2/16/2017 It s All Wind Communicating Damaging Wind & Tornado Threats in an Impact-based Environment Rick Smith - NWS Norman, OK Justin Dougherty Our Challenge Given the history and types of weather threats we face, how can we best provide warnings for the storms that pose a threat to life and safety, but weigh our actions against acting so often that warnings lose their intended response from the public? 1
Which is more deadly in OK? A. EF0/EF1 tornado B. lightning C. thunderstorm wind D. extreme cold Which is more deadly in OK? A. EF0/EF1 tornado B. lightning C. thunderstorm wind D. extreme cold Thunderstorm Wind Hazards don t fit neatly into boxes Weak Tornado Strong Tornado Violent Tornado Thunderstorm Wind Hazards don t fit neatly into boxes Weak Tornado Strong Tornado Violent Tornado S t r a i g h t L i n e W i n d downburst microburst gustnado derecho leading edge vortex bow echo EF0 EF1 EF2 EF3 EF4 EF5 65 mph 86 mph 111 mph 136 mph 166 mph 200 mph EF0 EF1 EF2 EF3 EF4 EF5 65 mph 86 mph 111 mph 136 mph 166 mph 200 mph NWS A Recent Severe Thunderstorm EM Integrated Team Media Geronimo, OK May 12, 2016 Winds around 90 MPH Baseball sized hail 2
Deciding on type of warning: Severe Thunderstorm vs Tornado NWS s Severe Thunderstorm Tornado The tornado warning decision The tornado warning decision Preponderance of the evidence Radar data Reports Storm history Damage potential Duration The environment 3
2/16/2017 Supercell thunderstorms are responsible for virtually all deadly tornadoes in Oklahoma. We know the weather environment that forms supercell storms. -Based Impacts We generally know which days will support supercell storms with the most deadly form of tornado. -Based Impacts Thunderstorm Wind Hazards don t fit neatly into boxes Weak Tornado Strong Tornado Violent Tornado S t r a i g h t L i n e W i n d downburst microburst gustnado derecho leading edge vortex bow echo EF0 EF1 EF2 EF3 EF4 EF5 65 mph 86 mph 111 mph 136 mph 166 mph 200 mph 4
NWS s NWS s Severe Thunderstorm Tornado Severe Thunderstorm Severe Thunderstorm elevated wording Severe Thunderstorm tornado possible Radar Observed Tornado Considerable Catastrophic Oklahoma Tornadoes Perception Reality Tornado Frequency Perception Reality EF1 + Tornadoes Average Per Year 1954-2014 Oklahoma has a lot of tornadoes YES! Walker Ashley 5
Tornado Intensity Perception Reality Oklahoma has a lot of intense tornadoes YES! Probably even more than we think! EF2 EF0 EF1 Tornado Trends Perception Reality Tornadoes are getting stronger bigger worse Not really 1950 1960 1970 1980 1990 2000 2010 45 Total Housing Units 3829 What is the deadliest weather hazard in OK? A. flood/flash flood B. extreme heat C. tornado D. lightning RECIPE FOR DISASTER: How the Dynamic Ingredients of Risk and Exposure Are Changing the Tornado Disaster Landscape by Walker S. Ashley and Stephen M. Strader BAMS May 2016 6
What is the deadliest weather hazard in OK? A. flood/flash flood B. extreme heat C. tornado D. lightning Weather Deaths OKLAHOMA US Tornado 62 Heat 18 Flood 11 Wind 3 Lightning Winter Cold Heat 30 Tornado 22 Flood 20 Lightning 9 Wind Cold Winter Tornado Deaths Perception Reality Deaths from tornadoes are decreasing Deaths from tornadoes are not decreasing in OK 1950-2016 339 people killed by tornadoes in Oklahoma Tornado Deaths by Year 1999 1960 2013 80 70 Tornado Deaths by Decade 60 50 40 30 20 10 0 1950s 1960s 1970s 1980s 1990s 2000s 2010s 7
70% of Oklahoma tornado deaths were in EF4 and EF5 tornadoes The majority of OK tornado deaths occur in A. mobile homes B. vehicles C. outdoors D. permanent homes The majority of OK tornado deaths occur in A. mobile homes B. vehicles C. outdoors D. permanent homes 49% of Oklahoma tornado deaths were in permanent homes 295 of 339 locations known 36% of Oklahoma tornado deaths were in mobile homes and vehicles 295 of 339 locations known Our Challenge Given the history and types of weather threats we face, how can we best provide warnings for the storms that pose a threat to life and safety, but weigh our actions against acting so often that warnings lose their intended response from the public? 8
Rick Smith richard.smith@noaa.gov National Weather Service Norman, Oklahoma Our Challenge Deadliest Tornado Days in Oklahoma 1950-2016 Communicate tornado risk to maximize respect and preparedness while minimizing unnecessary fear and anxiety 11 40 8 24 8 22 11 16 32 10 16 Tornado Deaths By County 1950-2016 Killer Tornadoes Average Per Year 1954-2014 2 6 2 4 2 4 20 1 7 1 1 2 1 2 4 1 15 2 1 3 25 2 1 17 16 11 5 2 17 38 9 5 3 15 3 3 1 13 19 3 1 8 1 7 1 6 2 11 1 1 5 2 4 Walker Ashley 9
2/16/2017 Thunderstorm Wind Hazards philosophies Superimposed on central Oklahoma don t fit neatly into boxes Straight Line Wind Tornado Tornado a line of severe thunderstorms capable of producing multiple tornadoes Tornadoes may form rapidly anywhere in this line of storms. 2.4% of Oklahoma tornadoes are killers Very Close! s of the Future Overwarned Advanced Notice Be Alert! Tornado Location Take Cover Now! Be Alert! 58 10