SPC MESOSCALE DISCUSSION 1624 FOR CENTRAL/SRN IA AND EXTREME
WRN/NWRN IL
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL...

VALID 222025Z - 222300Z

TSTMS MAY BECOME SEVERE OVER CENTRAL IA DURING THE NEXT 1-2 HOURS
WITH ADDITIONAL STORMS DEVELOPING EWD INTO EXTREME WRN AND NWRN IL.
AREA WILL CONTINUE TO BE MONITORED FOR POSSIBLE WW.

SATELLITE IMAGERY SHOWS TSTMS DEVELOPING OVER STORY COUNTY AND
BENTON COUNTY IA AT THE INTERSECTIONS OF OUTFLOW BOUNDARIES FROM
EARLIER CONVECTION OVER NRN IA.  OBJECTIVE ANALYSES SHOW AN
EXTREMELY UNSTABLE AIRMASS ALONG AND SOUTH OF THE OUTFLOW
BOUNDARIES WITH 100 MB MLCAPE VALUES FROM 3500-4000 J/KG.  AREA VAD
WINDS INDICATE GENERALLY LIGHT LOW-MID LEVEL WINDS...RESULTING IN
SLOW MOVING STORMS AT 5-15 KT WITH THE POTENTIAL TO PRODUCE LOCALLY
HEAVY RAINFALL.  HOWEVER...A LOW-MID LEVEL VEERING WIND PROFILE
SHOULD SUPPORT ISOLATED STRONG STORMS ALONG THE LOW-LEVEL
CONVERGENCE BOUNDARIES...WITH THE POTENTIAL FOR STRONG WIND GUSTS
AND ISOLATED LARGE HAIL.  

..PETERS.. 07/22/01