Damaging Wind in Illinois, July 9, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
320 PM CDT TUE JUL 9 2002

CNVCTN HAS DVLPD RATHER QUICKLY IN THE LAST HR OVR NC/NW MO IN BROAD
AREA OF MCON ASSOCD WITH BOTH CDFNT AND OUTFLOW BNDRY PUSHING SE OUT
OF IA.  HV SEEN LTL DVLPMNT THUS FAR ALG ERN PTN OF PRE-FRONTAL TROF
EXTDG FM SW OF PPQ TO SPI.  AMS IS VERY UNSTBL WITH CAPES IN EXCESS
OF 4000 J/KG AND VERTICAL DVLPMNT TO CU FIELD SUGGESTS LTL CIN
RMNS.  QUESTION IS HOW MUCH ORGANIZATION WL OCCUR VIA CLUSTERS OR
SHORT LNS...AND THUS HOW HI TO GO WITH POPS.  THIS WL BE A LAST
MINUTE CALL AND WL GO WITH EITHER SCT COVERAGE...HI CHC POPS OR
LIKELY CAT.  OTW THE SWD FRONTAL PUSH TNGT IS BCMG LESS AND LESS
PRONOUNCED WITH EACH NEW MDL RUN AND PRINDS ARE THAT THERE WONT BE
ANY DRYING OF THE LOW LVLS IN THE WAKE OF THE FNT WITH SFC DPTS RMNG
IN THE 70S.  THIS LKS RSNBL WITH DPTS STILL IN THE 70S WELL NORTH OF
THE FNT ATTM.  OTHER THING IS DEG OF COOLING IN THE WAKE OF THE FNT
ON WED.  GIVEN THE FACT THAT IT IS STILL WELL IN THE 80S IN THE UPR
MS VLY ATTM I HV TRENDED THE NEW ZNS TWDS THE WARMER ETA MOS.

BYD TNGT PCPN FCST GETS A BIT TRICKY ON WHERE WHEN AND HOW HI TO
FCST POPS WITH THE MDLS GENERATING QUITE A BIT OF PCPN THRU THE REST
OF THE WK.  IT WUD SEEM TMW THE GREATEST THREAT WUD RESIDE IN THE
VCNTY OF THE FNT.  FM WED NGT ON THE UPR LOW/TROF AND ASSOCD FRCG
AND LOW LVL RSPNS WL BCM MORE IMPORTANT AND I DONT REALLY HV ALOT
OF CONFIDENCE IN THE DETAILS.  PRVSLY IT LOOKED AS THOUGH FM TMW NGT
INTO THURS THE GREATEST POTNTL FOR WDSPRD PCPN WUD BE ACRS THE WRN
HALF OF MO. NOW IT LKS LIKE THE ERN HALF...WITH BOTH THE ETA AND AVN
INDCTG A PRETTY GOOD THREAT.  THIS HAS BEEN ACCEPTED AND HV KEPT
POPS IN ALG AND AHD OF THE UPR TROF AXIS THRU SAT...GRDLY TAPERING
THEM DWNWD.  AS FOR TMPS...UNLESS WE KP CONTINUOUS PCPN AND LOW CIGS
IN ON THURS...THE MAV GUID LKS TO LOW.  THE AVN IS ALSO INDCTG MUCH
COOLER AIR ADCTG INTO THE RGN AS THE HI BLDS IN FM THE N/NE.  ATTM
HV LEANED MORE TWDS THE WARMER ETA...WHICH IS STILL QUITE A BIT
COOLER THAN THE PRVS FCST.

WL LET HEAT ADVSRY EXPIRE WITH NEW ZN PCKG.  COOLER TMPS INTO THE
ERLY PART OF THE WKND AND THREAT OF WDSPRD PCPN ARE WELCOME CHG FM
HEAT AND DRY CONDS.

.STL...NONE
GLASS