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Lessons learned from the May 3, 1999 tornado

By: Dr. Jeff Masters , 2:39 PM GMT on March 21, 2007

Storm Warning: The Story of a Killer Tornado, which I reviewed earlier this month, recounts the story of the May 3, 1999 monster F5 tornado that ripped through the southern suburbs of Oklahoma City. In addition to providing an exciting fast-paced narrative of the tornado's rampage, author Nancy Mathis also brings up a number of important lessons learned from this storm, which I detail below. With two strong spring storms capable of trigging tornado outbreaks expected to move through the Midwest U.S. Tuesday and Friday next week, everyone living in Tornado Alley would be wise to pay attention to these lessons learned!

A F-4 tornado rips through Kansas, May 8, 2003. Image credit: wunderphotographer Mike Theiss.

Reasons for the low death toll in the May 3, 1999 tornado
Considering that the May 3, 1999 tornado was the strongest ever measured (302 mph winds), hit a major metropolitan area, and destroyed or damaged over 11,000 buildings, the death toll of 38 was remarkably low. It's worth reviewing the major reasons for the low death toll:

1) National Weather Service Doppler radars. The NWS just completed installation of the new NEXRAD Doppler radars nation-wide in 1998. The NEXRAD radars increased tornado warning time from 5.3 to 9.5 minutes, and roughly doubled the percentage of tornadoes warned for from 30% to 60%. Warning times were as long as 39 minutes for the May 3, 1999 tornado. Mathis notes that the number of tornado deaths in the U.S. was cut in half, to roughly 80 per year, after the NEXRAD radars became operational. It took 20 years for the new radars to get procured, thanks to cost overruns and bureaucratic wrangling. Politicians, NOAA administrators, and private contractors involved during the procurement of the next generation of tornado detection equipment should seek to avoid a similar delay. The procurement process for the NEXRAD radars was a disaster that undoubtedly cost lives.

2) A great warning system. A coordinated warning effort by NOAA's Storm Prediction Center, the local NWS office, local media, and Oklahoma local government personel worked brilliantly. The big money and training pumped into tornado preparedness paid big dividends.

3) A tornado-savvy population. Oklahomans are the most tornado-savvy people in the world. They took warnings seriously, and acted on them. A survey of those injured found that the vast majority knew of the warnings and the tornado, but just did not have a proper place for shelter.

4) Luck. The tornado leveled schools that had already dismissed classes for the day, and a shopping mall that had closed earlier. Had the tornado hit several hours earlier, or late at night when its movement could not have been shown on live TV, the death toll could have been as high as 600, according to a NOAA study.

Highway overpasses are the worst place to shelter from a tornado!
Three people died at overpasses during the May 3, 1999 tornado. The presence of the bridge acts to focus the wind, making it stronger under the bridge. Some drivers abandoned their cars on the Interstate under overpasses, blocking traffic and creating a traffic jam where people were trapped when the tornado swept over. If you're caught in your car on the road and choose to abandon the vehicle, pull off the road and seek shelter in a ditch, not under a highway overpass!

Poor home construction contributed to the deaths and injuries
Tornado fatalities were primarily from those in mobile homes, cars, and homes without shelters. The tornado revealed many homes where builders had failed (illegally) to build up to code. Enforcing existing codes and mandating stronger building codes would have reduced the death toll. This, of course, is not popular with the powerful building industry, since better construction costs more.

Tornado forecasting is still in a primitive stage
A day before the May 3 tornado outbreak, the Storm Prediction Center was only forecasting their lowest alert level for severe weather, a "Slight Risk". The computer models were highly scattered in their predictions, and made significant changes with each new run. Nothing about the outbreak was textbook. Most supercell thunderstorms that spawn tornadoes form along a warm or cold front (or a "dryline" where a sharp gradient of moisture is present). However, none of the first few supercells in the May 3 outbreak were near a front or dryline. The classic clash of warm moist Gulf air with cold, dry Canadian air that usually provides the lift needed for supercells was not present. Researchers have a huge amount of work to do before they understand what causes tornadoes like the May 3, 1999 storm.

I'll be back Friday with a new blog.

Jeff Masters

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166. hurricane23
11:41 EDT le 22 mars 2007
Interesting that the high of the eastcoast has pretty much been parked there all year long so far,might it be a sign of bad things to come?
Member Since: May 14, 2006 Posts: 8 Comments: 13857
165. weathersp
11:29 AM EDT on March 22, 2007
I think the NWS Radars need a major upgrade (AKA) All new Radars. The WSR-88D Radar was built in 1988 thus the 88 in the name. Its been 20 years since they have had a upgrade and technology has improved so much.

