http://lwf.ncdc.noaa.gov/img/climate/research/tornado/tornadotrend.jpg
Another bit of alarmist nonsense gets flushed. Violent (F3-F5) tornadoes peaked during the ice age scare of the 1970s, and have been declining ever since. The graph below plots the ten year running mean in red.
The next graph shows the ten year running mean of violent tornadoes vs. the GISS US anomaly. Warmer years have fewer tornadoes.
A warming planet means less violent weather. Which means we are in trouble, because temperatures are dropping precipitously. The spring of 2008 was very cold in the US, and it had a lot of tornadoes.
That is something only a person interested in weather could understand and apparently has nothing to do with Climatology!
To be fair, the data has been skewed a a bit by one huge tornado outbreak in 1974
Not really. It is just one data point.
Changes in rating procedures (pre-1975 tornadoes were rated stronger than 1975-2000 tornadoes and post-2000 tornadoes were rated weaker than 1975-2000 tornadoes) have also been discussed in the literature. The “signal” is an artifact of those changes.
Verbout, S. M., H. E. Brooks, L. M. Leslie, and D. M. Schultz, 2006: Evolution of the US tornado database: 1954-2003. Wea. Forecasting, 21, 86-93.
Doswell, C. A. III, H. E. Brooks, and N. Dotzek, 2009: On the implementation of the Enhanced Fujita Scale in the USA. Atmos. Res., 93, 554-563, doi:10.1016/j.atmosres.2008.11.003.
Ahh … So older tornadoes need to be adjusted downwards. That is a familiar theme!
When the records do not show the desired results change the rules of the game after the game is played!
None of the 1975 and older tornadoes (except the 1974 outbreak) were rated at the time the events occurred. Their ratings were produced in ~1977 by summer undergraduate students reading the text descriptions of damage. Grazulis, in his compilation for his 1993 book, Significant Tornadoes, pointed out that they appeared to have overrated them.
We always need to adjust the past downwards.
Steven your straw man (there isn’t any consensus on how tornadoes will be affected by climate change) ironically supports some climate research;
“A U.S. study suggests the climate change effect of dry autumns and winters may lead to fewer tornadoes developing during the spring season.”
“Our results suggest that there is a statistically significant reduction in tornado activity during a tornado season following drought the preceding fall and winter,”
http://www.upi.com/Science_News/2009/07/01/Climate-change-affects-tornado-activity/UPI-29391246480329/
Climate science is so loose that it can explain anything