Deadly Tornadoes

Why are most deadly tornadoes east of tornado alley? It even seems that a lot of tornadoes in general are moving more east and south over the past few years...
 
I think most would argue that most tornadoes are "moving" north over the past few years (i.e. NE and KS comparatively more active than OK and TX). Regardless, the population density in the Plains can be very sparse in many places. Personally, I think it's a combination of population density, typical timing and forward motion of tornadoes (daytime vs. nightime; slow-moving vs. fast-moving), and hazardous weather awareness. When I think of deadly tornadoes east of the Plains, I think of nocturnal, fast-moving storms (whether that's verifiable or not I do not know). Whenever a violent tornado occurs in a major metropolitan area without causing a single death (May 8th, 2004, F4 tornado in Moore, OK, and adjacent areas) is quite an event, and a testament to the general awareness of the public and to the effectiveness of the media and NWS in disseminating warning information efficiently and quickly.

The only "stats" I could find on this are from some research two NWS meteorologists (from Jackson and Louisville NWSFOs). Their work does indicate that killer tornadoes are more prevalent over "Dixie Alley" than "Tornado Alley". As I suspected, their stats also indicate that more deaths occur during the nighttime hours. You can download their Powerpoint presentation at http://www.amsmemphis.org/DixieAlley_megams.ppt
 
Friends

I was reading the Tom Skilling blog and he presents a very interesting data regarding fatalities causuded by tornadoes this year.

SM022507SUN.jpg
 
Keep in mind that outside "traditional" tornado prone areas that warning systems such as sirens are not available (Nashvile did not have a siren system until after the May 1998 event and a similar system was voted down in Morgan County, TN after Mossy Grove because of the feeling that "it won't happen again") and that people are simply not weather aware. Particularly in the southeastern US, there is the prevailing attitude that tornadoes do not occur there because of "protection" by hills, lakes, rivers or mountains. There is also the belief that tornadoes happen only in the spring. I would guess that the majority of both severe storms and tornadoes in the southeast are nocturnal events (it seems like I have read studies with the particular statisics, but can't recall the data right now), and are outside the "traditional" storm season, i.e Oct-Feb (...hmmm, I feel a research project coming on...where am I going to find the time?). More deaths probably occur in these areas because of increased population density, the prevalence of mobile homes and marginally constructed permanent homes, lack of storm shelters (including basements), lack of warning sirens, lack of use of weather radios, and just general lack of weather awareness.
 
Angie

According to data presented by Daniel Sutter of the University of Texas today at the Annual Meeting of the American Meteorological Society, violent tornadoes (F4 and F5) are responsible for the majority of tornado fatalities in the U.S.Adjusted for population, mobile homes are 10 to 15 times more dangerous than more permanent homes, amounting to about 40% of all tornado fatalities. Tornadoes during the nighttime hours (midnight to 6 a.m.) also result in a disproportionate number of fatalities, with 64% fewer fatalities occurring between 6 a.m. and 6 p.m. Weekend tornadoes result in 70% more fatalities than on a weekday and that casualties tend to be higher for storms during the "off-season" months of October through March. That is the content of a material I read recently.

Alexandre
 
How in general does the climate "move" like that? Specifically targeting tornadic supercells in the climate.

The climate doesn't move so much as it's related to the general upper-air circulation patterns. There are some cycles and differences from year-to-year (i.e., ENSO, La Nina, etc.) in the positions of polar and subtropical jets, etc. In turn, that affects the propagation and positions of synoptic scale features.
 
I think a lot of the reason that tornados are more "deadly" out east is simply because it is more densly populated out this way. Seems to be a lot more little towns around than in the plains. So therefore, then a tornado hits out east, it is more likely to hit a populated area.

Plus, I think less people out here are as weather-savy as in Oklahoma..you don't have choppers flying around the meso filming the tornado or anything like that. Asheville rarely gets tornados, being in the mountains and all, but I know that hardly anyone out this way have storm cellers.
 
