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The 2011 Groundhog Day Blizzard: A Synoptic and Mesoscale overview

Stephen Rodriguez, Jr. National Weather Service Chicago, IL. The 2011 Groundhog Day Blizzard: A Synoptic and Mesoscale overview. Introduction. Brief background. Purpose of Study. Synoptic background and forcing mechanisms. Synoptic/ Mesoscale features: Moisture, Forcing, Instability.

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The 2011 Groundhog Day Blizzard: A Synoptic and Mesoscale overview

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  1. Stephen Rodriguez, Jr. National Weather Service Chicago, IL The 2011 Groundhog Day Blizzard: A Synoptic and Mesoscale overview

  2. Introduction • Brief background. • Purpose of Study. • Synoptic background and forcing mechanisms. • Synoptic/Mesoscale features: Moisture, Forcing, Instability. • Conclusions.

  3. Radar Storm Evolution

  4. Observed Snowfall Totals CHICAGO

  5. Wind Gusts/Visbys/Lightning 65 STRIKES! 1/4 MILE VISBYS.

  6. Purpose of Study • Synoptic/Mesoscale Overview. • Pattern Recognition/Conceptual Models. • “How to Forecast” Blizzards? • What are we forecasting?

  7. Purpose - NWS Blizzard Definition • Sustained wind or frequent gusts to 35 miles an hour or greater; and • Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¼ mile). • For a period of 3 hours or longer.

  8. Purpose - Blizzard Elements • Heavy snowfall. • Snow efficiency. • Strong winds.

  9. Synoptic Overview 300 MB 02/02/11 00Z

  10. Synoptic Overview 700 MB 02/02/11 00Z

  11. Synoptic Overview 850 MB 02/02/11 00Z

  12. Synoptic Overview SFC 02/02/11 00Z

  13. Synoptic Overview 02/02/00 00Z ROAB KDVN

  14. Low/Isallobaric Component 00Z 03Z 06Z

  15. Well-Mixed Environment 04Z RUC Sounding

  16. Moisture 850 MB Moisture Transport

  17. Moisture TROWAL structure identifiable by 02Z-3Z. CHICAGO

  18. Forcing - Deformation

  19. Forcing - Isentropic Lift 22Z/00Z/02Z RUC 290K CHICAGO Persistent isentropic lift from late afternoon through late evening.

  20. Forcing - Frontogenesis RUC 02Z MSN ORD EVV

  21. Instability - EPV RUC 02Z MSN ORD EVV

  22. Instability – CAPE/Lapse Rates NORTH CENTRAL ILLINOIS 04Z RUC Sounding

  23. Snow Efficiency NORTH CENTRAL ILLINOIS 00Z-03Z

  24. Conclusions - Review • Copious amounts of moisture. • Persistent strong forcing due to both synoptic/meso forcing mechanisms. • Instability – an added benefit. • Snow efficiency.

  25. Conclusions – Key Factors • Heavy Snowfall – Yes! • Snow efficiency – Yes! • Strong winds – Yes! Yes! Yes!!!

  26. Blizzard Climatology

  27. Conclusions – Lessons Learned • Stick to “base” data. • Pattern Recognition of three elements. • All come together – Blizzard.

  28. Questions? • References: • NOAA/NWS/Storm Prediction Center • Schwartz, 2001.

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