Sporadic showers from a large but lackadaisical storm that stalled for days off the coast of California are expected to continue into Wednesday as the Southland nears the end of its rainy season.
Meteorologist John Sherwin said the heaviest rain from the storm will probably fall today, with a quarter- to a half-inch expected at the Civic Center and about twice that much in the foothills and mountains.
Sherwin, who works for WeatherData Inc., a firm that provides forecasts for The Times, said the on-again, off-again showers that began Saturday are the product of a classic "cutoff low"--a vast but relatively weak low-pressure system that has fallen off the main jet stream storm track "like a drop falling from a stream of water."
Abandoned over the eastern Pacific late last week by the powerful, high altitude winds that keep most northern hemisphere weather systems moving steadily to the east, the stalled storm, rotating counterclockwise, has been spinning band after band of light precipitation inland across California.
"When a storm gets cut off like that, it behaves like a knuckle ball pitch in baseball, and you can't tell where it's going to go," Sherwin said. "This one's sort of been sitting there, and at one point it even started moving to the southwest, which is counter to the way storms are supposed to move in this hemisphere."
Finally, about midday Monday, another weather system well to the north set off a ripple of air that started nudging the storm toward the California coastline, Sherwin said. He said the center of the storm should move into Central California early this afternoon, bringing substantial rain to most of the state.
"A quarter- to a half-inch of rain in Los Angeles may not sound like much, but it's quite a bit for this late in the year," he said.
Only about 0.3 of an inch of rain normally falls on the Civic Center during May, so it looks as though long-range forecasts calling for at least 25% more rain than normal this month will prove correct. By Monday evening, the showers in some areas of the Los Angeles Basin were increasing in intensity, bringing May's rainfall total to at least 0.24 of an inch, with 27 days still to go.
The 0.05 of an inch of rain that fell in downtown Los Angeles during the day Monday raised the total for the season--which runs from July 1 through June 30--to 28.10 inches, almost twice the normal total for the date of 14.6 inches. As the showers continued late Monday, forecasters said those totals would increase.
Sherwin said that although El Nino is responsible for the forecast of more rain than usual this winter and spring, it probably had little to do with the current storm.
Meteorologists say the widely discussed oceanographic and meteorological phenomenon is weakening rapidly and is expected to disappear within a few months.
"El Nino's not having that much effect in Southern California any more," Sherman said.
Showers from the current storm are expected to continue into Wednesday, with partial clearing Wednesday afternoon.
After that, Sherwin said, Southern Californians probably will get a preview of "June gloom," with foggy, overcast mornings giving way to hazy, partially cloudy afternoons through the weekend.