT PROBABILITY IS LIKELY
REPRESENTATIVE FOR ANYWHERE THAT SEES PRECIP TODAY.
OUTLOOK...
RESTRICTIONS WILL GRADUALLY IMPROVE HEADED INTO TUESDAY MORNING
WITH MIXING, BUT AN UNSETTLED PATTERN WILL CONTINUE FOR MUCH OF
THE REST OF THE WEEK AS MONDAY'S COLD FRONT SLOWS AND STALLS.
DIURNALLY DRIVEN STORM CHANCES WILL GOVERN CONDITIONS THE REST
OF THE WEEK WITH PERIODIC AFTERNOON AND EVENING IMPACTS
POSSIBLE EACH DAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...MILCAREK
NEAR TERM...MILCAREK
SHORT TERM...MILCAREK
LONG TERM...MLB
AVIATION...MLB
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