296  
FXUS61 KPBZ 242159  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
559 PM EDT WED JUL 24 2024  
   
SYNOPSIS
 
 
SHOWERS AND STORMS ARE EXPECTED THROUGH THROUGH A THURSDAY  
AHEAD OF A COLD FRONT. DRY CONDITIONS AND A WARMING TREND ARE  
EXPECTED INTO THE WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
 
 
KEY MESSAGES:  
 
- REMNANT SHOWERS AND STORMS ARE EXPECTED THROUGH THE LATE  
EVENING AND OVERNIGHT TIME PERIOD.  
- PROBABILITY OF STORM BEING SEVERE HAS DECREASED SIGNIFICANT  
OVER THE LAST 2 HOURS.  
 
----------------------------------------------------------------  
 
CONVECTION OUTFLOW HAS OVERSPREAD WESTERN PENNSYLVANIA AND  
EASTERN OHIO REGION OVER THE LAST 2 HOURS. DRIER AIR ALOFT,  
NOTED EARLIER, IS NO LONGER AVAILABLE FOR STRONG TO SEVERE WIND  
GUSTS ASSOCIATED WITH DOWNDRAFTS. AT THE MOMENT, LIGHTNING AND  
SUB- SEVERE WIND GUSTS (LESS THAN 45MPH) WILL BE THE MAIN  
THREAT. A FEW STORMS MAY PRODUCE HEAVY RAINFALL RATES; AN  
OBSERVER IN WHEELING, WV RECEIVED A QUICK 0.80 INCHES IN LESS  
THAN AN HOUR.  
 
A FEW RUMBLES OF THUNDER ARE POSSIBLE THROUGH THE EARLY  
OVERNIGHT HOURS AS THE LINE PROGRESSES THROUGH AREAS SOUTH OF  
PITTSBURGH IN PERHAPS A COUPLE HUNDRED JOULES OF ELEVATED  
INSTABILITY, WITH SHOWERS MORE LIKELY LATE OVERNIGHT TONIGHT.  
 
FOG AND LOW STRATUS ARE EXPECTED FOR AREAS DOWSED WITH  
PRECIPITATION OVER THE LAST 8 HOURS. FOG PROBABILITIES ARE  
HIGHEST IN THE I-80 CORRIDOR AND EASTERN OHIO GIVEN THE RECENT  
RAIN AND GREATEST LIKELIHOOD OF CLOUDS CLEARING. DENSE FOG  
PROBABILITIES ARE AROUND 30% TO 40% FOR NOW IN THOSE AREAS.  
 

 
   
SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/
 
 
KEY MESSAGES:  
 
- A COLD FRONT BRINGS ADDITIONAL SHOWER AND THUNDERSTORM  
CHANCES, MAINLY TO THE SOUTHERN HALF OF THE AREA.  
- COOLER AND DRIER WEATHER MOVES INTO THE AREA IN THE WAKE OF  
THE COLD FRONT.  
 
_________________________________________________________________  
 
WITH THE UPPER TROUGH CONTINUING TO ADVANCE EASTWARD TOWARDS THE  
NORTHEASTERN CONUS AND A SURFACE LOW OVER SOUTHERN ONTARIO  
LIFTING QUICKLY AWAY TO THE NORTHEAST, A WEAK COLD FRONT SAGS  
SOUTHEASTWARD ACROSS THE LOWER GREAT LAKES AND INTO THE LOCAL  
AREA DURING THE DAY THURSDAY. THIS WILL BE THE LAST SOURCE OF  
LIFT TO AID IN THE DEVELOPMENT OF SCATTERED SHOWERS AND  
THUNDERSTORMS, THOUGH BY THAT TIME THE BEST FORCING ALOFT WILL  
HAVE SHIFTED EAST OF THE AREA. WITH THESE FEATURES BEING OUT OF  
PHASE, NOT EXPECTING THE CONVECTIVE COVERAGE ONE MIGHT  
TYPICALLY EXPECT ALONG A SUMMER COLD FRONT. THE BEST RAIN  
CHANCES WILL BE SOUTH OF I-70 WHERE SCATTERED SHOWERS AND STORMS  
MAY DEVELOP AS THE FRONT MOVES THROUGH IN THE HEAT AND  
INSTABILITY OF THE AFTERNOON/EVENING, WHILE AREAS FARTHER NORTH  
MAY VERY WELL SEE A DRY FROPA. THE FRONT PUSHES THROUGH THE  
AREA BY LATE THURSDAY EVENING, WITH COOLER AND DRIER AIR  
SETTLING IN BEHIND IT. LOWS THURSDAY NIGHT DIP BELOW SEASONAL  
NORMALS, INTO THE MID/UPPER 50S (LOW 50S NORTH OF I-80).  
 

 
   
LONG TERM /FRIDAY THROUGH WEDNESDAY/
 
 
KEY MESSAGES:  
 
- DRY CONDITIONS WITH A WARMING TREND EXPECTED FRIDAY THROUGH  
THIS WEEKEND.  
- A COUPLE DISTURBANCES MAY PASS THROUGH EARLY NEXT WEEK.  
- MODERATE RISK OF EXCESSIVE HEAT BEGINNING IN AUGUST.  
 
