046  
FXUS61 KPBZ 181906  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
306 PM EDT FRI JUL 18 2025  
   
SYNOPSIS
 
 
A STALLED BOUNDARY ACROSS THE SOUTHERN PART OF THE AREA WILL  
CONTINUE TO PROVIDE A HEAVY RAINFALL THREAT THIS EVENING, MAINLY  
SOUTH OF I-70. ADDITIONAL CHANCES FOR FLASH FLOODING, AS WELL AS  
AT LEAST ISOLATED SEVERE STORMS, WILL OCCUR THIS WEEKEND AS A  
WARM FRONT LIFTS THROUGH SATURDAY, AND A COLD FRONT PASSES  
SUNDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
KEY MESSAGES:  
 
- A STALLED BOUNDARY WILL BE A FOCUS OF A HEAVY RAINFALL THREAT,  
MAINLY SOUTH OF I-70, WITH LIGHTER RAIN TO THE NORTH  
- FOG DEVELOPMENT IS LIKELY OVERNIGHT IN AREAS THAT GET HEAVY  
RAIN TODAY.  
---------------------------------------------------------------  
 
A BOUNDARY REMAINS STALLED IN THE GENERAL VICINITY OF THE  
MASON-DIXON LINE THROUGH TONIGHT. CROSSING PERTURBATIONS IN THE  
QUASI-ZONAL MID-LEVEL FLOW HAVE FOSTERED MORE OF A STRATIFORM  
RAIN TO THE NORTH OF THE BOUNDARY, AND MORE OF A CONVECTIVE  
NATURE TO THE SOUTH, IN AN AREA WITH 1000-2000 J/KG OF SURFACE-  
BASED CAPE AND PRECIPITABLE WATER VALUES IN THE 1.9 TO 2.0 INCH  
RANGE. THERE HAS ALREADY BEEN SOME TRAINING OF SHOWERS IN THE  
AREA OF THE ONGOING FLOOD WATCH, AND THIS POTENTIAL WILL  
CONTINUE INTO THIS EVENING. HREF MAXIMUM RAINFALL POTENTIAL  
SUGGEST POCKETS OF 2-3 INCHES OF RAINFALL THROUGH THIS EVENING  
IS POSSIBLE, WHICH REPRESENTS A FLOODING RISK, ESPECIALLY IF IT  
FALLS ON GROUND THAT IS MORE SATURATED FROM PREVIOUS RAIN.  
 
IN CONTRAST, THE RISK OF SEVERE THUNDERSTORMS APPEARS QUITE LOW.  
THE HIGH PWAT AND SKINNY CAPE PROFILES SUGGESTS THAT UPDRAFTS  
WILL BE RELATIVELY WEAK, AND DCAPE LEVELS REMAIN RELATIVELY LOW.  
CANNOT TOTALLY RULE OUT A WIND GUST OR TWO IN TUCKER COUNTY AND  
VICINITY, WHERE HIGHER CAPE AND EFFECTIVE SHEAR MAY SUPPORT  
ENOUGH STORM ORGANIZATION FOR A WIND THREAT.  
 
MUCH OF THE ACTIVITY WILL BEGIN TO WEAKEN AFTER SUNSET, WITH  
ONLY SCATTERED/ISOLATED ACTIVITY IN THE RIDGES BY 06Z AS  
INSTABILITY DIURNALLY DECREASES. LINGERING LOW-LEVEL MOISTURE  
AND DAYTIME RAIN WILL LED TO SOME FOG DEVELOP TONIGHT,  
ESPECIALLY OVER THE RIDGES AND LOCATIONS IN WV THAT RECEIVED  
THE HEAVIER TOTALS.  
 

 
   
SHORT TERM /SATURDAY THROUGH SUNDAY/
 
 
KEY MESSAGES:  
 
- THE FRONT LIKELY RETURNS NORTH ON SATURDAY, BRINGING A RISK OF  
HEAVY RAIN AND FLOODING AT LEAST TO AREAS SOUTH AND WEST OF  
PITTSBURGH.  
- A MORE ISOLATED FLOODING THREAT IS POSSIBLE SUNDAY WITH A COLD  
FRONTAL PASSAGE.  
- SEVERE POTENTIAL FOR SATURDAY AND SUNDAY, WITH DAMAGING WIND  
GUSTS BEING THE MOST LIKELY THREAT.  
----------------------------------------------------------------  
 
THE BOUNDARY WILL BEGIN TO LIFT NORTHWARD ACROSS THE REGION AGAIN ON  
SATURDAY, AS A SHORTWAVE TROUGH CROSSES THE MIDDLE/UPPER OHIO  
VALLEY, AND AS SURFACE LOW PRESSURE CROSSES THE UPPER MIDWEST INTO  
LOWER MICHIGAN BY 00Z SUNDAY.  
 
