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.
Damage from winds associated with severe thunderstorm 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 for injury and death. Even anchored mobile homes can be seriously damaged when winds gust over 80 mph.
Straight-line wind is a term used to define any thunderstorm wind that is not associated with rotation, and is used mainly to differentiate from tornadic winds.
A downdraft is a small-scale column of air that rapidly sinks toward the ground.
A macroburst is an outward burst of strong winds at or near the surface with horizontal dimensions larger than 4 km (2.5 mi) and occurs when a strong downdraft reaches the surface. To visualize this process, imagine the way water comes out of a faucet and hits the bottom of a sink. The column of water is the downdraft and the outward spray at the bottom of the sink is the macroburst. Macroburst winds may begin over a smaller area and then spread out over a wider area, sometimes producing damage similar to a tornado. Although usually associated with thunderstorms, macrobursts can occur with showers too weak to produce thunder.
A microburst is a small concentrated downburst that produces an outward burst of strong winds at or near the surface. Microbursts are small — less than 4 km across — and short-lived, lasting only five to 10 minutes, with maximum windspeeds sometimes exceeding 100 mph. There are two kinds of microbursts: wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground.
A downburst is the general term used to broadly describe macro and microbursts. Downburst is the general term for all localized strong wind events that are caused by a strong downdraft within a thunderstorm, while microburst simply refers to an especially small downburst that is less than 4 km across.
A gust front is the leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.
A derecho is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. A typical derecho consists of numerous microbursts, downbursts, and downburst clusters. By definition, if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length, then the event may be classified as a derecho.
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 several 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 50-60mph.
What are straight-line winds?
Straight-line winds are generally any thunderstorm wind that is not associated with rotation, and is used mainly to differentiate from tornadic winds.
What causes straight-line winds?
Most straight-line winds are a result of outflow generated by a thunderstorm downdraft.
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 of injury and death. Even anchored mobile homes can be seriously damaged when winds gust over 80 mph. Winds from thunderstorms can cause EF-2 damage.
Why is the wind gust limit set at 58 mph?
In the 1950's and 1960's, there were three types of convective watches that could be issued: Tornado Watches, Public Severe Thunderstorm Watches, and Aviation Severe Thunderstorm Watches. At first, the public severe thunderstorm watch wind criterion was 75 mph, while the limit for aviation watches was 50 mph. Negotiations with the Air Force raised the minimum speed required for an aviation watch to 58 mph (50 knots) in 1962. In 1970, the Aviation Severe Thunderstorm and Public Severe Thunderstorm watches were combined into a single Severe Thunderstorm Watch, with a minimum wind gust criterion of 50 knots, to reduce confusion.
What is the difference between a microburst and a downburst?
A downburst is the general term for all localized strong wind events that are caused by a strong downdrafts within a thunderstorm, while microburst simply refers to an especially small downburst that is less than 4 km across.