________________________________________________________________  
 
ENSEMBLE CLUSTERS HAVE SURPRISINGLY FEW DIFFERENCES THROUGH THE  
LONG RANGE FORECAST, SUGGESTING HIGH CONFIDENCE IN THE PATTERN  
THROUGH THE REST OF THE MONTH.  
 
THAT PATTERN BEGINS WITH RIDGING THROUGH THIS WEEKEND WITH  
HEIGHTS OF 500MB HEIGHTS OF 890-940DM FORECAST THROUGH AT LEAST  
SUNDAY. FROM THERE, THE AREA SITS ROUGHLY ON THE BACKSIDE OF THE  
SURFACE RIDGE AXIS, ALLOWING A BRIEF RETURN OF WARM AND MOIST  
SOUTHWEST FLOW. THIS WOULD SUPPORT A BRIEF UNSETTLED PATTERN  
THROUGH THE MIDDLE OF NEXT WEEK WITH A FEW PASSING DISTURBANCES.  
 
BY THE END OF NEXT WEEK, ENSEMBLES ARE HIGHLY CONFIDENT IN A  
STRONG CENTRAL CONUS RIDGE THAT WOULD PLACE OUR AREA IN  
NORTHWEST FLOW ALOFT. WHILE THESE PATTERNS TEND TO BE DRY ON  
AVERAGE, THEY ARE ALSO SUPPORTIVE OF SEVERE WEATHER CHANCES.  
SEVERE PROBABILITIES INCREASING ARE ALSO REFLECTED IN THE CSU-  
MLP. IN ADDITION, HEAT CONCERNS RETURN. ACCORDINGLY, CPC HAS  
ISSUED ANOTHER MODERATE RISK OF EXCESSIVE HEAT FROM AUGUST 1ST  
THROUGH AUGUST 7TH. LASTLY, WITH FLOW FROM THE CANADIAN ROCKIES  
ALOFT, WILDFIRE SMOKE COULD MAKE ITS DEBUT TO THE PITTSBURGH  
REGION THIS YEAR.  
 

 
   
AVIATION /22Z WEDNESDAY THROUGH MONDAY/
 
 
STORMS HAVE FIRED A LITTLE SOONER AND IN A LITTLE MORE  
WIDESPREAD MANNER THAN ANTICIPATED EARLIER, AS INSTABILITY HAS  
TENDED TOWARDS THE HIGHER END OF MODEL GUIDANCE. STILL EXPECT  
SOME FORM OF STORM ORGANIZATION INTO LINE SEGMENTS WITH TIME,  
WHICH WILL PRESENT THREATS OF BRIEF IFR/LIFR VISIBILITY IN HEAVY  
RAIN AND WIND GUSTS OF 30 TO 45 KNOTS IN THE STRONGER STORMS.  
HAVE TRIED TO PROVIDE MOST LIKELY TIMING OF HIGHER IMPACTS IN  
TAFS. LBE AND MGW ARE LEAST LIKELY TO SEE STRONGER STORMS AND  
HAVE USED VCTS FOR THOSE LOCATIONS. OTHER SITES, PARTICULARLY  
FKL AND DUJ, ARE MORE LIKELY TO GET THE STRONGER IMPACT.  
 
ACTIVITY WILL BEGIN TO WEAKEN AFTER 00Z WITH SUNSET AND LOSS OF  
INSTABILITY, ALTHOUGH WE HAVE ALLOWED VCTS MENTIONS TO LINGER  
FOR A FEW HOURS. A LATE EVENING LULL IS ANTICIPATED AT MOST  
TERMINALS WITH VFR CONDITIONS. HOWEVER, THE EXPECTED RAIN AND  
SOME PARTIAL CLEARING WILL ALLOW FOR MVFR/IFR CONDITIONS IN LOW  
CLOUDS AND FOG LATER TONIGHT. IFR IS MORE LIKELY NORTH AND WEST  
OF PIT, WHERE MORE RAIN IS EXPECTED AND WHERE CLEARING MAY BE A  
BIT MORE PRONOUNCED BEHIND AN ADVANCING COLD FRONT.  
 
IMPROVEMENT BACK TO VFR MAY BE A BIT SLOW PAST 12Z AS THE FRONT  
CONTINUES TO WORK ITS WAY ACROSS THE REGION. SCATTERED SHOWERS  
MAY FIRE ONCE AGAIN AHEAD OF THE BOUNDARY AS IT APPROACHES FAR  
SOUTHERN PA AND THE MASON-DIXON LINE BY MIDDAY, BUT VFR MAY BE  
ACHIEVED AREAWIDE BY 18Z SAVE FOR MGW/ZZV.  
 
   
OUTLOOK
 
 
ANY SHOWERS WILL END BY THURSDAY EVENING AS THE FRONT EXITS THE  
REGION. AFTER POSSIBLE FOG THURSDAY NIGHT, VFR RETURNS FRIDAY  
UNDER HIGH PRESSURE.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
OH...NONE.  
WV...NONE.  
 

 
 

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