SPC AC 201951

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0251 PM CDT Mon Jun 20 2022

   Valid 202000Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   SD...SOUTHEAST ND...AND NORTHWEST/WEST-CENTRAL MN...

   ...SUMMARY...
   Scattered to numerous severe thunderstorms are likely across the
   northern Great Plains through this evening. Destructive wind gusts,
   very large hail, and a couple tornadoes are possible.

   ...20z Update...

   The ongoing outlook remains on track and no changes have been made
   with the 20z update. A cluster of severe thunderstorms within Severe
   Thunderstorm Watch 393 is currently moving into the Nebraska
   Panhandle. This activity is showing some characteristics toward
   upscale development recently. With time, this activity may develop
   into a bow capable of producing a swath of intense, damaging gusts
   as it tracks northeast into central SD. Additional thunderstorm
   development is expected over the next few hours across parts of the
   eastern Dakotas/northwest MN within the baroclinic zone and ahead of
   a stalled front. This activity also will pose a threat for intense
   gusts and large hail. For additional information on short term
   severe potential, reference MCD 1233. More forecast details can be
   found in the previous outlook discussion below.

   ..Leitman.. 06/20/2022

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Jun 20 2022/

   ...Northern Great Plains...
   A vigorous shortwave trough near the UT/ID/WY border area will eject
   northeast into ND tonight, around the northwest periphery of a
   closed high over the Mid-South. Attendant mid-level jet will
   strengthen as it spreads from the central Rockies towards the Red
   River Valley. A wavy surface front extending southwest from a
   primary cyclone over northwest Ontario will move little today, and
   then begin to accelerate eastward tonight in response to the
   ejecting mid-level trough and convective outflows. A plume of upper
   60s to lower 70s boundary-layer dewpoints will be maintained along
   the front from north-central/northeast SD and ahead of it across MN.
   The dryline should effectively mix into south-central SD through
   central NE where mid to upper 90s surface temperatures become
   common. Beneath steep mid-level lapse rates, the largest MLCAPE of
   2500-4000 J/kg should become established across MN into the eastern
   Dakotas, with a bent-back plume of moderate buoyancy extending
   southwest along and to the cool side of the surface front into the
   NE Panhandle.

   Scattered thunderstorms are expected to develop by mid afternoon in
   advance of the ejecting mid-level trough, within the post-frontal
   environment from eastern WY into the NE Panhandle. Convection will
   subsequently spread northeast across the Dakotas, as well as likely
   develop separately along the baroclinic zone over the Red River
   Valley through early evening. Vertical shear will be strongest along
   and west of the stalled front, especially within the strengthening
   500-mb southwesterly jet. Thus, the best chance for long-track
   supercells with significant severe hail amid highly elongated and
   nearly straight-line hodographs should be across northwest NE to
   central SD. As this activity approaches larger buoyancy during the
   evening, and likely impinges on downshear convection along the
   front, multiple MCSs with sustained bowing segments will probably
   develop, increasing the threat for severe wind gusts, some of which
   may reach 80-90 mph. Greater tornado potential is more nebulous, but
   a focused corridor for a couple tornadoes is apparent across
   north-central SD and southeast ND into northwest MN with any
   supercells/bows along this portion of the initially stalled front.
   Overall severe potential should diminish overnight through a
   combination of extensive convective overturning and increasing
   warm-sector MLCIN.

   ...Central/south FL...
   Scattered pulse thunderstorms will again develop along sea breezes
   this afternoon within a large buoyancy environment characterized by
   near 3000 J/kg of MLCAPE. Weak vertical shear will limit potential
   for more organized convection, but localized damaging downbursts
   will be possible in the strongest cells.

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