SPC AC 232000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Thu Jun 23 2022

   Valid 232000Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
   KS/NE/SD/MN...

   ...SUMMARY...
   Scattered severe thunderstorms are most likely over parts of the
   central Great Plains and the central portions of Minnesota to South
   Dakota, mainly this evening.

   ...20Z Update...
   The 2% and 5% tornado areas have been expanded slightly southward
   across parts of north-central KS, based on the current position of
   the effective warm front, but otherwise no major changes have been
   made to the outlook. See MCD 1264 for more information regarding the
   threat across NV/UT, MCD 1265 for more details across KS/NE, and the
   previous outlook discussion below for details regarding the threats
   in MN/SD and MT. 

   Isolated strong wind gusts will also be possible with storms across
   parts of AZ/NM, though deep-layer flow/shear is quite weak across
   this region, which should preclude a more organized severe wind
   risk.

   ..Dean.. 06/23/2022

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jun 23 2022/

   ...Northern KS/southern NE...
   Low-level warm theta-e advection has maintained a swath of elevated
   convection centered on northeast to east-central KS, just northeast
   of the surface warm front. To the south and west of this activity,
   robust boundary-layer heating is underway, likely increasing
   baroclinicity across the front by late afternoon. A low-amplitude
   mid-level perturbation over the southern Rockies should be favorably
   timed to aid in scattered high-based convection developing along the
   lee trough in western KS to its intersection with the warm front
   near southwest NE. While morning guidance varies substantially with
   the overall thermodynamic environment, the 12Z HRW-NSSL/ARW and
   NAM-Nest all suggest potential for at least a couple long-lived
   supercells slowly spreading east-southeast from southwest NE across
   northern KS. Midlevel flow will not be strong, although speed shear
   into the upper levels will favor large hail growth. Hodographs will
   depend on the degree of low-level easterly flow component in the
   warm advection zone along and north of the warm front, which
   guidance also varies substantially on. Even so, an increase in a
   nocturnal southerly low-level jet will likely assist in potential
   for a small MCS this evening. Given the conditionally favorable
   setup, potential for sig hail and wind is apparent in addition to a
   tornadic supercell or two.

   ...Central portions of MN/SD...
   A weak surface trough, associated with a low-amplitude shortwave
   impulse over northern ON, will drift southeast across northeast to
   west-central MN, with a separate surface trough extending north from
   western KS/NE into central SD. An increase in low-level
   moisture from the south and southwest, combined with strong daytime
   heating and modest convergence along the troughs, should support
   isolated to scattered thunderstorm development during the late
   afternoon to early evening. While model moisture forecasts are
   likely overdone, and weak large-scale forcing for ascent limits
   confidence, steep mid-level lapse rates and adequate deep-layer
   shear will support conditional potential for a few supercells and
   multicell clustering. Most morning CAM guidance suggests a narrow
   corridor of cat 2/SLGT-risk caliber storms should form with a threat
   for large hail and damaging winds. 

   ...Central/eastern MT...
   A mid-level closed low over southern BC will move eastward, with the
   primary jet crossing northern MT through tonight. Associated surface
   cold front will push east and provide a focus for isolated to
   scattered thunderstorm development across central to eastern MT
   during the late afternoon and evening. Low-level moisture will
   remain limited with boundary-layer dew points in the 40s, yielding
   MLCAPE to only around 500 J/kg. Still, inverted-v thermodynamic
   profiles and some increase in mid-level flow will support the threat
   for isolated severe gusts and small to marginally severe hail.

   ...Eastern NV/western UT...
   A low-amplitude shortwave trough over the Sierra NV will gradually
   progress east across parts of NV into western UT through tonight.
   Moderate forcing for ascent ahead of this trough, combined with
   daytime heating/mixing, will support scattered high-based
   thunderstorm development. Limited boundary-layer moisture will
   result in only meager MLCAPE and effective bulk shear will remain
   weak. But deeply mixed inverted-v thermodynamic profiles and DCAPE
   greater than 1000 J/kg will support a threat for isolated severe
   gusts.

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