Severe Thunderstorm Warning 227, NWS St. Louis, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
325 PM CDT FRI AUG 1 2003

.DISCUSSION...
OVERALL...NOT MUCH DIFFERENCE IN SHORT TERM MODELS WITH THE GENERAL
PATTERN ACROSS THE CENTRAL CONUS...BUT BOTH ETA/GFS HAVE PROBLEMS
WITH CONVECTIVE FEEDBACK OVER SRN 2/3RDS OF MO BOTH TONIGHT AND
SATURDAY EVENING.  PLAN ON USING A COMPROMISE OF ETA/GFS/NGM MASS
FIELDS...ACCOUNTING FOR THESE PROBLEMS...TO DETERMINE SENSIBLE
WEATHER FIELDS.

CURRENT THINKING IS THAT AREA OF PCPN OVR NRN AND CNTRL MO LIMITING
THE AMOUNT OF INSTABILITY AVAILABLE FOR SEVERE WEATHER.  S OF
I-70...DAYTIME HEAT AND BOUNDARY ASSOCIATED WITH PCPN/CLOUD SHIELD
IS SETTING UP BOUNDARY THAT HAS TRIGGERED SVR TSRA IN THE LAST
HOUR.  BEST MID LEVEL Q-VECTOR CONVERGENCE/0-6KM SHEAR IS STAYING N
OF THIS AREA ATTM FAVORING THE POTENTIAL OF SVR MULTICELL
CLUSTERS/BOWS.  AS THIS BOUNDARY MOVES FARTHER S TONIGHT...SRN MO
INCLUDING FAR SRN PART OF CWA WILL HAVE HEAVY RAINFALL THREAT FROM
MCS THAT WILL MOVE ACROSS SRN MO/NRN AR LATE TONIGHT.

OTHERWISE...KEPT CHC PCPN SATURDAY AND SUNDAY AS SERIES OF SHORTWAVE
THROUGHS MOVES THROUGH PERSISTENT NWLY FLOW.  USED A BLEND ON
GUIDANCE FOR TEMPERATURES NEXT COUPLE OF DAYS.

IN THE EXTENDED...MEDIUM RANGE MODELS SHOWING GOOD AGREEMENT WITH
PERSISTENT WRN CONUS RIDGE AND ERN TROF.  HAVE SOME ISOLD/SCT
CONVECTION IN THE NERN 1/2 ON MONDAY BASED ON PROXIMITY OF UPR LOW
AND ASSOCIATED COLD POOL.  ALSO HAVE SCT TSRA LATE MON NIGHT/TUE
MORN OVR WRN 1/3RD OF CWA FOR MCS DEVELOPMENT. OTHERWISE...WENT DRY
WED THRU FRI AS 500MB HEIGHTS SLOWLY INCREASE.  GENERALLY FOLLOWED
THE MRF ENSEMBLE MOS GUIDANCE FOR TEMPS.

&&

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

BRITT

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-021100-

HAZARDOUS WEATHER OUTLOOK...UPDATE
NATIONAL WEATHER SERVICE ST LOUIS MO
915 AM CDT FRI AUG 1 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND EASTERN MISSOURI
AND WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT

THE RISK FOR SEVERE THUNDERSTORMS HAS BEEN UPGRADED TO A MODERATE
RISK FOR THE ENTIRE FORECAST AREA FOR THIS AFTERNOON AND TONIGHT.
THUNDERSTORMS WILL DEVELOP AHEAD OF A COLD FRONT THIS AFTERNOON.
THESE STORMS WILL DEVELOP QUICKLY AND MOVE SOUTHEAST ACROSS THE
AREA.  THE PRIMARY SEVERE THREAT FROM THESE STORMS WILL BE DAMAGING
WINDS.  LARGE HAIL IS ALSO POSSIBLE WITH SOME OF THE STORMS.
WIDESPREAD WIND DAMAGE IS POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE WILL BE CHANCE FOR THUNDERSTORMS SATURDAY MORNING GENERALLY
SOUTH AND EAST OF INTERSTATE 55 IN ILLINOIS AND INTERSTATE 44 IN
MISSOURI. THE CHANCE OF THUNDERSTORMS WILL CONTINUE FOR THE
AFTERNOON ACROSS SOUTHEAST MISSOURI AND PARTS OF SOUTHERN ILLINOIS.
MORE THUNDERSTORMS WILL BE POSSIBLE LATE TUESDAY...PRIMARILY ACROSS
SOUTHERN MISSOURI.

SPOTTER ACTIVATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED ACROSS THE FORECAST AREA
THIS AFTERNOON AND TONIGHT.

&&

MORE INFORMATION MAY BE OBTAINED AT...
HTTP://WWW.CRH.NOAA.GOV/LSX (ALL LOWER CASE)

PEDIGO