Just about perfect July weather for the next few days. The chance for hot weather is gone for now since weak ridging is forecast overhead instead of a strong ridge. So expect light onshore flow through early next week. Of course the ebb & flow of marine air regulates the amount of morning cloud cover too.
You may be wondering why we get the onshore flow to start with? In the warm season the continent (North America) is much warmer than the ocean. Rising air produces lower pressure at the surface inland, which creates a flow of air from ocean to inland or "onshore flow". But it’s a bit more complicated than that. Upper level disturbances moving by can increase the onshore flow, such as yesterday’s cold front. If we get a strong ridge overhead, rising surface pressure inland can even briefly turn the flow offshore for awhile. That’s our hot easterly wind…very rare in the summer. So it all comes down to the wind always trying to move cool air inland, and occasional ridging slowing down the onshore flow, letting us warm up. It’s a constant battle between the two from June-September…Mark