TRENDS IN THE CAMS SUGGEST LATER TIMING FOR THE BULK OF THE  
PRECIPITATION, MORE TOWARDS THE VERY LATE AFTERNOON AND  
EVENING. MODEL SOUNDINGS ARE SUGGESTING SOME MID-LEVEL WARM  
AIR/CAPPING THAT MAY INHIBIT CONVECTION UNTIL THE SHORTWAVE  
ARRIVES LATER IN THE DAY. THIS LATE-DAY CONVECTION MAY ARRIVE IN  
THE FORM OF A WEAKENING MCS IN OHIO, AT A TIME WHEN INSTABILITY  
MAY BE DIURNALLY DECREASING. SPC HAS PULLED THE DAY 2 SLIGHT  
RISK A BIT FURTHER WEST, ESSENTIALLY OUT OF THE FORECAST AREA,  
WHILE MAINTAINING A MARGINAL RISK OVER AREAS NORTH AND WEST OF  
MGW. THIS SEEMS REASONABLE, AS INCREASING LOW- LEVEL FLOW AND  
20-30 KNOTS OF DEEP SHEAR MAY SUPPORT STORM CLUSTERS CAPABLE OF  
DAMAGING WIND GUSTS MAINLY, WITH A LESSER RISK OF LARGE HAIL.  
 
THE FLOODING RISK STILL EXISTS AS WELL GIVEN THE LIKELIHOOD OF PWATS  
RISING ABOVE THE 90TH PERCENTILE ONCE AGAIN BY LATER  
SATURDAY/SATURDAY NIGHT, WITH SOUNDINGS SUPPORTING WARM RAIN  
PROCESSES ESPECIALLY IN EASTERN OHIO. INTERESTINGLY, HREF  
PROBABILITIES OF GREATER THAN AN INCH OF RAIN OVER 24 HOURS ARE  
FAIRLY SUPPRESSED THROUGH SATURDAY NIGHT, MAXIMIZING IN THE  
30-50% RANGE WEST OF THE OHIO RIVER AND SOUTH OF I-70. WHILE THE  
BEST FLOOD RISK MAY EXIST TO THE SOUTHWEST OF PITTSBURGH  
THROUGH TOMORROW NIGHT, THINK THAT THESE PROBABILITIES MAY BE A  
BIT UNDERDONE. WHILE STORM MOTIONS WILL BE HIGHER, THE  
POTENTIAL FOR HEAVY RATES AND AN ALREADY SATURATED GROUND WILL  
KEEP THE FLOOD RISK ELEVATED.  
 
SUNDAY WILL FEATURE A COLD FRONTAL PASSAGE AS THE MICHIGAN  
SURFACE LOW TRACKS INTO NEW ENGLAND. ENSEMBLES SUGGEST A SEVERE  
THREAT PERHAPS AS EARLY AS THE LATE MORNING HOURS AND INTO THE  
AFTERNOON, WITH POTENTIAL FOR 1000-1500 J/KG OF SURFACE-BASED  
CAPE OVERLAPPING WITH 30-40 KNOTS OF DEEP SHEAR, MAINLY FROM  
PITTSBURGH ON SOUTH. THIS SUPPORTS THE DAY 3 MARGINAL RISK IN  
THIS AREA FROM SPC FOR MAINLY A WIND THREAT. THE FLOODING RISK  
WILL LIKELY BE CONFINED TO AREAS WHERE EAST-WEST TRAINING MAY  
OCCUR AHEAD OF THE ADVANCING FRONT.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
KEY MESSAGES:  
 
- BUILDING HIGH PRESSURE ALOFT MAY PROVIDE RELATIVELY DRY  
WEATHER EARLY NEXT WEEK.  
- HEAT AND HUMIDITY BEGIN TO INCREASE DURING THE MIDDLE PART OF  
THE WEEK.  
- SHOWER/THUNDERSTORM CHANCES INCREASE THURSDAY AND FRIDAY.  
-------------------------------------------------------------------  
 
 
THERE IS GOOD CONFIDENCE AMONG THE ENSEMBLES THAT STRONG RIDGING  
BUILDS OVER THE MISSISSIPPI VALLEY AND INTO THE EASTERN CONUS NEXT  
WEEK. ALONG WITH CROSSING HIGH PRESSURE TO OUR NORTH, A MAINLY  
DRY PATTERN APPEARS TO EXTEND INTO TUESDAY, AND POSSIBLY INTO  
WEDNESDAY, WITH THE POTENTIAL FOR SUBSIDENCE/WARM AIR ALOFT TO  
SUPPRESS CONVECTION. OF COURSE, THIS WILL ALSO LEAD TO ABOVE-  
NORMAL TEMPERATURES. NBM PROBABILITIES OF 90+ HIGHS INCREASE TO  
40-70% OVER MUCH OF THE AREA BY WEDNESDAY, AND THEN 50-80% ON  
THURSDAY. COMBINED WITH HIGH DEWPOINTS, HEAT RISK IS SET TO  
RISE BY THE END OF THE FORECAST PERIOD.  
 
