191  
FXUS63 KLSX 181950  
AFDLSX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
150 PM CST SAT JAN 18 2025  
   
KEY MESSAGES  
 
- VERY COLD CONDITIONS WILL PERSIST THROUGH WEDNESDAY MORNING,  
WITH THE COLDEST VALUES EXPECTED TOMORROW MORNING AND TUESDAY  
MORNING. WIND CHILLS ARE LIKELY TO FALL TO BETWEEN 5 AND -10  
DEGREES DURING THE COLDEST MORNINGS, AND PERHAPS A FEW DEGREES  
COLDER IN FEW SPOTS.  
 
- ASIDE FROM SOME FLURRIES OR VERY LIGHT SNOW SHOWERS ACROSS THE  
OZARKS TONIGHT, PRECIPITATION IS NOT LIKELY FOR THE NEXT WEEK.  
 
 
   
SHORT TERM  
(THROUGH LATE SUNDAY NIGHT)  
ISSUED AT 149 PM CST SAT JAN 18 2025  
 
AFTER A BRIEF WARMUP THAT LASTED THROUGH YESTERDAY EVENING, THE  
FIRST IN A SERIES OF COLD AIR SURGES HAS MOVED INTO THE AREA  
BEHIND AN ADVANCING COLD FRONT. THIS HAS BROUGHT TEMPERATURES  
TUMBLING BACK BELOW FREEZING ACROSS MUCH OF THE AREA, AND ABOUT 25  
TO 30 DEGREES BELOW YESTERDAY'S VALUES AT THE SAME TIME.  
MEANWHILE, BREEZY NORTHWEST WINDS ARE ADDING A BIT OF EXTRA BITE  
TO THOSE TEMPERATURES, WITH OBSERVED WIND CHILLS ONLY IN THE MID  
TEENS TO MID 20S AS OF 1 PM. MEANWHILE, STUBBORN STRATOCUMULUS  
CONTINUES TO LINGER ACROSS PARTS OF CENTRAL MISSOURI AND THE  
OZARKS, AND IT WOULDN'T BE A COMPLETE SHOCK TO SQUEEZE OUT A FEW  
FLURRIES HERE AND THERE, PARTICULARLY WHERE THE TERRAIN OF THE  
OZARKS CAN PROVIDE A SLIGHT BOOST IN LIFT.  
 
THIS EVENING AND OVERNIGHT, A SHORTWAVE PIVOTING AROUND THE SYNOPTIC  
SCALE TROUGH ACROSS THE EASTERN U.S. WILL ARRIVE FROM THE NORTHWEST,  
AND WILL PHASE WITH AN EVEN MORE SUBTLE IMPULSE ARRIVING FROM THE  
WEST. THIS WILL ACCOMPLISH TWO THINGS. MOST IMPORTANTLY, THE  
NORTHERN SHORTWAVE WILL BRING A REINFORCING SURGE OF EVEN COLDER  
AIR, ALONG WITH EVEN GUSTIER NORTHWEST WINDS. THIS IS LIKELY TO SEND  
ACTUAL TEMPERATURES WELL INTO THE TEENS AND SINGLE DIGITS BY  
TOMORROW MORNING, WITH WIND CHILL TEMPERATURES DROPPING TO BETWEEN 5  
AND -10 DEGREES AND POSSIBLY EVEN A FEW DEGREES COLDER IN NORTHERN  
AREAS. MEANWHILE, THE SHORTWAVE ARRIVING FROM THE WEST WILL ALSO  
BRING WITH IT A BAND OF MODEST MID-LEVEL FRONTOGENESIS, AND THIS MAY  
HELP TO PRODUCE MORE FLURRIES OR EVEN LIGHT SNOW SHOWERS ACROSS THE  
OZARKS THIS EVENING AND OVERNIGHT. ACCUMULATIONS ARE NOT LIKELY  
(LESS THAN 20% CHANCE), BUT A VERY LIGHT DUSTING IS NOT COMPLETELY  
OUT OF THE QUESTION ACROSS THE OZARKS AS A "WORST CASE" SCENARIO.  
 
