SPC AC 151246

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0746 AM CDT Wed Jul 15 2020

   Valid 151300Z - 161200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FROM CENTRAL MO INTO WEST CENTRAL IL...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   INTO EARLY TONIGHT FROM SOUTHEAST CO/NORTHEAST NM INTO THE TX
   PANHANDLE...

   ...SUMMARY...
   Severe storms are most probable 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.

   ...MO/IL today...
   A couple of overnight MCSs across KS/MO/IA have effectively merged
   into one large cluster now over northeast KS and northern MO. 
   Outflow with the MO convection has sagged southward to the I-70
   corridor, and could continue slowly southward through the morning
   given the large mass of rain and ongoing thunderstorms.  Meanwhile,
   a well-developed MCV over northeast KS will move eastward or
   east-northeastward today over northern MO, with the southern fringe
   of the MCV coinciding roughly with the west-east outflow near and
   just south of I-70.  A feed of low-mid 70s boundary-layer dewpoints
   will be maintained today across MO to the south and east of the
   ongoing convection, and moisture will also spread into IL during the
   day.  The moistening will occur beneath the northeastern extent of a
   steep midlevel lapse rate plume from the southern Plains.  The net
   result will be a corridor of strong buoyancy (MLCAPE of 2500-3500
   J/kg) along and south of the MO outflow boundary to roughly the
   Saint Louis area.

   Additional thunderstorm development is expected by afternoon along
   the outflow boundary, and perhaps a little to its south in the warm
   sector in MO.  Some enhancement of low-midlevel shear along the
   southeast flank of the MCV will contribute to an environment
   supporting supercells, within what is expected to become another
   larger storm cluster moving from MO into IL this afternoon. 
   Damaging winds will be the main severe threat (along with isolated
   large hail), though there will be enough increase in low-level
   moisture and shear near the outflow boundary/MCV to support the
   threat for a couple of tornadoes.  The convection will likely weaken
   this evening once it moves east of the primary moisture/buoyancy
   corridor.

   ...Southern High Plains this afternoon/evening...
   An outflow-assisted cold front has moved south to the TX South
   Plains and eastern NM, in the wake of overnight convection. 
   Low-level flow will become more easterly/upslope through the day
   from northeast NM into southeast CO, which will again support
   thunderstorm development this afternoon on the Front Range.  The
   initial storms could be supercells capable of producing large hail,
   given MLCAPE in excess of 2000 J/kg with steep midlevel lapse rates
   and effective bulk shear of 30-40 kt.  Convection will likely grow
   upscale into a cluster or two capable of producing damaging winds
   this evening while moving east-southeastward toward the TX
   Panhandle, where the severe threat may persist through about 06z. 

   ...Southeast WI to Northern Lower MI today...
   Some cirrus blow off from the large MO storm complex may persist
   enough to slow surface heating some today along the synoptic front
   from southeast WI into northern Lower MI.  Assuming a few cloud
   breaks can occur by afternoon, there will be a corridor of
   weak-moderate buoyancy along the front, which will help focus
   thunderstorm development.  Isolated strong/damaging outflow gusts
   appear to be the main threat with these storms for a few hours this
   afternoon/evening.

   ...Southern AL to southeast LA this afternoon...
   A weak midlevel trough will over the north central Gulf coast, along
   with daytime heating and local sea breeze circulations, will support
   scattered thunderstorm development by this afternoon.  Very isolated
   strong downburst winds may occur with the strongest storms, but the
   overall severe threat appears too low to warrant adding wind
   probabilities.

   ..Thompson/Dial.. 07/15/2020

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z