Ozarks Weather Observer Logo
Volume XIV - Number 3
Editor: Brian Barjenbruch  Web Editor: Steven Lindenberg
June 2009
Ozark Weather Observer - Table of Contents


Derecho!!! Winds Roar on May 8, 2009
by Brian Barjenbruch

For many across the Ozarks region, he morning of May 8, 2009 greeted them with all of the fury and intensity that mother nature could find. Winds of 70 to 90 mph pelted houses with heavy rain and flying debris. Hail larger than golfballs dented cars while rain fell at up to three inches per hour, closing numerous roads including Interstate 44 at one location. 20 tornadoes, up to EF-3 in strength, touched down over portions of southwestern and south central Missouri.
All of this occurred in a matter of only a few hours as a powerful line of thunderstorms raced across the Ozarks between 7 and 11 AM. A line of thunderstorms which such intense windspeeds as these is known as a derecho. In addition to strong winds, the storm system lasted for several hours, beginning as a few thunderstorms over Kansas, and ending up more than a thousand miles off to the east. One reason that the storms lasted so long was that they developed their own very powerful area of low pressure immediately in their wake. This acted to increase the forward speed of the storm system, and produced extremely strong winds to more than 80 mph well behind the main convective line of thunderstorms.

Storm damage was extensive with this system. A large area of southeastern Kansas and the Missouri Ozarks experienced the most significant wind damage it had seen in several years. Thousands upon thousands of trees were uprooted or snapped. A 1000+ foot tower was snapped off just above ground level. Fair Grove schools received substantial structural damage, along with hundreds of other homes region wide.


In addition to the winds, 20 tornadoes developed along the line of storms as it passed through. These included 1 EF-3 and 5 EF-2 tornadoes. Most of these tornadoes touched down along and east of highway 160 in Missouri. One interesting aspect is that as the line of thunderstorms moved to the east, the tornadoes tended to move northeast, or even north. The tornadic activity damaged or destroyed numerous houses, many barns and outbuildings, threw vehicles, caused substantial tree damage, and unfortunately caused one fatality. May 8, 2009 will be a day not soon forgotten by those who endured the powerful storms.




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