Some tragic tornadoes this year, but on track for record low count, overall. Keep track via @NWSSPC.

Some tragic tornadoes this year, but on track for record low count, overall. Keep track via @NWSSPC.

Important paper shows “sharp” post-1950 drop in “normalized” tornado damage losses (if human settlement patterns held constant). Important way to assess if factors other than economic growth are affecting damage rates. 2011 among top 3 for period. The analysis is by Kevin Simmons (Austin College), Daniel Sutter (Troy University) and Roger Pielke, Jr. Earlier analysis of tornado damage patterns by Sutter and Simmons has been featured on Dot Earth. Pielke post has abstract and more.

Important paper shows “sharp” post-1950 drop in “normalized” tornado damage losses (if human settlement patterns held constant). Important way to assess if factors other than economic growth are affecting damage rates. 2011 among top 3 for period. The analysis is by Kevin Simmons (Austin College), Daniel Sutter (Troy University) and Roger Pielke, Jr. Earlier analysis of tornado damage patterns by Sutter and Simmons has been featured on Dot Earth. Pielke post has abstract and more.

Tornado drought (probably record low for July) one upside of hot, dry summer in Midwest. Check diamond in graph to see just how anomalous July has been. @AtmosNews provides the details: 
Clearly, this month’s vanishing act is related to the intense ongoing drought, which is the nation’s most widespread since the 1950s. If thunderstorms aren’t happening, you can’t get a tornado—but not all thunderstorms can produce twisters. Violent tornadoes, in particular, need a complex blend of upper-level winds, unstable air near the ground, and other ingredients still being studied. This month, where thunderstorms have managed to form, they’ve been largely of the scattered, “air mass” variety, driven by local instability and limited by the lack of strong upper-level winds. Read the full report.

Tornado drought (probably record low for July) one upside of hot, dry summer in Midwest. Check diamond in graph to see just how anomalous July has been. @AtmosNews provides the details: 

Clearly, this month’s vanishing act is related to the intense ongoing drought, which is the nation’s most widespread since the 1950s. If thunderstorms aren’t happening, you can’t get a tornado—but not all thunderstorms can produce twisters. Violent tornadoes, in particular, need a complex blend of upper-level winds, unstable air near the ground, and other ingredients still being studied. This month, where thunderstorms have managed to form, they’ve been largely of the scattered, “air mass” variety, driven by local instability and limited by the lack of strong upper-level winds. Read the full report.

The federal Storm Prediction Center has released its latest tally of tornadoes and deaths for 2011, with the current count of 519 surpassing the previous record set in1953. Not surprisingly, the storms in the most potent categories on the five-step Enhanced Fujita scale, while rare, caused nearly 75 percent of deaths.
Four tornadoes in the strongest category, EF5, killed 228 people at last count (with some still missing in the Joplin, Mo., disaster); 11 EF4 funnels killed 157; and 134 people have died in less potent tornadoes.
Visit Dot Earth for more exploration and discussion of the factors that lead to deadly outcomes in America’s tornado hot zones. 

The federal Storm Prediction Center has released its latest tally of tornadoes and deaths for 2011, with the current count of 519 surpassing the previous record set in1953. Not surprisingly, the storms in the most potent categories on the five-step Enhanced Fujita scale, while rare, caused nearly 75 percent of deaths.

Four tornadoes in the strongest category, EF5, killed 228 people at last count (with some still missing in the Joplin, Mo., disaster); 11 EF4 funnels killed 157; and 134 people have died in less potent tornadoes.

