Lessons learned from the May 3, 1999 tornado

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

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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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116. V26R
8:57 PM GMT on March 21, 2007
Hello
Spring is finally rearing its head up here in NYC Temps supposed to hit 60 tomorrow
maybe it will melt this damn Ice!
Member Since: July 20, 2006 Posts: 0 Comments: 1762
115. weathersp
8:43 PM GMT on March 21, 2007
That last one was the great lake ocachobie (Sry floridans can spell that LOL) hurricane right?
Member Since: January 14, 2007 Posts: 17 Comments: 4140
114. Tazmanian
8:42 PM GMT on March 21, 2007
wow hurricanes most love FL
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
113. hurricane23
8:41 PM GMT on March 21, 2007
Here are a few others...








Member Since: May 14, 2006 Posts: 8 Comments: 13841
112. MisterPerfect
8:40 PM GMT on March 21, 2007
Ah, Flagler Street...passed it twice earlier today...it has changed much since 1926...you can imagine what it looked like then...
Member Since: November 1, 2006 Posts: 71 Comments: 20140
111. hurricane23
8:27 PM GMT on March 21, 2007
Left flagler street nearly under water.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
110. weathersp
8:26 PM GMT on March 21, 2007
Man Hurricanes must love this track!

Great Miami Hurricane of 1926.

Member Since: January 14, 2007 Posts: 17 Comments: 4140
109. Tazmanian
8:23 PM GMT on March 21, 2007
would the may 3dr 1999 tornado be a EF5 has well
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
108. weathersp
8:22 PM GMT on March 21, 2007
Side by Side comparason...
1947: Unnamed


1992: Andrew
Member Since: January 14, 2007 Posts: 17 Comments: 4140
107. snotly
8:18 PM GMT on March 21, 2007
last 1500 miles of that path looks a lot like Andrew
Member Since: August 27, 2005 Posts: 0 Comments: 686
106. Tazmanian
8:15 PM GMT on March 21, 2007
hello
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
105. weathersp
8:13 PM GMT on March 21, 2007
Check out the path of this 1947 hurricane.... Why wasnt this one named it was a cat 5 out at sea for almost 30 hrs and it made landfall as a cat 4. Looks suppriseingly like andrew exept it was cat 5 just before it made landfall instead of Andrew hitting the US as a cat 5.



Member Since: January 14, 2007 Posts: 17 Comments: 4140
104. Drakoen
8:13 PM GMT on March 21, 2007
The NHC is predictining a Cyclone huricane23???? The current structure of the system is ragged and you can see the shear, regardless of system's circular appearance.
Member Since: October 28, 2006 Posts: 57 Comments: 30674
103. weatherboykris
8:08 PM GMT on March 21, 2007
Stacy hypes more than JB.BBL
Member Since: December 9, 2006 Posts: 125 Comments: 11346
102. hurricane23
8:07 PM GMT on March 21, 2007
Thankgod for those mountians kris!

Look what Stacy put out at 5:00am that morning which gave me chills.

THE INTENSITY FORECAST REMAINS QUITE COMPLICATED DUE TO POSSIBLE
LAND INTERACTIONS WITH CUBA. IF ERNESTO EMERGES SOONER AND A LITTLE
FARTHER NORTH OFF THE COAST OF CUBA...THEN THE CYCLONE WILL HAVE
MORE TIME TO STRENGTHEN OVER VERY WARM SSTS OF 86-88F AND IN A VERY
FAVORABLE UPPER-LEVEL FLOW REGIME. THE SHIPS INTENSITY MODEL IS
FORECASTING NEAR-ZERO VERTICAL WIND SHEAR...JUST AS ERNESTO IS
APPROACHING THE SOUTHERN FLORIDA PENINSULA IN 48 HOURS. THESE
CONDITIONS WOULD FAVOR THE POSSIBILITY OF ERNESTO BECOMING A
CATEGORY 2 OR EVEN A CATEGORY 3 HURRICANE BEFORE MAKING LANDFALL
ALONG THE FLORIDA COAST.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
101. snotly
8:04 PM GMT on March 21, 2007
Hopefully none like a repeat of that '47 'cane... I dont like that path for N.O.
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100. weatherboykris
8:02 PM GMT on March 21, 2007
King took a track similar to Ernesto.What different outcomes.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
99. hurricane23
3:58 PM EDT on March 21, 2007
Florida indeed has experienced a couple of active landfalling seasons in 2004-2005 but its nothing compared to how bad times can get like for example the time period from 1941-1950 south florida was hit time after time from all directions,point being i think we have fairly lucky so far and hopefully 2007 wont bring any devastation in florida and any U.S. coastline.Adrian

