A persistent storm from the Gulf of Mexico is on a one-way track to Southern California, where it will bring San Diego its fair share of thundershowers today and Saturday, the National Weather Service said.
It is rare for San Diego to get any thunderstorm activity as early as May, National Weather Service forecaster Wilbur Shigehara said, and rarer still that a storm that originated in the gulf ever reaches Southern California.
"This type of subtropical weather we usually don't see until around the Fourth of July or so," he said. "Some very strong upper-level winds have been carrying this storm toward us for almost a week, through northern Mexico, Texas and Arizona. . . . It's as if it was aiming for us."
While the official chance of rain for the coastal and inland areas was set at between 20% and 30%, Shigehara said he "wouldn't be surprised at all" if there are periods of heavy rain today through Saturday morning.
The mountains and deserts will bear the brunt of the storm, with heavy rains, thunder and lightning expected to last through Sunday.
"We might be issuing a flash-flood watch (today) in the mountains and deserts if they do receive the amount of rain we think they will," Shigehara said.
Saturday afternoon will be partly cloudy as the storm moves out of the area, with the typical May/June pattern of night and morning low clouds clearing to afternoon sunshine Sunday.
Not only will the clouds persist in all areas through at least Saturday, the mugginess will continue as well. Humidity reached 70% along the coast on Thursday and 60% in inland areas. Shigehara said 50% humidity along the coast and 40% for the inland areas is normal for this time of year.
Daytime temperatures, however, were as close to normal as possible on Thursday, with the 68-degree high at Lindbergh Field the exact average for that date. The overnight low was 62, four degrees above average.
Coastal areas will have highs between 68 and 72 today and Saturday, nudging up two or three degrees Sunday as more sunshine breaks through. Lows will be in the upper 50s and low 60s.
The surf will be unaffected by the storm for the most part, remaining in the three- to five-foot range through Sunday. Ocean temperature has warmed up to 65 degrees.
Inland highs will be in the 70- to 80-degree range today, between 72 and 82 Saturday and between 75 and 84 Sunday. Lows will be in the mid-50s.
Mountain highs will range from 70 to 77 all three days, with lows in the upper 40s to mid-50s.
Deserts will have highs between 93 and 98 today and Saturday, jumping up to between 100 and 105 degrees on Sunday. Lows will be between 55 and 65.