EF0 tornado in Pawnee County, Oklahoma

This is the first segment of a three segment tornado. The tornado developed over Keystone Lake, west of Appalachia Bay Recreation Area. The beginning of this tornado was filmed by storm chasers. The tornado moved east-southeast across the lake waters and adjacent uninhabited land areas. Damage is strongly suspected to trees in this segment of the tornado but those suspected areas were not accessible by road. The tornado continued into Osage County, Oklahoma.

Severe thunderstorms developed during the afternoon hours to the east of a surface low pressure system located over southwestern Oklahoma and near a stationary frontal boundary that was draped across northeastern Oklahoma. Several of these storms developed supercell characteristics due to a very unstable air mass that was in place over the region coupled with strong vertical wind shear. These supercells produced several tornadoes, including a strong tornado that resulted in a fatality in Sand Springs. The storms also produced hail up to softball size and wind gusts to around 90 mph.

The storms evolved into a line during the evening hours and moved swiftly across eastern Oklahoma producing wind damage and hail to golfball size.

Locally heavy rainfall as a result of storms moving repeatedly across the same locations resulted in flash flooding. Two flash flood fatalities occurred in Muskogee County when a vehicle was driven into flood waters and was swept off the road.