Member Since: May 14, 2006 Posts: 8 Comments: 13841
98. Tazmanian
11:57 AM PDT on March 21, 2007
whats this drop it ok
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97. MisterPerfect
6:43 PM GMT on March 21, 2007
dropped
Member Since: November 1, 2006 Posts: 71 Comments: 20140
96. snotly
6:48 PM GMT on March 21, 2007
huh? - no taz .. thats how i feel... but I live inland a good deal... guess thats bad...pretty insensitive of me.... Ok calm weather is nice too... less people get hurt..
Member Since: August 27, 2005 Posts: 0 Comments: 686
95. pottery
2:41 PM AST on March 21, 2007
Taz, everything is cool, man.
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94. Tazmanian
11:30 AM PDT on March 21, 2007
for get it for get it for get it OK for get that i evere said any thing OK for get it for get it for get it i think you all this take thing way to hard on me when i was this kinding a round when i said poor FL OK i did not mean to say it OK get overe it YOU got it this get overe it


this for get about that i said poor FL and thing like that you take thing way out the air lock


i did not mean to say it ok
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
93. hurricane23
2:20 PM EDT on March 21, 2007
Posted By: stormhank at 1:48 PM EDT on March 21, 2007.

I just read the march 20th outlook from TSR their sayin 17 named storms 9 hurricanes and 4 major .. looks like an active year ahead.

That update is old,the new update is april 5th.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
92. snotly
6:14 PM GMT on March 21, 2007
cant take it no more... need F5 conditions over the entire Atlantic... weather too calm.. to peaceful.. too much shear.. too much sunshine and pretty girls... need blobs and 1000 degree SST.... whaaa whaaaa... cry... (pulling hair out) 300 mph winds 200 feet storm surge... (collapse in heap of desperation..)
Member Since: August 27, 2005 Posts: 0 Comments: 686
91. ProgressivePulse
6:16 PM GMT on March 21, 2007
Howdy Everyone! Must be about Hurricane Season, the bickering has starting up again!
Member Since: August 19, 2005 Posts: 5 Comments: 5452
90. LpAngelRob
1:02 PM CDT on March 21, 2007
Here's a good link to a NOAA study about tornadoes and overpasses. Good if you want to go in-depth on this particular topic.

http://www.srh.noaa.gov/oun/papers/overpass.html
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89. stormhank
5:46 PM GMT on March 21, 2007
I just read the march 20th outlook from TSR their sayin 17 named storms 9 hurricanes and 4 major .. looks like an active year ahead
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88. Patrap
12:43 PM CDT on March 21, 2007
NOVA story Linkie Dinkie..Link
Member Since: July 3, 2005 Posts: 427 Comments: 129354
87. Patrap
12:42 PM CDT on March 21, 2007
The Man Who Knew




Storm That Drowned a City homepage

"A slow-moving Category 3 hurricane or larger will flood the city. There will be between 17 and 20 feet of standing water, and New Orleans as we now know it will no longer exist."
—Ivor van Heerden, October 29, 2004

For years, Ivor van Heerden, a hurricane expert at Louisiana State University, has seen it coming. Since 2001, he and colleagues have been generating computer models of how a major storm could inundate the region in and around New Orleans. And he and his team sought tenaciously—at times desperately—to have their warnings heeded by government officials.

In an interview with NOVA ten months before Katrina, van Heerden expressed some of his worst fears as well as his understanding that the federal government, and the Federal Emergency Management Agency in particular, were finally grasping the need to prepare for a calamity. But in interviews conducted in Katrina's wake, van Heerden's anger at the federal government's response is clear.

Following are excerpts from van Heerden's interviews, both pre- (this page) and post-Katrina (next page).

Before the Flood

Interview conducted October 29, 2004

NOVA: If this region—New Orleans, the wetlands, and all—were a patient in the hospital, how would you describe them? At what stage are they?

VAN HEERDEN: Close to death.

NOVA: Really? Don't hold back.

