National Weather Service United States Department of Commerce

Monsoon Flood Threat in the Southwest; Hot in the South and Northwest

Monsoonal heavy rain will continue flash flood potential across the Southwest and Intermountain West to the central and southern Rockies through this weekend, especially in complex terrain, burn scars, and urban areas. Excessive heat and humidity with heat indices over 110 degrees will be common over much of the Deep South and interior Northwest this weekend. Read More >

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A tornado outbreak occurred during the afternoon and evening hours of the May 20, 2013, and was the last day of a three-day stretch of significant severe weather from May 18-20, 2013. This event also produced the most deadly and devastating tornado of the year for Oklahoma and the the United States.

Several supercell thunderstorms developed during early afternoon of May 20th along a dryline in central Oklahoma. One of these storms developed near Chickasha and rapidly intensified, producing a tornado which touched down at 2:56 PM CDT on the west side of Newcastle. The tornado became violent within minutes, then tracked east-northeastward across the city of Moore and parts of south Oklahoma City for about 40 minutes before finally dissipating near Lake Stanley Draper. The tornado caused catastrophic damage in these areas, and was given a maximum rating of EF-5. The tornado claimed 24 lives, injured scores of people, and caused billions of dollars in damage.

Several other tornadoes also occurred in Stephens and Lincoln Counties during the afternoon of May 20. In addition to the tornadoes, large hail and damaging winds caused damage in many areas.

Below is a map with the preliminary damage path of the Newcastle-Moore-South OKC tornado. Contours delineate the extent of EF-0 (light blue), EF-1 (green), EF-2 (yellow), EF-3 (orange), EF-4 (red), and EF-5 (purple) damage from the survey.