Literally the day after a dire report of the bleakest snow conditions in 500 years for the Sierra Nevada, snow began falling. It's not much and certainly won't matter for the four-year drought, but it's welcome.

The system was forecast to bring rain to the Valley Fire area, and a dusting of snow above 7,000 feet in Northern California, Idaho, Utah, and Colorado.

In Lassen Volcanic National Park, Caltrans closed Highway 89 Wednesday because of snow. The closure was from the southern boundary to the junction with State Route 44.

Already, social media is lighting up with photos of Mammoth Mountain in the Central Sierra getting a good coating of snow earlier this week, and other resorts getting snow overnight into Wednesday. Utah and Colorado also got a good dusting, with snow flurries continuing across the Western United States.

Earlier in the week, hydrologists lamented the lack of snow, and this week's scant flurries won't change the dire conditions.

"Snowpack conditions in the Sierra Nevada mountains present an ominous sign of the severity of this drought," said Valerie Trouet, a tree-ring specialist at the University of Arizona and lead scientist on the study. "We were expecting that 2015 would be extreme, but nothing like this."

The melting Sierra snowpack is important to the state's water supply because it traditionally provides at least one-third of California's water each year through the state's network of reservoirs, and also replenishes the groundwater in its deep aquifers.

Wet winter?

The promise of a wet fall and winter appears to be increasing as forecasters see El Niño conditions strengthening across the Pacific with tropical ocean temperatures rising toward record highs, said Daniel Swain, a Stanford graduate student who maintains the highly regarded California Weather Blog.

But that promise is speculative, and it doesn't necessarily mean this winter's Sierra snowpack will be any better than last year's, said Swain, who is not a part of the study.

Swain, a member of Stanford's Climate and Earth System Dynamics Science Group whose scientists have tied the drought to the increased pace of global warming, noted that while the future impact on California of the strengthening El Niño conditions in the tropical Pacific are uncertain, the evidence that the Pacific Ocean's water temperatures are rising is clear.

"El Niño conditions tend to shift the odds away from a dry winter," Swain said. "And water temperatures should be higher than normal."

Don't expect much snow

It means, he said, that while precipitation in the highest peaks of the Sierra this winter may fall as snow, at lower elevations, where most of the snowpack normally lies, the precipitation could be falling as rain.

Whatever happens with El Niño this year, Swain noted, even the wettest winter on record can't make California recover from this historic drought. It could help refill the state's reservoirs, he said, but a single wet winter can't refill the state's major underground aquifers like those beneath the Sacramento and San Joaquin valleys on which so much of California's agriculture depends.