MESOSCALE DISCUSSION 1497
   NWS STORM PREDICTION CENTER NORMAN OK
   0623 PM CDT MON JUL 20 2015

   AREAS AFFECTED...SRN IL /  SWRN IND / WRN KY / SERN MO / NERN AR / 
   WRN TN

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   VALID 202323Z - 210100Z

   PROBABILITY OF WATCH ISSUANCE...80 PERCENT

   SUMMARY...THE POTENTIAL FOR SEVERE STORMS CAPABLE OF LARGE
   HAIL...DAMAGING OUTFLOW WINDS AND PERHAPS A TORNADO APPEARS TO BE
   INCREASING ACROSS THE DISCUSSION AREA.  A WATCH IS LIKELY.

   DISCUSSION...RECENT TRENDS IN MOSAIC RADAR DATA INDICATE AN INCREASE
   STORM COVERAGE AND INTENSITY FROM W OF EVV WSWWD TO NORTH OF POF
   ALONG AND JUST TO THE IMMEDIATE COOL SIDE OF A ENE-WSW-ORIENTED
   BAROCLINIC ZONE STRETCHED ACROSS THE REGION.  LOW-LEVEL
   CONFLUENCE/UPLIFT ALONG THIS BOUNDARY IN CONCERT WITH DCVA ATTENDANT
   TO AN MCV PROGRESSING THROUGH THE MID-MS VALLEY ARE LIKELY THE
   PRIMARY MECHANISMS FORCING THIS ACTIVITY.

   RAP-BASED ANALYSES INDICATE THAT THE AIR MASS INVOF THIS BOUNDARY IS
   STRONGLY UNSTABLE WITH MLCAPE ESTIMATED AROUND 3000 J/KG.  WHEN
   COUPLED WITH A WIND PROFILE EXHIBITING SOME VEERING OF THE WINDS
   WITH HEIGHT AND MODEST /30-35 KT/ VERTICAL SHEAR /PER PAH WSR-88D
   VAD/...THE SETUP WILL SUPPORT SUPERCELLS AND POTENTIALLY BOWING LINE
   SEGMENTS WITH THE PRIMARY HAZARDS BEING LARGE HAIL AND LOCALLY
   DAMAGING WINDS AS STORMS SPREAD SEWD THROUGH WRN KY.  A BRIEF
   TORNADO IS ALSO POSSIBLE WITH STORMS THAT FAVORABLY INTERACT WITH
   THE SURFACE BOUNDARY WHERE LOW-LEVEL SHEAR IS ENHANCED.

   ..MEAD/DIAL.. 07/20/2015


   ATTN...WFO...LMK...OHX...PAH...MEG...LSX...LZK...SGF...

   LAT...LON   36549196 36929203 37519068 37868956 38168849 38248766
               37768698 37158723 36778749 36358813 36128944 36339166
               36549196