BTW I bought the book I was very interested about Dr. Tetsuya Fujita early life.(After he moved to the US he renamed himself Theodore or Ted)
Member Since: January 14, 2007 Posts: 17 Comments: 4140
164. hurricane23
11:06 EDT le 22 mars 2007
New radar HD is absolutely incredible!Look forward on useing this season.Updates every six minutes.

Member Since: May 14, 2006 Posts: 8 Comments: 13857
163. Madrid
2:49 PM GMT on March 22, 2007
And here is the culprit of Frozencanuck' question since I was the one raising it. I live in San Antonio, Texas and this is my wild guess at why we are not part of it:

By logic, I would think that any ondulance in the otherwise flat terrain would create enough turbulance in the physics of a tornado to prevent most formation of them. My guess only.

BTW, Thank you Dr Master's. I have been looking frantically for the tornado pic in the WU archives without success.
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162. Frozencanuck
10:13 AM EDT on March 22, 2007
Here is a question that has been posed this morning, why is San Antonio not included in Tornado Alley...is it because of location, is there a geophysical reason for it not seeing many tornados but alas it does get bad T storms.... Hope you can help answer that one. Thanks guys
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161. Frozencanuck
10:10 AM EDT on March 22, 2007
Ryang, now you know Toronto is not that bad, I lived there for over 25 yrs, its only the wind and the dampness that make it feel like that. You really want to complain, check out our own Plapman..He lives in Manitoba and there it really gets cold...he he he
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159. hurricane23
09:27 EDT le 22 mars 2007
Good morning,

Dark clouds over my neighborhood this morning in south florida but things seem to be clearing up slowly.

Member Since: May 14, 2006 Posts: 8 Comments: 13857
158. Skyepony (Mod)
1:12 PM GMT on March 22, 2007
refill~ check the 00Z cmc (scroll right, click fwd)

I got sprinkles this morning:)
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157. refill
7:56 AM AST on March 22, 2007
We need rain too in Puerto Rico!!!
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156. 882MB
11:11 AM GMT on March 22, 2007
Goodmorning, Very rainy day here across south florida very beneficial rains!
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155. hurricane23
12:03 AM EDT on March 22, 2007
Goodnight guys...
Member Since: May 14, 2006 Posts: 8 Comments: 13857
154. Patrap
10:24 PM CDT on March 21, 2007
Nitey to all.Cookies and Daily Show with a Lil Milk ..then snoozing invest!..LOL!
Member Since: July 3, 2005 Posts: 439 Comments: 137156
153. kmanislander
3:21 AM GMT on March 22, 2007
well guys I am out of here for now.
It was nice to say hi again after being absent for so long.
Won't be long now before we all get to play forecaster wannabe lmao

gnite all
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152. Patrap
10:23 PM CDT on March 21, 2007
Fine words kman..you wise owl to note that.
Member Since: July 3, 2005 Posts: 439 Comments: 137156
151. ryang
11:21 PM AST on March 21, 2007
MP everything is good.

Bye everyone,Kman see you later,will you be on often???
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148. kmanislander
3:13 AM GMT on March 22, 2007

It seems that all too often it takes a disaster and hand-wringing before " truth will out "
Many times no one is ever held accountable.

The hall mark of all great disasters is that with a little foresight and attention to detail most were capable of being averted.

I suppose the next big one will be a CAT 5 across some low lying over developed strip like Miami Beach/ Biscayne Bay.God forbid we ever see that
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146. ryang
11:12 PM AST on March 21, 2007
What a coincidence,i'm in Toronto as well!

You got that right....freezing cold!
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145. Patrap
10:11 PM CDT on March 21, 2007

More From The Times-Picayune | Subscribe To The Times-Picayune
Corps caused disaster, report says
State inquiry finds decades of blunders
Wednesday, March 21, 2007
By Bob Marshall

Decades of incompetence and neglect by the Army Corps of Engineers allowed Hurricane Katrina's storm surge to devastate New Orleans, according to a long-awaited report being released today, the state's only official investigation into the causes of the disaster.

In a sweeping indictment of corps stewardship, the report alleges that agency supervisors ignored increases in the threat level for their project, knowingly built levees and floodwalls lower than congressionally mandated, failed to detect or ignored glaring errors during the review process, underestimated the impact of the Mississippi River-Gulf Outlet on the city's defenses, and failed to properly maintain the system.

The report, conducted by Team Louisiana at the request of the Department of Transportation and Development, echoes many points made in other probes last year, including that of the Independent Levee Investigation Team, led by the University of California-Berkeley, and the interim report from the corps' own Independent Performance and Evaluation Team. But while those efforts focused largely on technical aspects of the structural failures, the LSU-based Team Louisiana sought to pinpoint the decisions that caused those failures.

