Correction: This story originally included a tweeted report that Caltrans had used salt on a freeway off-ramp in Oakland. The agency says that report was untrue and that it does not use salt.
Parts of the Bay Area woke up Monday morning to a pounding from the heavens -- hailstorms that coated roads, roofs and yards in some Oakland and Alameda neighborhoods with enough icy precipitation to make everyone stop and say, "Whoa! What the hell is going on here?"
The accumulation of hail -- possibly along with a related form of "soft hail" called graupel -- immobilized some drivers in the Oakland hills.
Here's a photo from an Oakland teacher who said she was forced to stop while crossing the hills to get to work:
The icy pummeling also prompted slowdowns on suddenly treacherous roads in the Oakland hills, including Skyline Boulevard, Redwood Road and Highway 13.
Significant hail was also reported on parts of the Peninsula and in downtown San Jose.
The hail is the result of thunderstorms that built in unusually cold, unstable air behind the storm front that passed through the Bay Area on Sunday. The National Weather Service Bay Area forecast office says there's a chance for scattered thunderstorms -- and thus for hail -- for much of the day.
Here's the Monday morning hailstorm via Twitter: