SPC AC 190732

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0232 AM CDT Thu Sep 19 2019

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
   KANSAS...NORTHERN MISSOURI AND IOWA...

   ...SUMMARY...
   Severe storms are possible across parts of the Plains on Saturday,
   most notably from Kansas into Iowa.

   ...Synopsis...
   An upper trough will move east across the northern Plains and toward
   the Great Lakes, with a broad zone of strong southwest winds aloft
   encompassing much of the central and northern Plains, upper MS
   valley and Great Lakes. The primary surface trough will extend from
   northern ND and MN into Ontario, with a cold front roughly from MN
   to KS by Saturday afternoon. Ahead of this front, mid to upper 60s F
   dewpoints will be widespread, and will contribute to areas of
   moderate instability. The most favorable combination of instability,
   lift, and shear appears to be from KS northeastward into IA and
   northern MO, although severe storm potential exists as far north as
   MN and WI. 

   ...Central Plains...
   Upper 60s to near 70 F dewpoints are forecast to move north over OK,
   KS, MO and IA, with a cold front roughly from central KS into
   western IA by peak heating. Given the very moist air mass, capping
   will be minimal and storms may form early in the day from KS into MO
   in the moist sector with isolated severe possible. Veering winds
   with height and favorable effective SRH may favor a couple
   supercells producing either strong wind gusts or a brief/weak
   tornado. The most likely time for concentrated severe storms will be
   during the late afternoon and evening, beneath a strengthening 40-50
   kt low-level jet centered over KS. Good model agreement exists
   within the zone from KS into northern MO and IA depicting
   significant storm coverage. Damaging wind appears to be the main
   concern during the evening, and storms may persist into IA and even
   western IL given strong westerlies aloft.

   ...Upper Mississippi Valley...
   Scattered storms are expected throughout the day from MN into WI.
   Early day storms may be associated with warm advection at 850 mb,
   with a secondary area of storms along the cold front as it moves
   across MN during the day. Marginal instability is forecast, with
   long hodographs suggesting a wind or marginal hail threat. It
   appears that a dry slot will move over the region during the day,
   with veering winds above the surface. In addition, 850 mb wind
   convergence will focus farther north into Ontario, with some models
   showing speed divergence over MN. Therefore at this time, only
   isolated severe storms are forecast.

   ..Jewell.. 09/19/2019

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