VAN HEERDEN: (laughter) Thank you. Louisiana is a terminally ill patient requiring major surgery, a patient that if it was given a new heart and new lungs and a new liver would live. If it isn't, it's going to die. That's the equivalent.
An ominous scenario

NOVA: Walk me through the worst-case scenario—if a hurricane hits New Orleans.

VAN HEERDEN: If we look at the case of a slow-moving Category 3 passing west of the city, the floodwaters push into Lake Pontchartrain, and then they push through some highly industrialized areas. As they pass through these areas, they pick up a lot of chemicals. Remember, the flooding is occurring at the same time as a lot of wind damage, a lot of things breaking and coming apart. So these highly contaminated waters then flow into the city.

Within the city you have about 300,000 people who haven't left. There are about 57,000 families in New Orleans that don't own a motor vehicle. They can't get out. There are numerous homeless folk who can't get out. And then there's the disabled or bedridden. And those are the folk who have the least resources, the least ability to cope with what's going to happen.

While the flooding starts, these people are dealing with the winds pulling buildings apart, trees coming down, whatever. For the first five hours the water rises very slowly. But then it rises very, very rapidly. It rises higher than the average home's roof. So those 300,000 people, most of them, are going to have to leave their homes. They're going to end up hanging on to light poles, trees, trying to swim to high-rise buildings.

“We’re in essence going to have a refugee camp.”

There is the potential for extremely high casualties—people not only killed by flying debris, drowning in the soup, but also just imagine, how do we rescue the survivors? Unlike a river flood, it doesn't come up and go down. The water stays. And it stays for months and months and months. How do you rescue all of these people? If there's 200,000 survivors, you get 20,000 out a day, that's 10 days. So how are they going to hang on? You know, this is one of the big nightmares: how do you rescue those survivors? What are they going to need?

They're going to need to be detoxified. And this is Louisiana—it's 100 degrees Fahrenheit, 100 percent humidity. Putrefaction and fermentation go on very, very rapidly. So those folk are going to be surrounded by the proverbial witches' brew of toxins.

In addition to the folk that have to be rescued, we've got about 700,000 residents who can't come home. They're going to have to be housed in tent cities. When you start pulling groups of people like this into close confinement, the potential of very serious diseases goes up dramatically.

So just imagine, you've got this super, super crowding—highly, highly stressed folk. They don't have a home. They don't have a job. They don't see any future. They're living in tents. It's hot, humid Louisiana. And now you have the potential of disease.

These are some of the worst-case scenarios. We will have almost a million displaced persons that are going to be totally dependent on the state. We're in essence going to have a refugee camp. And it's going to require a massive operation to try and bring some normality into these people's lives.
Preparing for disaster

NOVA: Is this something that a state can handle? The State of Louisiana?

VAN HEERDEN: No, this is definitely something that requires the full resources of the U.S. government. We are fortunate that the federal government is starting to recognize that this is a serious problem. In July of this year [2004] we had an exercise called the Hurricane Pam exercise, where all the federal agencies got together with state agencies. We did a simulation of what would happen, and then these agencies got together and tried to decide how they would deal with a flooded New Orleans. So there is some recognition now, especially by the Federal Emergency Management Agency, that this is a catastrophe that's right on the horizon.

NOVA: How great is the risk of this happening?

VAN HEERDEN: If we look in the last eight years, we have had two near misses of New Orleans [Hurricane Georges in 1998 and Hurricane Ivan in 2004]. And as the wetlands fall apart, the potential of these hurricanes to do major destruction through storm surges rises and rises and rises. So every year that goes by, the probability of this killer storm occurring increases. Statistics right now would suggest maybe once every seven to eight years we're going to have a near miss.

NOVA: So if there's a chance of a big hurricane and this scenario playing out every seven or eight years, what's the solution? What could be done?

VAN HEERDEN: There are two very important mitigation activities that the federal government has to pursue today. Number one is our wetlands protect us from a surge. Our wetlands and barrier islands are our outer line of defense. We need to restore them. Now, that's in the longer term.

In the shorter term, we can start thinking about how can we reduce the amount of water that flows into Lake Pontchartrain and then floods the city? We need to be really innovative, think outside the box, and in addition we've got to change the way federal government does business. You can't give these sort of projects to the Corps of Engineers and have them mull over it for 20 years before it gets built. We need a group that's independent of the political system, that's well funded, has the right experts advising it, and then gets in and does it.

