Rainy Weekend? It’s Up to Selma the Unpredictable

It will probably rain again this weekend. But once again, the big question is how much.

It all depends on our old friend, Selma, according to Mike Smith, a meteorologist for WeatherData Inc., which provides forecasts for The Times.

Selma, a tropical weather system that has been hanging around off the coast of Baja California for the last few days, is causing all the uncertainty.

On Tuesday, the disturbance appeared to be in a race for the Southern California coast with another weather system, blowing in from north of Hawaii. The other system got here first, and that accounted for the showers, heavy at times, that fell on the Los Angeles Basin on Wednesday night and Thursday morning.

Those showers, which snarled both evening and morning rush-hour traffic, dropped .18 of an inch at the Los Angeles Civic Center on Thursday, with about half an inch in some of the foothill communities.

The rainfall at the Civic Center raised the season’s total for Los Angeles to 1.07 inches, which compares with 2.68 inches by this time last year and a normal total by Oct. 29 of .54.

Smith says that if Selma had won the race, the storm would have been whipped into Southern California by the winds circulating around the other weather system. If that had happened, we would have gotten a lot more rain on Thursday, something more like the 3.5 inches or so that fell in the San Fernando and San Gabriel valleys last week.

But, although Selma lost that race, the stubborn system is not through, Smith said. In fact, another race is brewing between Selma and a brand new storm that is blowing toward the California coast from the northwest.

This new storm, which Smith described as “the first winter-type low-pressure system of the season,� is expected to get here this weekend, bringing along some more showers that will fall late Saturday and early Sunday.

Because the new storm, born in the Arctic, will be coming from the northern Pacific, the accompanying temperatures will be on the cool side, with downtown highs in the 70s on Friday and Saturday, and perhaps in the high 60s on Sunday.

Smith said the rain in Southern California will probably be “pretty light.� That is, unless Selma starts moving north again.

He said that if that happens, Selma could get caught in the winds circulating around the new storm and get sucked in here about the same time it arrives, “and that could mean a lot of rain.�

He’s not saying it will happen. But it might.