SHORTWAVES RIDING THE TOP OF THE RIDGE MAY BEGIN TO SUPPRESS HEIGHTS  
SLIGHTLY BY THE THURSDAY/FRIDAY PERIOD. THIS COULD LEAD TO BETTER  
RAIN CHANCES DURING THIS PERIOD. LONGER-RANGE MACHINE LEARNING  
GUIDANCE SUGGESTS AN UPTICK IN SEVERE STORM POTENTIAL AS WELL, WHICH  
MAKES SENSE GIVEN THE AMOUNT OF INSTABILITY/MOISTURE THAT MAY BE  
AVAILABLE.  
 

 
   
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
 
 
CROSSING MOISTURE ON A SHORTWAVE TODAY WILL CONTINUE TO ALLOW A  
MIXED BAG OF RESTRICTIONS, WITH VFR GENERALLY MORE LIKELY IN  
THE NORTH, AND IFR MORE LIKELY IN THE SOUTH WITH LOWER CLOUD  
BASES AND MORE INTENSE RAIN NEAR A STATIONARY FRONT.  
 
IN TRACKING WITH TRENDS, WE EXPECT A DECREASE IN SHOWER COVERAGE  
INTO THE EVENING, WITH SOME MORE CONVECTION POSSIBLE IN THE  
PERIPHERY OF THE FRONT. FOR THIS REASON, A VCTS WAS MAINTAINED  
IN THE MGW TAF WITH CONVECTION TIED TO THE PA/WV BORDER JUST  
NORTH.  
 
NEARLY ALL AREA PORTS EXPERIENCED AT LEAST SOME RAIN TODAY,  
WHICH WILL BE FOLLOWED BY ONLY A SCT/BKN DECK AND ALLOW SOME  
COOLING OVERNIGHT. WITH CALM WINDS AND MOISTURE, AT LEAST EVERY  
PORT HAS THE CHANCE TO SEE FOG OR LOW STRATUS. WHILE POINT  
PROBABILITIES OF DENSE FOG ARE GENERALLY 20% TO 40%, THESE MAY  
BE UNDER-DOING POTENTIAL GIVEN THE AMOUNT OF DAYTIME RAIN. THE  
LOWEST VIS WAS NOTED FOR THE MOST SUSCEPTIBLE PORTS, AND ONES  
THAT SAW THE MOST RAIN TODAY.  
 
SOME CLEARING IS EXPECTED BEYOND DAYBREAK, THROUGH CIG LIFTING  
MAY BE SLOWER FOR SOUTHERN PORTS (NOTABLY MGW, ZZV, AND HLG)  
WITH PROBABILITY OF MVFR CIGS THROUGH 16Z >50%. ANOTHER ROUND OF  
AFTERNOON STORMS IS POSSIBLE AS A WARM FRONT LIFTS NORTH, BUT  
COVERAGE SHOULD REMAIN ISOLATED, IF ANY, INTO THE DAYTIME HOURS  
SATURDAY.  
 
OUTLOOK...  
A CHANCE OF SHOWERS/STORMS IS POSSIBLE OVERNIGHT SATURDAY ON A  
PREFRONTAL TROUGH, THROUGH CHANCES OF RAIN AND GUSTY WINDS HAVE  
DECREASED SINCE THE LAST UPDATE. THE ACTUAL COLD FRONT PASSAGE  
SUNDAY WILL ALLOW ADDITIONAL LATE-MORNING TO AFTERNOON STORM  
CHANCES INCLUDING, AND SOUTH OF, PIT. DRY WEATHER RETURNS EARLY  
NEXT WEEK BEFORE MORE RAIN CHANCES MID-TO-LATE WEEK.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
OH...FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR OHZ057-058-068-069.  
WV...FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR WVZ012-021-509>514.  
 

 
 

 
 
SYNOPSIS...CL  
NEAR TERM...CL  
SHORT TERM...CL  
LONG TERM...CL  
AVIATION...MILCAREK  
 
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