Why so quiet??

[Eric Matthews]

I think counting tornado days is a valid way to measure changes in tornado activity/frequency. As has been noted several times in the discussion, we are likely able to find/report/document more tornadoes due to technology, spotters/chasers, etc.

Another question came to mind regarding the number of tornadoes based on my experience. When I started chasing 20 years ago, if you were on a tornado and it lifted, then set back down a mile later, it was considered (at least unofficially in the chase community) to be one single tornado. Today, that same storm would count as two tornadoes.

My question is, could some of the increase in the number of reported tornadoes be related to how we count tornadoes? If the answer is yes, then the number of tornado days seems to be an even better measuring stick.

 

[Patrick Marsh]

Excluding yesterday's (5-25-12) tornadoes in Kansas, we needed 48 preliminary tornado reports before the end of June just to tie the lowest number of (inflation-adjusted) preliminary tornado reports in any May.

 

[jshields]

it looks like 139 preliminary tornado reports for the month of May. not sure what the record low is, but that's got to be close

http://www.spc.noaa.gov/climo/online/monthly/newm.html

 

[JamesCaruso]

Eric,

Thanks for the analysis and trend graphs! I am coming to this discussion late so I hope you will still see this. I was always under the assumption that long-term peak tornado frequency in the Alley was the last two weeks of May and the first week of June, but anecdotally it seems like the peak has been occurring earlier or later in recent years. Would you be able to present similar trend graphs just for that smaller period? Hope I am not out of line asking you to do my homework for me, but I figure you've got the model built and can easily restrict the date criteria without me having to reinvent the wheel!




Sent from my iPad using Tapatalk HD

 

[Jonathan Jones]

Looking at the trends it seems to have puffed itself out, and the season may be foreshortened. Time will tell but the annual numbers this year are well down even for an average year.

 

[Eric Bucsela]

Thanks Jim & Jonathan for your comments. Climatology is always fun (for me at least), especially in crappy years. I'll look at trends in season peak dates with this dataset - or maybe add thru 2011. My impression is there's been more variability lately from year to year but no trend. But I also don't trust impressions! Will try to crunch some numbers in the next week or so. Stay tuned.

 

[jshields]

here's a short little story on the "Tornado drought of 2012". From April 15th(the day after the last big outbreak this year), to the end of July, the U.S. is at under 300 tornadoes vs. the average of 850. This year has sucked My last action was the April 14th outbreak...

http://www.norman.noaa.gov/2012/08/the-tornado-drought-of-2012/

 

[Boris Konon]

here's a short little story on the "Tornado drought of 2012". From April 15th(the day after the last big outbreak this year), to the end of July, the U.S. is at under 300 tornadoes vs. the average of 850. This year has sucked My last action was the April 14th outbreak...

http://www.norman.noaa.gov/2012/08/the-tornado-drought-of-2012/

Look at the graph...the current record low year is 1988, and that was a huge drought year for the CONUS as well. 2012 is on pace to beat that year though.
http://www.norman.noaa.gov/wp-content/uploads/2012/08/AprJul2012tors.png