712  
FXUS61 KPBZ 221214 AAB  
AFDPBZ  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
814 AM EDT THU AUG 22 2019  
   
SYNOPSIS
 
 
SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON WITH THE PASSING OF A  
COLD FRONT. COOLER, DRIER AIR WILL THEN RETURN FOR THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
8AM UPDATE...INCREASE MORNING POP ACROSS SOUTHEAST OH AS AN  
OVERNIGHT STORM COMPLEX HAS MAINTAINED ENOUGH STRENGTH/ORGANIZATION  
TO INCREASE THE LIKELIHOOD OF RAIN IN THE AREA THIS MORNING. NO OTHER  
NOTABLE CHANGES MADE, THOUGH CONFIDENCE IS LOW ON THE EFFECTS THIS  
COMPLEX WILL HAVE ON THE ANTICIPATED STORM DEVELOPMENT THIS AFTERNOON  
WITH THE COLD FRONT.  
 
PREVIOUS DISCUSSION...  
 
A WEAK SHORTWAVE, EMBEDDED IN A BROAD UPPER-LEVEL TROUGH, IS  
PROVIDING ENOUGH FORCING WITH JUST ENOUGH INSTABILITY TO ALLOW  
SHOWERS TO PERSIST THROUGH CENTRAL OH THIS MORNING. AN MORE STABLE  
ENVIRONMENT ACROSS EASTERN OH/WESTERN PA SHOULD CAUSE THESE STORMS TO  
DISSIPATE THIS MORNING, BUT UNCERTAIN HAVE FAR IT WILL PROGRESS EAST  
BEFORE TAPERING OFF. TO THE NORTH, A SWATH OF LIGHTER RAIN SHOWERS  
WILL CONTINUE TO TRAVERSE EAST ALONG THE COLD FRONTAL BOUNDARY THIS  
MORNING.  
 
A MORE PROMISING UPPER-LEVEL SHORTWAVE WILL HELP ADVECT DEEPER  
MOISTURE INTO THE REGION BY THIS AFTERNOON, WITH PWAT VALUES AROUND 1  
SD ABOVE NORMAL. AS THE TROUGH DEEPENS, THE SURFACE COLD FRONT WILL  
SAG SOUTH OUT OF LAKE ERIE, HELPING PROVIDE LIFT FOR STORM  
INITIATION. THE COMBINATION OF HIGH MOISTURE CONTENT, WESTERLY FLOW  
ALOFT, AND AN WEST-EAST ORIENTED FRONT, THERE IS INCREASED POTENTIAL  
FOR FLASH FLOODING DUE TO TRAINING OF STORMS THAT PRODUCE HIGHER  
RAINFALL RATES. HOWEVER, THE LACK OF STRONGER INSTABILITY DUE TO  
CLOUD COVER FROM MORNING CONVECTION WILL MUTE THE THREAT ENOUGH TO  
PRECLUDE WATCH ISSUANCE. AT THE MOMENT, AREAS ALONG AND SOUTH OF I-70  
WILL HAVE THE BEST CHANCES FOR THE HEAVIEST ACCUMULATIONS DUE TO THE  
EXPECTED GREATER INSTABILITY IN THE REGION.  
 
THE COLD FRONT SHOULD COMPLETE ITS PASSAGE BY LATE THURSDAY NIGHT FOR  
AREAS NORTH OF I-70.  
 

 
   
SHORT TERM /FRIDAY/
 
 
A FEW STRAY SHOWERS MAY LINGER IN NORTHERN WV/WESTERN MARYLAND EARLY  
FRIDAY MORNING AS THE FRONTAL BOUNDARY EXITS TO THE SOUTHEAST.  
TEMPERATURES ARE EXPECTED TO BE NEAR OR JUST BELOW THE CLIMATOLOGICAL  
AVERAGE, WITH HIGHS IN THE 70S ON FRIDAY. DEW POINTS TOO ARE  
EXPECTED TO DROP INTO THE LOW-50S, UPPER-40S NEAR I-80, AND BRING  
COMFORTABLE CONDITIONS.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
 
 
SURFACE HIGH PRESSURE AND NORTHWEST FLOW ALOFT IS ANTICIPATED TO  
BRING DRY AND COMFORTABLE WEATHER THROUGHOUT THE WEEKEND.  
 
RETURN, SOUTHWESTERLY FLOW ALOFT ASSOCIATED WITH A DEEPENING CENTRAL  
PLAINS TROUGH IS EXPECTED TO SUPPORT AN INCREASE IN BOTH TEMPERATURE  
AND MOISTURE BY EARLY NEXT WEEK, WITH HIGH TEMPERATURE REBOUNDING TO  
NEAR CLIMATOLOGICAL NORMALS. PRECIPITATION CHANCES WILL BE LARGELY  
DETERMINED BY SHORTWAVE ACTIVITY TRAVERSING THROUGH THE BASE OF THE  
TROUGH THROUGH MID-WEEK.  
 

 
   
AVIATION /12Z THURSDAY THROUGH MONDAY/
 
 
AN UPPER LEVEL SHORTWAVE PLUS A SFC COLD FRONT WILL MOVE SLOWLY  
THROUGH THE REGION TODAY, BRING SHOWERS/TSTMS TO MOST SITES.  
RESTRICTIONS ARE LIKELY WITH ANY STORMS IN ADDITION TO LOWERED CIGS  
BEFORE/JUST BEHIND THE COLD FRONTAL PASSAGE. SHOWERS/STORMS WILL  
END SHORTLY AFTER THE FRONTAL PASSAGE, WITH THE FRONT EXPECTED TO  
STOP SOMEWHERE SOUTH OF I-70.  
 
MOST AREAS WILL REMAIN DRY/VFR OVERNIGHT BEHIND THE FRONT, THOUGH A  
PERIOD OF LOW STRATUS/FOG COULD DEVELOP IF ENOUGH CLOUDS CLEAR AND  
DRY AIR IS SLOWER TO MOVE IN. AROUND AND SOUTH OF THE STALLED FRONT,  
MVFR/IFR RESTRICTIONS WILL BE MORE LIKELY WITH OCCASIONAL WAVES OF  
SHOWERS DUE TO PASSING WEAK DISTURBANCES THROUGH FRIDAY MORNING.  
 
THERE REMAINS UNCERTAINTY IN THE TIMING/PROGRESSION OF THE FRONT,  
THE AMOUNT OF INSTABILITY AVAILABLE FOR STORM GENERATION, AND THE  
DEGREE OF CLEARING BEHIND THE FRONT AS MODELS CONTINUE TO STRUGGLE  
WITH THESE DETAILS. IT IS FURTHER COMPLICATED BY THE PRESENCE OF  
CONVECTION THAT MOVED THROUGH OH THIS MORNING AND ITS IMPACTS ON THE  
ENVIRONMENT.  
   
OUTLOOK
 
 
VFR CONDITIONS WILL RETURN FOR ALL LOCATIONS BY FRIDAY AFTERNOON  
THROUGH THE WEEKEND.  
 

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

 
 

 
 
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