SPC AC 111641

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1141 AM CDT Thu May 11 2023

   Valid 111630Z - 121200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   OKLAHOMA AND KANSAS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
   MISSISISPPI VALLEY...

   ...SUMMARY...
   Scattered severe thunderstorms are expected this afternoon and
   evening across parts of the Great Plains centered on Kansas and
   Oklahoma. The greatest threat for a couple strong tornadic
   supercells should exist across central and southern Oklahoma between
   5 to 9 PM CDT. Isolated severe storms including a couple of
   tornadoes and damaging winds are also expected across the Lower
   Mississippi Valley.

   ...Southern/Central Great Plains...
   A cluster of storms continues to persist at late morning across
   south-central Oklahoma, and remain somewhat strong in proximity to
   the Red River, with other more recent/initial arcing bands of
   thunderstorm development in a separate regime across southeast
   Colorado. This is occurring near/ahead of the largely stacked
   cyclone centered near the Raton Mesa vicinity of northeast New
   Mexico/southeast Colorado. 12z upper-air analysis features of a zone
   of stronger mid/high-level winds across the south-central High
   Plains immediately preceding this cyclone, while winds aloft
   (especially high level) are otherwise relatively weak across the
   region. A moist boundary layer is noted across the south-central
   High Plains, with relatively high PW values and 12+ C 850mb
   dewpoints observed at both Dodge City and Amarillo per 12z RAOBs, a
   northwestward extension of the rich low-level moist axis that
   otherwise extends across the middle part of Texas.

   The surface cyclone is expected to deepen as it develops toward
   southwest Kansas today, with the dryline mixing into western
   Oklahoma and arcing south-southwest into the Edwards Plateau. A
   north/south-oriented inverted trough/quasi-stationary front will
   extend north to the western Dakotas.

   Multiple corridors of increasing severe potential are expected this
   afternoon. As focused ascent overspreads southeast Colorado into
   western Kansas, low-topped supercells will become increasingly
   probable midday to early afternoon within a marginally buoyant
   environment initially. A smaller area of supercell development may
   also form in the wake of this activity near the Colorado/Kansas
   border later in the afternoon and yield a persistent severe threat
   into early evening.

   Farther south, the aforementioned early day persistent cluster of
   storms across south-central Oklahoma casts some uncertainty,
   particularly in regards to its north, with potential ramifications
   for areas such as northern Oklahoma/far southern Kansas with the
   possibility of somewhat more isolated storms. A volatile supercell
   environment should still evolve to the west of this cluster and
   ahead of the dryline, especially across southwest into
   west-central/south-central Oklahoma. A pronounced gradient in MLCAPE
   is likely by late afternoon to early evening as the most robust
   boundary-layer heating post-dryline occurs in Texas, while a plume
   of richer moisture advects north ahead of it. This should support
   MLCAPE approaching 1500 J/kg near the OK/KS border to around 3500
   J/kg along the Red River. 

   While a mid-level jetlet over the southern High Plains will be in an
   overall weakening state, its favorably timed eastward translation
   across the dryline should support sustained supercells. Upper-level
   wind fields will weaken with height and the bulk of hodograph
   structure will consist of enlarged curvature from 0-3 km. This
   suggests supercells should tend towards an HP character with a
   slow-moving cluster type evolution. A moderate increase in low-level
   flow early this evening could support a strong tornado risk,
   especially across southern/central Oklahoma with the most intense
   supercells. A small MCS/embedded supercell cluster will probably
   persist into eastern Oklahoma before eventually weakening during the
   overnight.

   ...ArkLaMiss/Lower Mississippi Valley to Southeast...
   The environment that potentially produced a couple of tornadoes this
   morning across northern Louisiana is expected to generally persist
   eastward across the ArkLaMiss into the afternoon, with a continued
   potential for mostly brief tornadoes. There will also likely be some
   increase in damaging wind potential as storm mergers occur and the
   downstream boundary layer warms and destabilizes. Other more
   localized/episodic strong to severe storms capable of damaging winds
   are possible farther east into Alabama, southwest Georgia, and
   northern Florida, primarily before sunset.

   ..Guyer/Bentley.. 05/11/2023

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