387  
FXUS63 KLSX 241018 CCA  
AFDLSX  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
418 AM CST FRI NOV 24 2017  
   
SHORT TERM
 
(THROUGH LATE TONIGHT)  
ISSUED AT 404 AM CST FRI NOV 24 2017  
 
THE UPPER AIR PATTERN WILL BE PROGRESSIVE BUT WILL UNDERGO A GOOD  
DEAL OF AMPLIFICATION OVER THE NEXT 30 HOURS. THE SHORT WAVE TROF  
CURRENTLY EXITING THE NORTHERN ROCKIES WILL AMPLIFY AS IT MOVES EAST  
AND INTO THE MS VALLEY BE EARLY THIS EVENING. ACCOMPANYING THIS  
SHORT WAVE WILL BE A COLD FRONT WHICH SHOULD EXTEND FROM EASTERN IA  
THROUGH NW MO INTO SE KS AT 00Z TONIGHT. MILD TEMPERATURES AND  
BREEZY CONDITIONS WILL BE THE STORY FOR TODAY. A BATCH OF HIGH  
CLOUDS WILL SLIDE SOUTHEAST ACROSS THE AREA THIS MORNING, WHILE THE  
SURFACE PRESSURE GRADIENT AND LOW LEVEL HEIGHT GRADIENT TIGHTEN.  
THIS WILL RESULT IN INCREASING AND GUSTY SOUTH-SOUTHWEST WINDS FROM  
MID-LATE MORNING INTO THE AFTERNOON AND PROMINENT LOW LEVEL WAA.  
HIGHS TODAY WILL BE QUITE MILD RANGING FROM 15-20 DEGREES ABOVE  
NORMAL.  
 
THE SHORT WAVE TROF WILL CONTINUE TO MOVE EAST TONIGHT AND INTO THE  
OH/TN VALLEYS SENDING THE COLD FRONT THROUGH THE AREA. THERE IS SOME  
WEAK LARGE SCALE FORCING ACCOMPANYING THE UPPER TROF AND COLD  
FRONT, AS WELL A BAND OF MID LEVEL MOISTURE. INTERESTINGLY, A FEW  
OF THE CAMS ALSO HAVE A LITTLE LIGHT PRECIPITATION. WE PREVIOUSLY  
HAD SOME SPRINKLES IN THE FORECAST AND THE NEW FORECAST EXPANDS  
THE COVERAGE IN A SWATH THAT MIGRATES SOUTHEAST TONIGHT COINCIDENT  
WITH THE WEAK FORCING AND MOISTURE. EVEN THOUGH WE WILL SEE A  
COLD FROPA TONIGHT, THE AIR IS NOT PARTICULARLY COLD, AND MINS  
WILL BE ABOVE NORMAL.  
 
GLASS  
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 404 AM CST FRI NOV 24 2017  
 
CORRECTED LONG TERM DISCUSSION.  
 
THE FIRST PART OF THE LONG-TERM FORECAST WILL CONTINUE TO BE  
TRANQUIL AS A LONGWAVE TROF REMAINS IN PLACE OVER THE EASTERN U.S.  
THIS WILL KEEP THE MID MISSISSIPPI VALLEY IN NORTHWEST FLOW THROUGH  
MUCH OF THE TROPOSPHERE AND LOCK A RELATIVELY MILD RIDGE OF HIGH  
PRESSURE AT THE SURFACE OVER THE AREA THROUGH AT LEAST SUNDAY NIGHT  
INTO MONDAY. TEMPERATURES FOR SATURDAY AND SUNDAY WILL CONTINUE TO  
BE ABOVE NORMAL IN THE MID AND UPPER 50S WITH PLENTY OF SUNSHINE.  
GUIDANCE IS IN GOOD AGREEMENT IN BEGINNING A PATTERN SHIFT ON MONDAY  
IN BUILDING AN UPPER RIDGE EAST INTO THE MISSISSIPPI VALLEY. THE  
SURFACE HIGH WILL BE SHUNTED FURTHER EAST AS THIS HAPPENS RESULTING  
IN LOW LEVEL SOUTHWEST FLOW. GUIDANCE MEMBERS ARE IN GENERALLY GOOD  
AGREEMENT ON THIS SHIFT, THOUGH THE ECMWF IS A BIT SLOWER THAN THE  
GFS AND CANADIAN. AM SIDING A LITTLE BIT WITH THE WARMER AND  
BREEZIER SOLUTION IN THIS CASE SINCE HIGHS ON SUNDAY WILL ALREADY BE  
RUNNING AS MUCH AS 10 DEGREES ABOVE NORMAL AND MONDAY SHOULD BE EVEN  
WARMER THAN THAT.  
 
