By Jim Purpura. Posted September 10, 2011, 11:10 AM.

An area of low pressure near Point Conception will remain there much of this weekend. This will lead to sharply cooler temperatures, with some places ten to fifteen degrees below normal for this time of year. The low will also bring more unstable air above the surface, and is beginning to pull monsoonal moisture across the high desert into southwest California.

Severe thunderstorms occurred across Orange County this morning....and at 11:15 am Saturday morning storms with hail up to 3/4 inch diameter were moving toward the cities of Riverside and San Bernardino.

Isolated heavy rain and hail are possible. Fire starts are possible where lightning strikes dry vegetation outside the rain areas. A Flash Flood Watch is in effect this afternoon for the mountains of Ventura County.

The chance of storms will continue most areas into Sunday.

Jim Purpura

jpurpura@weathercurrents.com

Weekend thunderstorms over the mountains, deserts and perhaps the Inland Empire (National Weather Service)