Chasing storms

Storm chaser photographer Brad Mack watches thunderstorms supercells pass through areas in Kamay, Texas, April 23, 2014.

Thunder storms on Wednesday were a precursor of what's forecast for this coming weekend, that could be the most significant multi-day tornado outbreak in the U.S. since 2011.

Storm Chasers

Storm chaser photographer Brad Mack checks out the radar on his laptop as thunderstorms supercells pass through areas in Erick, Okla., late April 23, 2014.

Storm Chasers

Huge lightning strikes cross the skies as thunderstorms supercells pass through areas in Archer City, Texas, April 23, 2014.

Storm Chasers

A storm chaser photographer looks at thunderstorms supercells pass through areas in Vinson, Okla., late April 23, 2014.

Storm Chasers

Huge lightning strikes hit the ground along a highway as thunderstorms supercells pass through areas in Kamay, Texas, April 23, 2014.

Storm Chasers

A large TVS (tornadic vortex signature) thunderstorm supercell passes over storm chaser Brad Mack in Graham, Texas, April 23, 2014.

Storm Chasers

A large TVS (tornadic vortex signature) thunderstorm supercell passes over Newcastle, Texas, April 23, 2014.