AREAS AFFECTED...CNTRL IL INTO PORTIONS OF CNTRL/NRN INDIANA
CONCERNING...TORNADO WATCH 118...
VALID 180121Z - 180245Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 118 CONTINUES.
SUMMARY...THE SVR THREAT CONTINUES ACROSS REMAINING VALID PORTIONS
OF WW118.
DISCUSSION...IN NRN INDIANA...ONE CLUSTER OF WAA-RELATED CONVECTION
CONTINUES TO ADVANCE NWD/EWD AWAY FROM ANY RESIDUAL BOUNDARY-LAYER
BUOYANCY RESIDING S OF A QUASI-STATIONARY FRONT STRETCHING FROM
W-CNTRL OHIO WWD INTO CNTRL IL AND CNTRL MO. ASIDE FROM A RISK FOR
MARGINALLY SVR HAIL...THIS ACTIVITY SHOULD WEAKEN AS IT BECOMES
INCREASINGLY ELEVATED...AND BUOYANCY ATOP THE SFC COLD DOME WEAKENS
WITH NOCTURNAL COOLING.
ADDITIONAL CLUSTERS OF CONVECTION UPSTREAM ACROSS NERN MO...W-CNTRL
IL...AND SERN IA WILL CONTINUE SPREADING ENEWD...POTENTIALLY
ORGANIZING INTO ONE OR MORE ORGANIZED LINES OF STORMS. THIS ACTIVITY
WILL LIKELY REMAIN ELEVATED TO THE N OF THE SFC FRONT...WHERE STRONG
STATIC STABILITY IS NOTED IN THE LOWEST 1 KM AGL PER THE ILX 00Z
RAOB. NEVERTHELESS...STRONG 0-6-KM SHEAR WILL MAINTAIN ORGANIZED
CONVECTION...WITH SVR HAIL BEING THE PRIMARY CONCERN. HOWEVER...SVR
WINDS CANNOT BE RULED OUT IF DOWNDRAFTS CAN PENETRATE THROUGH THE
STABLE LAYER TO THE SFC...ESPECIALLY WITH ELEVATED BOWING LINE
SEGMENTS/SUPERCELLS. VERY SMALL TEMPERATURE-DEWPOINT SPREADS IN THE
LOW LEVELS...AND ONLY MODEST MID-LEVEL LAPSE RATES...WILL GREATLY
MITIGATE SUCH POTENTIAL.
..COHEN.. 04/18/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...IND...LOT...ILX...LSX...DVN...
LAT...LON 40378603 39938652 39388846 39348975 39589051 40249050
40949002 41098925 41118635 40378603
