SPC AC 051948

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0148 PM CST Sat Mar 05 2022

   Valid 052000Z - 061200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHERN IA AND
   FAR NORTHERN MO...

   ...SUMMARY...
   Severe thunderstorms are expected this afternoon through tonight
   across the lower Missouri Valley into southern portions of the Great
   Lakes region. A few tornadoes, damaging winds, and large hail will
   be likely in portions of Iowa and northern Missouri. Isolated
   damaging gusts will be possible through tonight toward the Great
   Lakes.

   ...Midwest/Lower MO Valley to Great Lakes...
   Previous forecast reasoning remains largely on-track with somewhat
   greater confidence in the number of discrete supercells developing
   along and just east of the MO River into southern IA and northern
   MO. Increasingly agitated CU/CB development is ongoing near the
   surface cyclone across southeast NE and northeast KS with around 100
   miles of clearing immediately east. Further destabilization through
   boundary-layer heating and cooling mid-level temperatures will
   support a narrow corridor of MLCAPE reaching 1000 J/kg. Despite
   boundary-layer dew points only in the mid to locally upper 50s, low
   to mid-level lapse rates greater than 8 C/km and enlarging low-level
   hodographs suggests a few tornadoes appear likely. See MCD 194 for
   additional near-term discussion.

   Only other change is to expand lower tornado probabilities eastward
   across northern IL to southern Lower MI. Environment should remain
   favorable for a conditional tornado threat in addition to damaging
   winds, although the bulk of CAMs still suggest convection should
   nocturnally weaken later this evening.

   ..Grams.. 03/05/2022

   .PREV DISCUSSION... /ISSUED 1029 AM CST Sat Mar 05 2022/

   ...Midwest/Lower Missouri Valley to Great Lakes...
   A negatively tilted shortwave trough and attendant 70-80 kt H5 jet
   streak visible across the central High Plains on morning water vapor
   imagery are forecast to rapidly eject northeastward reaching the
   upper Midwest/Great Lakes over the next 12-16 hours. Strong dynamic
   lift associated with this trough/jet and a 40-50 kt low-level jet
   have advected modest (50-55 F) dewpoints across eastern KS, northern
   MO and far southern IA. As the trough continues northeastward during
   the day, a deepening surface cyclone will continue pulling moisture
   northward, toward a slowly advancing warm front stretching from the
   low northeastward into central IA.

   North of the warm front, a band of elevated convection is ongoing
   within the strong warm advection regime at the nose of the low-level
   jet. Modest buoyancy aloft may favor some potential for isolated
   severe hail trough the morning, before these storms move far enough
   north and eastward away from the jet and into more stable
   conditions.

   Behind the initial convection, strong dynamic lifting from the
   approaching trough and isolated cloud breaks should work to
   destabilize the boundary-layer ahead of a fast moving cold
   front/dryline near the low across northeastern KS and southeastern
   NE. With the modest surface moisture in place, destabilization
   should remain mostly weak to moderate, with regional model soundings
   showing between 500 and 1000 J/kg of MLCAPE developing beneath -20 C
   500 mb temps by early afternoon. Some uncertainty exists regarding
   destabilization in the wake of early-day convection, though clearing
   evident across northeastern KS this morning lends some confidence to
   at least patchy sunshine through the early afternoon. Strong
   convection appears likely to initiate near the triple point in
   vicinity to the Missouri River between 19 and 21z, and track
   northeastward across south-central IA and northern MO. Wind profiles
   near and southeast of the low and the warm front strongly favor
   supercells with enhanced low-level curvature (200-250 0-1km SRH)
   evident on model hodographs. Aloft, more straight line structure
   suggests some potential for left splits and upscale growth resulting
   in a mixed storm mode of broken/semi discrete bands of convection.

   Fast storm motions and the potential development of small but
   moderately strong low-level mesocyclones will support all severe
   hazards including a few tornadoes. Steep lapse rates, both low and
   in the mid-levels will facilitate efficient transfer of strong winds
   aloft to the surface with scattered damaging gusts likely,
   especially after the initial cellular development. Some potential
   for damaging gusts will also extended farther south along the cold
   front across eastern KS and southwestern MO and into the western
   Great Lakes later tonight. Displaced from the stronger ascent,
   convective organization is less certain, but the strong wind fields
   suggests some threat for damaging wind gusts and small hail.

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