Severe Weather 101
- What are damaging winds?
- Damaging winds are often called “straight-line” winds to differentiate the damage they cause from tornado damage. Strong thunderstorm winds can come from a number of different processes. Most thunderstorm winds that cause damage at the ground are a result of outflow generated by a thunderstorm downdraft. Damaging winds are classified as those exceeding 50-60 mph.
- Are damaging winds really a big deal?
- Damage from severe thunderstorm winds account for half of all severe reports in the lower 48 states and is more common than damage from tornadoes. Wind speeds can reach up to 100 mph and can produce a damage path extending for hundreds of miles.
- Who is at risk from damaging winds?
- Since most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft, anyone living in thunderstorm-prone areas of the world is at risk for experiencing this hazard.
People living in mobile homes are especially at risk from injury and death. Even anchored mobile homes can be seriously damaged when winds gust over 80 mph.
What we do: BAMEX (Bow Echo and MCV Experiment) was a field experiment involving scientists from NSSL, NCAR, the National Weather Service, and the University of Oklahoma that was designed to gather data to understand bow echoes and their resulting high damaging surface winds. The mobile project tried to understand and improve prediction of mesoscale and storm-scale processes that produce severe winds in bowing convective systems lasting at least four hours. The project used aircraft and mobile ground-based instruments to map the thermodynamic and environmental structure of thunderstorm complexes and mature mesoscale convective vortices.
An NSSL scientist studied low-altitude “mesovortices,” (atmospheric spin on the scale of a few km to several hundred km) and learned that they may be one of the causes of damaging straight-line winds. These results helped motivate the objectives for the BAMEX program defined above.