AREAS AFFECTED...PORTIONS OF CENTRAL/NRN IL...PORTIONS OF NRN IL
CONCERNING...TORNADO WATCH 118...
VALID 172346Z - 180115Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 118 CONTINUES.
SUMMARY...THE THREAT FOR SVR TSTMS AND PERHAPS A TORNADO CONTINUES
ACROSS MAINLY EAST-CENTRAL IL/WEST-CENTRAL IN PORTION OF WW.
ELSEWHERE...CONVECTIVE OUTFLOW WILL INCREASINGLY STABILIZE BOUNDARY
LAYER RESULTING IN MAINLY A LARGE HAIL THREAT THROUGH 05Z.
DISCUSSION...A COMPLEX SURFACE PATTERN EXISTS ACROSS WW AREA AS
CONVECTIVE OUTFLOWS HAVE MASKED THE WARM FRONT RESULTING IN A
REDUCED TORNADO THREAT OVER MUCH OF THE WW AREA. AT 23Z SURFACE
OBSERVATIONS AND RADAR TRENDS SHOW A NWWD-MOVING OUTFLOW BOUNDARY
FROM JUST SOUTH OF GUS TO HUF. FARTHER WEST...CONVECTIVE OUTFLOW HAD
SPREAD EAST TO ROUGHLY FROM NEAR TAZ TO 25 S OF SBN. TSTMS WITHIN A
SMALL CORRIDOR BETWEEN THESE TWO OUTFLOWS MAY BRIEFLY POSE A RISK
FOR LOW-LEVEL ROTATION BEFORE BEING UNDERCUT BY OUTFLOW BY 0030Z.
AFTERWARD...EFFECTIVE SHEAR VALUES AVERAGING 45-55KT AND MUCAPES
FROM 500 J/KG OVER NRN PORTIONS OF WW AND TO AROUND 2000 J/KG OVER
SRN PORTIONS WOULD FAVOR MAINLY LARGE HAIL. AN ISOLATED DAMAGING
WIND GUST CANNOT BE RULED OUT WHERE STRONG WINDS CAN PENETRATE THE
SHALLOW CONVECTIVE OUTFLOW OVER SRN PORTIONS OF WW AREA.
..BUNTING/THOMPSON.. 04/17/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...IND...LOT...ILX...LSX...DVN...
LAT...LON 41418559 40058601 39658713 39338911 39508980 39699057
40499068 41138742 41418559
