I got the graph above from GRR NWS meteorologist Bill Marino along with this note: “So, what happened to our severe storms frequency in 2009? Check my attached chart out, I found it odd…I really can’t explain it, why has our severe storm frequency plunged from 2009 on? The average from 1986 to 1990 was 60 per year, our average from 2009 to 2016 is the same, 60 per year. However from 1991 through 2008 was 135 per year. It just seems odd!
The attached chart shows our Official Severe Storm Data Base (using Storm Data) with our 23 county CWA (county warning area) from 1986 to now.”
The first thing I thought of (and others) was that 2008 was the year that Craig James retired (good example of “correlation without causation“…another example of c w/o c that I’ve used is what I call the “Maranda Effect” – that it doesn’t seem to rain during Maranda Park Parties)! So, what’s happening? We get a day that 24-hours out looks like it’s going to be a big severe weather day for the G.R. area, but the severe weather doesn’t happen here (though it does happen in surrounding areas…to our north: http://kamala.cod.edu/mi/latest.nwus53.KGRR.html southwest: http://kamala.cod.edu/il/latest.nwus53.KLOT.html and west: http://kamala.cod.edu/offs/KMKX/1707122150.nwus53.html
While I haven’t looked into it…I would guess that we wouldn’t find as big a drop-off in neighboring states, but there would still be a decline in the last 10 years. Nationally:
We had more tornado fatalities in January than in February through June combined! In the U.S.. We had more tornadoes from Jan. 1-22 than from June 1-26! This graph shows tornadoes in the U.S. by year since 2005. The two years with the most tornadoes were 2008 and 2011, with 2010 ending a touch above 10 year average. All five years from 2012 to 2016 (note – 2016 is not added to the graph yet, but we know where it will come out on the graph) had tornado counts below the 10-year average.
This graph is the ACE Index (courtesy of WeatherBell). This is a measure of the number and strength of tropical cyclones. Note that both globally and in the N. Hemisphere – hurricane activity peaked in the mid 1990s, spiked in 2005 (the year of Katraina and Rita) and then we’ve had mostly low count years since 2005. “In the pentad since 2006, Northern Hemisphere and global tropical cyclone ACE has decreased dramatically to the lowest levels since the late 1970s. Additionally, the frequency of tropical cyclones has reached a historical low.” Southern Hemisphere wraps up a record-quiet year for Troipical Cyclones.
Here’s a graph of strong to violent tornadoes by year from 1954 to 2014 (2015 and 2016 were also low count years). These are strong tornadoes that would have been recorded during these years. Many small (EF0 – EF1) tornadoes were not recorded in decades past – now we have 100 cars – storm chasers – following every dark cloud – so some tornadoes get recorded more than once and we have to take time to weed out duplicate sightings. Note that the graph (NOAA data) shows more strong to violent tornadoes in ithe 1960s and 1970s than since the 1970s.
Here’s historic Great Lakes ice cover since 1973. Note that we had a lot of winters with a higher than average ice cover from 1976 (coldest winter in G.R. in the last 100 years) through about 1989. Two of the four winters with the highest percentage of ice cover were 2013-14 and 2014-15. I would add that temperature is not the only factor in Great Lakes ice cover…there is the amount of wind (strong winds break up ice) and the amount of effort made to break up ice to allow for ships to continue to get into places like Green Bay.
I was on vacation in Tennessee last week, so I was not following weather as closely as I usually do, so I can’t personally comment on why we didn’t see much severe weather last Thursday, but I will see what we can learn and post that in the future. Feel free to bounce the graphs around that I’ve included here (especially to those who claim that we’re have so much more weather mayhem in the U.S. than in the past (clearly not true). While we don’t have comments on the blog, feel from to send me your comments at firstname.lastname@example.org.