SPC AC 071248

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0748 AM CDT Tue Jun 07 2022

   Valid 071300Z - 081200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS WESTERN AND
   SOUTHERN NE TO NORTHERN KS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST OK TO
   WESTERN TN...

   ...SUMMARY...
   Significant severe thunderstorms are most likely across parts of the
   central Great Plains during the late afternoon and evening. Very
   large hail and destructive wind gusts are possible.

   ...NE and northern KS vicinity...
   A low-amplitude shortwave trough over the northern Rockies will
   eject east into SD/NE by evening. A belt of 50-60 kt 500-mb
   westerlies to the south of this wave will likely intensify to 70-80
   kt over NE by 06Z. A lee surface trough will remain anchored along
   the I-25 corridor in CO with a separate low near the CO/KS/NE
   border, with a west/east-oriented portion of the surface front
   across southern NE.

   Large-scale ascent through a combination of mid-level height falls
   and weak upslope flow will aid in scattered thunderstorms forming by
   early afternoon across eastern WY and spreading into the NE
   Panhandle. Additional storms will likely along the baroclinic zone
   eastward across NE during the late afternoon, while more isolated
   storms developing across eastern CO. With effective bulk shear
   strengthening to in excess of 60 kts, a highly elongated and nearly
   straight-line mid/upper hodograph will favor numerous supercells and
   both left/right splits. The main uncertainty is with the degree of
   buoyancy in this region given current presence of mid 50s to low 60s
   surface dew points. It does appear that moderate boundary-layer
   heating south/west of the surface front amid steep mid-level lapse
   rates should support MLCAPE increasing to 1000-2000 J/kg. This will
   likely be sufficient for significant severe hail as the primary
   initial hazard.

   During the evening, consolidating cells will likely grow upscale
   into an MCS across southern NE into northern KS. The degree of shear
   and synoptic pattern would favor a potential derecho with bowing
   linear segments and significant severe wind gusts in excess of 80
   mph, which is most supported by the 00Z HRW-ARW. However, both the
   06Z NAM/09Z RAP and recent HRRR runs suggest that a buoyancy donut
   may linger across parts of central/eastern KS in the wake of
   recently decayed convection across southern KS and a deeper cluster
   in central to eastern OK. This renders enough thermodynamic
   uncertainty in cold pool intensity tonight to preclude an upgrade to
   cat 4/MDT-risk.

   ...South-central High Plains into OK...
   Mid to late afternoon thunderstorm development appears probable off
   the Sangre de Cristos and Raton Mesa vicinity, which will likely
   include a few supercells given 30-40 kt 500-mb westerlies.
   Confidence is low in subsequent evolution eastward across the
   Panhandles and southwest KS this evening into tonight. A substantial
   frontal surge has occurred into the TX South Plains. Although
   modification will occur, it is plausible that the boundary-layer
   over the Panhandles will remain well capped beneath a stout EML.
   Ascent from the LLJ will mainly be focused across western to central
   OK, which might support some uptick in isolated severe potential
   overnight.

   ...Eastern OK to Western TN...
   A slow-moving but deep convective cluster is ongoing across
   south-central OK in association with a lead frontal surge. Evening
   to overnight CAM guidance is quite varied in how this activity will
   evolve. If a surface cold pool can become established the threat for
   strong to severe wind gusts will increase prior to peak diurnal
   heating. Otherwise, if convection weakens for a time as low-level
   warm theta-e advection subsides, remnants of it would potentially
   restrengthen this afternoon in the Mid-South.

   ...OH to western NY...
   Stratiform rain occurring from the Lower Great Lakes to the
   Cumberland Plateau within a pronounced low-level jet is expected to
   translate northeast across the northern Appalachians into this
   afternoon. Most guidance suggests in the wake of this activity
   isolated to scattered moderate-topped thunderstorms may develop
   along the surface cold front. Low-level winds will weaken/become
   veered ahead of the front, suggesting that isolated damaging winds
   and small to marginally severe hail will be the primary hazards.

   ..Grams/Broyles.. 06/07/2022

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