To add to to what Melissa said...storm cellars, tornado sirens and choppers flying around covering a supercell are unheard of in the Eastern U.S. The only "tornado-siren like" sirens you'll hear are the one that are activated for each fire call that a volunteer fire department has. They sound just like tornado sirens but go off ALL of the time. My fire dept. gets on average 1-2 fire calls a day, and the siren cycles through 10 times each time the fire pager is activated.

Back to the topic...Population density alone is probably the main answer. A small town out here will have an enormous number of more people than the same sized town in Oklahoma.
 
Asked Ricky Shanklin same thing He's head of WFO KPAH. He said its expanded east, not shifted, big difference, also may be direct result of global warming why the expansion of tornado alley
Kevin
 
Another thing to consider is that many fatalities occur when people are asleep and TV sets and Radios are turned off, and sirens often are not heard indoors. In Florida, survivors said that NOAA Weather Radio was the warning device that alerted them. NWR is finally getting the positive publicity it deserves, from TV and radio stations, of all places. People are becoming increasingly aware of the need to have an alarmable NWR-SAME radio and to keep it on at night when the storms move through.
 
Well, wont start with global warming but its a possibility. Bottom line is "East tornado alley" has become much more active since about 2000 for some reason....
 
Well, wont start with global warming but its a possibility. Bottom line is "East tornado alley" has become much more active since about 2000 for some reason....

Not true. This southern- or eastern-tier killer tornado "alley" has been "active" since tornado and tornado fatality statistics have been kept with some consistency (~1880s).

You cannot link a single tornado, outbreak, and/or series of outbreaks (and more so, their fatalities!) to global warming. If someone has done this through sound research, point me to it. I will gladly nominate them for the AMS's Rossby Research Medal.
 
Below is a 2000 pop. density map...and the most active tornado corridor between the Mississippi River and the Rockies is roughly outlined on the map. Certainly would have to argue strongly for the higher population east of the Mississippi as being a reason for higher fatality counts. One thing of note also...I have noticed a pronounced trend lately that many of the killer tornadoes are in the F2-F3 range, even though historically this has not been the case.

Popdensitymap.jpg
 
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April 3-4, 1974
April 11, 1965
March 31, 1973
April 8, 1957

and so on.
 
Hailing from Middle Tennessee, it has seemed more tornadoes are occuring in the East. Many of the recent tornadoes show the biggest rend that always has been here in the South, nighttime. The Enterprise tornado is about the strongest one to hit the South in the day in a long time. Also, the fact that limestone is very dominant makes it very difficult for cellars to be built, because most Southern areas you can't dig more than a foot before you hit bedrock, and in some areas, you have barely 1 inch of topsoil. We also have to seasons, and the seasons usually conincide with standard time, allowing more nighttime. Perfect examples of midnight tornadoes are Jan 1999 in Clarksville and Jackson,TN , the F-5s in Alabama in 1974, April 8,1998, Feb 23,1998 and Feb 2,2007 are perhaps the most recognizable outbreaks. Perhaps the biggest factor is forest cover, yes the South is becoming more dense, but it you threw a dart, your likely to land in some nonchalant locale or the woods. Nashville, Birmingham, Memphis, Montgomery, Orlando, Tampa, and Little Rock metros are the most prone to tornadoes, or so it has seemed. Charlotte and Atlanta, they have a few notables, but because of their location, especially Charlotte's the right ingredients rarely ever show. The last factor is the fact most supercells are HP, due to extremly rich moisture, due to close proximety to the Gulf of Mexico. This makes them incredibly hard to see Thats why in the summer you can get 2 inches of rain in 10 minutes in a popcorn cell. Perhaps the biggest oddity was the downtown Nashville tornado. When I lived in Murfreesboro, I was in downtown Nashville to see it, scary crap to say the least. Anyways, there was no visible funnel until dissipation In Mt. Juliet, the whol wall cloud came down over Nashville, which resulted in a wide damage swath, but of relatively F1 damage.
 
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