SPC AC 131955

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0255 PM CDT Wed Oct 13 2021

   Valid 132000Z - 141200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE EASTERN DAKOTAS/MINNESOTA AREA...CENTRAL/SOUTHWEST
   MISSOURI...AND FROM THE TX HILL COUNTRY INTO NORTHEAST TX...

   ...SUMMARY...
   Marginal severe-weather potential (in the form of thunderstorm wind
   and tornado threat) is apparent today over parts of the eastern
   Dakotas/Minnesota area, and from south/central Texas and Missouri.

   ...Discussion...
   No appreciable change was made to the previous convective outlook.

   ..Smith.. 10/13/2021

   .PREV DISCUSSION... /ISSUED 1129 AM CDT Wed Oct 13 2021/

   ...Synopsis...
   A mid-latitude cyclone continues to mature as it gradually moves
   northeastward toward the northern Plains. Recent surface analysis
   places the occluded low associated with this cyclone over
   south-central SD. An occluded front extends southeastward from this
   low to the triple point over southeast NE, with a cold front
   extending from the triple point southward across eastern KS and then
   back south-southwestward through central OK and northwest TX into
   the TX Permian Basin. A decaying convective line/outflow boundary
   precedes this cold front, currently extending from far southeast IA
   southwestward across MO and eastern OK into western north TX. 

   Given the narrowing warm sector and anticipated northward shift in
   the stronger low to mid-level flow, reinvigoration appears unlikely
   along the majority of this outflow as it transitions to more of an
   anafrontal character. The only exception is from north TX into the
   TX Hill County (discussed in more detail below). Potential exists
   for additional thunderstorm development along the occluded front as
   it moves through the western Dakotas and into MN as well as along
   the cold front across a portion of MO.

   ...TX Hill Country into Northeast TX/Southeast OK...
   Widespread showers and thunderstorms are expected across the region
   as an influx of mid-level moisture associated with TC Pamela spreads
   northeastward. This increased moisture in the presence of the
   frontal boundary should contribute to continued regeneration of
   showers and thunderstorms. While much of this activity will likely
   be elevated behind the front, vertical shear supports supercells
   with any surface-based development. A somewhat messy storm mode is
   likely, but the potential for bowing line segments and a brief
   tornado exists with any surface-based development that persists
   ahead of the front. 

   ...Eastern Dakotas/Western MN...
   An arc of low-topped showers and thunderstorms is still expected
   this afternoon just ahead of the deep-layer cyclone. Cool mid-level
   temperatures will result in modest buoyancy despite limited diurnal
   heating while backed low-level flow will enlarge hodographs in a
   narrow corridor near the arc of strongest low-level lift. This will
   support some potential for storm-scale rotation and perhaps a few
   stronger storms capable of damaging wind gusts and maybe even a
   brief tornado. The limiting factor will be amount of low-level
   destabilization and result buoyancy. Even with relatively cool
   surface temperatures in the upper 50s to near 60 F in forecast
   soundings, a narrow area of 200-700 J/kg MLCAPE may develop.

   ...MO...
   Recent convection-allowing guidance continues to show the potential
   for isolated thunderstorms along the front as it moves through MO
   this afternoon/evening. Heating will be limited but the air mass is
   expected to remain moist and modestly buoyant. This area will remain
   within the southern extent of the stronger low to mid-level flow.
   These conditions could result in the development of a strong storm
   or two, with damaging wind gusts as the primary threat.

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