There's a metal sign in the road, on the bottom left, that isn't in pictures of this intersection that I can recall seeing before.
Pretty common at major intersections back then for LAPD traffic detail to roll "No Left Turn" signs out for rush hours (remember when it was only an hour or two?) or other congested times and then roll them back onto the sidewalk afterward. IIRC, this practice ended with the adoption of left-turn-only lanes, etc. Traffic in the photo doesn't look bad at all, so maybe the lads didn't get around to putting the sign back after the morning rush..
Photo taken at 3:20 p.m. (Assuming the clock isn't broken.)
Shadows suggest closer to early afternoon to me, FWIW.
I see Charlie Barnet is playing at the Palladium!
Johnny Magnus likes to tell the story about his slogan: "Swing and sway with Sammy Kaye? Well, swing and sweat with Charlie Barnet!"
And, as it happens, KPOP and predecessors and successors have had quite a run:
https://www.radioheritage.net/Story28.asp