The National Weather Service has surveyed the damage from Saturday night/Sunday morning's storm damage in Okmulgee County. The NWS said in a tweet that damage was caused by straight line winds.
NWS-Tulsa Twitter: We surveyed extensive damage in the Okmulgee and Morris areas today and determined the damage to be the result of straight-line wind. The damage swath was up to six miles wide at times and indicated wind speeds approached 90 mph in spots.