As clearly stated below, this blog posting was based on Seth Borenstein's story about the Gensini and Brooks study. The story states (link below):
Because tornadoes sometimes go undercounted, especially in the past and in less populous areas, scientists don't like to study trends by using counts of tornadoes.
I have since heard from Dr. Gensini and I have read the paper itself. They do count number of tornadoes and the story is clearly incorrect. My objection as to the conclusions of the paper itself stand. They are:
- Back to Dr. Ted Fujita in the 1970's, there has been speculation about an east-west cycle regarding tornado maxima. It wish this study had referenced his work and commented on it.
- Forty years is too short a period of time in and of itself and, because,
- From 1979 to 1996 (release of Twister) tornado chasing was restricted to the Great Plains which might have had the effect of inflating tornado numbers versus the areas farther east where tornado chasing was much more rare.
- The STP (see below) is often not a good proxy for number of tornadoes.
I have stricken out the incorrect information in the original posting.
-- original posting --
|Tornado near Tescott, Kansas, May, 2018|
"Because tornadoes sometimes go undercounted, especially in the past and in less populous areas, scientists don't like to study trends by using counts of tornadoes. Gensini and tornado scientist Harold Brooks of the National Severe Storms Lab looked at "significant tornado parameters," a measurement of the key ingredients of tornado conditions."
Unfortunately, the "significant tornado parameter" is not a good proxy for the total number of tornadoes. For example, on a given day the "STP" can be high but because the parent thunderstorms are elevated, no tornado occurs. There is also the fact that a study of less than forty years is too short in climatological terms to draw any real conclusions.