GRADUALLY CLEARING SKIES ARE EXPECTED DURING THE DAY TOMORROW ASIDE  
FROM PERHAPS SOME LINGERING LOW LEVEL STRATOCUMULUS, BUT THE COLD  
TEMPERATURES WILL PERSIST ALONG WITH BITING NORTHWEST WINDS. IN  
FACT, AFTERNOON TEMPERATURES ARE NOT LIKELY TO CLIMB OUT OF THE  
TEENS FOR MOST AREAS, WITH WIND CHILLS REMAINING IN THE SINGLE  
DIGITS (BOTH ABOVE AND BELOW ZERO). AS A RESULT, SUNDAY AFTERNOON  
WILL BE IN CONTENTION FOR THE "COLDEST HIGH" TEMPERATURE OF THE  
WEEK, ALTHOUGH TUESDAY WILL LIKELY CHALLENGE IT FOR THAT IGNOMINIOUS  
DISTINCTION.  
 
OVERNIGHT SUNDAY, HIGH PRESSURE WILL SETTLE INTO THE AREA AND WIND  
SPEEDS WILL DIMINISH. WHILE THIS WILL KEEP THE WIND CHILLS IN CHECK,  
ACTUAL TEMPERATURES ARE LIKELY TO FALL EVEN LOWER THANKS TO THE MORE  
EFFICIENT RADIATIONAL COOLING. AS SUCH, EXPECT MORNING LOWS TO FALL  
INTO THE POSITIVE SINGLE DIGITS TO NEAR ZERO AREA-WIDE WITHOUT  
CONSIDERING WIND CHILLS, WHICH ARE LIKELY TO BE ONLY AROUND 5  
DEGREES LOWER THAN ACTUAL TEMPERATURES THANKS TO THE LIGHTER WINDS.  
 
BRC  
 
 
   
LONG TERM  
(MONDAY THROUGH NEXT SATURDAY)  
ISSUED AT 149 PM CST SAT JAN 18 2025  
 
THIS UNCOMFORTABLY COLD AIR WILL CONTINUE INTO THE WORK WEEK AS  
WELL, AS HIGH TEMPERATURES MONDAY ARE LIKELY TO ONLY REACH INTO THE  
UPPER TEENS TO LOW 20S AFTER STARTING OFF THE DAY IN THE SINGLE  
DIGITS. AS COLD AS THIS IS, IT MAY VERY WELL END UP BEING THE  
"WARMER DAY" BETWEEN SUNDAY AND TUESDAY, AS ANOTHER NORTHWEST FLOW  
SHORTWAVE WILL ESCORT A SECOND REINFORCING SURGE OF COLD AIR INTO  
THE AREA TUESDAY. WITH ENSEMBLE MEAN 850 MB TEMPERATURES PLUMMETING  
TO BETWEEN -20 AND -26 C AND NARROW ENSEMBLE FORECAST TEMPERATURE  
SPREADS, CONFIDENCE IS HIGH THAT TUESDAY WILL BE ON PAR WITH SUNDAY  
IN TERMS OF AFTERNOON HIGHS (IN THE TEENS), EXCEPT THIS TIME WITH  
EVEN COLDER MORNING LOW TEMPERATURES (ACTUAL TEMPERATURES OF -5 TO  
10 DEGREES). WINDS ARE ALSO LIKELY TO BRING WIND CHILLS BELOW ACTUAL  
VALUES BY ANOTHER 5 TO 10 DEGREES AS WELL, ALTHOUGH CURRENT FORECAST  
WIND CHILLS COME UP JUST SHORT OF ADVISORY-LEVEL VALUES. HOWEVER, A  
SLIGHT INCREASE IN WIND SPEEDS OR DROP IN TEMPERATURES FROM THE  
CURRENT FORECAST WOULD BRING US WITHIN RANGE OF ADVISORY-LEVEL  
HEADLINES IN AREAS LARGELY NORTH OF I-70, SO THIS WILL NEED TO BE  
WATCHED CLOSELY.  
 
