321  
FXUS61 KPBZ 201817  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
217 PM EDT WED JUN 20 2018  
   
SYNOPSIS
 
 
A FRONTAL BOUNDARY WILL REMAIN IN THE REGION INTO THE WEEKEND  
AND WILL KEEP ACTIVE WEATHER IN THE FORECAST.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
CONVECTION WILL LARGELY BE FOCUSED SOUTH OF I-80 THROUGH EARLY  
EVENING ALONG A FRONTAL BOUNDARY RUNNING WEST TO EAST THROUGH  
THE FORECAST AREA.  
 
COVERAGE OF SHOWERS AND STORMS WILL CONTINUE TO INCREASE  
THROUGH THE AFTERNOON AS CONVECTIVE TEMPERATURES ARE REACHED  
THROUGH DAYTIME HEATING...MAINTAINED THROUGH THE EVENING WITH  
THE PASSAGE OF A SHORTWAVE. AFOREMENTIONED FRONTAL BOUNDARY WILL  
TRANSITION SOUTH TONIGHT FOLLOWED BY BUILDING SFC HIGH PRESSURE  
KEEPING ANY ANY LINGERING RAIN FOCUSED IN THE RIDGES.  
 
PRIMARY CONCERN FOR TODAY IS HEIGHTENED FLASH FLOOD RISK WITH  
PLENTY OF MOISTURE AVAILABLE FOR LOCALIZED DOWNPOURS AND AN  
IDEAL SETUP FOR TRAINING OF STORMS. WITH THAT AND RELATIVELY LOW  
FLASH FLOOD GUIDANCE VALUES IN CONSIDERATION...OPTED TO ISSUE A  
FLASH FLOOD WATCH THROUGH MID-EVENING.  
 

 
   
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
 
 
THURSDAY WILL BE LARGELY DRY AS WEAK SHORTWAVE RIDGING  
TRANSITIONS OVER THE FORECAST AREA. TEMPERATURES WILL BE VERY  
CLOSE TO NORMAL FOR THIS TIME OF YEAR...AND WINDS WILL BE  
LIGHT.  
 
PRECIPITATION CHANCES WILL INCREASE THURSDAY NIGHT AND FRIDAY AS  
A WARM FRONT APPROACHES THE REGION AHEAD OF A DEEPENING MIDWEST  
TROUGH. CLOUD COVER MAY LIMIT HEATING A BIT MORE ON FRI, WITH  
TEMPS IN THE 70S SLIGHTLY BELOW SEASONAL AVERAGE. SURFACE BASED  
CONVECTION LOOKS UNLIKELY BASED OFF MODEL SOUNDINGS BUT KEPT  
A SLIGHT CHANCE MENTION FOR STORMS AS THERE LOOKS TO BE SOME  
ELEVATED INSTABILITY.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
A STRONG LOW PRESSURE SYSTEM IN THE CENTRAL PLAINS WILL APPROACH  
THE GREAT LAKES REGION FRI NIGHT AND SAT, WITH SHOWERS AND  
STORMS EXPECTED AS IT CROSSES. GIVEN THE EXPECTED NEGATIVE TILT  
OF THE SYSTEM AND STRONG FORCING FOR ASCENT, THE POTENTIAL FOR  
DAMAGING WIND GUSTS WILL NEED TO BE MONITORED DESPITE THE  
LESS FAVORABLE TIMING OF THE SFC TROUGH PASSAGE.  
 
A SUBSEQUENT SHORTWAVE TROUGH COULD SPELL ADDITIONAL RAIN  
CHANCES ON SUN BEFORE HIGH PRESSURE BUILDS INTO THE REGION ON  
MON AND TUE AND ERODES MUCH OF THE LOW-LEVEL MOISTURE.  
SEASONABLE TEMPERATURES SHOULD CONTINUE INTO NEXT WEEK.  
 

 
   
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
 
 
PRIMARILY VFR CONDITIONS WILL CARRY THROUGH THE EVENING, BUT  
INCREASING SHOWERS AND THUNDERSTORMS WILL RESULT IN TEMPORARY  
RESTRICTIONS SOUTH OF I-80. THE SURFACE LOW WILL SHIFT TO OUR EAST  
TONIGHT AND THUNDERSTORMS ARE EXPECTED TO DIMINISH NEAR MIDNIGHT.  
LOW-LEVEL MOISTURE WRAPPING AROUND THE BACK OF THE LOW WILL RESULT  
IN ADDITIONAL RESTRICTIONS OVERNIGHT INTO EARLY THURSDAY. EXPECTING  
A MIX OF IFR AND MVFR CEILINGS ALONG THE EASTERN PERIPHERY,  
PERSISTING LONGEST OVER LBE/MGW. GRADUAL IMPROVEMENT IS EXPECTED  
INTO THURSDAY MORNING AS DRIER AIR MOVES IN FROM THE NORTH.  
 
LIGHT AND VARIABLE WINDS COULD BE INTERRUPTED BY GUSTS IN SOME OF  
THE STRONGER THUNDERSTORMS THIS EVENING. LIGHT NNE WINDS WILL  
ESTABLISH THURSDAY MORNING.  
 
OUTLOOK...  
A BRIEF RESPITE ON THURSDAY WILL BE FOLLOWED BY PERIODIC  
RESTRICTIONS INTO THE WEEKEND AS THE FRONT WAVERS ACROSS THE OH  
VALLEY REGION.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
MD...FLASH FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR MDZ001.  
OH...NONE.  
PA...FLASH FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR PAZ021-029-  
031-073>076.  
WV...FLASH FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR WVZ002>004-  
012-021-509>512.  
 

 
 

 
 
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