000 
FXUS63 KLSX 212110
AFDSTL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
410 PM CDT THU AUG 21 2003

.DISCUSSION...
CURRENT SURFACE OBS AND SATELLITE PICS SHOWING SURFACE FRONT 
EXTENDING FROM WEST CENTRAL ILLINOIS SOUTHWESTWARD TO VICINITY OF 
KANSAS CITY.  SURFACE CONVECTION BREAKING OUT WELL IN ADVANCE OF THE 
FRONT AS SHOWN BY SATELLITE PICS AND KLSX 88D.  THE CU FIELD IN 
VICINITY OF THE FRONT IS PUNY AT BEST...AND EVEN FURTHER SOUTH INTO 
THE COLUMBIA AND ST LOUIS AREA...LITTLE VERTICAL DEVELOPMENT IS 
NOTED...THOUGH A FEW ECHOS ARE BEGINNING TO POP ON RADAR.  GFS AND 
ETA ARE SHOWING GOOD CONTINUITY WITH FRONTAL POSITION THIS 
AFTERNOON...AND THEY ARE VERY CLOSE ON THEIR HANDLING OF THE FRONT.  
THE DIFFERENCES ARE GOING TO BE RIGHT IN VICINITY OF THE ST LOUIS 
METRO AREA UNFORTUNATELY.  IF THE ETAS RIGHT...THEN WELL STILL BE 
IN THE HEAT AND HUMIDITY...IF THE GFS IS RIGHT...THEN WELL BE 
COOLER AND DRIER.  SINCE THE FRONT IS MAKING GOOD PROGRESS...AND THE 
GFS SEEMS TO BE HANDLING IT JUST SLIGHTLY BETTER...WENT WITH GFSS 
SOLUTION AND COOLED US OFF.  UNFORTUNATELY THE SOUTHERN AREAS OF OUR 
FORECAST AREA WILL LIKELY STILL BE IN THE LOWER 90S WITH LOW TO MID 
70S FOR DEWPOINTS TOMORROW TILL THE FRONT FINALLY PUSHES THROUGH 
FRIDAY EVENING.  LEANED ON LOWER MOS NUMBERS FURTHER NORTH...AND 
HIGHER NUMBERS SOUTH.

THE REMAINDER OF THE SHORT TERM LOOKS PRETTY QUIET.  HIGH PRESSURE 
SHOULD BUILD IN BEHIND THE COLD FRONT ON SATURDAY AND EASTERLY WINDS 
SHOULD KEEP US RELATIVELY COOLER.  850MB TEMPS IN THE 16 TO 18 
DEGREE RANGE GENERALLY SUPPORT TEMPS IN THE MID TO UPPER 80S...AND 
AGAIN MOS NUMBERS LOOK PRETTY REASONABLE.  THE ONLY QUESTION 
IS...HOW FAST WILL THE HEAT RETURN TO CENTRAL MO?  500MB RIDGE 
STARTS BUILDING BACK INTO MISSOURI ON SATURDAY...AND THERE IS THE 
POTENTIAL THAT WE COULD SEE HOT TEMPS AGAIN AS EARLY AS SUNDAY IN 
CENTRAL MO.  WENT ABOUT A CAT HIGHER THAN GUIDANCE FOR SUNDAY...THIS 
WILL NEED TO BE WATCHED AND MAY NEED TO BE ADJUSTED UPWARDS IF THE 
MODELS START TRENDING WARMER.

IN THE EXTENDED...THE GFS ENSEMBLE CONTINUES BUILDING THE 500MB 
RIDGE EASTWARD INTO KANSAS AND WESTERN MISSOURI BY 00Z MONDAY.  
850MB THERMAL RIDGE STRETCHES ALL THE WAY EASTWARD INTO NORTHERN 
ILLINOIS BY 00Z TUESDAY...THESE COULD BE OUR WARMEST DAYS NEXT WEEK 
AS THE THE FLOW GOES MORE ZONAL ACROSS THE MID-WEST INTO WEDNESDAY.  
WOULD EXPECT TEMPERATURES TO MODIFY SLIGHTLY AS WE GET INTO THE MORE 
ZONAL PATTERN.  AS RIDGE FADES...LESS ANTI-CYCLONIC FLOW/LESS 
SUBSIDENCE AND MORE LITTLE SHORTWAVES RIPPLING ALONG THE BAROCLINIC 
ZONE WHICH SHOULD BE JUST NORTH OF US.  COULD SEE SOME OF THE 
EFFECTS AT THE SURFACE AS FAR SOUTH AS QUINCY OR EVEN ST LOUIS.  
WOULD GENERALLY EXPECT MORE AFTERNOON CONVECTION...EVEN THOUGH MOS 
KEEPS US DRY.  DONT FEEL STRONGLY ENOUGH AT THIS TIME TO INTRO POPS 
INTO THE EXTENDED SINCE NEITHER THE OPERATIONAL NOR THE ENSEMBLE 
GUIDANCE HAS ANY GLARING SURFACE FEATURE TO FORCE CONVECTION.  
THEYRE BOTH SORT OF LEANING TOWARD SOME GENERAL SURFACE 
TROFFYNESS...BUT ITS WEAK AND DIFFUSE AND COULD JUST BE A FIGMENT 
OF THE MODELS IMAGINATION OUT THAT FAR.  NOT SURE I CAN DO BETTER 
THAN CLIMO FOR TEMPERATURES FOR WEDNESDAY AND THURSDAY AS THE 
PATTERN GOES MORE ZONAL AS THERES NO OUTSTANDING FEATURE TO REALLY 
KEY IN ON...AND BOTH MOS AND NCEP ARE TRENDING THAT WAY ANYWAY.

&&

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

$$

CARNEY