National Weather Service United States Department of Commerce

Severe Weather for the Central High Plains; Heavy Rain/Flood Concerns in Parts of the East

Strong to severe thunderstorms capable of strong winds and large hail are possible over portions of the central High Plains this afternoon, including parts of the Denver metro area. A stalled front is expected to bring additional rain and flash flood risks in the Mid-Atlantic and Southeast through Thursday. Red flag warnings are in effect across the Interior Northwest and Great Basin today. Read More >




Severe thunderstorms developed along and ahead of a dry line across central Oklahoma during the afternoon of May 9, 2016. The storms moved across central and eastern Oklahoma during the late afternoon evening hours. Prior to the storms moving into the area, the atmosphere ahead of the dry line in central and eastern Oklahoma had become very unstable.

This instability, combined with very strong wind shear associated with a strong trough of low pressure that moved into the Southern Plains from the Southern Rockies, resulted in the development of supercell thunderstorms. Several of these supercells produced a dozen tornadoes. Some of these tornadoes were damaging and long-lived tornadoes, and two were also killer tornadoes. One of the tornadoes, the "Katie tornado", killed one person and was rated EF-4.  Another tornado that occurred in Johnston and Coal counties also killed one person and was rated EF-3.

One of the supercells produced multiple tornadoes as it tracked along and near an outflow boundary produced earlier by morning thunderstorms associated with a previous weather system. This outflow boundary had settled across southeastern Oklahoma by the afternoon. The most significant tornado associated with this thunderstorm was the EF-3 tornado which occurred near the towns of Bennington and Boswell.

In addition to the tornadoes in central and southeastern Oklahoma, the severe thunderstorms produced hail up to baseball size and damaging wind gusts across other portions of central and eastern Oklahoma.

Map with damage paths for most of the tornadoes that occurred in Oklahoma on May 9, 2016.