ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 030900
   SPC AC 030900

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0400 AM CDT Fri May 03 2024

   Valid 061200Z - 111200Z

   ...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/MON...

   ...DISCUSSION...
   A multi-day period of organized severe thunderstorm potential
   appears likely across parts of the central to eastern CONUS next
   week, beginning on Day 4/Monday across the Plains, and continuing
   through at least Day 6/Wednesday.

   ...Day 4/Monday...
   A negatively tilted upper trough will eject northeastward over the
   northern/central Plains on Monday. Pronounced low-level mass
   response will encourage rich low-level moisture to advect northward
   over the southern/central Plains, as a surface low rapidly deepens
   over the northern High Plains. Strong deep-layer shear and at least
   moderate instability are expected to be in place ahead of a surface
   dryline extending across the southern/central Plains.

   Thunderstorms will likely erupt along the length of the dryline by
   late Monday afternoon from southern NE into central KS and
   north-central OK. Supercells are likely to be the dominant mode
   initially given the strength of the deep-layer shear. Both very
   large hail and tornadoes will be possible with these supercells as
   they spread eastward across the southern/central Plains through
   Monday evening. With a southerly low-level jet forecast to
   strengthen to at least 50-60 kt Saturday evening, a corresponding
   rapid increase in low-level shear will likely support a continued
   threat for tornadoes with any discrete convection. Some of these
   tornadoes could be strong. The severe threat will likely continue
   Monday night with eastward extent across the Plains, before
   convection possibly weakens some towards early Tuesday morning.
   Given increased confidence in high-end severe potential, a 30%
   severe area has been introduced from parts of southern NE into
   central KS and north-central OK.

   ...Day 5/Tuesday...
   The large-scale upper trough/low is forecast to gradually occlude
   over the northern Plains on Tuesday. But, an enhanced mid-level jet
   and embedded vorticity maximum will likely overspread parts of the
   Upper Midwest, mid MS Valley, and OH Valley through Tuesday evening.
   An expansive warm sector will likely be in place across these
   regions ahead of a surface cold front/dryline. Robust convection
   should develop along/ahead of these boundaries through the day.
   Sufficient instability and deep-layer shear will likely exist to
   support organized severe thunderstorms, including supercells posing
   a threat for all severe hazards. The northeastward extent of the
   warm sector remains somewhat uncertain into the OH Valley. Still,
   some severe risk will probably persist into Tuesday evening/night
   with eastward extent across the mid MS Valley and lower OH
   Valley/Midwest. Expansion of the 15% severe area may be needed in
   later outlooks, pending better model agreement and increased
   confidence in the eastward extent of rich low-level moisture and
   related instability.

   ...Day 6/Wednesday...
   The upper trough/low should gradually evolve eastward across the
   northern Plains on Wednesday. While there are still some differences
   in model guidance regarding the evolution of an embedded shortwave
   trough, there appears to be enough agreement in the synoptic pattern
   to include a 15% severe delineation for Wednesday for parts of the
   southern Plains into the ArkLaTex/Ozarks and towards the mid MS
   Valley. Across these areas, strong instability is forecast to
   develop east of a front/dryline. With enhanced mid-level flow
   persisting with a westerly mid/upper-level jet, organized severe
   thunderstorms should once again develop Wednesday afternoon.
   Supercells posing a threat for all severe hazards may occur. The
   northern/eastern extent of the severe threat is unclear, as the
   convection from Tuesday may tend to limit better low-level moisture
   return into the OH/TN Valleys. Depending on model trends over the
   next few days, the 15% severe area may need to be expanded to
   include these regions.

   ...Day 7/Thursday and Day 8/Friday...
   Some severe threat may continue on Thursday from parts of TX into
   the lower MS Valley/Southeast, generally along/south of a front and
   any convection that develops Wednesday. Too much uncertainty
   currently exists to include a 15% severe area at this time, but
   trends will be monitored. A severe risk also appears possible next
   Friday across the same general regions, but confidence in the
   placement of the front and convection is even lower than Thursday.

   ..Gleason.. 05/03/2024

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