downburst

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Related to Straight-line winds: downburst, Macroburst

downburst

downburst
A local high-velocity downward movement of air mass flowing out of a thunderstorm. It is the chief cause of severe wind shear. The size of a downburst may vary from a ¼ mile to more than 10 miles. It can last from 5 to 30 minutes. The wind speed can go as high as 120 knots. It is potentially very dangerous, especially during the takeoff and landing phases.
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"Because of the localized nature of individual hailstorms and straight-line winds as well as potential for major outbreaks affecting the ever-changing built environment, using historical losses for risk assessment and management is not sufficient," said Dr.
Most of the insurable losses from severe convective storm resulted from major thunderstorms in the United States that prompted widespread hail, damaging straight-line winds, and tornadoes.
Since then, remote sensing has revealed the variety of convective mechanisms that whip up damaging straight-line winds. Meanwhile, "derecho" has become a public term for a wide range of severe weather.
The door has been tested to withstand pressures of +52 and -52 pounds per square foot and remain intact during straight-line winds. Equipped with 48-inchhigh, 4-inch-thick closed cell foam panels, the door offers R-23 insulation and has fewer panel joints for a tighter seal.
"The recent outbreaks of tornadoes, large hail and damaging straight-line winds in the United States have emphasized the importance of historical data analysis for insurers and reinsurers when trying to forecast future losses," said Adam Podlaha, head of Impact Forecasting with Aon Benfield, in the report.
"One of the most common injuries that people may sustain during tornadoes, storms or straight-line winds are injuries from falling or flying debris, so it's important to take shelter,'' said Keli Cain, spokeswoman for the Oklahoma Department of Emergency Management.
Gust fronts contain potentially severe straight-line winds. The further the gust front is from the radar, the less likely the radar will see it.
After the event, dubbed the Super Tuesday Tornado Outbreak, the National Oceanic and Atmospheric Administration's National Weather Service Storm Prediction Center collected more than 130 reports of tornadoes, more than 250 reports of straight-line winds and 128 reports of hail--including several reports of hailstones the size of softballs.
Authorities logged more than 40 tornado reports, 160 reports of hail and 70 reports of straight-line winds. Two people were killed by the violent weather.
"In 2006, the high rise we were in was hit by straight-line winds. We had to vacate our building for 12 weeks," says George Smith, Krieg DeVault's IT director.
While straight-line winds are common across west Texas--especially during the late spring and early summer--the magnitude of the wind speeds for this event is quite rare.
The storms, which began on Wednesday, unleashed tornadoes and straight-line winds that overturned mobile homes and HGVs, uprooted trees and knocked down power lines across the South.