Hail in Missouri, June 27, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
417 PM CDT TUE JUN 27 2006

.DISCUSSION...
SHORTWV TROF/VORT MAX QUITE EVIDENT ATTM IN THE PROFILER AND
SATELLITE DATA FROM WCNTRL IL THRU CNTRL MO INTO SE KS HAS HELPED
INITIATE ISOLD TO WIDELY SCT TSRA.  THE AIR MASS IT IS INTERACTING
WITH IS ONLY MARGINALLY UNSTABLE WITH CAPES ALG AND NORTH OF I-70
RUNNING 1000-1400 J/KG IN THE LATEST LAPS DATA.  THIS SHRTWV TROF
WILL CONT TO MOVE SEWD THIS EVENING WITH ATTENDANT THUNDERSTORMS.
COVERAGE SHOULD DIMINISH DRAMATICALLY AFTER SUNSET AS THE
INSTABILITY WANES WITH LOSS OF HEATING. SCT THUNDERSTORMS OCCURRING
IN ADVANCE OF THE NEXT CDFNT ACRS SRN NEBRASKA AND SW IA SHOULD
EXHIBIT SIMILAR TENDENCIES...DIMINISHING LATER THIS EVENING.

THE AFOREMENIONED E/W COLD FRONT WILL MEANDER SLOWLY SWD THRU NRN MO
AND WRN IL ON WED. THE GUIDANCE IS RELATIVELY CLOSE BRINGING THE
FRONT IN A EAST-WEST LINE TO THE NORTH OF I-70 BY 00Z THURS. UNLIKE
TODAY WHERE WE HAVE A DEFINED SHRTWV THERE IS A LACK OF A LARGER
SCALE UPPER LVL FEATURE TO HELP WITH THUNDERSTORMS...THUS IT APPEARS
THAT FRONTAL CONVERGENCE WILL BE THE MAIN FORCING MECHANISM...AND IT
IS ONLY WK.  USING MORE CONSERVATIVE BOUNDARY LAYER DEW POINTS YIELDS
AFTERNOON CAPES ALONG AND IN ADVANCE OF THE FRONT OF AROUND 2000
J/KG.  THIS IS MORE THAN TODAY AND COMBINED WITH BETTER DEEP LAYER
SHEAR OF 30-40 KTS...SHUD RESULT IN SOME ORGANIZED CONVECTION AND IF
IN FACT THE INSTABILITY IS THAT LARGE...PSBLY SOME SHORT-LIVED
SUPERCELLS.  THE WK FRONTAL CONVERGENCE HOWEVER SUGGESTS COVERAGE
WILL BE ONLY WDLY SCT/SCT TSRA WITH DEVELOPMENT IN THE AFTERNOON.

THE PROBABILITY OF PCPN ON WED NGT AND THE EXTENT WILL BE LARGELY
DEPENDENT ON WHETHER THE AFTERNOON STORMS CAN ORGANIZE A COLD POOL
WHICH WOULD ENHANCE THE LOW LVL FORCING.  OTHERWISE ANTICIPATING LOW
COVERAGE OF STORMS ON THE SLOW-MOVING FRONT DURING THE EVENING. AT
FIRST I WAS THINKING THE ONLY THREAT OF STORMS WOULD BE DURING THE
EVENING AND IT WOULD END BY MIDNIGHT AS THE BOUNDARY LAYER
STABILIZES...HOWEVER THE WRF-NAM IS SHOWING THE WLY LLJ WILL RAMP-UP
TO 25 KTS OR SO.  ITS ORIENTATION NEARLY PARALLEL TO THE FRONT IS
NOT REAL FAVORABLE...BUT ENOUGH TO CONT POPS THROUGH THE NIGHT.

THE BIGGEST DISCREPENCY BEYOND WED NGT IS THE SWD PENETRATION OF
THIS FRONT AND MOVEMENT THRU FRI.  THE UKMET QUICKLY REBOUNDING THE
FRONT NWD ON 72H AFTER MOVING INTO THE OZARKS...THE WRF-NAM WANTING
TO HOLD ONTO A PSN ACRS THE OZARKS AND THE GFS MORE OR LESS IN BTWN
EARLY ON AND THEN TRENDING TOWARDS THE UKMET. THIS FCST TRENDS
CONSERVATIVELY MORE WITH THE GFS. I HAVENT MENTIONED POPS GREATER
THAN 20% ON THURS/THURS NGT ANTICIPATING ANY STORMS WITH THE
RETREATING FRONT WILL BE MORE ISOLD. THE SUMMER WARMTH SHOULD
RETURN IN ERNEST BY FRI INTO THE FIRST PART OF THE WEEKEND AND
THEN WE DEAL WITH ANOTHER E/W FRONT. ONCE AGAIN THE PSN AND TIMING
OF THIS NEXT FRONT THIS WEEKEND INTO THE 4TH OF JULY IS THE BIG
QUESTION MARK. ATTM I FAVORED THE NCEP GUIDANCE AND GFS WITH THE
BEST THUNDERSTORM CHANCES LATE WEEKEND INTO MON NGT.

GLASS

&&

.AVIATION...
FOR THE 18Z TAFS...MAIN PCPN THREAT FOR THE EARLY PART OF THIS PERIOD...
THRU TONIGHT...WILL COME FROM RATHER STRONG VORT MAX OVER N CNTRL
MO THAT WILL ACT ON MARGINALLY MOIST AND UNSTABLE ATMOSPHERE. MUCH
OF WHAT IS PRODUCED WILL BE DIURNAL...WITH A DIMINISHING/DISSIPATING
TREND FROM SUNSET ON. THINGS WILL THEN RESET FOR WEDNESDAY...AS A
CDFNT DROPS DOWN FROM THE N...LOOK FOR PCPN CHANCES TO INCREASE
DURING THE AFTERNOON...JUST BEYOND THE VALID TAF PERIOD.

OTHERWISE...VFR CIGS/VSBYS TO CONTINUE THRU THE VALID TAF PERIOD
OUTSIDE OF PCPN. NW SFC WNDS AOB 10KTS WILL BECOME VRBL TONIGHT
AND THEN RESUME OUT OF THE W ON WEDNESDAY. SOME LIGHT MIST
POSSIBLE IN AREAS THAT WILL SEE LITTLE CLOUD COVER.

TES

&&

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

WFO LSX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
350 PM CDT TUE JUN 27 2006

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-281200-
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-
350 PM CDT TUE JUN 27 2006

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

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED EARLY THIS EVENING...MAINLY FOR
NORTHEAST AND CENTRAL MISSOURI. NO ORGANIZED OR WIDESPREAD SEVERE
WEATHER IS EXPECTED...BUT SOME STORMS MAY PRODUCE GUSTY WINDS AND
HAIL APPROACHING PENNY SIZE. FROM LATE EVENING ON...THE CHANCE FOR
THUNDERSTORMS IS EXPECTED TO BE CONFINED TO NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THERE IS A CHANCE FOR THUNDERSTORMS ACROSS THE AREA FROM WEDNESDAY
AFTERNOON AND NIGHT AS A WEAK COLD FRONT MOVES THROUGH THE
AREA...ESPECIALLY FOR AREAS ALONG AND NORTH OF INTERSTATE 70.  SOME
OF THE STORMS COULD BE SEVERE...WITH LARGE HAIL BEING THE PRIMARY
SEVERE WEATHER THREAT.

THERE IS AN ADDITIONAL CHANCE FOR THUNDERSTORMS FROM SATURDAY NIGHT
THROUGH MONDAY NIGHT AS ANOTHER COLD FRONT PUSHES INTO THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

TES