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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65. HobeSoundShudders
4:48 PM GMT on March 21, 2007
yikes taz, get a dog that will give you something to talk about! jo
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64. HurricaneMyles
4:47 PM GMT on March 21, 2007
Excuse me, Kris. I live in FL, and his opinions, please forgive me for being mean, are based on nothing but him wanting to see somebody getting hit by a bunch of hurricanes.
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62. HobeSoundShudders
4:47 PM GMT on March 21, 2007
tazzy-poo, no talk of blob-forming or pin-hole eyes til august!! xxooxx jo
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61. weathersp
4:44 PM GMT on March 21, 2007
Good I want that... Notice how 6 systems go within 200 miles of my house.

But we do not want a repeat of Ivan and Charlie.
Member Since: January 14, 2007 Posts: 17 Comments: 4140
60. weatherboykris
4:46 PM GMT on March 21, 2007
Mind your bussiness Myles.His opinions,his right to post them.
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59. HurricaneMyles
4:44 PM GMT on March 21, 2007
Taz, plesae dont go making comments like that. You, like the rest of us, have no clue what will setup and making comments like 'poor FL' is in very bad taste.
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56. hurricane23
12:38 PM EDT on March 21, 2007
Stormhank here is a link to my model page.

Adrian's Model Page
Member Since: May 14, 2006 Posts: 8 Comments: 13839
55. HurricaneMyles
4:38 PM GMT on March 21, 2007
stormhank...FSU Models Page. There are links to other great tropical pages there too.

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54. stormhank
4:34 PM GMT on March 21, 2007
anyone have a reliable model page link? I had puter problems and lost all my model pages
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53. Oreodog
11:25 AM CDT on March 21, 2007
I've often been called weak in nature but interesting. It's TS Oreodog!
52. hurricane23
12:32 PM EDT on March 21, 2007
Perdicting were the bermuda high will park itself this season this early in the game is just not possible but if i had to pick a season with similar tracks we might see iam going to go with 2004 with a strong ridge putting florida at an above average risk of seeing several landfalls.What kind of Steering currents might be in place this season?We could either see a troffiness sending everything out to sea as we saw in 06 or will a strong ridge send systems towards florida and the eastcoast.Alot of questions still yet to be answered and will likely remain that way for atleast for another 2-3 months.In my opinion numbers predicted arent really that important because even a quite season can be deadly as we have seen in several ocations with 1992 being a prime example.It only takes one to ruin lives and haveing 25 systems develope this season is not important as the ones that actually make landfall are the ones that have the greatest impact.Adrian
Member Since: May 14, 2006 Posts: 8 Comments: 13839
51. weatherboykris
4:31 PM GMT on March 21, 2007
Yes it is Taz.
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50. hurricane23
12:29 PM EDT on March 21, 2007
Kris the 12Z GFS @ about 144 hours has some sort of development pushing of to the NE.Chances of this event occuring aren't that great.
Member Since: May 14, 2006 Posts: 8 Comments: 13839
48. weatherboykris
4:27 PM GMT on March 21, 2007
I'm getting convinced we will see some sort of hybrid development.Last nigh's 00z CMC,GFS,NOGAPS,all were calling for a brief warm core system in the area.
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46. stormhank
4:26 PM GMT on March 21, 2007
Thanks kris.. Ive read that the El Nino is dissapating.. so I was thinking that would probably increase number of storms for this season
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44. HurricaneMyles
4:24 PM GMT on March 21, 2007
stormhank... Most of the pros that do this like Dr. Grey, TSR, ect, think it will be more active then 2006, but not like 2005. So in the middle I suppose.
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43. hurricane23
12:26 PM EDT on March 21, 2007
Pushes of to the NE on the 12Z GFS in a very weak state.


Member Since: May 14, 2006 Posts: 8 Comments: 13839
42. weatherboykris
4:25 PM GMT on March 21, 2007
Hank...probably closer to '04 than '05.13-16 named storms.
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41. weatherboykris
4:21 PM GMT on March 21, 2007
H23...NAM's crappy for TCs.I don't even look at that for tropical forecasts.
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39. stormhank
4:21 PM GMT on March 21, 2007
good day everyone.. does anyone have any ideas on how much hurricane activity we can expect for 2007? quiet like last year or busy like 2004 n 2005?
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38. hurricane23
12:20 PM EDT on March 21, 2007
TAZ this event is unlikely to happen but it should be served as a wake up call that hurricane season is approaching.
Member Since: May 14, 2006 Posts: 8 Comments: 13839
36. hurricane23
12:15 PM EDT on March 21, 2007
Indeed weathersp ive been waiting for the complete run to come out.Movement is off to the NE.


