AREAS AFFECTED...EAST-CENTRAL IL TO WESTERN INDIANA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 012039Z - 012245Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...MONITORING FOR INCREASING SIGNS OF SURFACE BASED DEEP
CONVECTIVE DEVELOPMENT ACROSS EAST-CENTRAL IL INTO WESTERN
INDIANA...WHICH DOES REMAIN POSSIBLE THROUGH LATE AFTERNOON. SHOULD
TSTMS OCCUR/INCREASE...AT LEAST AN ISOLATED TORNADO/SEVERE HAIL RISK
WOULD EXIST.
DISCUSSION...RECENT VISIBLE SATELLITE TRENDS REFLECT A THICKENING CU
FIELD ACROSS PORTIONS OF EAST-CENTRAL/SOUTH-CENTRAL IL...ESPECIALLY
WITH A GENERAL CORRIDOR AROUND THE DECATUR/TAYLORVILLE AREAS AS OF
2030Z. THIS AREA IS IN VICINITY OF A WEST-EAST WARM/STATIONARY FRONT
ACROSS THE REGION...AND IS ON THE SOUTHERN PERIPHERY OF A MID-LEVEL
IMPULSE/MCV ACROSS NORTHERN IL. A KEY UNCERTAINTY EXISTS REGARDING
THE LIKELIHOOD/EXTENT OF DEEP CONVECTION WEST OF TORNADO WATCH
218....GIVEN THAT THE REGION WILL BEGIN TO INCREASINGLY COME UNDER
THE INFLUENCE OF SHORTWAVE RIDGING/WEAKENING MASS CONVERGENCE AS THE
AFOREMENTIONED MID-LEVEL IMPULSE CONTINUES TO SHIFT
EAST-NORTHEASTWARD AWAY FROM THE AREA. THAT SAID...A MOIST AND
MODERATELY UNSTABLE/WEAKLY CAPPED AIRMASS DOES REMAIN ACROSS THE
REGION...WITH VERTICAL SHEAR/SRH ACCENTUATED NEAR THE WARM FRONT.
INCREASING SIGNS/CONFIDENCE OF DEEP CONVECTIVE INITIATION COULD
PROMPT A WATCH ISSUANCE ACROSS IL AND/OR EXPANSION OF WW 218 ACROSS
INDIANA. CONVECTIVE TRENDS WILL BE CLOSELY MONITORED FOR A
TORNADO/HAIL THREAT THROUGH LATE AFTERNOON/EARLY EVENING.
..GUYER/MEAD.. 05/01/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IND...LOT...ILX...LSX...
LAT...LON 39228897 40278868 40668715 39448695 38968817 39228897
