SPC AC 261730

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Fri Apr 26 2024

   Valid 271200Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHERN/CENTRAL PLAINS...

   ...SUMMARY...
   Numerous severe thunderstorms are likely Saturday into Saturday
   night. The greatest severe threat is currently anticipated across
   parts of the central and southern Plains, where very large hail,
   damaging winds, and multiple strong tornadoes will be possible. A
   broader area of potential threat will extend from south-central
   Texas north-northeastward to the Great Lakes.

   ...Synopsis...
   A shortwave trough over the Upper Midwest Saturday morning should
   further de-amplify as it moves across the Great Lakes through the
   day in tandem with a weakening surface low. A large-scale upper
   trough over the Southwest will eject across the southern/central
   Plains through the period, while an attendant 50-70 kt southwesterly
   mid-level jet overspreads these same regions. At the surface, lee
   cyclogenesis is expected to occur over western KS through Saturday
   afternoon, before the low eventually develops towards central KS
   Saturday night. A dryline will extend southward from this low across
   the southern/central High Plains, and a warm front will extend
   northeastward from the low across the central Plains into the Upper
   Midwest.

   ...Southern/Central Plains...
   Most guidance develops thunderstorms early Saturday morning across
   northwest TX into central OK. This activity will likely be related
   to a subtle mid-level shortwave trough ejecting northeastward across
   the southern High Plains, along with ascent along a westward
   retreating dryline and warm/moist advection attendant to a southerly
   low-level jet. Steep lapse rates aloft fostering moderate to strong
   MUCAPE, along with sufficient deep-layer shear, should support some
   large hail threat with this early day convection. The potential for
   these morning thunderstorms to continue into the afternoon across
   central/eastern OK and eastern KS remains uncertain. Even so, some
   severe threat may persist with this activity as it spreads eastward.
   Fairly meridional flow at low/mid levels suggests a messy mode may
   develop, with numerous thunderstorm mergers/interactions possible.

   In the wake of this activity, it still appears likely that
   substantial destabilization will occur along/east of the dryline and
   south of the warm front, with daytime heating of a moist low-level
   airmass supporting MLCAPE of 2000-3500 J/kg from north-central KS
   southward into parts of western OK and northwest TX. As ascent with
   the ejecting upper trough overspreads this warm sector, multiple
   attempts at supercell development will likely occur both along the
   dryline and warm front, as 40-50 kt of deep-layer shear promotes
   robust thunderstorm organization. Any supercells that can form and
   persist will be capable of producing very large hail in excess of 2
   inches in diameter. With time Saturday evening, a steadily
   strengthening low-level jet will foster increased low-level shear,
   and greater tornado potential. Multiple strong tornadoes appear
   possible during the late afternoon to early evening time frame, as
   effective SRH of 150-250+ m2/s2 supports low-level updraft rotation.
   Locally greater low-level shear will probably be realized along/near
   the warm front Saturday evening, and the Enhanced Risk has been
   expanded slightly northward to include more of
   south-central/southeast NE. It remains unclear how long a discrete
   mode will be able to be maintained, as a tendency for convection to
   grow upscale into one or more bowing clusters appears likely
   Saturday evening/night. As this mode transition occurs and
   convection spreads eastward, a greater threat for severe/damaging
   winds will probably be realized across the southern/central Plains.

   Due to the influence of the morning convection and potential for
   messy storm modes/convective evolution Saturday afternoon,
   confidence was not high enough to include greater tornado and/or
   hail probabilities across the southern/central Plains at this time.

   ...Northwest Kansas into Southwest Nebraska and Northeast
   Colorado...
   Low-level easterly flow will maintain modest low-level moisture
   within the post-frontal regime from northwest KS/southwest NE into
   northeast CO. Steep midlevel lapse rates will support MLCAPE
   increasing to around 500 J/kg, with veering wind profiles with
   height through mid levels supporting some potential for organized
   convection. A supercell or two could evolve within this regime, with
   an attendant threat of large hail and possibly a tornado.

   ...Upper Midwest/Great Lakes...
   A mostly separate regime of at least isolated severe thunderstorm
   potential remains evident along/ahead of the front from eastern IA
   into parts of the Great Lakes region. While the influence of the
   weakening shortwave trough initially over the Upper Great Lakes may
   remain mostly displaced to the north of the warm sector, diurnal
   heating/destabilization and gradually lessening convective
   inhibition may support isolated storm development by late afternoon
   along the front. Deep-layer shear will remain sufficient for updraft
   organization, supporting a potential for supercells and/or stronger
   clusters capable of producing severe hail, damaging gusts, and
   possibly a tornado or two. Some increase in storm coverage will be
   possible into the evening as the cold front moves southeastward.
   Thunderstorms should weaken overnight across this region, though a
   stronger cluster to two could move from eastern portions of the
   central Plains toward the upper MS Valley before the end of the
   forecast period.

   ..Gleason.. 04/26/2024

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