Member Since: May 14, 2006 Posts: 8 Comments: 13839
35. weathersp
4:11 PM GMT on March 21, 2007
At 114 hrs the GFS puts an area of low pressure of 1012mb about 500 miles NNE of Puerto Rico.
Member Since: January 14, 2007 Posts: 17 Comments: 4140
33. hurricane23
12:11 PM EDT on March 21, 2007
Interesting to note the NHC is forcasting development in the next 48-72 hours.With a ridge to its north it wont be going anywere fast.

Member Since: May 14, 2006 Posts: 8 Comments: 13839
31. homegirl
4:07 PM GMT on March 21, 2007
the models have been quite consistent about something in this area. Most have moved it ene. need to look at the low level stearing currents. shear will keep development to a minimum. hopefully it will move west and bring fl some much needed rain!!!
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30. hurricane23
12:09 PM EDT on March 21, 2007
12Z NAM..Weak in nature but interesting.



Member Since: May 14, 2006 Posts: 8 Comments: 13839
28. weathersp
4:04 PM GMT on March 21, 2007
You can see the shear in the Floter 1 Visible animated imagery. The lower level clouds are being blown west and the upeer level clouds are being blown east.

Visible
Member Since: January 14, 2007 Posts: 17 Comments: 4140
26. hurricane23
11:59 AM EDT on March 21, 2007
Taz I posted that a little up in the blog....Shear is quite high across this area and even if some type of sub-tropical or Hybrid development took place it would probably be sheared.
Member Since: May 14, 2006 Posts: 8 Comments: 13839
23. weathersp
3:54 PM GMT on March 21, 2007
Still not to late to take a whack at my 2007 Hurricane Contest!

Hurricane Contest!


Member Since: January 14, 2007 Posts: 17 Comments: 4140
21. hurricane23
11:56 AM EDT on March 21, 2007
Taz read up in the blog...
Member Since: May 14, 2006 Posts: 8 Comments: 13839
19. weathersp
3:49 PM GMT on March 21, 2007
Anyone seen the 12z NAM. IT looks very interesting with a low devloping and moveing west in the next 84 hrs.

12z NAM
Member Since: January 14, 2007 Posts: 17 Comments: 4140
18. hurricane23
11:51 AM EDT on March 21, 2007
Basically i forsee an active season number wise this time around with a weak nina to neutral conditions across the atlantic basin.Perdicting were the bermuda high will park itself this season this early in the game is just not possible but if i had to pick a season with similar tracks we might see iam going to go with 2004 with a strong ridge putting florida at an above average risk of seeing several landfalls.What kind of Steering currents might be in place this season?We could either see a troffiness sending everything out to sea as we saw in 06 or will a strong ridge send systems towards florida and the eastcoast.Alot of questions still yet to be answered and will likely remain that way for atleast for another 2-3 months.In my opinion numbers predicted arent really that important because even a quite season can be deadly as we have seen in several ocations with 1992 being a prime example.It only takes one to ruin lives and haveing 25 systems develope this season is not important as the ones that actually make landfall are the ones that have the greatest impact.Hopefully the 2007 hurricane season will once again spare our shores.


PS! Use this time wisely and create a hurricane plan for you and your family and know what would you do if your emergency management asked you to evacute and begin trying to get into the mode that in a few months we may once again be faced with the possiblity of a significant event in the united states.Overall my advise get your essentials and dont wait till june1 do it now.Adrian
Member Since: May 14, 2006 Posts: 8 Comments: 13839
17. Dropsonde
3:38 PM GMT on March 21, 2007
I cannot decide about the strength of the La Nina, or even if it'll "officially" develop. I am only holding off because the models are not in universal consensus that it will happen, and NOAA certainly wasn't predicting an El Nino for 2006 at this point last year (although I don't think we'll revert to El Nino again). The cool water continues to rise but it hasn't reached the surface yet; in fact the surface was cooler at the beginning of the month. However, it's a big pool of water and has the makings of a significant event. If it makes it to the surface intact, it's all about the timing at that point.

What concerns me the most is a 2005 setup: a marginal or hostile Atlantic, but a strong Bermuda high and a warm, low-shear Caribbean and Gulf that allow storms to blow up once they hit it. That part of the ocean never cooled properly. Dust and shear are all that kept storms from developing there last year, despite how Alberto made a valiant effort at it. People talk about the number of storms, well I'm concerned about the meteorological setup and where those storms occur.
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16. hurricane23
11:39 AM EDT on March 21, 2007
12Z coming out but it will be about an hour or so before the complete run comes out.
Member Since: May 14, 2006 Posts: 8 Comments: 13839

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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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