“Every year that goes by, the probability of this killer storm occurring increases.”

This is the United States of America. This is the most powerful country in the world. It has unbelievable resources. At, literally, the snap of the President's finger, we can spend $40 billion in Iraq. If we can start rebuilding their infrastructure immediately, we can do the same thing back home. At the snap of the President's finger, perhaps, we could spend the $16-20 billion that's needed to save New Orleans. All it takes is the will to do it.

NOVA: What do you think it takes to create that will? Does it take a catastrophe?

VAN HEERDEN: The unfortunate thing is, it does look like it's going to need a catastrophe in order to mobilize it.
Member Since: July 3, 2005 Posts: 427 Comments: 129354
86. ricderr
12:23 PM EST on March 21, 2007
1


I love the talk of hurricanes in the morning, sounds like Doc Masters blog.
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85. Tazmanian
10:23 AM PDT on March 21, 2007
for get it for get it for get it OK for get that i evere said any thing OK for get it for get it for get it i think you all this take thing way to hard on me when i was this kinding a round when i said poor FL OK i did not mean to say it OK get overe it YOU got it this get overe it


this for get about that i said poor FL and thing like that you take thing way out the air lock
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
84. HobeSoundShudders
5:17 PM GMT on March 21, 2007
wbk leave taz alone and don't put the rest of us in your boat ("no one understood...") jo
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83. weatherboykris
5:14 PM GMT on March 21, 2007
sorry Taz.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
81. Oreodog
12:08 PM CDT on March 21, 2007
We have no idea what you just said. But you said it with authority.
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80. Tazmanian
10:01 AM PDT on March 21, 2007
for get it for get it for get it OK for get that i evere said any thing OK for get it for get it for get it i think you all this take thing way to hard on me when i was this kinding a round when i said poor FL OK i did not mean to say it OK get overe it YOU got it this get overe it
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
79. Oreodog
12:02 PM CDT on March 21, 2007
Taz -- it is spring. The flowers are in bloom, pretty girls are everywhere, the days are warming up. Go outside and smell the flowers and chase the girls -- the fresh air will do you some good.
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78. Tazmanian
10:00 AM PDT on March 21, 2007
i hate this time of year
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
77. Tazmanian
9:57 AM PDT on March 21, 2007
: weatherboykris hey can i help it ?
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
76. Tazmanian
9:54 AM PDT on March 21, 2007
come on no it been a long long time from the last time we talk about a hurricane and was i wishing a hurricane on any one NO i was this saying that i this want a hurricane that is out to sea looking at the same maps evere is makeing me nuts and i cant take it any more
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
75. HobeSoundShudders
4:55 PM GMT on March 21, 2007
of course you don't taz, you are just interested in storms and weather like most of us that hang around here, anyone that knows you knows that, you are a kind and gentle guy jo
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74. weatherboykris
4:55 PM GMT on March 21, 2007
Taz...you video tape the CNN coverage of storms.Of course you like seeing storms hit.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
73. hurricane23
12:49 PM EDT on March 21, 2007
Guys many of us live in south florida and it indeed has been rough that pass couple of seasons.Myself ive lived in miami all my life 29 years and hurricanes are indeed a way of life down here but its important to keep in mind that we are all here to learn from each other and help one another during difficult times during tropical season.My best advise take advantage of this time now and be ready come june1.Adrian
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72. Tazmanian
9:54 AM PDT on March 21, 2007
NO i dont
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71. HurricaneMyles
4:51 PM GMT on March 21, 2007
HSS...All I did was ask him not to say things like 'poor FL' and 'run for your lives'. I rarely tell Taz what to do, I can only remember one time in the past, but posting things like that serves no use except to scare people.
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70. weatherboykris
4:50 PM GMT on March 21, 2007
And I gotta agree,Taz likes seeing people get hit.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
69. Tazmanian
9:49 AM PDT on March 21, 2007
me want a hurricane to talk about any out there i had it of waiting
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68. HobeSoundShudders
4:49 PM GMT on March 21, 2007
lighten up Hmyles, we have time to worry later (and yes, i DO live in Fl) jo
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67. weatherboykris
4:49 PM GMT on March 21, 2007
I know Myles.I shouldn't have been like that.
Member Since: December 9, 2006 Posts: 125 Comments: 11346

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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