Straight Line Winds
Straight line winds sometimes accompany thunder storms. The strength of these winds can lead to damage on your commercial roof by lifting panels, blowing gutters, and loosening flashings. Debris can also damage your roof surface. Damage from severe thunderstorm winds (exceeding 50-60mph) account for half of all severe damage reports in the continental United States. This is more common than tornado damage and can leave a path of damage entending for hundreds of miles.
Thunderstorms have the ability to shift wind energy from the upper atmosphere to ground level. In the upper atmosphere, wind speeds are normally high. The wind energy is shifted through a rain-induced downdraft. The ground interrupts the downdraft, causing it to spread out and accelerate. This can sometimes result in destructive speeds.
The National Weather Service has separate categories for damage form a tornado and that of straight line winds. In a tornado, the damage and debris may be found in several directions. This is because of the violent rotation of the winds. Straight line winds may be just as intense as those of a tornado, but the damage and debris are pushed into the same direction the wind is traveling. Because of the powerful force behind the straight line winds, there may be confusion as to if a tornado occurred.
For safety during a storm with straight line wind potential, please seek shelter in a sturdy structure or follow a tornado safety plan. Storms with straight line winds typically can also have hail and tornadoes. Prior to the onset of a storm, objects which may be blown around should be secured. It is also a good idea to keep trees trimmed to reduce the risk of damage from limbs and branches.