124  
FXUS61 KPBZ 201720  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
120 PM EDT SUN MAY 20 2018  
   
SYNOPSIS
 
 
DRY CONDITIONS AND NEAR NORMAL TEMPERATURES EXPECTED TODAY  
BEFORE RAIN CHANCES RETURN EARLY IN THE WEEK WITH CROSSING LOW  
PRESSURE.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
HIGH PRESSURE WILL MAINTAIN DRY CONDITIONS TODAY AND  
OVERNIGHT OUTSIDE OF A POSSIBLE STRAY SHOWER OVER THE RIDGES  
THIS AFTERNOON. SURFACE DEWPOINTS THIS AFTERNOON IN THE LOW 60S  
TO UPPER 50S HINT AT A FAVORABLE HYDROLAPSE OVERNIGHT FOR FOG  
DEVELOPMENT AS PARTIAL CLEARING WITH INCREASING SUBSIDENCE INTO  
THE EVENING ALONG WITH LESSENING WINDS WILL ALLOW DECOUPLING  
AND RADIATIONAL COOLING TO A DEGREE.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
SFC HIGH PRESSURE ACROSS ONTARIO AND THE ERN GREAT LAKES SHOULD  
MAINTAIN DRY WEATHER THROUGH MOST OF TONIGHT. LOW PRESSURE IS  
EXPECTED TO TRACK ACROSS THE MIDWEST LATE TONIGHT THROUGH  
MONDAY, DRAGGING THE STALLED SFC FRONT BACK N AS A WARM FRONT.  
MODELS TRENDED SLOWER WITH THIS SCENARIO WITH A STRONGER SFC  
HIGH TO THE N, SO SLOWED THE RETURN OF THE SHOWER/TSTM POPS IN  
THE FORECAST.  
 
THE SFC LOW IS EXPECTED TO TRACK ACROSS THE UPPER OH VALLEY AND  
EASTERN GREAT LAKES REGION TUESDAY, AS THE LOW'S ASSOCIATED COLD  
FRONT APPROACHES AND CROSSES THE AREA. MAINTAINED LIKELY POPS  
FOR SHOWERS/TSTMS AS THIS OCCURS. THE POTENTIAL FOR STRONGER  
STORMS WILL BE DEPENDENT ON HOW MUCH DESTABILIZATION AND SFC  
HEATING TAKES PLACE. THE FRONT SHOULD COMPLETE ITS PASSAGE  
TUESDAY NIGHT WITH DECREASING POPS. ABOVE SEASONAL AVERAGE  
TEMPERATURES ARE EXPECTED TO CONTINUE.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
RIDGING SHOULD RETURN DRY WEATHER TO THE FORECAST THROUGH THE  
END OF THE WORK WEEK AS A TROUGH SLOWLY ADVANCES EWD FROM THE  
WRN CONUS. THE TROUGH IS EXPECTED TO APPROACH THE UPPER OH  
VALLEY REGION BY THE WEEKEND, WITH SHOWER AND TSTM CHANCES  
RETURNING. TEMPERATURES ARE EXPECTED TO AVERAGE ABOVE SEASONAL  
LEVELS.  
 

 
   
AVIATION /17Z SUNDAY THROUGH THURSDAY/
 
 
LOW VFR / HIGH MVFR STRATOCU WILL PERSIST THROUGH MUCH OF THE  
AFTERNOON. EXPECT RESTRICTIONS OVERNIGHT AS FOG DEVELOPS WITH  
LIGHT WINDS AND A FAVORABLE HYDROLAPSE.  
 
OUTLOOK...  
BRIEF RESTRICTIONS ARE EXPECTED INTO THE MIDDLE OF NEXT WEEK AS  
THE WEATHER PATTERN REMAINS ACTIVE. NO SUSTAINED PERIODS OF IFR  
ARE PREDICTED, ALTHOUGH THUNDERSTORMS ON MON/TUE COULD LEAD TO  
SUCH RESTRICTIONS.  
 

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

 
 

 
 
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