MESOSCALE DISCUSSION 1074
   NWS STORM PREDICTION CENTER NORMAN OK
   0620 PM CDT THU JUN 02 2011
   
   AREAS AFFECTED...E-CNTRL MO...W-CNTRL IL
   
   CONCERNING...TORNADO WATCH 420...
   
   VALID 022320Z - 030015Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 420 CONTINUES.
   
   LATEST VISIBLE SATELLITE TRENDS SUGGEST THAT THE MCV...WHICH CROSSED
   PARTS OF NRN KS AND NRN MO AND WAS PARTLY RESPONSIBLE FOR EARLIER
   CONVECTIVE INITIATION OVER N-CNTRL MO...HAS BECOME ILL-DEFINED. THE
   ASSOCIATED CONVECTION HAS SINCE DISSIPATED AFTER HAVING CROSSED A
   SFC BAROCLINIC ZONE EXTENDING FROM N-CNTRL MO INTO S-CNTRL
   IL...LEAVING BEHIND AN EXTENSIVE MID/HIGH-LEVEL DEBRIS CLOUD CANOPY
   ON EITHER SIDE OF THE BAROCLINIC ZONE. THIS IS SERVING TO MAINTAIN
   CONVECTIVE INHIBITION ACROSS MUCH OF TORNADO WATCH 420. DESPITE
   CONDITIONALLY FAVORABLE SEVERE PARAMETERS NEAR AND SW OF THE
   BAROCLINIC ZONE -- I.E. MLCAPE VALUES AOA 2000 J/KG JUXTAPOSED WITH
   EFFECTIVE BULK SHEAR MAGNITUDES OF 30 TO 40 KT -- THE ABSENCE OF ANY
   SUBSTANTIAL FORCING FOR ASCENT COMBINED WITH THE CONVECTIVE
   INHIBITION WILL LARGELY MITIGATE THE THREAT FOR CONVECTIVE
   RE-INITIATION. AS SUCH...THE THREAT FOR SVR STORMS APPEARS TO BE
   DIMINISHING...AND PORTIONS OF THE WW WILL BE CANCELLED PRIOR TO THE
   SCHEDULED EXPIRATION TIME OF 02Z UPON COORDINATION WITH THE SAINT
   LOUIS WEATHER FORECAST OFFICE.
   
   ..COHEN.. 06/02/2011
   
   
   ATTN...WFO...LSX...
   
   LAT...LON   38369049 38449169 38919231 39469191 39489114 39239026
               38369049