SPC AC 080600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Wed May 08 2024

   Valid 081200Z - 091200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR
   SOUTH-CENTRAL/SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...NORTHWEST
   INTO MIDDLE TENNESSEE...WESTERN KENTUCKY...

   ...SUMMARY...
   Numerous severe thunderstorms appear likely Wednesday from parts of
   the mid Mississippi, Ohio, and Tennessee Valleys into the southern
   Plains. All severe hazards, including tornadoes, very large to giant
   hail, and potentially significant damaging winds are possible. Some
   of the tornadoes may be strong.

   ...Synopsis...
   Within a seasonably deep upper-level trough, one embedded mid/upper
   low is forecast to move eastward from the north-central Plains into
   the upper MS Valley, while another mid/upper-level low is forecast
   to develop within the trailing portion of the upper trough across
   the Great Basin. To the south of the Great Plains midlevel low, an
   embedded shortwave trough and attendant jet maximum will move from
   the central Plains toward the mid Mississippi Valley. Farther
   northeast, a shortwave trough and attendant surface low will move
   from the upper Great Lakes region into the Northeast. 

   ...ArkLaTex into the Mid-MS/OH/TN Valleys...
   A complex but potentially significant severe weather episode still
   appears possible over a broad region from the ArkLaTex vicinity into
   parts of the mid MS/OH/TN Valleys. All severe hazards will be
   possible, with some threat for strong tornadoes, very large to giant
   hail, and swaths of damaging wind. 

   A very moist and unstable warm sector will already be in place this
   morning across parts of OK/TX, and eastward along/south of a warm
   front into the mid Mississippi, lower Ohio, and Tennessee Valleys.
   Strong to extreme instability (aided by a plume of midlevel lapse
   rates spreading eastward from the Plains) and moderate to strong
   deep-layer shear will support a potentially volatile severe
   thunderstorm environment through the day into the evening. 

   Initial storm development is expected near/north of the warm front
   from southeast KS into southwest MO, which may already be underway
   at 12Z with a threat of hail and localized severe gusts. The early
   convection will play a major role in the evolution of downstream
   severe potential through the day, with some potential for a MCS to
   develop and move east-southeastward. Should this occur, a swath of
   damaging wind could spread toward the TN and lower OH Valleys, along
   with a threat for line-embedded tornadoes and some hail. If morning
   convection does not evolve into an MCS, then there may be a somewhat
   greater potential for supercell development during the afternoon,
   though an eventual evolution into multiple intense storm clusters is
   expected with time, with an attendant threat of large to very large
   hail and damaging winds (with at least isolated gusts in excess of
   75 mph possible). 

   Storm coverage southwestward into the ArkLaTex region and central TX
   remains more uncertain, but the environment across this region will
   be quite volatile, with extreme instability and sufficient
   deep-layer shear for supercells. Very large to giant hail and
   significant severe gusts could accompany any storms in this area
   from late afternoon into the evening. 

   A Moderate Risk for hail and wind has been introduced in the
   vicinity of the expected frontal zone position from southern MO into
   northwest/middle TN, where multiple storm clusters with significant
   severe potential appear possible. Some expansion of this Moderate
   Risk to the south/west may be needed, depending on trends regarding
   storm coverage into the ArkLaTex region. 

   The magnitude of the tornado threat will be dependent on storm mode,
   with the coverage and longevity of discrete or clustered supercells
   remaining highly uncertain at this time. However, any stronger
   supercell moving through the warm sector or within modifying outflow
   could pose a strong tornado threat, given the magnitude of
   instability and sufficient low-level and deep-layer shear. A
   corridor of higher tornado probabilities may be needed if confidence
   increases in several persistent supercells across the region.  

   ...Southern Appalachians into the Carolinas...
   Convection will likely be ongoing this morning across the southern
   Appalachians vicinity. Some intensification of this morning
   convection, along with potential redevelopment, will be possible
   into the afternoon. Diurnal heating of a warm and moist airmass will
   support moderate to locally strong destabilization, with MLCAPE
   increasing above 2000 J/kg. Moderate midlevel westerly flow will
   support sufficient deep-layer shear for storm organization, and a
   couple supercells and/or stronger clusters could evolve during the
   afternoon and evening. Large hail and strong/damaging gusts are
   expected to be the primary hazards, though a tornado cannot be ruled
   out with any sustained supercell. 

   ...Iowa and vicinity...
   Modest low-level moisture will return to parts of Iowa and adjacent
   areas of the Midwest/Plains during the day, though the quality of
   this moisture may be affected by early convective development to the
   south. Cool temperatures aloft will support MLCAPE potentially
   increasing near/above 1000 J/kg, with sufficient deep-layer shear to
   support organized convection. Guidance varies somewhat regarding the
   placement and magnitude of the most favorable instability, but a
   couple stronger cells/clusters will be possible with a threat of
   hail, damaging wind, and possibly a tornado or two. 

   ...Parts of New England and the Northeast...
   A few strong storms will be possible this afternoon and evening
   across parts of the Northeast and New England, in conjunction with
   the eastward moving shortwave trough and attendant cold front. The
   strongest ascent will likely remain displaced to the north of the
   more favorable moisture and instability, but a few cells/clusters
   may develop and pose a threat of isolated hail and strong/damaging
   gusts.

   ..Dean/Wendt.. 05/08/2024

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