Storm could affect morning rush hour traffic Tuesday in San Diego County

A cold Pacific storm will drop into San Diego County before dawn Tuesday and drop up to a quarter-inch of rain in coastal areas and nearly twice as much across some inland valleys, foothills and mountains, says the National Weather Service.

The leading edge of the storm will begin producing sporadic showers late Monday night, followed by the core of the system on Tuesday. The storm is expected to reach North County first, then spread south and east.

It is possible that thunderstorms and lightning will break out at Camp Pendleton, especially near the border of Orange and San Diego counties.

The surf will reach 3 to 5 feet in some spots, with occasional sets of 6 feet, on Tuesday. The afternoon high tide will rise to 4 feet 9 inches at 4:33 p.m.

Forecasters say motorists descending the east side of the mountains along Interstate 8, near the border of San Diego and Imperial counties, could face 35 mph winds. And drivers are likely to encounter tall, swirling columns of dust as they continue on toward Phoenix.

The winds will produce unusually cold temperatures. San Diego’s daytime high is expected to only reach 68, seven degrees below average. Other projected highs: Oceanside, 68; Mira Mesa, 67; San Ysidro, 67; Julian, 52; Palomar Mountain, 51; and Mount Laguna, 48.

The storm will be followed on Wednesday and Thursday by warmer weather and possibly weak offshore winds that would minimize the marine layer. The winds will be tied to the storm, rather than the formation of Santa Ana winds, forecasters say.