Tuesday, September 11, 2012

While on the Subject of Joplin

Two postings below, I talk about the continuing overuse of tornado sirens by officials in the Joplin area.  As I talk about in When the Sirens Were Silent there is a second aspect to the overwarning problem in southwest Missouri and that is too many tornado warnings issued by the National Weather Service office in Springfield, MO.

A second researcher has confirmed the findings presented in Sirens.
Patrick Marsh, a PhD candidate in meteorology at the University of Oklahoma, has looked at the frequency of tornado warnings by NWS local office. Darker shading = more tornado warnings. You can see there is a tremendous variation between the Springfield warning area, which includes Joplin (JLN), versus the Wichita office's immediately west and Tulsa's immediately southwest. Joplin simply gets far more tornado warnings than the number of actual tornadoes justifies.

Here is his map of the entire U.S. I've highlighted Springfield's county warning area. 
click to enlarge; source: patrickmarsh.com
There are good climatological reasons for some of the variance: Tornadoes are rare in Maine and Utah, so fewer warnings will be issued there. 

But, where there are large differences between adjacent offices, a problem may exist. For example, Wichita, Oklahoma City, Ft. Worth, Kansas City and Tulsa, areas that frequently deal with tornadoes, generally issue fewer tornado warnings than some of the surrounding offices that receive tornadoes less frequently. This can be due to staff experience. Also, since this is ten years of data, there may be some areas that actually had unusually high or low numbers of tornadoes in short (in climate terms) period of time.

That said, I've long believed that a weakness in the National Weather Service's usually fine service is the office-to-office variation in warning strategies. This is something I urge the NWS to evaluate and, if warranted, correct.

If you are interested in learning more about this topic, visit Patrick's site here.

ADDITION in response to comments (see below):
Number of tornadoes and tornado warnings for the four year period 2008-2011.
Craig and Ottawa counties are both handled by Tulsa NWS.
Jasper Co. handled by Springfield NWS.

2 comments:

  1. I agree there needs to be some consistency between NWS offices, however according to one source Jasper Co, MO does get more tornadoes than any other county in the state. http://www.crh.noaa.gov/images/sgf/papers/severe_climo/ghfig1.jpg.....Maybe the reason the SGF is so trigger happy, so to speak to issue a tornado warning?

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  2. Thanks for the comment and interesting link.

    The link refers to tornadoes from 1961 through 1995 which is almost entirely pre-Doppler era and more than 2/3rds was the period when we were labeling microbursts "tornadoes." The the data in that study is questionable.

    I have added information to the original posting in response to your comment, see above. It shows that, for the last four calendar years, the number of actual tornadoes in Joplin and the two upstream counties is about the same. But, there are FIVE TIMES the number of tornado warnings for Jasper Co. (Joplin)!

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