Flash Flooding and Hail in Illinois, May 10, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1130 AM CDT THU MAY 10 2007

.DISCUSSION...
SCT CONVECTION ACRS CNTRL MO ATTM MAINLY FM NR IRK S-SE TO NR VIH.
THESE SHRA/TSRA ARE AHD OF A WK VORT MAX MOVG NEWD THRU SWRN MO.
THIS PCPN MAY ALSO BE ASSOCIATED WITH WK TEMPERATURE AND MOISTURE
ADVCTN ON NOSE OF 20 KT SWLY LLJ OVR SWRN MO.  BOTH NAM AND GFS MDLS
FCST RELATIVELY HI POPS OVR THE SRN PTN OF THE CWA TDA.  WILL LIKELY
NEED TO RAISE POPS SLIGHTLY TDA ALTHOUGH IT APRS THE MDLS MAY BE
A LTL OVERDONE WITH CLOUD CVR...POPS AND A LTL TOO COOL WITH MAX
TEMPS TDA THRU FRI. PLAN TO GO CLOSE TO PERSISTANCE WITH HI TEMPS
TDA AND LOW TEMPS TGT WITH A CONTD WK SFC PRESSURE GRADIENT
CAUSING LGT SFC WNDS OVR THE CWA WITH NO CHANGE IN AIR MASS. A FEW
SLOW MOVG TSRA MAY PRODUCE LOCALLY HEAVY RAINFALL AMOUNTS WITH
FAIRLY ABUNDANT LOW-MID LVL MOISTURE AND INSTABILITY ACRS THE
AREA. ON FRI IT APRS THAT MOST OF THE CONVECTION WILL OCCUR OVR
THE SRN HALF OF THE CWA WITH N-NELY LOW LVL WNDS POSSIBLY BRINGING
SLIGHTLY DRIER AIR INTO THE N-NERN PTN OF THE CWA. THIS SHOULD BE
MORE PRONOUNCED ON FRI NGT AND SAT WITH SFC RDGG OVR THE GRT LKS
REGION. SHOULD SEE LESS CLOUDS FRI NGT AND SAT AND WILL GO WITH A
DRY FCST. WITH PLENTY OF SOLAR INSOLATION AND SLIGHTLY LWR SFC
DWPTS THE NAM MDL MOS GUIDANCE LOOKS TOO COOL FOR HI TEMPS ON SAT.
LOOKS LIKE MOST OF THE COOLER AIR WILL REMAIN N-NE OF THE CWA.
FORCING FOR CONVECTION SHOULD REMAIN ACRS THE NRN PLAINS ON SAT
NGT...ALTHOUGH WITH NWLY MID-UPR LVL FLOW COULD NOT RULE OUT THE
POSSIBILITY OF AN MCS ROLLING SEWD INTO THE NRN PTN OF THE CWA.

GKS

&&

.AVIATION...
FOR THE 18Z TAFS...LIGHT SURFACE WINDS WILL PREVAIL AREAWIDE THROUGH
THE VALID TAF PERIOD. VFR CONDITIONS ARE FORECAST EXCEPT IN HEAVIER
SHOWERS/THUNDERSTORMS. AN UPPER LEVEL DISTURBANCE IS FORECAST TO
DRIFT SLOWLY INTO CENTRAL MO THIS AFTERNOON. AS A RESULT, SCATTERED
CONVECTION WILL OCCUR. THE LATEST RADAR IMAGES INDICATES ISOLATED
CONVECTION WAS DEVELOPING ACROSS CENTRAL PORTIONS OF MO. CONVECTION
SHOULD CONTINUE TO INCREASE DURING THE AFTERNOON WITH HEATING.

TPS

&&

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

WFO LSX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
624 AM CDT THU MAY 10 2007

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-111130-
GREENE IL-MACOUPIN IL-MONTGOMERY IL-BOND IL-FAYETTE IL-CLINTON IL-
MARION IL-WASHINGTON IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL-
CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-KNOX-LEWIS-
SHELBY-MARION-MONROE-RALLS-PIKE-BOONE-AUDRAIN-MONITEAU-COLE-OSAGE-
CALLAWAY-MONTGOMERY-LINCOLN-GASCONADE-WARREN-ST. CHARLES-FRANKLIN-
ST. LOUIS-ST. LOUIS CITY-JEFFERSON-CRAWFORD-WASHINGTON-
ST. FRANCOIS-STE. GENEVIEVE-IRON-MADISON-REYNOLDS-
624 AM CDT THU MAY 10 2007

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A CHANCE OF THUNDERSTORMS TODAY AND TONIGHT AS UPPER
LEVEL DISTURBANCES INTERACT WITH THE WARM...MOIST AND UNSTABLE AIR
ACROSS THE BI-STATE REGION. SOME OF THE SLOW MOVING THUNDERSTORMS
MAY PRODUCE LOCALLY HEAVY RAINFALL AMOUNTS. A FEW STORMS MAY
PRODUCE A BRIEF PERIOD OF SMALL HAIL AND STRONG WIND GUSTS THIS
AFTERNOON AND THIS EVENING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE CHANCE OF THUNDERSTORMS WILL CONTINUE OVER THE AREA ON FRIDAY.

THE MISSOURI RIVER IS ABOVE FLOOD STAGE FROM JEFFERSON CITY TO
ST. CHARLES. MAJOR FLOODING IS FORECAST LATER THIS WEEK INTO
EARLY NEXT WEEK ALONG PARTS OF THE MISSOURI RIVER. PLEASE REFER
TO FLOOD SPECIFIC PRODUCTS FOR FURTHER INFORMATION.

THERE IS ANOTHER CHANCE FOR THUNDERSTORMS ON TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

GKS