For most of us, the reliability of the weather forecast is a minor concern, a question of whether to take along an umbrella or to when to quit watering the yard.
But to the managers of California's vast water systems, the question is more critical. A badly-timed decision can worsen the long-term effects of a drought on one hand, or allow a catastrophic flood on the other.
So on the cusp of the rainy season, managers at the Sonoma County Water Agency would very much like to know what the next few months will bring, weatherwise. With two unusually dry years behind them, supplies of water are dwindling, particularly in Lake Mendocino, which is down to a little more than a third of its maximum capacity. A solid prediction about the weather over the next couple of months would let engineers know whether to breathe a sigh of relief or tighten up even more for a bad summer next year.
Unfortunately, the forecasting tools available to them aren't any better than those used by your local TV news show. And even big picture indicators, like the cyclical El Nino phenomenon in the Southern Pacific, aren't offering any clear suggestions of what to expect this year.
"It has an equal chance to be incredibly dry, or to be incredibly wet. Or somewhere in the middle," said Don Seymour, principal water agency engineer. Scientists "don't have a strong indicator of what this year could be."
Realistically, the best weather forecasters can do for worried water managers is give an indication of patterns up to perhaps a week in the future, engineers say. And the longer the range of the forecast, the less reliable those forecasts become.
"The tools we have available to us, frankly, aren't great," agency Chief Engineer Jay Jasperse said. "We feel we're making the best of what's out there."
But that hazy picture of the weather future could be changing, thanks to new research and a network of detailed monitoring stations being built along the West Coast, starting with a new facility installed this month near Bodega Bay.
"I fully expect to see improvements over the next decade" in long range weather forecasting, said Marty Ralph, director of the Center for Western Weather and Water Extremes at the Scripps Institute of Oceanography.
In his former job as a scientist for the National Oceanic and Atmospheric Administration, Ralph led pioneering research in the Russian River watershed into understanding the effects of "atmospheric rivers," long, narrow plumes of moist air that gather along the boundaries of cold fronts and are responsible for as much as half of all precipitation that drops on the West Coast.