248  
FXUS63 KLSX 211133  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
633 AM CDT SUN OCT 21 2018  
   
SHORT TERM
 
(THROUGH LATE TONIGHT)  
ISSUED AT 245 AM CDT SUN OCT 21 2018  
 
HIGH PRESSURE HAS SETTLED OVER THE MID-MISSOURI VALLEY AND WILL BE  
THE FOCUS FOR THIS FORECAST PERIOD. THE CLEAR SKIES AND LIGHT WINDS  
ASSOCIATED WITH THE HIGH HAVE ALLOWED TEMPS TO QUICKLY FALL THIS  
MORNING, AND AS OF 2 AM, NEARLY ALL AREAS HAVE FALLEN INTO THE MID  
TO LOW 30S. WITH SEVERAL HOURS REMAINING PRIOR TO SUNRISE, CHANCES  
LOOK GOOD FOR EVERYONE TO FALL BELOW FREEZING, SO THE FREEZE WARNING  
SEEMS TO BE IN GOOD SHAPE.  
 
NW FLOW IN THE WAKE OF YESTERDAY'S SHORTWAVE WILL CONTINUE TO USHER  
BONE DRY AIR INTO THE REGION. THE UPPER LEVEL FLOW WILL THEN TURN  
ZONAL THIS AFTERNOON, SHUNTING THE SURFACE HIGH TO THE EAST,  
SWINGING SURFACE WINDS AROUND TO THE SW. THE SW FLOW COUPLED WITH  
CLEAR SKIES WILL ALLOW FOR AFTERNOON TEMPERATURES TO REBOUND QUITE  
WELL FROM THIS MORNING'S FREEZING TEMPERATURES. WINDS WILL BE QUITE  
A BIT WEAKER THAN WHAT WE SAW YESTERDAY.  
 
BSH  
   
LONG TERM
 
(MONDAY THROUGH SATURDAY)  
ISSUED AT 245 AM CDT SUN OCT 21 2018  
 
FOCUS CONTINUES TO BE TEMPS WITH PRECIP CHANCES LATE THIS WEEK  
DIMINISHING.  
 
NOT A LOT HAS CHANGED THROUGH THE FORECAST PERIOD COMPARED 24 HOURS  
AGO. MODELS ARE STILL IN GENERALLY GOOD AGREEMENT THROUGH WED.  
PERIOD BEGINS WITH THE SFC RIDGE OVER THE CWA THIS MORNING BUILDING  
SOUTHEAST OUT OF THE REGION. MEANWHILE, A SFC COLD FRONT JUST NORTH  
OF THE CWA WILL PUSH SOUTH THROUGH THE AREA ON MON AS AN UPPER LEVEL  
TROF APPROACHES THE GREAT LAKES REGION. AS THE SFC RIDGE BUILDS INTO  
THE REGION BEHIND THIS FRONT, COOLER TEMPS ARE EXPECTED FOR TUES AND  
WED. HOWEVER, WITH WEAK CAA AT THE SURFACE AND HEIGHTS RISING OVER  
THE REGION, HAVE TRENDED TOWARD THE WARMER GUIDANCE ON TUES. WITH  
EASTERLY FLOW ANTICIPATED ON WED, HAVE TRENDED COOLER.  
 
THE GEM BECOMES AN OUTLIER WITH A STRONGER SFC LOW ON THURS AND HAVE  
TRENDED TOWARD A ECMWF/GFS COMPROMISE FOR THURS AND BEYOND.  
CONFIDENCE IN TIMING OF PRECIP LATE THIS WEEK REMAINS LOW DUE TO  
CONTINUED A LACK OF CONSISTENCY FROM ONE CYCLE TO THE NEXT. HAVE  
THEREFORE KEPT POPS LOW ACROSS THE REGION. WITH DRY AIR IN PLACE AND  
WEAK FORCING OVERALL, THE CHANCE OF PRECIP IS LOW REGARDLESS.  
 
WITH A TROF OVER THE AREA LATE THIS WEEK, EXPECT TEMPS TO BE BELOW  
SEASONAL AVERAGE. HAVE HELD OFF MAKING DRASTIC CHANGES TO TEMPS FOR  
SAT AT THIS TIME DUE TO LOW CONFIDENCE MENTIONED ABOVE. HOWEVER, IF  
TRENDS CONTINUE, GOING FORECAST IS MUCH TOO WARM.  
 
TILLY  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 623 AM CDT SUN OCT 21 2018  
 
HIGH PRESSURE WILL RESULT IN A VERY QUIET FORECAST. LARGELY CLOUD  
FREE SKIES WILL PERSIST THROUGH THE TAF PERIOD. SOUTHERLY  
AFTERNOON WINDS WILL TOP OUT AROUND 10 KTS ACROSS MUCH OF THE  
AREA, WITH PERHAPS A FEW GUSTS 15 KT IN NORTHERN MO AND WEST  
CENTRAL IL. WINDS WILL COME BACK DOWN THIS EVENING.  
 
BSH  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SAINT LOUIS 55 42 69 44 / 0 0 0 0  
QUINCY 54 40 65 38 / 0 0 0 0  
COLUMBIA 57 39 69 41 / 0 0 0 0  
JEFFERSON CITY 58 39 69 41 / 0 0 0 0  
SALEM 52 37 65 41 / 0 0 0 0  
FARMINGTON 54 37 65 40 / 0 0 0 0  
 

 
   
LSX WATCHES/WARNINGS/ADVISORIES
 
 
MO...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR CRAWFORD MO-  
FRANKLIN MO-GASCONADE MO-IRON MO-JEFFERSON MO-MADISON MO-  
REYNOLDS MO-SAINT CHARLES MO-SAINT FRANCOIS MO-SAINT LOUIS  
CITY MO-SAINT LOUIS MO-SAINTE GENEVIEVE MO-WASHINGTON MO.  
 
IL...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR BOND IL-CLINTON  
IL-FAYETTE IL-MADISON IL-MARION IL-MONROE IL-RANDOLPH IL-  
SAINT CLAIR IL-WASHINGTON IL.  
 

 
 

 
 
WFO LSX  
 
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