SPC AC 020600

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Tue Jun 02 2020

   Valid 031200Z - 041200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
   NORTH-CENTRAL PLAINS TO THE MIDWEST/OHIO VALLEY AND NORTHEAST
   STATES/DELMARVA...

   ...SUMMARY...
   Severe thunderstorms are expected on Wednesday from the
   North-central Plains to the Midwest, Ohio Valley, and parts of the
   Northeast States/Delmarva.

   ...Overview...
   An extensive west/east zone of severe-weather potential is expected
   on Wednesday, influenced by a south/southeastward-moving front
   across the Midwest/Ohio Valley to Northeast States/Delmarva, and a
   supercell-favorable environment across the north-central High
   Plains.

   ...North-central High Plains/Central Plains...
   A belt of strengthening westerlies over the northern Plains will
   influence the region into Wednesday afternoon/night. Severe
   thunderstorms will initially be possible across the north-central
   High Plains Wednesday afternoon in vicinity of a prefrontal trough
   and/or southeastward-moving front. This includes western South
   Dakota and possibly southwest North Dakota/northwest Nebraska. Other
   storm development may focus in vicinity of northeast
   Colorado/southwest Nebraska into northwest Kansas. At least isolated
   supercells are expected across these regions with large hail and
   strong wind gusts probable. Into Wednesday evening/night, there is
   the possibility than an MCS or at least several storm clusters could
   persist and move southeastward Wednesday night, generally near the
   Kansas/Nebraska border. If so, a severe threat could continue into
   the overnight.

   ...Upper Ohio Valley/Northeast States...
   A low-amplitude shortwave trough and a related belt of strong
   cyclonically curved west-northwesterly winds aloft (40-55 kt at 500
   mb) will overlie a south/southeastward-spreading front. The
   potential exists for early day convection across the region, and
   this convection and related cloud cover casts some uncertainty 1)
   regarding the exact degree of destabilization and 2) a preferred
   corridor of any higher coverage severe potential. 

   That said, moderate buoyancy (upwards of 2000 J/kg MLCAPE) is
   plausible near/south of the front and to the south of any residual
   early day precipitation/outflow. Storms will likely
   increase/intensify through early/mid afternoon near the effective
   front. The strong mid/high-level westerlies and 40+ kt effective
   shear would support some initial supercells along with
   well-organized southeastward-moving clusters. Damaging winds and
   severe hail are expected. Although low-level winds will tend to
   remain veered in areas near/south of the front, moderately strong
   low-level shear/SRH could yield a non-zero tornado risk during the
   afternoon and early evening hours.

   ...Midwest including Missouri to Ohio...
   The boundary layer should become moderately to strongly unstable
   Wednesday afternoon along and south of a southward-advancing front,
   with the strongest destabilization (3000+ J/kg MLCAPE) expected
   across northern/central Missouri into much of Illinois/Indiana.
   Sufficient near-frontal convergence and forcing for ascent should
   allow for at least widely scattered deep convective development
   through the afternoon. While deep-layer/low-level winds will be not
   be overly strong, the degree of instability and roughly 20-30 kt
   effective shear will support sustained multicellular clusters
   capable of wind damage and severe hail.

   ..Guyer.. 06/02/2020

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