Severe Thunderstorm Warning 484, NWS St. Louis, MO

000 
WWUS53 KLSX 092220
SVSLSX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
520 PM CDT WED AUG 9 2006

MOC071-092230-
/O.CAN.KLSX.SV.W.0484.000000T0000Z-060809T2245Z/
FRANKLIN MO-
520 PM CDT WED AUG 9 2006

...THE SEVERE THUNDERSTORM WARNING FOR FRANKLIN COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED AND NO LONGER
APPEARED TO BE SEVERE.

LAT...LON 3868 9135 3822 9137 3821 9088 3853 9088

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
406 PM CDT WED AUG 9 2006

.DISCUSSION...
FOR THE SHORT TERM...FCST DIFFICULTIES REMAIN THE SAME AS THEY HAVE
BEEN THE PAST FEW DAYS. NAMELY PRECIP CHCS...TIMING OF PRECIP...AND
POSSIBLE SVR WX FOR TNGT INTO TMW MRNG.

FOR TNGT...WITH FNT RETREATING NWD...EXPECT SCT TSRA TO DEVELOP JUST
S OF FNT. WRMFNT CURRENTLY STRETCHES FROM NRN NEB SEWD THRU ERN MO
INTO CNTRL KY. THIS WILL ALLOW SCT TSRA TO FORM...MV FURTHER NWD
THAN YDA. AFTR THIS AFTN CONVECTION...ATTENTION TURNS TO MCS
DEVELOPMENT OVRNGT IN IA AS LLJ FORMS OVR MO AND IA AGAIN TNGT. SREF
MEMBERS DEVELOP PRECIP IN NRN CWA BY 03Z THURS. THINK THIS TIMING IS
TOO FAST AND HAVE TRENDED TWD THE 12Z WRF AND GFS SOLNS. MDLS
BRING MCS INTO NRN CWA BY 09Z THURS. NAM-WRF HAS DONE EXCELLENT JOB
ON TIMING AND MOVEMENT OF MCS PAST COUPLE OF DAYS SO NAM IS MDL OF
CHOICE. HAVE LITTLE CONFIDENCE IN GFS SOLNS DUE TO CONVECTIVE
FEEDBACK. WRF DOES SUFFER THIS AS WELL...BUT DOES NOT APPEAR TO BE
AS BAD. WRF ALSO SEEMS TO BE HANDLING FNT MVMNT FOR THE PAST 12 HRS
BETTER THAN GFS.

CHCS OF PRECIP TMW WILL GREATLY DEPEND ON CLD CVR FROM OVRNGT MCS.
MDLS INDICATE MDT MOISTURE CONVERGENCE AND INSTABILITY ALONG FNT BY
15Z THURS. MOISTURE RETURN AND ONGOING CONVECTION WILL PROVIDE A
MOIST BDRY LYR WITH SFC DWPTS IN LWR 70S S OF FNT. EXPECT ENUF
INSOLATION TMW TO ALLOW TSRA TO FORM BY EARLY AFTN ALONG FNT...IF
NOT EARLIER. FCST HODOGRAPHS SHOW CONVECTION MODE TMW MAY BEGIN AS
SUPERCELLS. HOWEVER...ANY STORMS THAT DO FORM WILL MORE LIKELY
DEVELOP INTO A MORE LINEAR STRUCTURE DUE TO MID LVL NWLY FLOW.

TEMPS FOR TMW WILL REMAIN A FCST PROBLEM. IF MCS DOES NOT FORM AS
EXPECTED...OR IF MCS PROPAGATES FURTHER E THAN EXPECTED...TEMPS MAY
BE MUCH WARMER THAN FCST.

PRECIP CHCS CONTINUE IN SRN CWA AS THE CDFNT CONTINUES TO MV SWD.
AMT OF INSTABILITY IS UNCERTAIN DUE TO CLD CVR AND OUTFLOW BDRYS
FROM DAY 2 CONVECTION.

FOR THE EXTD...FCST DIFFICULTIES WILL BE TIMING OF FROPA ON MON INTO
TUES. GFS IS A LITTLE SLOWER TDA THAN YDAS MDL RUN. DGEX AND ECMWF
ARE FASTER AND MORE CONSISTANT RUN TO RUN. THEREFORE...MADE ONLY
MINOR CHANGES TO POPS AND TEMPS AND WILL NAIL DOWN TIMING IN FUTURE
UPDATES. AS FOR TEMPS...WENT ABV MOS GUIDENANCE CLOSER TO THE
ENSEMBLE MEAN. FCST STILL BLW SEASONAL AVG AFTR FROPA ON MON.

