Severe Thunderstorm Warning 220, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
300 PM CDT MON AUG 23 1999

WATER VAPOR AND STLT IMAGERY SHWG UNSEASONABLY STG UPR LOW CONTG TO
DIGG RAPIDLY SEWD WITH 19Z PSN NR THE CNTRL IA/MN BORDER.  ASSOCD
SFC FNT HAS MOVD INTO NW MO WITH FAIRLY XTNSV CU FIELD IN ADVANCE
OF THE FNT WITHIN AXIS OF MDTLY UNSTBL AIR.  INTENSE MID/UPR JET IN
SW QUAD AND NOW NOSING INTO NW MO INDCT UPR LOW SHUD CONT DIGG SEWD
MUCH AS PROGGED BY MDLS WITH LRG SCALE LIFT ONLY IMPVG FOR THE RMNDR
OF THE AFT INTO THE EVNG HRS OVR NE/EC MO INTO IL.  RIGHT NOW JUST
WAITING FOR STRMS TO CONT DVLPG.  STG WNDS ALF AND FVRBL DP LYR
SHR /0-6KM/ CONT TO SUPPORT THREAT OF ORGANIZED SVR STRMS WITH
DAMAGING WNDS THE GREATEST SVR THREAT.  ANY POTNTL FOR SUPERCELLS
ATTM WUD APPEAR TO BE OVR NE MO INTO WC IL COUNTIES WHERE LOW LVL
SHEAR PROFILES ARE BTR.  STMRS WHICH DO DVLP SHUD MOV QUICKLY SE AND
THINK THAT MOST OF THE CWFA SHUD BE OUT OF THE WOODS BY MIDNIGHT OR
SO.

WL DCRS THE AMT OF CLDS FOR TNGT FM PRVS FCST BHD THE FNT.  THERE
ARE SOME STORMS AND CLDS IMMEDIATELY BENEATH THE UPR SYS BUT FOR THE
MOST PART...ALOT OF DRY AIR IS BEING ADVECTED SE.

THE MDLS ARE GETTING IN BTR AGREEMENT FOR THE RMNDR OF THE FCST
ALTHO CONT TO EXHIBIT VARIANCES WITH RESPECT TO EXACT PSN OF THE
UPR LOW...AND THIS IS THE MOST CRITICAL PART OF THE FCST FOR ERN MO
AND WRN IL.  ETA RMNS THE MOST PROGRSV OF THE SHRT RNG MDLS WITH
THE LOW IN CNTRL IL BY 12Z TUE...ADVANCING INTO ERN INDIANA BY 12Z
WED.  WITH THIS PSN IT IS DOWNPLAYING THE WRAP ANRD LOW LVL MSTR...
SC DVLPMNT IN THE CD AIR...AND HENCE ANY THREAT OF -SHRA.  NGM/AVN
SLOW THINGS DOWN A BIT TMW THEN BCM MORE PROGRSV WITH THE SYS LATE
TMW NGT INTO WED.  NGM EVEN INDCTG LESSER THREAT OF CLDS AND
BACKWASH INSTABILITY -SHRA.

WHILE I THINK SC DVLPMNT IS A PRETTY GUD BET TMW ACRS THE CWFA...
SPCLY NE AND FAR EAST SXNS...MY CONFIDENCE LVL IN PCPN IS NOT VERY
HI SO FAR WEST OF THE UPR LOW BACK INTO MO.  ATTM WL RETAIN CURRENT
FCST OF LOW POPS IN ERN MO ZNS INTO IL.  WHILE AVN FCST OF VORT
LOBES ROTG ABT LOW AND INTO MO BEAR WATCHING...OVERALL...UPR SYS
SHUD HV LESSENING EFFECT ON WX ACRS MO IN THE LATER PDS AS UPR COLD
POOL RETREATS TO THE EAST.  RIGHT NOW WILL TAKE IT ONE DAY AT A TIME
AS FOR PCPN CHCS.

.STL...NONE
GLASS