"It's one thing to use modern, state-of-the-art computer modeling and determine what happened, and the other teams did a very good job of that," said Ivor van Heerden, a director of the LSU Hurricane Center who led Team Louisiana. "But the only way to really understand if mistakes were made was by relying entirely on using the (engineering) tools the corps would have used -- or should have used -- when they did their designs."

A spokesman for the corps' hurricane protection office in New Orleans said officials there have not yet seen the report and had no comment.

18-month effort

The 10-member investigative team, including seven Louisiana State University engineering and storm researchers and three private sector engineers, spent almost 18 months and $200,000 on the effort, including a $100,000 grant from its major backer, the state Department of Transportation and Development. Among the key findings:

-- By ignoring two increases in the severity of the Standard Project Hurricane -- the model storm the system was designed to thwart -- the corps knowingly failed its 1965 congressional charge to protect the city against "the most severe combination of meteorological conditions reasonably expected."

The original model was based on research through 1959. But the corps did nothing to strengthen the system in response to two increases in the projected strength of the model storm, in 1972 and 1979.

"The standard set by Congress in 1965 was very specific -- 'the most severe threat that could be expected,' " van Heerden said. "Our research shows very clearly that the standard was changed, but the corps just kept going about its business as if nothing happened." Katrina, a Category 3 storm when it made landfall, fell far short of the expectation of the most severe hurricane.

-- In 1985, the head of the project ordered his staff to ignore an official reduction in the elevation of the land they were building on, which meant the corps finished levees and floodwalls it knew were as much as 2 feet lower than claimed. That decision helped turn Katrina from an inconvenience into a catastrophe.

"Had the walls been built as high as called for, the floodwalls in the Lower 9th Ward would have been overtopped for 1.5 hours, but instead water poured over them for 4.5 hours," van Heerden said.

He said the extra three hours resulted in deep trenching on the protected side of the floodwalls, contributing to the collapse that sent a wall of water roaring through the neighborhood, killing more than 100 people and displacing an entire sector of the city.

Below-design walls and levees contributed to many of the more than 50 breaches the system sustained during Katrina, the researchers said.

More findings

-- Applying the corps' own design manuals in use at the time, Team Louisiana found instances where the agency missed glaring engineering mistakes by subcontractors, which led to breaches including those on the 17th Street and London Avenue canals.

In one instance, local firm Eustis Engineering botched a standard engineering formula in deciding that a thin layer of clay at the bottom of the London Avenue Canal could prevent water from seeping into highly porous sands below, the report said. During Katrina, water pushed through the clay, quickly traveling through the sand to the dry-land side of the sheet pilings, weakening the levee and leading to a catastrophic breach. Eustis Engineering has declined to comment in the past on the matter and could not be reached for comment Tuesday.

"Had the corps caught that error -- as it is supposed to -- and required the work to have been done properly, in all likelihood the design would have been changed, which could have prevented this failure," van Heerden said.

"We found several stances where (better) designs were originally proposed -- T-walls instead of I-walls -- and then changed for no apparent reason." -- The corps failed to maintain the parts of the system properly, including keeping pace with subsidence. Moreover, the agency ignored advances in engineering knowledge and technology that could have prevented the flood.

The system "was managed like a circa 1965 flood-control museum," the report reads, pointing out that the corps made no improvements to account for well-known changes in elevations, sea-level rise or even gaps left in the system.

Paul Kemp, who was part of Team Louisiana as an LSU storm modeler, said he was "struck by the fact that the corps showed no sense of mission on this project, even though it was involved with it for more than 40 years.

Instead, the agency showed "absolute adherence" to obsolete standards -- a 1959 model for the Standard Project Hurricane. And yet the corps seemed willing, Kemp said, to make other wholesale changes midstream, such as abandoning a proposal to install floodgates at the canals in the mid-1980s, which might have stopped the Katrina surge that broke through their walls.

"It looked like no one was really in charge," he said.

Calls for 8-29 panel

The report also calls for the state and Congress to hold "8-29 Commissions" for a full investigation of the disaster, passage of a "Katrina Recovery Bill" to ensure coastal restoration and flood protection are fully financed by the federal government, and more transparency on the part of federal and state authorities when discussing flood protection plans.

"Citizens of New Orleans were never told by those with both knowledge and responsibility just how vulnerable they were to flooding, or the public safety compromises made in designing and building structures," the report states
Member Since: July 3, 2005 Posts: 439 Comments: 137156
144. kmanislander
3:09 AM GMT on March 22, 2007
Canada !

