692  
FXUS63 KLSX 162048  
AFDLSX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
348 PM CDT MON SEP 16 2019  
   
SHORT TERM
 
(THROUGH LATE TONIGHT)  
ISSUED AT 255 PM CDT MON SEP 16 2019  
 
WEAK CONVERGENCE WAS NOTED ALONG A BACK-DOOR COLD FRONT WHICH HAD  
SETTLED INTO THE REGION. SCATTERED SHRA/TSRA HAVE ALREADY  
DEVELOPED FARTHER EASTWARD ALONG THE BOUNDARY IN IN/KY/OH WHERE  
METARS SHOWED STRONGER SURFACE CONVERGENCE. BASED ON SATELLITE  
DEPICTIONS OF THE CUMULUS FIELD OVER MO/IL AS WELL AS BUFKIT  
SOUNDINGS SHOWING VERY LITTLE CINH, THE PREVIOUS SHIFT'S  
EXPECTATION FOR ISOLATED SHRA/TSRA STILL LOOKS ON TRACK. HOWEVER,  
THE LOCATION OF THESE POPS HAS BEEN ADJUSTED SLIGHTLY EASTWARD TO  
REFLECT THE LATEST POSITION OF THE SURFACE FRONT.  
 
LOWS TONIGHT SHOULD RANGE FROM THE MID 60S IN SW IL (ON THE COOLER  
SIDE OF THE STALLED BOUNDARY) TO AROUND 70 IN CENTRAL MO. THE  
COMBINATION OF LIGHT WINDS AND MOISTURE POOLING NEAR THE FRONT  
COULD ALSO LEAD TO LIGHT FOG DEVELOPMENT TONIGHT. THE ONLY  
INHIBITING FACTOR WILL BE SOME MID/HIGH CLOUDS SPILLING INTO THE  
REGION, AND THIS MAY RESULT IN PATCHY FOG DEVELOPMENT WITHIN ANY  
BREAKS IN THE CLOUDS.  
 
KANOFSKY  
   
LONG TERM
 
(TUESDAY THROUGH NEXT MONDAY)  
ISSUED AT 255 PM CDT MON SEP 16 2019  
 
WARM AND HUMID CONDITIONS ARE EXPECTED TO PERSIST FOR THE REST OF  
THE WEEK DUE TO THE COMBINED INFLUENCE OF AN UPPER RIDGE AXIS AS  
WELL AS SOUTHERLY FLOW ALONG THE PERIPHERY OF A SURFACE HIGH  
PRESSURE CENTER. HIGHS WILL GENERALLY BE IN THE UPPER 80S TO LOWER  
90S AND OVERNIGHT LOWS WILL BE IN THE 60S TO LOWER 70S.  
 
SOME MODELS SHOW A FEW WEAK DISTURBANCES DURING THE WEEK WHICH  
COULD PRODUCE ISOLATED SHRA/TSRA, BUT THE BEST CHANCE FOR  
WIDESPREAD RAINFALL APPEARS TO BE FROM FRIDAY THROUGH SUNDAY NIGHT  
WHEN A LOW PRESSURE SYSTEM LIFTS THROUGH THE NORTH-CENTRAL CONUS  
TOWARDS CANADA. MODELS ALL SHOW A SECONDARY DISTURBANCE MOVING  
INTO THE TROUGH AFTER THE FIRST LOW PRESSURE SYSTEM HAS LIFTED  
NORTHEASTWARD, BUT THERE IS POOR AGREEMENT BETWEEN MODELS ON THE  
RESULTING LARGE SCALE UPPER AIR PATTERN. THAT SAID, MODELS DO  
APPEAR TO BE IN GENERAL AGREEMENT THAT A PATTERN CHANGE WILL BRING  
A PERIOD OF WETTER WEATHER TO THE REGION THIS WEEKEND AND PERHAPS  
INTO EARLY NEXT WEEK. TEMPERATURES SHOULD BE LOWER THIS WEEKEND  
DUE TO CLOUDS AND RAIN, AND THERE IS AT LEAST A CHANCE THAT A  
FRONTAL BOUNDARY COULD EVEN PUSH THROUGH THE REGION AND BRING  
COOLER TEMPERATURES TO THE AREA.  
 
KANOFSKY  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 1226 PM CDT MON SEP 16 2019  
 
VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS. THERE IS A SLIM  
CHANCE OF A THUNDERSTORM BETWEEN 18-24Z NEAR A WEAK COLD FRONT  
WHICH IS MOVING INTO THE AREA FROM THE NORTHEAST, BUT SHRA/TSRA  
CHANCES ARE TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. PATCHY  
LIGHT FOG IS ALSO POSSIBLE AFTER 17/09Z.  
 
KANOFSKY  
 

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

 
 

 
 
WFO LSX  
 
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