514  
FXUS61 KPBZ 271502  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
1102 AM EDT THU APR 27 2017  
   
SYNOPSIS
 
 
A VERY WARM DAY WILL BE INTERRUPTED BY SHOWERS AND STORMS WITH A  
WEAK FRONT.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
THE LATE MORNING UPDATE FEATURED ADJUSTMENTS TO POPS BASED ON  
THE LATEST RADAR AND HIGH RES MODEL TRENDS.  
 
A WEAK COLD/OCCLUDING FRONT WILL IS TRIGGERING SHOWERS AND  
STORMS OVER AREAS WEST AND SOUTH OF ZANESVILLE. THESE WILL  
PROGRESS EASTWARD AND ARE EXPECTED TO INTENSIFY AS THE BOUNDARY  
LAYER DESTABILIZES THIS AFTERNOON, ESPECIALLY OVER AREAS EAST OF  
A DUBOIS TO PARKERSBURGH LINE WHERE PEAK HEATING WILL DRIVE  
TEMPERATURE TOWARD THE MID 80S.  
 
DESPITE IMPRESSIVE DEEP LAYER SHEAR, THE AREA HAS BEEN LIMITED  
TO A "MARGINAL" SEVERE RISK. THIS SEEMS APPROPRIATE GIVEN  
INSTABILITY LIMITATIONS IMPOSED BY SUB 60 DEWPOINTS AND A PLUME  
OF WARMER MID LEVEL AIR ADVECTING ALONG THE ADVANCING FRONT.  
 
SHOULD STORMS DEVELOP AND ORGANIZE, THE PRIMARY SEVERE THREAT  
STILL LOOKS TO BE FROM DAMAGING WIND VIA SHORT BOWING SEGMENTS.  
 
PASSAGE OF THE FRONT WILL HERALD DIMINISHED CONVECTION AS THE  
EVENING PROGRESSES.  
 

 
   
SHORT TERM /FRIDAY THROUGH SATURDAY/
 
 
DRY WEATHER RETURNS FRIDAY WITH HIGH PRESSURE. ANY COOLER AIR  
BEHIND TODAY'S FRONT WILL BE QUICKLY EJECTED TO THE NORTH AS  
STRONG WARM AIR ADVECTION TAKES OVER.  
 
EASTERN RIDGE WILL TRY TO BUILD LATE FRIDAY, BUT WILL BE SHUNTED  
BY A SERIES OF UPPER LEVEL WAVES WHICH WILL RIDE OVER THE TOP OF  
THE RISING HEIGHTS. THESE WAVE WILL BRING SHOWERS AND STORMS  
BACK TO THE AREA LATE FRIDAY NIGHT AND SATURDAY. SEEING  
DISCREPANCIES IN MODELS SOLUTIONS ON SATURDAY WITH THE POSITION  
AND TIMING OF THE SHORTWAVES. HAVE LEANED TOWARD A MORE  
NORTHERN TRACK, WHICH COMPLIES WITH SLOWLY RISING 500MB HEIGHTS  
ON SATURDAY.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
AN ACTIVE PATTERN IS FIGURED FOR THE REMAINDER OF THE WEEKEND  
INTO EARLY NEXT WEEK. A FEW SHORTWAVES WILL CROSS IN CONTINUED  
MOIST SOUTHWEST FLOW ALONG THE FRONT OF A BROAD TROUGH, LEADING  
TO RAIN CHANCES AGAIN ON SUNDAY. TIMING REMAINS TRICKY, BUT  
SATURDAY NIGHT CURRENTLY LOOKS TO BE THE PERIOD WITH THE LOWEST  
COVERAGE IN THE WARM SECTOR. TEMPERATURES REMAIN ABOVE NORMAL.  
 
THE TROUGH LIFTS OUT AS A CLOSED UPPER LOW INTO THE GREAT LAKES  
BY MONDAY, PUSHING A FAIRLY STRONG BOUNDARY ACROSS US. GIVEN  
SYSTEM STRENGTH, THE AMOUNT OF MOISTURE, AND A POSSIBLY NEGATIVE  
TILT TO THE UPPER TROUGH, STRONG STORMS APPEAR POSSIBLE. BEHIND  
THIS SYSTEM, QUIETER WEATHER AND SEASONABLE TEMPERATURES ARE  
EXPECTED INTO THE MIDDLE OF NEXT WEEK.  
 

 
   
AVIATION /15Z THURSDAY THROUGH MONDAY/
 
 
VFR CONDITIONS EXPECTED MUCH OF THE DAY. WINDS WILL PICK UP OUT  
OF THE SOUTH AND GUST TO 20 TO 25 KNOTS ONCE MIXING GETS GOING.  
TIMING FOR THE FRONTAL PASSAGE WILL BE BETWEEN ROUGHLY 18Z AND  
02Z, WITH SHOWERS AND THUNDERSTORMS ALONG AND AHEAD. EXPECTING A  
BRIEF PERIOD OF MVFR SHOWERS WITH VCTS, WITH EXACT TIMING STILL  
A BIT UNCERTAIN, TEMPORARY IFR POSSIBLE IN ANY DOWNPOURS.  
STRONGER WIND GUSTS ARE ALSO POSSIBLE IN THE STRONGEST STORMS.  
 
BEHIND THE FRONT, WINDS WILL DIMINISH AND MVFR CEILINGS WILL  
LINGER.  
   
OUTLOOK
 
 
OCCASIONAL RESTRICTIONS ARE POSSIBLE THIS WEEKEND ALONG A  
STALLED FRONTAL BOUNDARY. BETTER RESTRICTION CHANCES ARRIVE WITH  
A STRONG COLD FRONT SUNDAY NIGHT INTO MONDAY.  
 

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

 
 

 
15  
 
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