Reports of snow in Los Angeles set social media abuzz with photos and video of frozen precipitation falling from the sky Thursday. Some people were tagging their posts with #snowmageddon.
In most cases the National Weather Service was unable to confirm actual snow fell. The precipitation was likely hail or gaupel, said NWS meteorologist Kristen Stewart.
Social media proclamations, photos and videos claimed possible snow in urban zones such as West Hollywood, Eagle Rock and Pasadena. It did fall in the Santa Monica Mountains above Malibu, Stewart said, and reports of snow in nearby communities such as Westlake Village, Thousand Oaks and Calabasas were likely true.
The National Weather Service's Twitter account responded to one video post claiming snow in Thousand Oaks: "Correct, that is snow! Lots of confusion today. If precip bounces it contains ice - call it sleet or small hail. If precip in flakes it's snow, white balls are melted flakes called graupel."
The NWS says measurable snow hasn't fallen in downtown Los Angeles since 1949, and Thursday's sightings weren't likely to change that.
Snow did fall in the usual places, including in the San Gabriel and San Bernardino mountains. Snow fell in areas with elevations as low as 1,000 feet in parts of greater Los Angeles, Stewart said, but precipitation was spotty.
The portion of Interstate 5 known as the Grapevine, which connects northern Los Angeles County to the Central Valley farm region, was closed for a few hours Thursday as about an inch of snow accumulated on the roadway, said Sgt. Michael Karr of the California Highway Patrol.
A cold front from Canada pushed down temperatures and attracted moisture that fell in Las Vegas overnight and in parts of Southern California on Thursday, Stewart said.
The Clark County School District in Las Vegas said in a statement that school and after-school activities were canceled Friday "due to reports of potential freezing conditions on the roads that would be unsafe for school buses during the morning commute."
On Thursday, the high temperature in downtown Los Angeles was 57 degrees, according to the NWS.
A nighttime freeze warning was issued for Los Angeles County, with some temperatures early Friday reaching low enough — 29 to 32 degrees — to temporarily preserve any possible snow.
San Diego, Riverside and San Bernardino were the subjects of a winter storm warning Thursday night, but the cold front was expected to blow through by morning, Stewart said.
Federal forecasters called for sunny skies over the weekend and above-normal temperatures in Southern California by next week.