VIII. Modified Peoria Hodograph (using 18 UTC surface winds in AZO)

The hodograph from the 1200 UTC Peoria sounding modified with the surface winds at 18 UTC in Kalamazoo is quite interesting. As we would expect in this environment, the length of the hodograph certainly indicated that there was a lot of speed shear. However, note the counterclockwise shape of the hodograph. A closer look at the raw wind data entries reveals why the hodograph is shaped this way. Note that in the 1-1.5 km AGL layer, winds are out ~260 degrees (almost due west). As soon as you get up above 1.5 km, winds are actually backing (slightly) with height to the southwest. Obviously, an ideal tornado environment would feature veering winds through the layer and a clockwise shaped hodograph and this profile is likely not representative of the hodograph in the vicinity of the Kalamazoo storm. This hodograph emphasizes how quickly the environment can change on relatively small spatial scales. Another consideration when looking at hodographs is the importance of the low level shear. If we focus on that, we see that surface winds were out of the east, winds 0.5 km AGL were out of WSW, and at 1.0 km AGL almost directly out of the west. This is a very abrupt change in wind direction from 0-1 km. Recent research has consistently indicated the importance of examining the 0-1 km layer in anticipation of tornadogenesis.

May 13, 1980 Hodograph 18Z

Below is the composite hodograph from our Significant Tornado Climatology for Lower Michigan for all “Type One” events. Note that it does not really show your classic clockwise curved hodograph either, but it does indicate substantial amounts of 0-1 km and 0-3 km storm-relative helicity. The length of the hodograph is indicative of strong speed shear environments, which are conducive to supercell thunderstorm formation. This long, straight hodograph also suggests potential for splitting supercell thunderstorms. Another interesting thing to do is compare raw wind data from the Kalamazoo modified hodograph (above) with the raw wind data for the composite “type one” hodograph below. The Kalamazoo case indicated a more abrupt wind direction change in the 0-1 km layer (E to WSW to W) than the composite hodograph for all type one cases below (SE to S), while the composite hodograph below indicated a more gradual veering wind profile with height from 0 to 3 km AGL.

Significant Tornado Type 1 Composite Hodograph

  1. Introduction
  2. Methodology
  3. Large Scale Synoptic Pattern over the United States on May 13, 1980
  4. Hourly Surface Weather Maps Focused on Great Lakes Region from 12 UTC May 13 to 00 UTC May 14
  5. Observed 12 UTC Soundings for Flint, MI and Peoria, IL and Data Derived from them
  6. Modified Flint Sounding
  7. Flint and Peoria hodographs from 12Z observed soundings
  8. Modified Peoria Hodograph (using 18 UTC surface winds in AZO)
  9. What are our most important significant research findings? What do we believe caused the Kalamazoo tornado? What can we learn from this? How can we use this information to aid in anticipating tornadogenesis in the Grand Rapids CWA?
  10. So what exactly happened? Chronology of events occurring between 3:30 and 4:25 p.m. EDT across Van Buren and Kalamazoo Counties.
  11. Tornado Victims
  12. Dr. T. Theodore Fujita’s Kalamazoo Tornado Findings
  13. A Personal Account of the Kalamazoo Tragedy
  14. Bronson Park Devastated
  15. Acknowledgments
Return to The May 13, 1980 Kalamazoo Tornado Case Study Main Page

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