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Mesoscale Discussion 1855
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   Mesoscale Discussion 1855
   NWS Storm Prediction Center Norman OK
   0753 PM CDT Sat Aug 05 2023

   Areas affected...Northwest Iowa

   Concerning...Tornado Watch 589...

   Valid 060053Z - 060300Z

   The severe weather threat for Tornado Watch 589 continues.

   SUMMARY...The threat for severe winds and perhaps a tornado or two
   continues across northwest Iowa.

   DISCUSSION...Regional radar trends over the past 1-2 hours continue
   to depict a combination of discrete cells and thunderstorm clusters
   developing along a surface warm front and in the vicinity of a
   surface low centered roughly over the Sioux Falls, SD region. Storm
   motions to the east/northeast off the warm front and into a more
   stable air mass have limited storm longevity thus far, but a few
   cells have demonstrated transient low/mid-level mesocyclones per
   KOAX and KFSD velocity imagery. The 00 UTC OAX sounding within the
   warm sector sampled ample buoyancy (MLCAPE near 2100 J/kg) with some
   veering of the wind profile in the lowest 2 km. This veering is
   likely exacerbated over northwest IA where surface winds are out of
   the east/southeast; however, buoyancy quickly diminishes within the
   warm frontal zone as temperatures fall from the mid-80s to the 70s
   with northeast extent. There is likely a spatial window along the
   frontal zone across northwest IA where low-level thermodynamics and
   kinematics are favorably supportive of a tornado threat. This
   potential will most likely be realized by a cluster of discrete
   cells ahead of a congealing line approaching from the west. However,
   severe winds remain possible with a 71 mph wind gust noted over
   within the past 2 hours.

   ..Moore.. 08/06/2023

   ...Please see for graphic product...


   LAT...LON   41609535 41619583 41759622 42839659 43199649 43329603
               43149549 42889508 42559492 42129482 41879481 41709501

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