MESOSCALE DISCUSSION 0708
   NWS STORM PREDICTION CENTER NORMAN OK
   0608 PM CDT SUN MAY 19 2013
   
   AREAS AFFECTED...CNTRL INTO NRN IL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 192308Z - 200015Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...TSTMS INTENSIFYING ALONG THE MS RIVER BETWEEN MLI AND UIN
   MAY MOVE OUT OF TORNADO WATCH 183 PRIOR TO 00Z.  CONVECTIVE TRENDS
   ARE BEING MONITORED FOR A POSSIBLE WW.
   
   DISCUSSION...AS OF 2245Z...RADAR DATA INDICATED A CLUSTER OF
   INTENSIFYING TSTMS FROM ROCK ISLAND AND MERCER COUNTIES TO HANCOCK
   COUNTY IL.  THE ANCHOR STORM OF THIS CLUSTER OVER HANCOCK COUNTY HAS
   RECENTLY EXHIBITED RIGHTWARD PROPAGATION...SUGGESTING EVOLUTION INTO
   A SUPERCELL.  AREA VAD DATA AND MODEL-DERIVED FORECAST SOUNDINGS
   INDICATE A ENVIRONMENT FOR UPDRAFT SUSTENANCE/ROTATION WITH A
   MODERATELY UNSTABLE AIR MASS WHICH COINCIDES WITH A VERTICALLY
   VEERING WIND PROFILE AND 40-45 KT OF DEEP-LAYER SHEAR.  EXPECT
   VERTICAL SHEAR TO FURTHER STRENGTHEN THROUGH THIS EVENING AS THE
   EXIT REGION OF A 40-50 KT LLJ DEVELOPS NEWD INTO THE REGION.  AS
   SUCH...EXPECT THE POTENTIAL FOR ORGANIZED STORM MODES...INCLUDING
   SUPERCELLS TO PERSIST THROUGH THIS EVENING AND POSSIBLY DEVELOP EAST
   OF TORNADO WATCH 183 BY 00Z.
   
   ..MEAD/CORFIDI.. 05/19/2013
   
   
   ATTN...WFO...LOT...ILX...DVN...
   
   LAT...LON   40899030 41498963 41838940 41708887 41218890 40478936
               40248995 40399033 40899030