Elevated Fire Weather Threats for California; Cold Across Upper Midwest with Snow in Central Rockies

Unfortunately, elevated fire weather threats return this weekend for parts of California, as gusty offshore winds increase. Meanwhile, a large cold dome of surface high pressure will keep high temperatures 20 to 30 degrees below average across the Upper Midwest and down the High Plains. Also, heavy snowfall is expected from Wyoming into northeastern Colorado and western Nebraska. Read More >

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A tornado outbreak occurred over parts of northern and central Oklahoma during the day on May 24, 2011, with violent tornadoes devastating several communities. By the end of the day, one EF-5, two EF-4, and two EF-3 tornadoes destroyed buildings, ripped up trees and power poles, and unfortunately, resulted in 11 deaths and 293 injuries.

The day began with a strong upper level trough ejecting out of the southwestern United States. The trough took on a negative tilt as it approached the southern Plains. A strong jet stream was located at both the middle and upper levels rotating around the upper trough. At the surface, a low pressure strengthened rapidly over northwestern Oklahoma, keeping the low-level flow of warm, moist air to flow east of a dry line that had moved into western Oklahoma.

Thunderstorms developed by early afternoon over western Oklahoma, and quickly became supercells as they moved northeast. Strong low-level rotation developed early, with the first tornado occurring over Blaine County, and moved northeast into Major County. Another supercell rapidly gained low-level rotation as it moved from Caddo into Canadian County. This tornado became the strongest of them all as it moved north of El Reno, west of Piedmont, and to south of Guthrie in Logan county. Nine people died as a result of this violent tornado.

Two more powerful supercells developed over Grady county, and they moved northeast into McClain and Cleveland counties. Finally, the final tornado occurred east of Norman into Pottawatomie county. The timing of this outbreak could not have come at a worse time, as rush hour was just unfolding as the tornadoes neared the Oklahoma City metro area.


Radar reflectivity and storm relative velocity images for Central OK at 5:31 pm CDT on May 24, 2011	Tornado near Chickasha - Photo courtesy of Derrick James	Tornado near Lookeba - Photo courtesy of Dal Archer