490  
FXUS61 KPBZ 180041  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
841 PM EDT SAT APR 17 2021  
   
SYNOPSIS
 
 
GENERALLY COOL AND DRY WEATHER IS EXPECTED THROUGH SUNDAY MORNING,  
UNTIL ISOLATED SHOWERS RETURN SUNDAY AFTERNOON AND EVENING.  
TEMPERATURE WILL GRADUALLY WARM THROUGHOUT THE NEXT FEW DAYS.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
DIVERGENCE ALOFT AT 300MB COINCIDENT WITH COLD ADVECTION IN THE MID  
LEVELS WILL SUPPORT LOW LEVEL FRONTOGENESIS AND SCATTERED SHOWERS  
GENERALLY IN SE OH. ONCE THE JET STREAK ALOFT PROPAGATES TO THE  
EAST, LARGE SCALE SUBSIDENCE SHOULD RESULT IN MOSTLY CLEAR SKIES AND  
CALM WIND BY MORNING. AS SUCH, TEMPERATURE IS FORECAST IN THE MID TO  
LOW 30S.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
 
 
THE AFOREMENTIONED JET STREAK WILL BE MAINLY DISPLACED FROM THE OHIO  
VALLEY ON SUNDAY, BUT VORTICITY ADVECTION WILL BE IN PLACE AND PROMPT  
A SHORTWAVE PASSAGE SUNDAY AFTERNOON AND EVENING. AS THE SURFACE  
WARMS AND MIXES, ELEVATED SHOWERS ARE POSSIBLE WITH MUCH COLDER AIR  
ALOFT RESULTING IN MID-LEVEL LAPSE RATES OF 7-8C/KM.  
 
SHORTWAVE RIDGING AND SWLY FLOW WILL ALLOW FOR A QUIET AND WARM  
MONDAY.  
 

 
   
LONG TERM /TUESDAY THROUGH SATURDAY/
 
 
LONG RANGE DETERMINISTIC MODELS INDICATE A LOW PRESSURE SYSTEM  
UNDERGOING CYCLOGENESIS MAY MOVE SELY THROUGH THE GREAT LAKES MID TO  
LATE WEEK, AND IF IT DOES, WILL LIKELY BRING SEVERAL PRECIPITATION FORCING  
MECHANISMS INTO PLAY SUCH AS JET SUPPORTED ASCENT COINCIDENT WITH  
FRONTOGENESIS AT THE SURFACE, AND VORTICITY ADVECTION. THIS SYSTEM  
APPEARS AT THIS TIME TO USHER IN ANOTHER BRIEF INTERACTION WITH  
TEMPERATURE BELOW THE CLIMATOLOGICAL NORM.  
 

 
   
AVIATION /01Z SUNDAY THROUGH THURSDAY/
 
 
THE PASSAGE OF A SHORTWAVE TROUGH WL CONT TO SPAWN MVFR, TO LOW- END  
VFR STRATOCU, AND SOME ISOLATED SHRA THIS EVE. THE SHRA ARE EXPECTED  
TO RMN CONCENTRATED SOUTH OF I 70 WHERE UPR DIVERGENCE IS GENERATING  
MID LEVEL FRONTOGENESIS. PASSAGE OF THE DISTURBANCE LATER TNGT WL  
ALLEVIATE THAT CONCERN WITH THE SBSDNC ONSET DIMINISHING CLOUD COVER.  
 
SHORTWAVE RIDGING WITH DECREASED WIND AND RESIDUAL LLVL MOISTURE MAY  
SUPPORT SOME FOG, AND SOME ST AT FKL AND DUJ AS WEAK UPSLOPE IS  
PROJECTED TO CONTINUE. THAT CONCERN WL BE BRIEF THOUGH AS ANOTHER  
SHORTWAVE TROUGH IS PROJECTED TO INCREASE MID LVL CLD COVER AND BACK  
THE WIND AS SUNDAY PROGRESSES. ISOLD, TO SCT SHRA ARE AGAIN POSSIBLE  
WITH THAT DISTURBANCE.  
   
OUTLOOK
 
 
RESTRICTIONS ARE PSBL AGAIN SUN NIGHT AND MON AS THAT TROUGH  
COMPLETED PASSAGE AND A FRONTAL SYS ENCROACHES ON THE REGION.  
 

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

 
 

 
 
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