THE UPPER PATTERN BECOMES QUASI-ZONAL ON TUESDAY WITH A SHORTWAVE  
MOVING ACROSS THE U.S. CANADIAN BORDER AND ANOTHER WAVE MOVING OFF  
THE ROCKIES BY AROUND 00Z WEDNESDAY. THE NORTHERN WAVE WILL PUSH A  
COLD FRONT INTO THE MIDWEST TUESDAY NIGHT AND WEDNESDAY MORNING.  
WHILE THE ATMOSPHERE LOOKS PRETTY DRY, THERE MAY BE ENOUGH MOISTURE  
CONVERGENCE AHEAD OF THE FRONT TO SQUEEZE OUT SOME LIGHT RAIN BEFORE  
SUNRISE TUESDAY OVER WESTERN/NORTHERN PORTIONS OF THE FORECAST AREA,  
THOUGH QPF LOOKS PRETTY MEAGER. GUIDANCE IS IN DECENT SYNOPTIC  
AGREEMENT WITH THE SECOND WAVE MOVING FROM THE ROCKIES INTO THE  
PLAINS TUESDAY NIGHT AND WEDNESDAY. THE ECMWF IS ABOUT 6 HRS BEHIND  
THE GFS AND CANADIAN MODELS, AND IT'S ALSO AROUND 100-150 MILES  
FURTHER NORTH WITH BASE OF THE SHORTWAVE AND THE ASSOCIATED SURFACE  
LOW. BACKED POPS OFF A BIT ON WEDNESDAY TO GIVE A NOD TO THE  
ECMWF'S SLIGHTLY SLOWER AND MORE NORTHERLY SOLUTION, THOUGH IT DOES  
LOOK LIKE THE MUCH OF THE AREA SHOULD SEE A CHANCE OF PRECIP AT SOME  
POINT ON WEDNESDAY INTO WEDNESDAY NIGHT. THE SYSTEM SHOULD BE  
THROUGH THE AREA ON THURSDAY WITH HIGH PRESSURE BUILDING ACROSS THE  
PLAINS INTO THE MIDWEST. THE ECMWF KEEPS SOME LIGHT PRECIP OVER  
EASTERN PORTIONS OF THE AREA THURSDAY, BUT WITH DRIER AIR POURING  
INTO THE REGION THE CHANCE FOR PRECIP SHOULD BE MINIMAL.  
 
CARNEY  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1145 PM CST THU NOV 23 2017  
 
VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. HIGH CLOUDS OVER  
NORTHWEST MO WILL CONTINUE TO STREAM SOUTHEAST OVERNIGHT AND INTO  
THE DAY ON FRIDAY. SOUTHWESTERLY WINDS WILL INCREASE LATE FRIDAY  
MORNING INTO FRIDAY AFTERNOON, WITH GUSTS OF 20-25 KNOTS LIKELY  
AHEAD OF A COLD FRONT. THIS COLD FRONT WILL PUSH THROUGH ALL SITES  
FRIDAY EVENING, BRINGING A WIND SHIFT TO THE NORTHWEST ALONG WITH  
SOME ENHANCED MID/HIGH CLOUDINESS.  
 
SPECIFICS FOR KSTL:  
MAIN TAF CONCERN WILL BE CROSSWIND POTENTIAL ON THE PARALLEL  
RUNWAYS FRIDAY AFTERNOON. SOUTHWEST WINDS WILL INCREASE BY LATE  
FRIDAY MORNING, WITH GUSTS OF 20-25 KNOTS POSSIBLE FRIDAY  
AFTERNOON. OTHERWISE, A COLD FRONT WILL BRING A WIND SHIFT TO THE  
WNW FRIDAY EVENING WITH SOME INCREASE IN MID/HIGH CLOUDINESS.  
 
KD  
 

 
   
CLIMATE
 
 
ISSUED AT 404 AM CST FRI NOV 24 2017  
 
RECORD HIGH TEMPERATURES FOR NOV 24  
 
STL...74 1966  
COU...70 1966  
UIN...69 1931  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SAINT LOUIS 71 46 57 36 / 0 10 0 0  
QUINCY 68 40 55 33 / 5 10 0 0  
COLUMBIA 70 41 58 34 / 5 10 0 0  
JEFFERSON CITY 72 42 59 34 / 0 10 0 0  
SALEM 61 43 56 34 / 0 10 0 0  
FARMINGTON 66 44 59 34 / 0 10 0 0  
 

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

 
 

 
 
WFO LSX  
 
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