587  
FXUS63 KLSX 181037  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
437 AM CST SAT JAN 18 2025  
   
KEY MESSAGES  
 
- TEMPERATURES WILL REMAIN STEADY OR FALL INTO THE 20S AND 30S  
TODAY. WIND CHILLS WILL DROP BELOW ZERO OVER MUCH OF THE AREA  
LATE TONIGHT AND SUNDAY MORNING WITH HIGH TEMPERATURES IN THE  
TEENS AND 20S SUNDAY THROUGH TUESDAY.  
 
 
   
SHORT TERM  
(THROUGH LATE SUNDAY AFTERNOON)  
ISSUED AT 337 AM CST SAT JAN 18 2025  
 
REGIONAL RADAR IS SHOWING THE AREA OF LIGHT RAIN ACROSS SOUTHEAST  
MISSOURI AND SOUTHWEST ILLINOIS CONTINUING TO MOVE EAST, AND THE  
CAMS ARE STILL SHOWING IT EXITING THE CWA BY SUNRISE. THE LATEST  
SURFACE ANALYSIS IS SHOWING THAT A COLD FRONT EXTENDS FROM ROUGHLY  
DECATUR TO ST. LOUIS TO ROLLA WITH THE RAP MOVING IT SOUTH OF THE  
CWA BY SUNRISE. THERE WILL BE STRONG CAA TODAY ALONG WITH LINGERING  
CLOUD COVER WHICH WILL CAUSE FALLING OR NEAR STEADY TEMPERATURES.  
HIGHS WILL BE 20 TO 30 DEGREES COOLER COMPARED TO YESTERDAY. LOWS  
TONIGHT WILL DROP INTO THE SINGLE DIGITS AND TEENS WHILE HIGHS  
TOMORROW ACROSS MOST OF THE AREA WILL STAY IN THE TEENS. WIND  
CHILLS LATE TONIGHT INTO SUNDAY MORNING WILL BE BELOW ZERO ACROSS  
MOST OF THE CWA.  
 
ONCE THE RAIN MOVES OUT THE AREA EARLY THIS MORNING, THE REST OF THE  
DAY IS EXPECTED TO BE DRY. THE NAM/GFS IS SHOWING AN UPPER TROUGH  
DROPPING OUT OF THE NORTHERN PLAINS TODAY AND MOVING ACROSS  
MISSOURI/ILLINOIS TONIGHT. FORECAST SOUNDINGS ARE STILL SHOWING A  
SHALLOW LAYER OF MOISTURE THAT COMBINED WITH THE ASCENT CAUSED BY  
THE TROUGH WARRANTS KEEPING THE CHANCE OF FLURRIES ACROSS SOUTHEAST  
MISSOURI AND SOUTHWEST ILLINOIS TONIGHT.  
 
BRITT  
 
 
   
LONG TERM  
(SUNDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 337 AM CST SAT JAN 18 2025  
 
THERE IS HIGH CONFIDENCE THAT WE REMAIN BELOW FREEZING SUNDAY NIGHT  
THROUGH TUESDAY AS ALL OF THE ENSEMBLES IN CLUSTER ANALYSIS ARE  
SHOWING A DEEP LONGWAVE TROUGH OVER THE CENTRAL CONUS EARLY NEXT  
WEEK. THE 850MB TEMPERATURES WILL BE IN THE -15 TO -25 RANGE AS A  
SURFACE HIGH MOVES DOWN INTO MISSOURI AND ILLINOIS BY MONDAY. THIS  
HIGH WILL LINGER OVER THE AREA INTO TUESDAY WHICH WILL SUPPLY DECENT  
RADIATIONAL COOLING BOTH MONDAY AND TUESDAY MORNINGS. THE LREF  
PROBABILITIES ARE STILL SHOWING A 40-70 PERCENT CHANCE OF AOB  
-10F APPARENT TS EARLY ON MONDAY AND TUESDAY MORNINGS ALONG AND  
NORTH OF I-70 WHICH MEANS THERE IS STILL SOME POTENTIAL NEED FOR A  
COLD WEATHER ADVISORY EARLY NEXT WEEK. THE CLUSTER ANALYSIS BY LATE  
NEXT WEEK IS BEGINNING TO SHOW SOME SPREAD WITH THE MAJORITY OF THE  
MEMBERS SHOWING A MORE ZONAL FLOW VERSUS ONE THAT IS STILL SHOWING A  
DEEPER TROUGH OVER THE EASTERN CONUS. THE MORE PROGRESSIVE FLOW  
SUPPORTS THE GOING FORECAST OF MODERATING TEMPERATURES WITH HIGHS  
CLIMBING BACK ABOVE FREEZING WEDNESDAY INTO FRIDAY.  
 
THE DETERMINISTIC AND ENSEMBLE MEAN MODELS BRING A UPPER TROUGH AND  
ATTENDANT FRONT ACROSS THE AREA LATE IN THE WEEK. THE GFS/CANADIAN  
ARE DEPICTING SOME SPOTTY, LIGHT QPF WITH THIS, BUT WILL KEEP THE  
FORECAST DRY AS EVEN THE 10TH PERCENTILE OF THE NBM IS DRY THROUGH  
NEXT WEEK OVER THE CWA. THIS MATCHES UP WELL WITH THE THE NUMBER OF  
THE ENSEMBLES IN THE LREF WHERE GREATER THAN 90 PERCENT OF THEM ARE  
DRY.  
 
BRITT  
 
 
   
AVIATION  
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)  
ISSUED AT 429 AM CST SAT JAN 18 2025  
 
HIGH MVFR OR LOW VFR CEILINGS WILL LINGER AROUND THE ST. LOUIS  
AREA TERMINALS THIS MORNING, THOUGH CEILINGS SHOULD RISE ABOVE  
3000 FEET AGL BY 15Z. OTHER THAN A FEW SPRINKLES OR FLURRIES, DRY  
WEATHER IS EXPECTED THROUGH THE PERIOD. WINDS WILL GUST AT TIMES  
TO 20-25 KNOTS.  
 
BRITT  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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