Case Study: Thundersleet in Central Minnesota

1-January-2005

Summary

• 7-10 inches of snow in northern and northeastern Minnesota
• Thunderstorms in central Minnesota with sleet despite 850 mb temperatures colder than the critical values
  • KSTC 0.43 melted; 0.8 inch sleet and snow pellet accumulation
  • When precipitation hardest, it still was sleet.
  • Many ground strikes in KSTC area around 21Z

Important Processes:

• Elevated Convection

  Radar and Satellite from NWS Duluth
  Regional Surface Data Plots
  15Z 1-Jan-2005	18Z 1-Jan-2005	21Z 1-Jan-2005	00Z 2-Jan-2005
  Surface METARs
  KSTC	KBJI	KDLH	KFSD
  Soundings
  72649 Chanhassen, MN 12Z 1-Jan-2005		72649 Chanhassen, MN 00Z 2-Jan-2005
  72558 Valley, NE 12Z 1-Jan-2005		72558 Valley, NE 00Z 2-Jan-2005

   

• Frontogenesis/Deformation

850 mb 12Z 1-Jan-2005		850 mb 00Z 2-Jan-2005
Analysis	Temperature Advection	Analysis	Temperature Advection
700 mb 12Z 1-Jan-2005		700 mb 00Z 2-Jan-2005
Analysis	Temperature Advection	Analysis	Temperature Advection

• Jet Streak Circulation

  250 mb 12Z 1-Jan-2005		250 mb 00Z 2-Jan-2005
  Analysis	Convergence	Analysis	Convergence
  500 mb 12Z 1-Jan-2005		500 mb 00Z 2-Jan-2005
  Analysis	Absolute Vorticity	Analysis	Absolute Vorticity

• Snow/Rain Transition

Many more maps thanks to Amanda Brandt, NWS Duluth

 

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Last Updated: Tuesday, February 15, 2005 5:29 PM		Send comments to: Bob Weisman