After the driest December in 22 years, and a January that was merely damp, California weather watchers are hungry for any whiff of change in the air.

So when news seeped out that this winter's cursed La Niña conditions may at last be weakening, some of those eager observers began to pine for a repeat of the legendary "Miracle March" scenario of 1991 that helped California break a long drought.

Not so fast, say the forecasters.

The pattern is definitely shifting, but so far there are few signs of really big storms on the horizon that could salvage the ski season and stave off drought.

"I don't see it being a similar pattern," said Jim Mathews, a meteorologist at the National Weather Service in Sacramento. "To hang your hat on a wet March, I think the odds are not in our favor."

The weather service dug up some stats on the 10 driest November-through-January periods in Sacramento since the Gold Rush. This winter made the cut at No. 10.

Then it looked at how many of those winters, after January, concluded with above-normal rainfall. Only three did, including 1991.

Hence the long odds.

"We continue to do our snow dances, I can tell you that," said Andy Chapman, chief marketing officer at the North Lake Tahoe Chamber of Commerce. "We do whatever we can to help the skies open up a little bit."

Tahoe's ski industry went without natural snowfall over the economically vital Thanksgiving and Christmas holiday stretch. Many ski resorts managed to open terrain using snow-making machines.

But even now, after a handful of decent storms in January, Tahoe's major ski resorts don't have all their terrain open.

Chapman said hotel bookings in the region have "slipped a little bit" compared with last winter. But those who do visit are taking advantage of the mild weather to try less typical winter activities, including kayaking and paddleboarding.

"It's not our first rodeo, so to speak, where we've had weather issues," he said. "Tahoe is a resilient bunch up here."

La Niña is, in fact, weakening. But that doesn't necessarily guarantee more storms. The weather pattern, a cooling of the equatorial Pacific Ocean, is a fickle performer in Central California.

Last winter, La Niña brought heavy snow and rain to the region, including 13.6 inches of rain-equivalent precipitation in December 2010 over the Northern Sierra, a region critical to statewide water supplies. That's 160 percent of normal.

December 2011, however, got only 0.3 inches over the same region, just 4 percent of average and the lowest since 1990.

La Niña was at work in both seasons. The difference was another phenomenon called the Arctic oscillation, said Bill Patzert, a climatologist at NASA's Jet Propulsion Laboratory in Pasadena.

Last winter was dominated by a negative Arctic oscillation, which causes cold air circling the North Pole to drop farther south. This drove more cold, wet storms out of Canada into the United States.

This winter, the Arctic oscillation stayed positive from early November through mid-January, keeping all that cold air locked up in the north.

Now the oscillation is negative again, which explains the bitter cold and snowy conditions that have swept Europe lately, Patzert said.

"We should see this coming week, I think, a similar pattern across the U.S., where the jet stream comes down across the Sierra all the way into Texas," he said. "But let's get right down to it. The last day of winter is March 20. It had better hurry up if that negative oscillation is going to bail us out."

A storm concluding this morning and another coming Sunday will bring no more than a quarter-inch of rain to the Sacramento region, and maybe 8 inches of snow to Tahoe ski resorts, Mathews said.

Another storm is expected next weekend and may be wetter. But it's too soon to be sure.

"We've had some years that have been late bloomers, and some that have not," said Maury Roos, chief hydrologist at the California Department of Water Resources. "We're cautiously optimistic, but I would not expect average (snowpack) at this point. We're too far behind."

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Call The Bee's Matt Weiser, (916) 321-1264. Follow him on Twitter @matt_weiser.

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