Giant, 30- to 40-foot waves battered parts of the West Coast from Washington State south to Los Angeles, prompting warnings and even an unheard of tweet from the National Weather Service (NWS).
“STAY WELL BACK FROM THE OCEAN OR RISK CERTAIN DEATH,” the NWS San Francisco office posted on Saturday on Twitter, hoping to warn surfers about the perilous dangers of these giant waves.
The NWS issued high-surf alerts along the coast beginning on Sunday and running through Tuesday, and warning people to be careful on beaches and along jetties.
[ >> Trending: SEE: Surfing legend Kelly Slater pulls off unbelievable pipeline recovery ]
Another social media post from the NWS, this one from the Portland office, included a photo of the Tillamook Rock Lighthouse with waves crashing over the top of it. The top of the structure is 134 feet above sea level.
The director of the University of Georgia's Atmospheric Sciences program, Marshall Shepherd, told Live Science that the huge waves were caused by a low-pressure system centered in the Gulf of Alaska, and that while the waves can grow to dozens of feet high, they fortunately don't travel inland like tsunami waves.