Tornado Safe Rooms

Do they make sense in North Carolina?

What are the Options?• Do nothing• Promote individual responsibility• Provide grants for individual safe rooms• Provide grants for public/institutional safe rooms• Promote stronger building codes• Promote education and outreach to change

behavior

Problems with providing individual shelters through HMGP and similar

programs• Cost (Avg. grant in Mississippi $3500 x appx 5000 projects=$17.6 million —there

are 24 counties in NC identified by FEMA as High Risk for tornado—there are well over 1,000,000 structures in these counties—that’s at least $3.5 billion. PDM 2011 project for Raleigh calls for $1.2 million to build a saferoom in a mobile home park with capacity for appx 900 souls. Building to FEMA safe room standard is expensive.)

• Risk (even in Tornado Alley return freq for impact on a specific structure is about 1:50,000 years--.0002%/year—FEMA ranks NC # 20 in risk outside of tornado alley)

• Prioritization (what is basis for determining eligibility?)

Snakes or Speeding Cars?

Are tornadoes becoming more frequent?

Are tornadoes getting worse?

Any connection to climate change?

Are tornadoes becoming more deadly?

Almost 20,000 deaths have been reported associated with more than 3600 tornadoes in the United States since 1680. A cursory examination of the record shows a break in 1875. Prior to then, it is likely that many killer tornadoes failed to be reported. When the death toll is normalized bypopulation, a near-constant rate of death is apparent until about 1925, when a sharp fall begins. The rate wasabout 1.8 people per million population in 1925 and was less than 0.12 people per million by 2000. The decreasein fatalities has resulted from two primary causes: a decrease in the number of killer tornadoes and a decreasein the number of fatalities in the most deadly tornadoes. Current death rates for mobile home residents, however,are still nearly what the overall national rate was prior to 1925 and are about 20 times the rate of site-builthome residents. The increase in the fraction of the U.S. population living in mobile homes has importantimplications for future reductions in the death toll.

Deaths in the 3 May 1999 Oklahoma City Tornado from a Historical PerspectiveHAROLD E. BROOKS AND CHARLES A. DOSWELL III*NOAA/National Severe Storms Laboratory, Norman, Oklahoma

What’s the risk?How many people are killed by tornadoes each year?

NWS records indicate 360 people were killed by tornadoes during the month of April 2011.

TOP 5 U.S. ANNUAL TORNADO DEATH TOLLS:1) 1925-794 2) 1936-552 3) 1917-551 4) 2011-550 5) 1927-540

On the average tornadoes kill about 60 people each year, mostly from flying or falling debris. NC 1950-2011 ~132 (57 in 1984 and 26 in 2011—so weighted average is 1 or less per year in NC)

Source: NOAA Storm Prediction Center

Demographics of DeathMost tornado-related deaths occur:In the daytime-between 2pm and 8 pm

At home or in vehiclesAs of 1975, about 33% of deaths were in mobile homes, 25% in site-built homes and 13%

in vehicles

About evenly distributed Female/MaleTypical age 45-63-median age 54 +/- 9 yearsSource: NOAA

When is the risk highest?

How much time do you have?

How much advance warning can forecasters give us before a tornado strikes?The current average lead-time for tornado warnings is 11 minutes. NSSL is working to increase tornado warning lead-times to 20 minutes.

How long is a tornado usually on the ground?Detailed statistics about the time a tornado is on the ground are not available. This time can range from an instant to several hours. The average is about five minutes.

Source: NOAA

*NCEM began discussions and planning concerning the possibility of severe weather associated with the Saturday 4/16/11 tornado outbreak on the Tuesday before the event-4/12/11

What should we promote?• Good surveillance and warnings in plain

language• Availability of shelters in public places• Education to help people be aware and know

how to behave (where to go—what kind of places seek shelter)