http://www.telegraph.co.uk/earth/environment/climatechange/5406487/Climate-change-kills-300000-every-year.html

I suspect it’s yet another ‘this is the message we want, now lets fit the figures to justify it’, but I don’t know.

Has anyone read it/critiqued it/picked holes in the arguments?

It would appear that if AMO/ PDO both continue to decline and stay negative , the risk for severe tornadoes will also increase [ like it seemed to do during 1950-1976] . The threat seemed to diminish after 1976 when both indices went positive and the number of severe tornadoes seemed to decline . See the graph below [also repeated on above post]

http://www.ncdc.noaa.gov/img/climate/research/2008/ann/ann-F3-F5tornadoes08.png

This may be of interest to you.

http://www.bom.gov.au/climate/enso/

The correlation between La Nina’s and the severest tornadoes[ f3-f5] is a little more apparent if you look at these two web pages together especially during 1970-1976

http://www.ncdc.noaa.gov/img/climate/research/2008/ann/ann-F3-F5tornadoes08.png

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

You are right on about cooler weather affecting the the number of tornadoes but especially the f3 -f5 size or the larger and more severe ones . The period 1955 -1975 had the highest number of these more severe tornadoes and especially 1965 -1975, with 1974 being the worst with about 116 such severe tornadoes. This was a period[1964-1976] when PDO and AMO were both negative and cooler and there were more La Nina conditions . La Nina conditions are especially likely to produce more sever tornadoes like in 1974. We are in similar cool PDO or AMO levels like in the 1970′s but La Nina conditions only existed briefly in late 2007 to early 2008. If La Nina conditions return, the risk for more severe tornadoes also increases in my opinion as PDO and AMO are both negative and declining creating ideal conditions for more severe tornadoes.

I read elsewhere that the switch from La Nina to El Nino creates a shifting jet-stream which increases the (slight) possibility of tornadoes in the Northeast.

(Situations occur where a blast of hot and dry air comes over-the-top, as hot and humid air comes up-the-coast, and these two streams are met by a lobe of cold air back-dooring the northeast.)

Judging from the past, if there is any up-tick of tornadoes in the Northeast it will not matter that there are far fewer in the rest of the country. We will read about how the tracks of tornadoes have moved north, which is proof of Global Warming. We will read nothing about the F-4 Worchester Tornado which hit New England in 1953, which was the last time the AMO was like it is now.

Tornados larger than F-1 are very rare in New Hampshire, but we actually had one last summer, moving south to north. Should we have another this summer, the Alarmists will likely burst blood vessels.

Storm Chaser and meteorologist, Heidi Farrar over at TornadoVideos.net was saying a similar thing. They’ve had limited chasing oportunities so far this May.

http://www.climatedata.info/Impacts/impacts.html

and click on “Tropical cyclones”.

I noticed a couple of outstanding features.

First – from the mid-50′s to the mid-70′s the level of F2-F5 tornadoes was higher than in more recent years. Is it possible that in those higher years the measuring was less refined than now and what today would be more easily measured as an F1 might have been marked as an F2? It’s a thought.

Second – the increasing number of tornadoes might just represent the increasing sophistication of radar (esp. doppler rader) and that other new creature – the storm chaser. What was the coverage of rader & its sophistication in the 50′s & 60′s? And I bet there weren’t too many storm chasers around back then.

We need to keep all that data on file in context and remember that we’re seeing more things now that we might have missed 40 or 50 years ago.