875  
FXUS61 KPBZ 230040  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
840 PM EDT THU JUN 22 2017  
   
SYNOPSIS
 
 
DOWNPOURS ARE POSSIBLE THROUGH FRIDAY NIGHT WITH A TROPICAL  
AIRMASS IN PLACE. A COLD FRONT SWEEPING THROUGH EARLY SATURDAY  
WILL RETURN COMFORTABLE HUMIDITY LEVELS BY THE WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
WITH FLASH FLOODING STILL OCCURRING IN ARMSTRONG AND INDIANA  
COUNTIES, IT WAS AN EASY DECISION TO ADD THE TWO COUNTIES TO THE  
FLASH FLOOD WATCH THAT WILL GO INTO EFFECT OVERNIGHT. THE OTHER  
PRIMARY CHANGE TO THE FORECAST WAS TO CONTINUE DELAYING THE  
ARRIVAL OF PRECIPITATION WITH THE NEXT WAVE OF SHOWERS AND  
THUNDERSTORMS. HAVE STILL STUCK WITH CATEGORICAL POPS IN NEARLY  
ALL LOCATIONS EXCEPT FOR SOUTHEASTERNMOST COUNTIES. AN INCH OF  
RAIN CANNOT BE RULED OUT AFTER MIDNIGHT, ALTHOUGH MOST LOCATIONS  
ARE EXPECTED TO RECEIVE BETWEEN A QUARTER AND HALF INCH OF RAIN  
BETWEEN MIDNIGHT AND SUNRISE.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/
 
 
...DOWNPOURS POSSIBLE THROUGH FRIDAY EVENING WITH LEFT OVERS  
FROM TROPICAL STORM CINDY...  
 
FOR INFORMATION REGARDING THE THREAT OF HIGH WATER, PLEASE  
REFERENCE THE HYDROLOGY DISCUSSION LOCATED NEAR THE BOTTOM OF  
THE PRODUCT.  
 
THE REMNANTS OF CINDY PASS FRIDAY AFTERNOON AND EVENING. THIS  
WILL BRING A WIDESPREAD AREA OF SHOWERS AND STORMS TO THE REGION  
ESPECIALLY SOUTH OF I-70. THERE SHOULD BE NOT A LOT OF  
PRECIPITATION AROUND DURING THE MORNING AND EARLY AFTERNOON  
HOURS, HOWEVER WITH THE APPROACH OF A THE COLD FRONT DURING THE  
AFTERNOON HOURS THIS WILL TRIGGER STORMS AND INTERACT WITH  
MOISTURE ASSOCIATED WITH CINDY.  
 
THE COLD FRONT CROSSES DURING THE OVERNIGHT HOURS FRIDAY NIGHT  
SO COME DAYLIGHT SATURDAY ANY MEASURABLE QPF SHOULD BE EAST OF  
THE MOUNTAINS. CLEARING WILL RAPIDLY TAKE PLACE BEFORE 15Z THEN  
A CU FIELD WILL DEVELOP DURING THE AFTERNOON HOURS. HUMIDITY  
LEVELS WILL BE NOTICEABLE LOWER AS DEWPOINTS DROP INTO THE 50S  
SOME 20F LOWER THAN TODAY.  
 
BENIGN WEATHER SATURDAY NIGHT WITH MOISTURE ARRIVING FROM THE  
NORTHWEST AHEAD OF THE NEXT UPPER DISTURBANCE.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
 
HIGHLIGHTS:  
- COOLER WEATHER  
- NO SIGNS OF A HIGH WATER THREAT  
 
FULL LATITUDE TROUGH WILL BRING A PERIOD OF BELOW NORMAL  
TEMPERATURES TO THE REGION. AFTERNOON HIGH TEMPERATURES WILL BE  
RUNNING NEARLY TEN DEGREES BELOW THEIR NORMAL BENCHMARKS SUNDAY  
- TUESDAY. WITH THE TROUGH AXIS OVERHEAD, SCATTERED SHOWERS AND  
PERHAPS A THUNDERSTORM ARE POSSIBLE THROUGH MID WEEK, BUT WITH  
LOW LEVEL MOISTURE LACKING DUE TO THE PLACEMENT OF HIGH  
PRESSURE SOUTHEAST OF THE WESTERN GREAT LAKES. A TRANSITORY  
HIGH PRESSURE TAKES OVER AT WEEKS END BRINGING TEMPERATURES  
BACK TO THEIR NORMAL LOCATION AND RETURNING DRY WEATHER.  
 

 
   
AVIATION /01Z FRIDAY THROUGH TUESDAY/
 
 
ALTHOUGH ALL LOCATIONS START THIS EVENING WITH VFR CONDITIONS,  
RESTRICTIONS IN BOTH CEILING AND VISIBILITY WILL BEGIN AFTER  
MIDNIGHT. STILL DID NOT HAVE CONFIDENCE TO GO WITH WIDESPREAD  
IFR CONDITIONS, ALTHOUGH THIS CERTAINLY REMAINS A GOOD  
POSSIBILITY, ESPECIALLY IN HEAVIER SHOWERS.  
 
WIND WILL REMAIN WSW THROUGH THE PERIOD, WITH GUSTS EXPECTED  
FRIDAY AFTERNOON. IN ADDITION, SOME ISOLATED LLWS CANNOT BE  
RULED OUT AROUND SUNRISE, BUT CONFIDENCE IN LLWS IS LOW AND HAS  
NOT BE INCLUDED IN ANY TAFS AT THIS TIME.  
   
OUTLOOK
 
 
WIDESPREAD RESTRICTIONS ARE LIKELY THROUGH SATURDAY MORNING WITH  
THE PASSAGE OF A COLD FRONT.  
 

 
   
HYDROLOGY
 
 
A FLASH FLOOD WATCH HAS BEEN ISSUED FOR AREAS ALONG AND SOUTH  
OF INTERSTATE 70. ALLEGHENY AND WESTMORELAND COUNTIES ARE ALSO  
INCLUDED BECAUSE OF LOWER GUIDANCE IN THE URBAN AREAS, AS WELL  
AS ARMSTRONG AND INDIANA COUNTY BECAUSE OF FLASH FLOODING THAT  
ALREADY OCCURRED THURSDAY AFTERNOON. THE MAIN CONCERN WOULD BE  
QPF FRIDAY AFTERNOON AND EVENING.  
 
METEOROLOGICALLY VALUES ALL POINT TO HIGH WATER ISSUES WITH  
PWATS OVER TWO INCHES, WARM CLOUD DEPTHS ABOVE 13KFT, AND A  
STRONG LOW LEVEL JET. GEFS M-CLIMATE VALUES ARE NEAR OR AT  
RECORD LEVELS FOR PWATS ON RETURN INTERVAL, AND CLIMATE  
ANOMALY.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
MD...FLASH FLOOD WATCH FROM 2 AM EDT FRIDAY THROUGH LATE FRIDAY  
NIGHT FOR MDZ001.  
OH...FLASH FLOOD WATCH FROM 2 AM EDT FRIDAY THROUGH LATE FRIDAY  
NIGHT FOR OHZ057>059-068-069.  
PA...FLASH FLOOD WATCH FROM 2 AM EDT FRIDAY THROUGH LATE FRIDAY  
NIGHT FOR PAZ021>023-029-031-073>076.  
WV...FLASH FLOOD WATCH FROM 2 AM EDT FRIDAY THROUGH LATE FRIDAY  
NIGHT FOR WVZ002>004-012-021-509>514.  
 

 
 

 
 
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