Overnight, David Hutchinson shared that photo of the Thursday afternoon crowd at Alki – and also overnight, the National Weather Service updated its forecast for this first day of West Seattle Summer Fest. The “heat advisory” remains in effect till 9 tonight, and the projected high could reach the low 90s. Fabled forecaster Cliff Mass, though, thinks it could be as much as 7 degrees below Thursday’s high, which was a recordsetting 95 at Sea-Tac Airport. Back at the beach, David noticed this:

Was it an algae bloom? He points out a possible one was reported here on WSB exactly a year ago, also during hot weather.