SAN FRANCISCO (CBS SF) — A winter storm could wreak havoc on holiday travel and shut down the main artery connecting Northern and Southern California on Christmas Eve.

The National Weather Service issued a warning to holiday travelers on the Tejon Pass through the Grapevine for Thursday and Friday.

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Rain, ice, snow and winter conditions on Interstate 5 through the Grapevine could create travel problems.

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“The combination of snow and wind will lead to very hazardous conditions for anyone venturing into the mountains,” warned the NWS statement. “Roads will be icy and road closures are a strong possibility.”

“Even just an inch of snow will wreak havoc on the Grapevine,” said NWS meteorologist Dave Bruno.

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Snow levels will start around 5000 feet Thursday, lowering to near 2000 feet by Friday morning impacting the Grapevine, Tehachapi Pass and Walker Pass.