465  
FXUS63 KLSX 211125  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
525 AM CST MON JAN 21 2019  
   
SHORT TERM
 
(THROUGH LATE TONIGHT)  
ISSUED AT 336 AM CST MON JAN 21 2019  
 
LATEST SURFACE OBSERVATIONS AND SATELLITE IMAGERY IS SHOWING SOME  
MVFR AND LOW VFR CEILINGS ACROSS CENTRAL AND SOUTHEAST MISSOURI  
UNDERNEATH AN EXTENSIVE AREA OF MID-HIGH LEVEL CLOUDINESS THAT IS  
STREAMING ACROSS THE MIDWEST. THESE CLOUDS ARE MOVING OVER AN UPPER  
LEVEL RIDGE WHICH WILL MOVE ACROSS MISSOURI AND ILLINOIS LATER  
TODAY. MODEL PROGS ARE SHOWING ENOUGH MOISTURE BOTH IN THE LOW  
LEVELS AND STREAMING OVER THE RIDGE TO KEEP THE FORECAST MOSTLY  
CLOUDY TODAY. THE SUBSIDENCE UNDERNEATH THE RIDGE WILL KEEP THE  
FORECAST DRY OVER THE CWA THROUGH TONIGHT. SOUTHEAST WINDS WILL  
ALSO PICK UP TODAY AT 10-20 MPH, WITH SOME GUSTS TO 30 MPH AS THE  
SURFACE PRESSURE GRADIENT TIGHTENS UP.  
 
THERE HAS BEEN NO SIGNIFICANT CHANGE IN THINKING TO THE FORECAST FOR  
TUESDAY. THERE WILL BE AN INCREASE OF LOW LEVEL MOISTURE ADVECTION  
AND A GRADUAL INCREASE IN ASCENT FROM WEST TO EAST THROUGHOUT THE  
DAY. FORECAST SOUNDINGS FROM THE NAM/GFS STILL SUGGEST THAT DRIZZLE  
WILL BE BE MORE PREVALENT THAN RAIN IN THE MORNING BEFORE STRONGER  
ASCENT MOVES IN DURING THE AFTERNOON. THERE WILL ALSO BE TWO AREAS  
OF CONCERN FOR FREEZING DRIZZLE IN THE MORNING. THE FIRST WILL BE  
OVER NORTHEAST MISSOURI INTO WEST CENTRAL ILLINOIS BEFORE A WARM  
FRONT MOVES NORTH OF THE AREA. THE SECOND WILL BE IN THE EASTERN  
OZARKS WHERE MORNING LOWS WILL START OUT AROUND 30 DEGREES, AND  
THERE COULD BE SOME PATCHY FREEZING DRIZZLE BEFORE TEMPERATURES  
CLIMB ABOVE FREEZING. ANY ICE ACCRETION IN THE MORNING IS EXPECTED  
TO BE LIGHT BEFORE MELTING AS TEMPERATURES CLIMB QUICKLY THROUGH THE  
30S.  
 
TEMPERATURES THIS MORNING ARE STARTING OUT QUITE COLD, WITH READINGS  
IN THE SINGLE DIGITS AND TEENS. WITH THE COLD START AND EXPECTED  
MOSTLY CLOUDY SKIES, WILL KEEP WITH HIGHS THAT ARE 10-15 DEGREES  
BELOW NORMAL TODAY. WITH WARM AIR ADVECTION AND CLOUDS TONIGHT,  
EXPECT NEAR STEADY TEMPERATURES TONIGHT. KEPT CLOSE TO GOING  
TEMPERATURES ON TUESDAY WITH HIGHS IN LOWER TO MIDDLE 40S.  
 
BRITT  
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 336 AM CST MON JAN 21 2019  
 
SURFACE LOW WILL CONTINUE TO LIFT OUT TO THE NORTHEAST INTO THE  
GREAT LAKES REGION TUESDAY NIGHT WITH MUCH COLDER AIR SPILLING IN  
AS A STRONG COLD FRONT MOVES THROUGH. THE RAIN WILL BEGIN TO  
TAPER OFF WITH SOME DRIZZLE, FREEZING DRIZZLE, AND LIGHT SNOW  
EXPECTED BEFORE COMING TO AN END WEDNESDAY MORNING. ANY SNOW AND  
ICE ACCUMULATIONS WILL BE ON THE LIGHT SIDE. LOWS TUESDAY NIGHT  
WILL BE IN THE MID TEENS TO UPPER 20S.  
 
