SPC AC 150534

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1234 AM CDT Fri Sep 15 2023

   Valid 151200Z - 161200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Isolated severe thunderstorms are expected over the southern High
   Plains Friday afternoon and Friday night.

   ...Southern High Plains...

   Southern influence of Four Corners short-wave trough will shift into
   the southern Rockies later today. Latest model guidance maintains
   seasonally strong 500mb flow across NM into central TX with speeds
   on the order of 35kt during the afternoon/evening. Additionally,
   substantial midlevel cooling will spread across NM by peak heating
   where boundary layer lapse rates will be steepest along the western
   fringe of higher PW air mass.

   Early this morning, a weak midlevel disturbance was ejecting east
   along the TX/NM border. This feature appears partly responsible for
   small cluster of convection that has gradually organized near CVS.
   This activity is forecast to propagate southeast toward the Big
   Country by sunrise, then possibly continue southeast toward
   south-central TX by afternoon. Strong heating south of the boundary
   may result in additional surface-based storms evolving ahead of this
   activity where temperatures rise into the mid 90s.

   Weak upslope flow will persist across eastern NM today and strong
   surface heating will allow convective temperatures to be breached by
   mid afternoon. Forecast soundings across this portion of the high
   Plains exhibit supercell profiles with 35-40kt of surface-6km bulk
   shear. Steep lapse rates favor robust updrafts and isolated
   supercells are expected to develop then track southeast. Greatest
   risk with this activity should be hail and gusty winds, though a
   brief tornado can not be ruled out given the moist profiles and
   favorable low-level turning.

   ...Upper MS Valley...
    
   Narrow corridor of modest instability is expected to develop across
   the upper MS Valley from southern MN into northwest WI, immediately
   ahead of a progressive surface front. This boundary is supported by
   a strong short-wave trough that is digging southeast across SK/MB
   early this morning. Height falls ahead of this feature, along with
   strong heating near the boundary, suggest isolated thunderstorms
   could evolve by late afternoon. Forecast soundings do not exhibit
   much instability but strong shear does favor some potential for
   organization, albeit likely for only a few hours. Marginally severe
   hail appears to be the greatest risk with the isolated storms that
   evolve ahead of the front.

   ..Darrow/Bentley.. 09/15/2023

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z