Visit Dot Earth for more exploration and discussion of the factors that lead to deadly outcomes in America’s tornado hot zones

Anthony Watts has posted a @Wattsupwiththat item wrongly asserting that my concerns about statements implying a link between recent tornado outbreaks and human-driven climate change are NEW. I just told him that he must have missed my 2008 piece, including this section:
Tornadoes: There was a spate of Instanet attacks on Senator John Kerry yesterday for discussing projections of stronger storms in a warming world in the context of the catastrophic tornado strikes. His comment was nuanced, but by even bringing climate policy into a conversation on severe weather, he was probably destined to get roughed up. The reason? The science remains utterly equivocal on how global warming might boost the longstanding peril from tornadoes in the storm belt.
Making analysis tougher, any trends in annual counts of tornadoes are clearly a function of shifting patterns of monitoring and reporting, not actual changes in the numbers of funnel clouds, according to several experts at the National Severe Storms Laboratory. The ballooning numbers of weak tornadoes in the chart above are known to be the result of more weather watchers, with more ways to report funnel clouds, as well as more radars and the like. The steady drumbeat of potent twisters, which are easier to track, shows a declining trend, but that, too, the federal experts say, was likely the result of a change in data crunching, not a drop in actual tornado numbers.There is no evidence of any trend in the number of potent tornadoes (F2 and up) over the past 50 years in the United States, even as global temperatures have risen markedly. There has been one modeling study from NASA projecting that warming could make potent thunderstorms more powerful, and potentially tornado makers.
As Roger Edwards, a forecaster at the federal Storm Prediction Center in Norman, Okla., told me this morning, the data are not only “soft, but spongy, in other words full of holes through and through.”

Anthony Watts has posted a @Wattsupwiththat item wrongly asserting that my concerns about statements implying a link between recent tornado outbreaks and human-driven climate change are NEW. I just told him that he must have missed my 2008 piece, including this section:

Tornadoes: There was a spate of Instanet attacks on Senator John Kerry yesterday for discussing projections of stronger storms in a warming world in the context of the catastrophic tornado strikes. His comment was nuanced, but by even bringing climate policy into a conversation on severe weather, he was probably destined to get roughed up. The reason? The science remains utterly equivocal on how global warming might boost the longstanding peril from tornadoes in the storm belt.

Making analysis tougher, any trends in annual counts of tornadoes are clearly a function of shifting patterns of monitoring and reporting, not actual changes in the numbers of funnel clouds, according to several experts at the National Severe Storms Laboratory. The ballooning numbers of weak tornadoes in the chart above are known to be the result of more weather watchers, with more ways to report funnel clouds, as well as more radars and the like. The steady drumbeat of potent twisters, which are easier to track, shows a declining trend, but that, too, the federal experts say, was likely the result of a change in data crunching, not a drop in actual tornado numbers.There is no evidence of any trend in the number of potent tornadoes (F2 and up) over the past 50 years in the United States, even as global temperatures have risen markedly. There has been one modeling study from NASA projecting that warming could make potent thunderstorms more powerful, and potentially tornado makers.

As Roger Edwards, a forecaster at the federal Storm Prediction Center in Norman, Okla., told me this morning, the data are not only “soft, but spongy, in other words full of holes through and through.”

When Tornadoes Were Blamed on Atomic Bombs

Tornado expert Chuck Doswell looks back at the last horrific tornado year, 1953, when media blamed the deadly storm swarms on atmospheric testing of atomic bombs (@dotearth updated):

1953 was a terrible year, with three major single violent tornadoes: Waco, TX on 11 May (114 fatalities), Flint, MI on 08 June (116 fatalities), and Worcester, MA on 09 June (94 fatalities), as well as many lesser outbreaks. At the time, there was speculation that the severe weather was being “caused” by the nuclear explosions going on as the United States flexed its cold war muscles. The media did what the media always do: spread wild speculation about the influence of atomic tests on the weather without regard for its scientific validity. Such talk went on for years, to be raised again in 1957 (another big year for tornadoes, but without the extreme fatality count). Read the rest.

National Weather Service charts sprout TORNADO WARNINGS from Texas into Great Lakes.

National Weather Service charts sprout TORNADO WARNINGS from Texas into Great Lakes.

Central Oklahoma facing big threat of tornado outbreak later today. Exploration of tough issues with warnings in tornado zones
"INTENSE OUTBREAK OF TORNADOES AND WIDESPREAD SEVERE THUNDERSTORMS IS EXPECTED LATER TODAY OVER PORTIONS OF KS/OK/TX"

— Latest warning from NWS. @DotEarth update explores issues in translating warnings into effective responses.