SPC AC 301625

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1125 AM CDT Mon May 30 2022

   Valid 301630Z - 311200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FROM EASTERN SD INTO MN...

   ...SUMMARY...
   Numerous severe thunderstorms are forecast across parts of the
   Northern Plains and Upper Mississippi Valley, with more scattered to
   isolated activity southward into the central Plains today into
   tonight. Large to giant hail, 60-80 mph gusts, and a few
   long-tracked, intense tornadoes are possible.

   ...A substantial threat for severe storms with all hazards is
   expected this afternoon/evening from eastern South Dakota into
   Minnesota...

   ...Eastern SD into MN though late evening...
   A midlevel shortwave trough and associated 70-90 kt midlevel jet
   will progress quickly north-northeastward from western KS/NE toward
   the upper MS Valley by tonight.  An associated 992 mb surface low in
   central NE as of late morning will develop quickly
   north-northeastward across eastern SD to near the ND/MN border by
   early tonight.  Scattered elevated storms, some with large hail,
   will likely persist through the day in the warm advection zone to
   the north of the warm front across eastern SD into southwestern MN. 
   However, the warm sector with mid-upper 60s dewpoints now across
   eastern NE/western IA will spread northward during the day, with
   increasing potential for surface-based storm development near and
   just ahead of the surface cyclone and ejecting midlevel trough by
   midday/early afternoon.

   It appears the convection will begin as clusters by midday across
   east/southeast SD, and expand quickly northeastward into
   central/northern MN by late afternoon/evening.  All hazards can be
   expected with the surface-based storms during the afternoon, in an
   environment favorable for fast-moving supercells.  However, there
   are some concerns about mixed convective mode/bowing segments given
   potential storm interactions and strong forcing for ascent. 
   Deep-layer vertical shear will be quite strong (effective shear in
   excess of 65 kt), with long hodographs and low-level, clockwise
   curvature (effective SRH of 300-400 m2/s2).  These wind profiles, in
   combination with midlevel lapse rates greater than 8 C/km and MLCAPE
   of 2000-3000 J/kg, will support the threat for a few long-tracked,
   intense tornadoes and very large hail with any semi-discrete
   supercells.  As previously mentioned, there will also be some
   potential for storm interactions and upscale growth into line
   segments capable of producing significant outflow gusts up to 80
   mph, given the very strong environmental wind profiles. 
    
   ...IA/NE to KS/northern OK later this afternoon into tonight...
   The larger height falls and stronger forcing for ascent will spread
   northward toward eastern SD/MN through the afternoon/evening, but
   the warmest portion of the elevated mixed layer will be east of the
   dryline by late afternoon.  Forcing for ascent will be focused in
   the low levels from the dryline/cold front intersection southward
   along the dryline, and isolated storm development may occur by late
   afternoon/evening.  Lapse rates aloft will not be ideal, given
   fairly warm temperatures near 500 mb on the anticyclonic side of the
   jet.  Still, the storm environment conditionally favors supercells
   with all hazards, given sustained storm development.  Otherwise,
   despite height rises overnight, the threat for convection with
   occasional large hail/damaging winds will persist (especially toward
   northeast KS) as the cold front overtakes the remnant dryline, and
   with warm advection on the nose of a 50+ kt low-level jet.  

   ...FL/south GA this afternoon...
   Scattered sea breeze storms are expected this afternoon, skewed to
   the western half of the FL Peninsula given low-level easterly flow. 
   Strong surface heating and moderate buoyancy could support isolated
   wind damage with downbursts, as well as some hail.

   ..Thompson/Bentley.. 05/30/2022

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