Under the Weather : High Tides, Storms to Mount Double-Edged Assault on County

San Diegans will get it from both sides this weekend when the highest tides in 17 years pound the coast and thunderstorms pelt the mountains, according to the National Weather Service.

The welcome news is that the forecast for points between the shoreline and the mountains is for sunny skies and pleasant temperatures today through the weekend, forecaster Wilbur Shigehara said. However, forecasters are keeping watch on Hurricane Hilary and Tropical Storm Irwin, both of which are moving up the Baja California coast.

The highest astronomical tides in a 17-year cycle will surge onto county beaches at 9:16 p.m. Saturday as they reach a height of 7.8 feet, Shigehara said. Tides will not reach that level again until 2004, he added. Normally, high tides are in the 4- to 5-foot.

Though such tide levels are classified as “dangerous,” it’s unlikely they will cause any harm in San Diego. That’s because the time at which they will occur and the absence of very strong hurricane activity in the Pacific Ocean have lessened concerns about possible injuries or property damage, according to Shigehara.

Not Strong Enough

“Though Hurricane Hilary (currently 825 miles south of San Diego) may increase our surf slightly, she is not strong enough to cause us real concern about property damage,” he said. “Also, there aren’t many people in the water at 8, 9 o’clock at night, so it won’t affect most of the people visiting the beaches this weekend.”

“Surf will be rougher than normal because of these tides, so people going out to the coast to watch for them should exercise caution,” Shigehara said. “Though the surf should not be big enough to crash into houses, it will most likely crash onto the walkway at Pacific Beach, and might come close to lapping onto the different piers.”

Other “dangerous” high tide levels will be at 8:27 tonight and 10:03 p.m. Sunday, when surf reaches the 7.6-foot mark.

A flash-flood watch was issued for the county’s mountain areas at 1 p.m. Thursday, and thunderstorms brought .61 of an inch of rain to Campo and between .10 and .50 of an inch to most other mountain areas, according to Shigehara.

The storm activity is expected to peak today, though the chance of an isolated thunderstorm or two will continue through Saturday evening.

“There’s some very large thunderstorms moving through our mountains, and it’s raining pretty darn hard,” Shigehara said. “This instability will slowly be going away over the weekend as the high-level winds switch to the southwest.”

These thunderstorms were also the cause of the high clouds above San Diego’s coastal and inland areas Thursday, he said. The clouds kept the high temperature at Lindbergh Field at 76 degrees, a degree below normal for the date.

The high cloudiness is expected to disappear as high pressure builds today through the weekend, with sunny afternoons following night and morning coastal low clouds, he said.

However, Hurricane Hilary might disrupt that forecast, as segments of the storm move into the San Diego area as early as Saturday night, according to Shigehara. And if Hilary doesn’t, Tropical Storm Irwin might, he added.

“Hilary is the wild card throwing our forecast out of whack,” Shigehara said. “When a hurricane breaks up, the clouds that were wound tightly around it have to go somewhere. If these clouds get caught in some of the high level winds headed toward San Diego, we’ll have a much cloudier weekend than we planned.”

High temperatures along the coast will be in the 75- to 79-degree range today through Sunday, with lows between 64 and 68 all three days. Surf will be between three to five feet, with ocean temperature near 68 degrees.

Inland highs will range from 80 to 88 degrees through the weekend, with overnight lows between 60 and 65 degrees through Sunday.

Mountain areas will also have highs between 80 and 88 all three days, with lows in the 55- to 62-degree range through Sunday. Desert highs will be between 104 and 110 through the weekend, with overnight lows in the upper 70s and low 80s through Sunday.