F-Scale Converted to EF-Scale Enhanced Fujita Scale Feb 1 2007 F Scale Wind Speed EF-Scale F045-78EF065-85 F179-117EF186-109 F2118-161EF2110-137 F3162-209EF3138-167 F4210-261EF4168-199 F5262-317EF5200-234 Wind speeds in mph, 3-second gust Objectives: 3, EF-Scale structure; 4, EF vs F-Scale
DOD to Wind Speed to EF-Scale EF-Scale Categories Wind Speed Ranges EF065-85 EF1 86-110 86-110 EF2111-135 EF3136-165 EF4166-200 EF5>200 Objectives: 3, EF-Scale structure Wind speeds in mph, 3-second gust
Why the EF-Scale was created Need more damage indicators recalibrate winds associated with F-scale ratings better correlate wind and rating account for construction variability Flexibility, Extensibility, Expandability Evidence indicates a well constructed house can be blown away by winds much less than 260 mph (. Evidence indicates a well constructed house can be blown away by winds much less than 260 mph ( Phan and Simiu,2003). The framed house is one of only a few F-scale damage indicators.
Tornadoes Tornado outbreaks Families, super outbreak
Super tornado outbreak April 3-4, 1974 315 deaths http://www.april31974.com/
Palm Sunday April 11 1965 47 Tornadoes in 12 hours span 271 deaths, 3400 people injured 1.1 billion damage (2003 $$$$)
May 3-4 1999 Oklahoma City 66 tornadoes 46 fatalities, 800 injured 1.5 billion damage An F-5 tornado http://www.norman.noaa.gov/2000/05/first-anniversary-of-may-3-1999- tornado-outbreak-highlights-importance-of-warnings/ http://www.norman.noaa.gov/2000/05/first-anniversary-of-may-3-1999- tornado-outbreak-highlights-importance-of-warnings/
Two of the highest concentrations of tornadoes outside the U.S. are Argentina and Bangladesh. Both have similar topography with Brazil (Argentina) or from the Indian Ocean (Bangladesh). mountains helping catch low-level moisture from over Brazil (Argentina) or from the Indian Ocean (Bangladesh).
Tornadoes Tornado winds Measurement based upon damage after storm or Doppler radar For southwest approaching storms, winds strongest in the northeast of the storm, 220 kts maximum Multi-vortex tornados
Tornadic Formation Basic requirements are: an intense thunderstorm Vertical wind shear Cold air aloft and warm moist air near surface (unstable conditions) Initiation of convection Capping inversion
Vertical wind shear Cold air aloft and warm moist air near surface (unstable conditions) Initiation of convection Capping inversion
Tornadoes Seeking shelter Basement or small, interior room on ground floor Indoor vs. outdoor pressure The Fujita Scale Based upon the damage created by a storm F0 weakest, F5 strongest Enhanced Fujita Scale
Severe Weather and Doppler Radar Doppler radar measures the speed of precipitation toward and away radar unit Two Doppler radars can provide a 3D view TVS, Doppler lidar NEXRAD
Waterspouts Rotating column of air that is connected to a cumuliform cloud over a large body of water Tornadic waterspout