SPC AC 291718

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   1218 PM CDT Thu Jun 29 2023

   Valid 291630Z - 301200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF ILLINOIS...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
   FRONT RANGE AND CENTRAL HIGH PLAINS...

   CORRECTED FOR IMPROPERLY FORMATTED HAIL POINTS PRODUCT

   ...SUMMARY...
   Swaths of damaging winds of 60-80 mph, large hail, and a couple of
   tornadoes are expected today across Illinois and western/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.

   ...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.

   ..Guyer/Smith.. 06/29/2023

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