SPC AC 050548

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1248 AM CDT Tue Sep 05 2023

   Valid 051200Z - 061200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
   MISSISSIPPI VALLEY...

   ...SUMMARY...
   Isolated severe storms -- accompanied primarily by hail/wind
   potential -- will be possible on Tuesday across parts of the Upper
   Mississippi Valley. Gusty winds are also possible with isolated
   storms across the mid Mississippi Valley into portions of the
   southern Plains.

   ...Upper Mississippi Valley...

   Strong short-wave trough is progressing east across the northern
   High Plains early this morning. Latest water-vapor imagery depicts a
   well-defined mid-level vort near the Black Hills. This feature is
   forecast to eject across SD early in the period before approaching
   the SD/MN border around 05/00z. Associated surface front should sag
   southeast across northwestern MN by mid day as a weak surface low
   advances east across the upper MS Valley.

   Latest radar data depicts a notable MCS has evolved over eastern ND
   with a progressive-propagating squall line now spreading toward
   northwest MN. This activity should spread into southeast
   MB/northwest ON early in the period. By late morning, model guidance
   suggests boundary-layer heating will aid destabilization immediately
   ahead of the wind shift across northern/central MN. Renewed
   convection should initiate along the wind shift by 18z then
   spread/develop east toward the Arrowhead/northwestern WI. Forecast
   soundings exhibit substantial flow/shear for supercells and initial
   convection may be supercellular in nature. Thermodynamic profiles
   favor hail and wind with this activity. Strong deep-layer flow and
   adequate low-level shear suggest some tornado potential, but this
   should be secondary to the hail/wind threat.

   ...Mid MS Valley/Southern Plains...

   As the northern Plains short-wave trough advances toward the MS
   Valley, stronger mid-level flow will spread across KS toward MO.
   Some increase will likely be noted at lower latitudes into northern
   OK/AR. There is increasing concern that isolated severe storms will
   evolve along the southern influence of the short wave where intense
   surface heating is expected ahead of the front. Latest model
   guidance suggests a deep boundary layer along a corridor from
   northwest TX, across central OK into southeast KS by late afternoon.
   Forecast soundings suggest convective temperatures will be breached
   between 22Z and 00Z as temperatures soar to near/just above 100F.
   With seasonally high PW values, it appears gusty downbursts may be
   noted with this activity. At this time will introduce a MRGL to
   account for this threat, but some large-scale support appears
   possible across southeast KS into MO as the ridge is suppressed.
   This activity could be a bit more organized than convection farther
   southwest along the wind shift across central OK into northwest TX.

   ..Darrow/Wendt.. 09/05/2023

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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