The above graphic shows Severe Thunderstorm (blue) and Tornado (red) Watches currently in effect via the SPC in Norman, OK. You can go here for specifics on the valid times of the individual watches.
Strong to severe thunderstorms are in progress from northwest Texas to northeast Arkansas, as shown by the radar mosaic below:
At present, it appears that the storms over both northwest Texas and northeast Arkansas have the greatest potential of producing a tornado. All of the storms are capable of producing large hail and damaging winds.
The radar image below shows a close-up of the storms near Abilene in northwest Texas. Tornado Warnings are currently in effect for the areas in the purple polygons:
These dangerous storms are moving East at 20-25 mph and have produced tennis ball sized hail.
Other strong to severe storms are in progress across portions of the Northeast:
...and western Kentucky: