The warning is for the southern part of the county, along I-5 from Redding to Anderson, according to the NWS Sacramento.
Residents are advised to take shelter.
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Officials say half-dollar-sized hail could accompany the tornado.
A viewer sent ABC7 News photos of the tornado cell:
A Tornado Warning to our north in Shasta County and my friend sends me these pics of the cell from her back porch near Redding. Wow. pic.twitter.com/9IS7sOxooL— Drew Tuma (@DrewTumaABC7) May 25, 2019
Go here for tips on how to prepare for a tornado.