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California Update: Here Comes El Nino

 While much of the West suffers through an epic drought that has contributed to a deadly fire season, state and local officials are bracing for a severe El Nino winter that could bring substantial rain along the Pacific Coast and significant snowfall in the mountains.

 

California, expected to bear the brunt of the storms, may suffer the worst of both worlds. Forecasters say that massive storms could uproot trees, cause mudslides and trigger flooding without making much of a dent in a four-year drought.

 

That drought, which afflicts portions of eight other western states, has taken its heaviest toll in California, the nation’s most populous state and an agricultural bread basket. Brown is the new green in many communities as lawns have been allowed to die or have been replaced with desert vegetation. Some 560,000 acres, about one-seventh of the Golden State’s croplands, lie fallow. Many of the state’s reservoirs are down to a third or less of capacity and the snowpack in the Sierra is 5 percent of normal. Tree ring studies say this is the lowest snowpack in 500 years.

 

A healthy snowpack is a prerequisite for drought relief. Snowpack functions as a frozen reservoir, accumulating over the winter and melting during spring and summer to provide water for rivers and streams. Last April, in an iconic scene, California Gov. Jerry Brown (D) issued a clarion call for water conservation in a barren Sierra meadow that normally would have been covered by several feet of snow.

 

California residents responded to Brown’s call by reducing urban water use by 31 percent, more than the governor had sought. Previously sacrosanct agriculture has also been required to contribute. Early in the summer the State Water Rights Board ordered more than l00 growers and irrigation districts with some of the oldest water rights in California to stop drawing supplies from hard-pressed streams and rivers in the Central Valley.

 

Despite these efforts, the drought has tightened its grip. State climatologist Michael Anderson said that’s because the drought has been accompanied by record high temperatures that dry out vegetation and stress the environment, including reducing stream flow for native fish.

 

The combination of drought and high temperatures has spurred wildland fires, which this year are burning hotter and covering more ground because of the dry vegetation. California wildfires have burned more than 800,000 acres, destroyed hundreds of homes and caused six deaths. In Washington State wildfires have burned more than 500,000 acres. Three firefighters died in August battling the Okanogan Complex fire, a massive combination of five wildfires in the north-central section of the state.

 

Nationally, the amount of land burned by wildfires has surpassed nine million acres, most of it in the West, according to the National Interagency Fire Center. With at least six weeks left in the fire season in many parts of the region, wildfires may consume a record acreage before winter storms ease the danger.

 

These storms could be exceptional. Weather forecasters are counting on El Nino, a climate condition that occurs when ocean temperatures increase in the equatorial Pacific Ocean, sometimes bringing cooler and wetter weather to the southern United States, southern California in particular. Not all El Nino winters are wet, but this one has the potential, according to Bill Patzert, a climatologist with NASA’s Jet Propulsion Laboratory, of being a “Godzilla El Niño.” State and local emergency officials, aware of recent flooding after record rain in the Carolinas, are heeding the warning. Many California communities are stockpiling sandbags, trimming trees and clearing debris from river and stream beds that are bone dry now but could quickly pose a flood danger in a storm.

 

The March rains of 1991 caused extensive damage and California is more susceptible to weather-related calamities now because of population increases – 38 million people compared to 30 million in 1991 – and increased building on vulnerable hillsides and flood plains. State climatologist Anderson said that because of drought and high temperatures the tops of hillsides are drier than the bottom portions of the hills. This creates an instability that makes slides more likely in a heavy downpour.

 

For California, the benefits of a wet El Nino winter depend in large measure on where the rain and snow falls. Three-quarters of the population and urban water demand is in Southern California; nearly three-quarters of the state’s water storage facilities are in the north. Much of the rain that falls in the southern part of the state runs off into the Pacific Ocean, while precipitation in the north is captured in Lake Shasta and various reservoirs or, if cold enough, in the Sierra snowpack. Until recently, the National Oceanic and Atmospheric Administration (NOAA) had limited its predictions of substantial winter precipitation to Southern California with prospects for the north more problematic. But the latest forecasts have boosted the likelihood of El Nino rains all the way to the Oregon border.

 

The timing of the predicted storms is also an issue. The NOAA forecasts suggest that storms won’t arrive in California with force until after Jan. 1, narrowing the window for any precipitation. In California, most of the rain comes in the winter months. Even late March storms are relatively infrequent. In 1991, before the March miracle storms, many forecasters had given up on the rainy season and were reconciled to another year of drought.

 

All of the present forecasts come with caveats. Four of the last six El Nino winters produced no more than average rainfall on California’s central coast. Forecasters last year predicted a wet winter that never came. It’s also worth noting that a wet El Nino, if it comes, won’t help everywhere. El Nino winters are typically dry in the Northwest, for instance. Washington usually has ample rain, but Gov. Jay Inslee earlier this year issued drought proclamations for 24 watersheds, mostly because hot weather had, as in California, deprived the mountains of snowpack.

 

In addition to a deeper snowpack, water experts in California are hoping that the anticipated storms will benefit communities that depend on groundwater. For example, cities in Orange County, home to Disneyland, get about half their water from an underground aquifer that is dependent on rain and recycled water. The aquifer now is nearly depleted.

 

But even a very wet winter would not end the drought, climate scientists say. Writing in the New York Times, Stanford scientists Noah S. Diffenbaugh and Christopher B. Field said that California was too hot and dry for a winter’s rain to make a lasting difference. Global warming, they said had doubled the odds of the drought continuing. Theirs is not an isolated view. Writing in the journal Science Advances earlier this year, scientists from NASA, Columbia and Cornell relied on tree-ring studies to suggest that California may be in the beginning phase of a 35-year mega-drought of the sort that contributed to the extinction of the ancient Pueblo peoples, or Anasazi, of the Colorado Plateau.

 

However that may be, Californians with long memories do not have to rely on tree rings to know what a stormy El Nino season can bring. In the winter of 1982-83, after another four-year drought, El Nino-related storms triggered floods and coastal mudslides, killing 36 people and causing $1.2 billion in damage. So, in the popular saying, be careful what you wish for. California needs the rain, only not too much of it too fast.