La Nina Continues to Cast Dry Spell

It didn’t rain much last month, and it doesn’t look as though it’ll rain much this month, either. Blame La Nina.

Total rainfall at the Los Angeles Civic Center in December was a scant 0.54 of an inch, and so far in January--normally the wettest month of the year here--there hasn’t been a drop.

It has happened a few times before. During the La Nina winter of 1975-76, only 0.32 of an inch of rain fell in December, and none in January.

Although not record-setting, this is still one of the driest winters--thus far--since they started keeping records in Los Angeles in 1877. And meteorologists are not surprised.

“It still looks pretty much like a classic La Nina condition,” said Guy Pearson, a meteorologist with WeatherData Inc., which provides forecasts for The Times.

“Southern California’s a little drier than normal, with warm days, cool nights and more Santa Ana winds than usual,” he said. “I don’t see much of a change any time soon. There might be a few sprinkles as far south as the Bay Area later this week, but Southern California should continue dry for at least the next five to six days.”

Forecasters say the La Nina oceanographic and meteorological phenomenon is the widely anticipated counterpoint in Southern California to last winter’s drenching El Nino. The disparate meteorological patterns are generated by fluctuating ocean surface temperatures in the equatorial Pacific.

During typical El Nino winters, like last year’s, high-altitude Pacific jet stream winds are intensified and extended all the way across the ocean to California and Baja California. Large low-pressure centers over the central Pacific spin off an unusual number of storms, and the amplified storm track funnels more precipitation than normal into Southern California.

During typical La Nina winters--and thus far, it appears to be one--a large ridge of high pressure tends to remain anchored over the northern Pacific, diverting the jet stream and its accompanying storms well north of Southern California.

During seven of the eight previous La Nina winters that have occurred since 1949, Southern California experienced subaverage precipitation. The average annual rainfall in downtown Los Angeles during those La Nina years was 11.61 inches. The overall average since 1877 is 15.14 inches.

Total rainfall thus far this meteorological season, which runs from July 1 through June 30, is 1.87 inches. The normal total for the date is 5.75 inches, and last year’s total was 7.85 inches.

State officials say that even if this winter remains drier than normal, there is little threat of drought.

Subterranean water tables are high, and reservoirs throughout the state still brim with runoff from last year’s rain.

Pearson said Los Angeles should have mostly sunny days for the rest of the week after some morning clouds and low fog. Temperatures should be a little cooler, with highs in most areas in the mid- to upper 60s.