UPDATE (7:18 p.m.):

The tornado warning has been allowed to expire. 

The National Weather Service says the storms which prompted the warning have weakened below severe limits and have exited the warned area. 

However, hail and gusty winds are still possible with the thunderstorms in east-central Natrona County. 

A severe thunderstorm watch remains in effect until 10 p.m. for central Wyoming.

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Original Story:

A tornado warning is in effect for the Casper area until 7:15 p.m. Monday.

The National Weather Service is urging people to get inside immediately.

A confirmed tornado was located just west of Bar Nunn at 6:40 p.m., 11 miles north of Casper. Other weak tornadoes are also possible in north-central Natrona County.

The tornado is moving north at 30 mph. Ping pong ball-sized hail is expected as well.

The tornado was confirmed by emergency managers.

The tornado was expected to be near Antelope Hills at about 6:45 p.m. and Teapot Rock at roughly 6:55 p.m.

The warning includes I-25 from mile marker 190 to mile marker 234.

People in the north-central part of the county are urged to take cover immediately by moving to a basement or an interior room on the lowest floor of a sturdy building. Avoid windows.

Anyone outdoors, in a mobile home or in a vehicle should move to the closest substantial shelter and protect themselves from flying debris.

Motorists should not take shelter under highway overpasses. If you can't safely drive away from a tornado, either park your vehicle and stay put, or abandon your vehicle and lie down in a low-lying area and protect yourself from flying debris as a last resort.