SPC AC 150602

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0102 AM CDT Wed Jul 15 2020

   Valid 151200Z - 161200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF CENTRAL/EASTERN MO...WESTERN/CENTRAL IL...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
   SOUTHERN/CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Severe storms are most likely this afternoon and evening across
   parts of the mid Mississippi Valley, with damaging wind, large hail,
   and a couple of tornadoes possible. More isolated severe storms will
   be possible over portions of the southern and central High Plains,
   with large hail and damaging wind as the main hazards.

   ...Synopsis...
   A broad upper trough is expected to remain in place across the
   north-central CONUS today into tonight. Multiple embedded shortwave
   troughs will move eastward within the larger-scale trough, including
   a potentially vigorous MCV moving from the central Plains into the
   mid-MS Valley. At the surface, a weakening cold front will likely
   become nearly stationary across the southern Plains, while a surface
   wave associated with the MCV is forecast to move from the central
   Plains into the mid-MS Valley and Midwest by tonight. 

   ...Mid-MS Valley and Vicinity...
   The severe potential across this region will largely be tied to the
   MCV moving out of the central Plains, and some uncertainty remains
   regarding the intensity and timing of this feature. Along and east
   of the MCV track, and south of an outflow-reinforced boundary likely
   to be somewhere across eastern MO into central IL, moderate to
   locally strong buoyancy (MLCAPE of 2000-3500 J/kg) is forecast to
   develop this afternoon, as strong heating occurs within a very moist
   environment. 

   Intensification of any ongoing convection near the MCV track will be
   possible by early afternoon, with additional development to the
   south and east by late afternoon. Modestly enhanced midlevel flow
   attendant to the MCV will support effective shear of 30-40 kt,
   sufficient to support organized structures. Convection will likely
   evolve into one or more clusters, with corridors of damaging wind
   possible, especially where substantial boundary-layer
   warming/steepening of low-level lapse rates can occur. Some tornado
   risk may also evolve, either with any semi-discrete supercells early
   in the convective evolution, or associated with any cluster or QLCS
   that interacts with the effective surface boundary. 

   ...Southern/Central High Plains...
   Easterly low-level flow and modest (but sufficient) deep-layer
   flow/shear will again support a threat of severe thunderstorms
   across portions of the southern/central High Plains this afternoon
   and evening. Initiation is expected by early afternoon across the
   higher terrain of central/southern CO into NM, with convection
   spreading into a larger portion of the High Plains by late
   afternoon/early evening. Steep midlevel lapse rates/moderate
   buoyancy, and effective shear of 25-40 kt, will support a large hail
   risk with the initial semi-discrete activity, in addition to a
   threat of locally severe wind gusts. One or more clusters may spread
   eastward by early evening, with a continued threat of locally severe
   wind gusts. Overnight, a cluster of storms with a lingering marginal
   wind/hail risk may persist into portions of western/northern OK and
   far southern KS, within a plume of strong elevated buoyancy.

   ..Dean/Lyons.. 07/15/2020

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