TILLY

&&

.AVIATION...
FOR THE 12Z TAFS...
MESSY AUGUST FORECAST DEALING WITH MORNING IFR CIGS AND CHANCES OF
AFTERNOON TSRA. STATIONARY FRONT IS ROUGHLY ALG A KMKC-KVIH-KPAH
LINE AT 10Z. STRATUS DEVELOPED OVERNIGHT TO THE NORTH OF FRONT
AND HAS RESULTED IN IFR CIGS AT BOTH KUIN AND KSTL. AWOS AT
MOVERLY MO IS ALSO REPORTING CIGS AROUND 200 FT...SO ALSO HAVE A
LOWER CIG IN A TEMPO GROUP AT KCOU. GIVEN THAT THERE IS NO MID OR
HIGH CLOUDS IMMEDIATELY ABOVE THE STRATUS...FEEL THAT THE STRATUS
SHOULD BURN OFF THIS MORNING...SO HAVE IFR GOING THROUGH 14Z AND
MVFR THROUGH 15Z. CIGS SHOULD BE VFR BY LATE MORNING. FRONT SHOULD
REMAIN STATIONARY OR DRIFT SLOWLY NWD BEFORE MOVING BACK NWD AS A
WARM FRONT TONIGHT. HAVE INCLUDED PROB30 GROUPS FOR TSRA AT
KSTL/KSUS WHERE THE FRONT SHOULD BE IN CLOSE PROXIMITY DURING THE
MOST UNSTABLE PART OF THE DAY. THINK ANY DEVELOPMENT SHOULD BE NORTH
AND EAST OF COU. HAVE ALSO CHOSE TO LEAVE KUIN DRY THIS AFTN AS I
THINK THE CHANCES ARE TOO LOW TO INCLUDE IN THE TERMINAL FOR
NOW...BUT LOW LEVEL FORCING LATER TONIGHT WARRANTS A MENTION OF
TSRA AFT 09Z.

&&

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

WFO LSX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
450 PM CDT WED AUG 9 2006

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-101200-
ADAMS IL-AUDRAIN-BOND IL-BOONE-BROWN IL-CALHOUN IL-CALLAWAY-
CLINTON IL-COLE-CRAWFORD-FAYETTE IL-FRANKLIN-GASCONADE-GREENE IL-
IRON-JEFFERSON-JERSEY IL-KNOX-LEWIS-LINCOLN-MACOUPIN IL-MADISON-
MADISON IL-MARION-MARION IL-MONITEAU-MONROE-MONROE IL-MONTGOMERY-
MONTGOMERY IL-OSAGE-PIKE-PIKE IL-RALLS-RANDOLPH IL-REYNOLDS-
SHELBY-ST. CHARLES-ST. CLAIR IL-ST. FRANCOIS-ST. LOUIS-
ST. LOUIS CITY-STE. GENEVIEVE-WARREN-WASHINGTON-WASHINGTON IL-
450 PM CDT WED AUG 9 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND
CENTRAL MISSOURI AS WELL AS SOUTHWEST ILLINOIS.

.DAY ONE...TONIGHT

THERE IS A SLIGHT RISK FOR WIDESPREAD OR ORGANIZED SEVERE
THUNDERSTORMS LATE TONIGHT IN NORTHEAST MISSOURI AND WEST CENTRAL
ILLINOIS. A THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP TO OUR
NORTH LATER TONIGHT AND PROPAGATE TO THE SOUTHEAST INTO NORTHEAST
MISSOURI AND WEST CENTRAL ILLINOIS TOWARD DAYBREAK. THE PRIMARY
THREATS WITH THESE STORMS WILL BE LARGE HAIL...AND TO A LESSER
EXTENT...DAMAGING WINDS.

ELSEWHERE...THERE IS A CHANCE FOR THUNDERSTORMS THROUGH EARLY
EVENING FOR AREAS NEAR A SLOW MOVING FRONT...IN THE VICINITY OF
INTERSTATE 70. DUE TO THE LARGE AMOUNT OF INSTABILITY IN THE
ATMOSPHERE...ISOLATED SEVERE STORMS ARE POSSIBLE FOR BRIEF PERIODS
OF TIME...CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS AREAWIDE ON
THURSDAY AS A COLD FRONT MOVES THROUGH THE AREA AND INTERSECTS A
VERY MOIST AND UNSTABLE ATMOSPHERE.

THE CHANCE FOR THUNDERSTORMS WILL LINGER FOR AREAS MAINLY SOUTH
AND EAST OF ST. LOUIS ON FRIDAY.

THERE IS ANOTHER CHANCE FOR THUNDERSTORMS AREAWIDE ON MONDAY AS A
COLD FRONT MOVES THROUGH THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED IN THE VICINITY OF INTERSTATE 70
THROUGH EARLY EVENING AND AGAIN LATE TONIGHT IN NORTHEAST MISSOURI
AND WEST CENTRAL ILLINOIS.

TES