My sons were in school in Toronto and there is no place colder than that in Feb except the N pole lol
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143. ryang
11:08 PM AST on March 21, 2007
No Kman,in Canada!
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142. kmanislander
3:02 AM GMT on March 22, 2007

you down in Barbados ?
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141. kmanislander
2:59 AM GMT on March 22, 2007
nice link

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140. Patrap
9:59 PM CDT on March 21, 2007
Thats a big debate here...but I concentrate on Impacts and after effects..I have a good article released recently for ya..Wait one.
Member Since: July 3, 2005 Posts: 439 Comments: 137156
139. SteveDa1
10:58 PM EDT on March 21, 2007
Alright, thanks a lot Patrap. I use photobucket.
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138. ryang
10:59 PM AST on March 21, 2007
Hey Kman!
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137. kmanislander
2:55 AM GMT on March 22, 2007
I have been off the blog since Nov as winter weather is not our bag in the tropics !

Kinda been lurking for a bit recently watching the " la nina " debate heat up with all the predictions for what it might bring.

In the NW Caribbean we have had very brisk dry wind for many weeks and a couple of homes were damaged last Sunday by winds that seemed to come out of nowhere. No rain or anything with it. odd really
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136. Patrap
9:55 PM CDT on March 21, 2007
Heres a Great Link on the Storm here with THE man..Lotsa interactive stuff too Kman..Link
Member Since: July 3, 2005 Posts: 439 Comments: 137156
135. Patrap
9:54 PM CDT on March 21, 2007
Just the same ol early, early hype kicking in Kman.Good to see yas..!
Member Since: July 3, 2005 Posts: 439 Comments: 137156
134. kmanislander
2:46 AM GMT on March 22, 2007
Hi there Pat

How's the " off season " going ?.
We are well into our dry time of the year with no rain to speak of since last Nov.
Soon time for the waves again. Hard to believe we are near another season


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133. Patrap
9:46 PM CDT on March 21, 2007
just right click and save the jpeg..and link here too.
Member Since: July 3, 2005 Posts: 439 Comments: 137156
132. Patrap
9:43 PM CDT on March 21, 2007
,,heres an example
Member Since: July 3, 2005 Posts: 439 Comments: 137156
131. Patrap
9:42 PM CDT on March 21, 2007
Upload to photo sharing site like photobucket..and post .
Member Since: July 3, 2005 Posts: 439 Comments: 137156
130. SteveDa1
10:31 PM EDT on March 21, 2007
Could anyone tell me how to put a self-made JPEG animation on here?

Thank you.
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129. lightning10
1:36 AM GMT on March 22, 2007
As long as neuteral conditions hold on I will be happy. ^_^. I will be not happy with a La Nina on are hands.
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126. hurricane23
7:40 PM EDT on March 21, 2007
Nothing spectacular on the 18Z GFS which shows a low developing east of the bahamas and moving rapidly NE and of note it also shows a low developing near panama.Very long range though.

Low near panama moves in N-NE fashion.

Member Since: May 14, 2006 Posts: 8 Comments: 13857
125. 1900hurricane
5:39 PM CST on March 21, 2007
Posted By: Trouper415 at 4:43 PM CST on March 21, 2007.

Hello all. Anyone have a La Nina update i Could see?

I do! Here is an anomoly chart. Click to make bigger.

A couple of loops.

CPC Discussion
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124. Patrap
6:13 PM CDT on March 21, 2007
I smell Hurricane fever..
Member Since: July 3, 2005 Posts: 439 Comments: 137156
123. weatherguy03
6:44 PM EDT on March 21, 2007
Skyepony updates ENSO every Monday in her blog. She always has the latest on La Nina.
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122. Trouper415
10:38 PM GMT on March 21, 2007
Hello all. Anyone have a La Nina update i Could see?

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121. Skyepony (Mod)
10:34 PM GMT on March 21, 2007
Author Nancy Mathis was just on NPR news, along with mets from OK. Pushing to make more storm spotters & get people to get themselves a life saving NOAA radio.
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119. snotly
9:20 PM GMT on March 21, 2007
Hurricanes that move like the 1947 create a greater storm surge because of the east to west movement focusing the surge into the Pontchartrain.

...If the 1947 cane had been as strong and as big as Katrina in the Gulf...!! what then??
Member Since: August 27, 2005 Posts: 0 Comments: 689
118. V26R
9:15 PM GMT on March 21, 2007
Pulse if its the same system I looked at, Its just an Upper Level Low trying to get its act together, but kind of impressive anyway!Link
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117. ProgressivePulse
9:00 PM GMT on March 21, 2007
Been a while since I seen the low level clouds spinning around in the Atlantic. I am speaking of the area E of the Bahamas.
Member Since: August 19, 2005 Posts: 5 Comments: 6211
116. V26R
8:56 PM GMT on March 21, 2007
Spring is finally rearing its head up here in NYC Temps supposed to hit 60 tomorrow
maybe it will melt this damn Ice!
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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