216  
FXUS61 KPBZ 171721  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
1221 PM EST SUN DEC 17 2017  
   
SYNOPSIS
 
 
ANOTHER UPPER LEVEL DISTURBANCE WILL RESULT IN SCATTERED LIGHT  
PRECIPITATION DEVELOPING LATER THIS AFTERNOON. WARMER  
TEMPERATURES, CLOUDY SKIES, AND LIGHT DRIZZLE CAN BE EXPECTED  
MONDAY AND TUESDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
STATIONARY BOUNDARY REMAINS SITUATED AOA I-80 EARLY THIS  
AFTERNOON WITH BELOW FREEZING TEMPERATURE AND FOG PREVALENT ON  
THE NORTHERN SIDE OF THE FRONT. EXPECT CONDITIONS TO IMPROVE  
HERE, WITH WARM ADVECTION AND MIXING ALLOWING FOR FOG TO SCATTER  
OUT AND SURFACE TEMPS TO WARM. PRECIPITATION WITH THE  
APPROACHING SHORTWAVE OVER THE MID OHIO VALLEY WILL NOT REACH  
THESE ZONES UNTIL MUCH LATER, SO WHILE SOME WET-BULBING COULD  
OCCUR, IT LOOKS LIKE ANY WINTRY PRECIPITATION WOULD BE SNOW  
VERSUS FREEZING RAIN. WILL STILL MONITOR LOCAL ROAD SENSORS FOR  
ANY QUICK GLAZING CONCERNS.  
 
FURTHER SOUTH, ADJUSTMENTS WERE MAINLY MADE TO TIMING AND POPS  
FOR PRECIPITATION ASSOCIATED WITH THE WEAKENING SHORTWAVE AS IT  
CROSSES THROUGH THIS EVENING. AGAIN, WHILE SOME WET-BULBING IS  
EXPECTED, TEMPERATURES HAVE WARMED ENOUGH TO OVERCOME ANY WINTRY  
PRECIPITATION. THAT BEING SAID, WHILE WE'VE WARMED NICELY  
DESPITE CLOUD COVER, THIS MAY SLOW TO A HALT WITH PRECIPITATION  
THROUGH THE AFTERNOON.  
 
WHILE THE SHORTWAVE DEPARTS TONIGHT AND LITTLE FURTHER FORCING  
IS ANTICIPATED, MOISTURE TRAPPED IN THE INVERSION MAY KEEP LIGHT  
RAIN OR PATCHY DRIZZLE ACROSS MOST OF THE FORECAST AREA THROUGH  
THE NIGHT. TEMPERATURES SHOULD NOT FALL OFF TOO MUCH EITHER SO  
VALUES WERE FORECAST ABOVE SEASONAL AVERAGES.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
LATEST GUIDANCE SHOWS DECENT CONTINUITY WITH PREVIOUS  
RUNS WITH ZONAL FLOW ALOFT AND THE FORECAST AREA REMAINING WITHIN  
THE WARM SECTOR THROUGH TUESDAY. WEAK FORCING AND SATURATED  
LOWER LEVELS ALSO CONTINUE TO BE FORECAST...AND EXPECT  
EXTENSIVE CLOUD COVERAGE, PATCHY DRIZZLE, AND PERIODS OF LIGHT  
RAIN TO PERSIST THROUGH THE PERIOD.  
 
DESPITE EXPECTED CLOUD COVER, WARM ADVECTION SHOULD LEAD TO  
TEMPERATURES AT LEAST NEAR SEASONAL AVERAGES WITH A SOMEWHAT  
LIMITED DIURNAL RANGE THROUGH TUESDAY.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
TUESDAY NIGHT THE UPPER LEVEL FLOW WILL AMPLIFY AND THE  
AFOREMENTIONED BOUNDARY IS PROGGED DROP BACK SOUTH OVER THE  
AREA...FINALLY SCOURING LOW-LEVEL MOISTURE BUT ALSO RESULTING IN  
TEMPERATURES 10 DEGREES LOWER ON WEDNESDAY. SOME LOCATIONS MAY  
SEE SOME LIGHT SNOW WEDNESDAY BUT NO SIGNIFICANT ACCUMULATIONS  
ARE EXPECTED.  
 
DRIER AND WARMER CONDITIONS ARE EXPECTED THE LATTER PART OF THE  
WEEK AS ZONAL FLOW IS REESTABLISHED.  
 
MODELS HAVE SLOWED THE ARRIVAL OF THE NEXT SYSTEM TO IMPACT THE  
REGION TO LATE FRIDAY EARLY SATURDAY. CHANGES IN THE EXTENDED  
WERE LARGELY BASED ON LATEST SUPERBLEND GUIDANCE.  
 

 
   
AVIATION /17Z SUNDAY THROUGH THURSDAY/
 
 
OUTSIDE OF VARIABLE MORNING FOG FOR FKL AND DUJ THIS MORNING,  
ALL OTHER TERMINALS WILL REMAIN VFR. VFR CONDITIONS WILL CARRY  
THROUGH THIS AFTERNOON BEFORE MOISTURE INCREASES BEHIND A WARM  
FRONT LIFTING NORTHWARD. EVENTUAL DETERIORATION IS EXPECTED  
AREAWIDE LATER TONIGHT WITH CEILINGS FALLING AND MIST/DRIZZLE  
MAKING AN ENTRANCE.  
 
LIGHT SOUTHERLY FLOW WILL HOLD THROUGH THE BALANCE OF THE TAF  
PERIOD.  
   
OUTLOOK
 
 
RESTRICTIONS ARE LIKELY THROUGH TUESDAY, AS ABUNDANT LOW-LEVEL  
MOISTURE MAY BECOME TRAPPED UNDERNEATH AN INVERSION FOR AN  
EXTENDED PERIOD. IFR CONDITIONS ARE POSSIBLE AT TIMES.  
 

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

 
 

 
 
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