SPC AC 292001

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0301 PM CDT Thu Jun 29 2023

   Valid 292000Z - 301200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE OHIO VALLEY...SOUTHEAST WYOMING AND NORTHEAST COLORADO...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   PLAINS INTO THE OHIO/TENNESSEE VALLEYS...

   ...SUMMARY...
   Damaging wind and hail remain likely this afternoon over parts of
   southern Illinois and southern Indiana. Other severe storms with
   large hail and damaging winds gusts are expected across the
   Tennessee Valley, as well as the central High Plains.

   ...20Z Update...
   Only minor changes to the existing outlook include clearing
   probabilities from behind the IL/IN MCS where the air mass has
   stabilized. For more information see mesoscale discussions 1341.

   ..Jewell.. 06/29/2023

   .PREV DISCUSSION... /ISSUED 1218 PM CDT Thu Jun 29 2023/

   ...Midwest/Tennessee Valley including MO/IL/IN/KY/TN...
   An upper-ridge peripheral zone of locally intense/significant severe
   weather is expected today, especially across Illinois into
   western/southern Indiana and west-central Kentucky southward across
   the Tennessee Valley. 

   A prominent/relatively large MCS across northeast Missouri and
   northwest Illinois at late morning will continue to progress
   eastward through a very unstable air mass, with potential for
   significant wind gusts, occasional hail, and some convective
   line-embedded tornado risk. The eastern extent of the most intense
   severe weather is a bit uncertain given current air mass
   characteristics across far eastern Illinois into Indiana in the wake
   of early day storms, but severe weather can nonetheless be expected
   through the afternoon into evening.

   Another focused corridor of severe weather will exist from the Lower
   Ohio Valley southward into the Tennessee Valley, highlighted with a
   leading south/southeastward-moving MCS, as well as regenerative
   potentially severe convection on its trailing west/northwest flanks.
   Bouts of damaging winds and severe hail will be possible into this
   evening in this corridor.

   ...Front Range/Central Plains this afternoon/evening...
   Have upgraded portions of the Front Range and southeast Wyoming/far
   western Nebraska and northeast Colorado to an Enhanced Risk. Severe
   storms are expected later this afternoon into tonight within the
   post-frontal upslope low-level flow across eastern
   Colorado/southeast Wyoming, with appreciable low-level moisture
   having spread westward to the Front Range overnight. Breaks in the
   low clouds will support moderate buoyancy by mid afternoon (MLCAPE
   of 1000-2000 J/kg), when thunderstorm development will become more
   probable on and immediately east of the higher terrain from Colorado
   into southeast Wyoming. The moderate buoyancy and relatively long
   hodographs with effective bulk shear in excess of 40 kt will support
   supercells capable of producing large hail of 2-3 inches in
   diameter, along with some tornado potential. Upscale growth into a
   few clusters will be possible this evening, with an attendant threat
   for isolated severe-caliber winds. Some of the evening convection
   may persist into the overnight hours across southern
   Nebraska/northern Kansas with some threat for isolated large hail
   and wind damage, potentially as far east as southwest Iowa/northwest
   Missouri.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z