Rainy Season Gets Off to a Rather Dry Start : Weather: First 6 1/2 weeks are not promising. But experts say it is too soon to tell whether a sixth year of drought will occur.

California’s rainy season is nearly 7 weeks old but so far hardly deserves the name.

With only one good storm on record, rainfall is already three inches behind what is considered normal for this time of year.

But water officials, accustomed to the vagaries of California weather, insist that it is far too early in the season to draw any conclusions about the kind of water year that lies in wait for the state.

“We’re still wallowing in the drought, that’s for sure,” said Bill Helms, a hydrology expert for the state Department of Water Resources. “But you can’t really get concerned until about the first of February. By the end of February, if you don’t have anything yet, then you don’t have much time left.”

Another dry winter would plunge the state into a sixth year of drought.

The rainy season in California runs from the first of October to the end of May, but the heavy-duty rainfall, the downpours that fill the reservoirs and saturate the ground, typically occur in December, January and February. What happens before then is normally just a prelude.

Those three critical winter months usually provide more than 50% of the state’s annual rainfall and produce average monthly rainfall in the Sacramento River Basin of 8.3, 8.8 and 7.9 inches respectively. October, by contrast, averages only 3.2 inches and November, 6.6. The Sacramento River Basin normally provides much of the water used by Southern California farms and cities.

This year, after an ignominious beginning, October produced above-average rainfall statewide. In the Sacramento basin, rainfall was 106% of normal.

Disturbing to water officials was the small amount of runoff that came from the storm. After five years of drought, Helms said, the ground was so parched that it soaked up everything that fell on it.

“The concentration of rain is more important than the volume sometimes,” he said. “If we had had another storm right after that first October storm it would have been very good. Even another day of rainfall could have produced four or five times as much inflow” as the reservoirs received.

Even more discouraging, November debuted with the return of the same dry, sunny days that accompanied the early weeks of October. By midweek, precipitation for the year had dropped to about 60% of normal.

“None of us know as we begin this rainy season whether in fact it will be a rainy season,” resources head Douglas Wheeler said Friday at a Water Education Foundation conference. “We are planning on the assumption that we will have another dry year. We are making plans against that possibility.”

Although strict conservation policies enabled most of the state to cut back on water use this year by as much as 30%, Wheeler said all municipal water districts are required to submit plans by January for reductions of up to 50%.

Wheeler said the state is not ready to impose mandatory rationing, but officials want to have standby plans in case statewide rationing becomes necessary.

If there is a sixth year of drought, he said, the state will have slightly more water in storage than it did at the beginning of the fifth year of drought because of this year’s conservation efforts. State reservoirs are now about 60% full.

Long-range weather forecasts tend to conflict. The 90-day forecast provided to the Department of Water Resources by the National Weather Service suggests below-normal precipitation in November, December and January for most of California.

WeatherData Inc., a private firm that provides forecasts for The Times, has a more optimistic view. Its forecast for December, January and February calls for above-normal rainfall in Southern California from Ventura south and normal rainfall in the rest of the state.

With normal rainfall in the critical winter months, the State Water Project is likely to be able to resume full deliveries next year although it would not be able to refill depleted reservoirs. Last February, the water project stopped deliveries to agriculture and gave its urban customers only 30% of what they requested. The Metropolitan Water District, which serves Southern California and Los Angeles, is one of the project’s biggest customers.

“I’m not quite as pessimistic as the weather service,” said Mike Smith, a certified consulting meteorologist and president of WeatherData. “I think I see a pattern that will develop this winter that will give the state at least normal rainfall.”

Smith said a storm system seems to be developing in the Pacific and he is hopeful that it will reach Northern California by the middle of this week.

In the meantime, snow was reported falling in the Sierra on Thursday and WeatherData meteorologist Steve Burback said he expected a smaller storm to arrive there today.

Despite the dry weather in early November, some ski resorts in the Lake Tahoe region have managed to stay open.

Department of Water Resources meteorologist Bill Mork said in an advisory to his agency that there were other factors that could affect California rainfall this year but it was too soon to tell whether they would produce wet weather. He said an El Nino, which is an unusual warming of the equatorial Pacific Ocean off the coasts of Peru and Ecuador, seemed to be developing. In past years, he said, full-blown El Nino episodes were associated with extremely wet years while weak or moderate El Ninos coincided with dry years.

The volcanic eruption in June of Mt. Pinatubo in the Philippines, he said, could also affect weather patterns but how is unknown.

“If this current stable, dry pattern maintains itself through November, we will obviously be very concerned about the following winter months,” Mork said. “However, there are currently no signals which tell us this current dry pattern will be maintained for a long period of time. It’s just too early to speculate what winter will bring.”