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Posted at 11:00 AM ET, 04/27/2010

Saturday's tornadoes: Success amid devastation

By Capital Weather Gang

* Steady warm up: CWG's Full Forecast | Tornado Alley: What's that? *

By Robert Henson

Radar imagery from April 24 at 2:10 p.m. CDT shows a tornadic thunderstorm near Starkville, Miss. Courtesy NWS Forecast Office in Jackson, Miss.

As of last week, the nation's tornado activity for 2010 stood at record lows -- at least when adjusted for the "inflation" produced by ever more spotters, chasers and video cameras. But the relatively placid spring turned violent on Saturday across the Deep South as a swarm of tornadoes ripped from Louisiana to Tennessee. The NOAA Storm Prediction Center (SPC) tallied 69 preliminary tornado reports -- among the largest 24-hour totals logged in recent years -- from 7 a.m. CDT Saturday to 7 a.m. Sunday.

A total of 12 people were killed by the twisters, 10 of them in a violent, long-track tornado that carved a nearly continuous path of damage -- a stunning 149 miles long and up to 1.75 miles wide -- from extreme northeast Louisiana across central Mississippi, including particularly hard hit Yazoo City. The initial damage survey gave the tornado an EF4 rating on the enhanced Fujita scale, with EF2 and EF3 damage common along its path. The surveyors noted that this twister may later be reclassified as a series of tornadoes, rather than just one, after a more exhaustive analysis is conducted.

Tornadoes across the populous, forested South are notorious for producing many fatalities. Given this twister's huge swath and intense strength, how did the death toll remain so low?

One of several structures damaged or destroyed Saturday by a long-lived tornadic thunderstorm. Courtesy NWS Jackson.

Much of the credit goes to the National Weather Service, where recent advances in warning technology and preparedness strategies were put to superb use. On Thursday morning, more than two days before the event, the SPC declared all of Mississippi at risk for significant severe weather for Saturday, noting that "several tornadoes" could strike and that the threat would ramp up by late morning (which it did -- the long-track tornado was in progress by 11:15 a.m. CDT). The SPC's statements grew steadily more ominous and confident with time, culminating in a rare and large "high risk" area outlined on Saturday morning.

The Jackson NWS office took the threat equally seriously, issuing a discussion on Thursday afternoon that warned of a "particularly dangerous" situation for Saturday -- wording rarely used until the day of an event. A tornado watch was issued at 6:00 a.m. Saturday that included the entire path of the long-track tornado. Residents had ample warning of the twister itself, originating from the Jackson NWS office and amplified through local radio and TV. One sign of how seriously the day's storms were being taken: Major NASCAR events at the Talledega Speedway were shut down for the entire day, a decision never taken lightly. (When asked about his own tornado safety plan that day, driver Dale Earnhardt Jr., replied, "I ain't got my plan together yet. I'll look up in the sky a lot, I reckon.")

To say that Saturday's twister toll could have been worse is a gross understatement. Major outbreaks like this one often killed hundreds of people before the 1950s. (Even today, a tornado striking a venue like Talledega, with some 200,000 fans on hand but little shelter, could produce unfathomable tragedy.) Along with constantly evolving and improving warning systems, the people of Mississippi had the clock on their side this time. Midday tornadoes are far more likely to be seen and avoided than those occurring after dark, when many of the worst twisters in the Deep South strike.

Meteorologist Robert Henson is a writer and editor at the University Corporation for Atmospheric Research, which operates the National Center for Atmospheric Research. He is the author of "The Rough Guide to Climate Change" (second edition, 2008) and "Weather on the Air: A History of Broadcast Meteorology," to be published this summer by the American Meteorological Society.

By Capital Weather Gang  | April 27, 2010; 11:00 AM ET
Categories:  Thunderstorms  
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Similar tornadoes in Mississippi and neighboring states have killed as many as 210 in years past. This was a rare long-path storm which will probably prove to be a multi-storm tornado outbreak similar to the 1958 Colfax outbreak in Wisconsin and similar long-path storms in the Deep South. It's also possible that the Yazoo City storm was EF5 due to the storm's width and damage track.

Posted by: Bombo47jea | April 27, 2010 12:08 PM | Report abuse

“There is no question that “recent advances in warning technology and preparedness strategies were put to superb use”.

Keep in mind that two days ahead of the event there were no satellite pictures, radar images, or observations of any type that would of themselves raise any alarm. The key on being able to provide two days advance notice of a risk of severe weather was the direct or derived output from NOAA’s computer weather models combined with the skill and experience of NWS forecasters. That’s no small accomplishment and reflects more bang for the buck in providing a public service than probably any other federal agency.

Posted by: SteveT-CapitalWeatherGang | April 27, 2010 2:19 PM | Report abuse

Thanks, Steve--good point. By "warning technology," I meant to include the ever-evolving computer models that provide an early warning of possible storm types and help make the two- and three-day SPC outlooks possible.

Posted by: bhensonco | April 27, 2010 3:49 PM | Report abuse

Anyone "surprised" it stayed in the as-predicted low 60s today? I saw only 61F at DCA last hour... that NW flow really has given us an underlying airmass of chill. The sun couldn't really compensate as some were speculating that it might warm us beyond lower 60s this morning :)

Posted by: Camden-CapitalWeatherGang | April 27, 2010 4:16 PM | Report abuse

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