ACTIVE NORTHWEST FLOW ALOFT WILL USHER IN SEVERAL SYSTEMS THROUGH  
THE REMAINDER OF THE FORECAST PERIOD. DRY AND COLDER WEATHER  
EXPECTED WEDNESDAY THROUGH THURSDAY MORNING. HIGHS ON WEDNESDAY WILL  
BE IN THE MID 20S TO LOW 30S AND LOWS WEDNESDAY NIGHT WILL BE IN THE  
MID TEENS TO LOW 20S.  
 
NEXT CLIPPER SYSTEM WILL MOVE THROUGH THE REGION THURSDAY/THURSDAY  
NIGHT WITH LIGHT SNOW FOR MOST OF AREA, THOUGH SOME LIGHT RAIN/SNOW  
MIX IS POSSIBLE FOR SOUTHERN PORTIONS OF FORECAST AREA THURSDAY  
AFTERNOON, BEFORE TRANSITIONING TO ALL SNOW BY THURSDAY EVENING.  
STILL TOO EARLY TO TELL IF THERE WILL BE ANY DECENT SNOW  
ACCUMULATIONS WITH IT.  
 
AN ARCTIC RIDGE OF HIGH PRESSURE WILL BUILD IN BY FRIDAY WITH A  
STRONG SURGE OF MUCH COLDER AIR FOR THE WEEKEND. SUPERBLEND WAS A  
BIT COLDER THAN PREVIOUS LOAD, BUT NOT AS COLD AS GFS AND ECMWF ARE  
ADVERTISING, SO LOWERED TEMPERATURES A BIT DURING THIS PERIOD.  
ANOTHER CLIPPER SYSTEM WILL SLIDE IN LATE FRIDAY NIGHT THROUGH  
SATURDAY EVENING AND WITH THE MUCH COLDER TEMPERATURES, ALL THE  
PRECIPITATION WILL BE IN THE FORM OF SNOW.  
 
BYRD  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 520 AM CST MON JAN 21 2019  
 
MVFR CEILINGS ARE EXPECT TO STAY JUST EAST AND SOUTH OF THE ST.  
LOUIS AREA TERMINALS EARLY THIS MORNING. DRY AND VFR CONDITIONS  
ARE EXPECTED THROUGH THE PERIOD. A 40-50KT LOW LEVEL JET IS  
EXPECTED TO SET UP AFTER 06Z TONIGHT CAUSING LLWS TO DEVELOP AT  
ALL TERMINALS AROUND 2000FT AGL.  
 
SPECIFICS FOR KSTL:  
 
MVFR CEILINGS ARE EXPECT TO STAY JUST EAST AND SOUTH OF THE  
TERMINAL THROUGH 15Z. DRY AND VFR CONDITIONS ARE EXPECTED THROUGH  
AT LEAST 12Z TUESDAY, WITH SOME POTENTIAL FOR LIGHT DRIZZLE  
THEREAFTER. A 45KT LOW LEVEL JET IS EXPECTED TO SET UP AFTER 06Z  
TONIGHT CAUSING LLWS TO DEVELOP AT THE TERMINAL AROUND 2000FT AGL.  
 
BRITT  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SAINT LOUIS 27 27 44 26 / 0 0 80 90  
QUINCY 23 23 41 20 / 5 0 90 70  
COLUMBIA 30 29 44 20 / 0 0 90 60  
JEFFERSON CITY 32 30 46 22 / 0 0 90 60  
SALEM 25 24 43 29 / 0 0 70 100  
FARMINGTON 28 26 43 26 / 0 5 80 100  
 

 
   
LSX WATCHES/WARNINGS/ADVISORIES
 
 
MO...NONE.  
IL...NONE.  

 
 

 
 
WFO LSX  
 
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