IN ANY CASE, THESE TEMPERATURES ARE QUITE COLD, AND MAY NEGATIVELY  
IMPACT THOSE THAT ARE PARTICULARLY VULNERABLE TO COLD AND/OR NEED TO  
SPEND EXTENDED TIME OUTDOORS, EVEN THOUGH THEY DO NOT CURRENTLY MEET  
"HEADLINE" CRITERIA.  
 
THE GOOD NEWS IS THAT BY WEDNESDAY AN ABRUPT WARMUP REMAINS LIKELY  
AS THE EASTERN CONUS TROUGH WILL MOVE EAST OF THE AREA, AND  
SOUTHERLY LOW LEVEL FLOW WILL RESUME. AT THE VERY LEAST, THIS WILL  
PUT AN END TO THE BITTER COLD VALUES WE WILL EXPERIENCE EARLY IN THE  
WEEK, ALTHOUGH IT IS LESS CLEAR HOW TEMPERATURES WILL EVOLVE AS THE  
WEEK PROGRESSES. ENSEMBLE MEMBERS DO DISPLAY SIGNIFICANT VARIABILITY  
IN TEMPERATURE TRENDS AS WE REACH THE END OF THE WORK WEEK, LIKELY  
OWING TO DIFFERENCES IN THE TIMING OF ANOTHER DIGGING TROUGH. EVEN  
WITH THE DEEPER, COLDER MEMBER SOLUTIONS THOUGH, TEMPERATURES ARE  
NOT LIKELY TO APPROACH THE SAME LEVEL OF COLD.  
 
MEANWHILE, ENSEMBLES CONTINUE TO MAINTAIN A LARGELY DRY FORECAST FOR  
THE NEXT WEEK (ASIDE FROM TONIGHT'S VERY LIMITED POTENTIAL). THERE  
IS A MINORITY CONTINGENT OF MEMBERS THAT DO PRODUCE SOME LIGHT  
PRECIPITATION ASSOCIATED WITH THE AFOREMENTIONED LATE-WEEK TROUGH,  
BUT THIS IS WELL WITHIN THE MINORITY AND AMOUNTS ARE VERY LIGHT AT  
THIS TIME. AS SUCH, WE WILL MAINTAIN SUB-MENTIONABLE PRECIPITATION  
CHANCES THROUGH THE END OF THE FORECAST PERIOD FOR NOW.  
 
BRC  
 
 
   
AVIATION  
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)  
ISSUED AT 1216 PM CST SAT JAN 18 2025  
 
THE PRIMARY CONCERN IN THE 18Z TAF PERIOD CONTINUES TO BE THE  
PERSISTENCE OF SCATTERED TO BROKEN MVFR CEILINGS, WHICH IS DUE TO  
A SHIELD OF STRATOCUMULUS BEHIND AN ADVANCING COLD FRONT. THIS  
HAS CAUSED CEILING REDUCTIONS AT MANY LOCAL TERMINALS AT THE START  
OF THE PERIOD, PARTICULARLY AT COU/JEF. THIS STRATUS HAS BEEN  
SLOW TO ERODE, AND MAY LINGER FOR SEVERAL MORE HOURS AND POSSIBLY  
WELL INTO THE EVENING IN PLACES, WITH THE MOST PROLONGED STRATUS  
LIKELY AT CENTRAL MISSOURI TERMINALS. CONFIDENCE IS LOW REGARDING  
EXACTLY WHEN IT WILL DISSIPATE, AS IT IS LIKELY TO BE REINFORCED  
ACROSS THE OZARKS DURING THE EVENING AND OVERNIGHT.  
 
MEANWHILE, WE CAN'T RULE OUT A FEW SNOW FLURRIES AS WELL,  
ESPECIALLY THIS EVENING AND OVERNIGHT. THIS WILL BE MOST LIKELY  
ALONG I-70 TERMINALS, BUT ACCUMULATIONS OR OTHER  
VISIBILITY/CEILING REDUCTIONS ARE NOT LIKELY.  
 
OTHERWISE, GUSTY NORTHWEST WINDS WILL PERSIST THROUGHOUT THE  
PERIOD, AND VFR CONDITIONS ARE LIKELY DURING THE DAY TOMORROW.  
 
BRC  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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