The New York Times


March 21, 2006

More Western Drought, but With a Twist

DENVER, March 20 — Spring is here, and the West is dry and ready to burn. Winter is over, and the West is snowpacked and facing flood.

Meteorologists say both are true. What it adds up to, when the extremes of wet and dry are averaged out, is that the long Western drought, which began in the late 1990's, is still on but without some of its past punch.

"This year the magnitude of the variability is probably greater than we've seen in as long as I can recall," said Mike Gillespie, a snow survey supervisor for the Natural Resources Conservation Service, a federal agency that monitors soil and water conditions.

The Arkansas River is a case study in the region's bipolar condition. It drains the Colorado Rockies south and east toward Kansas and is socked with snow at its headwaters around the town of Leadville, where the snowpack is nearly 140 percent of average for mid-March. Just a few hours south on the river, however, are places that have not had significant precipitation since October and are setting records for drought.

Damage from wildfires is setting a record, too. From eastern Colorado to Oklahoma and Texas, nearly 1.8 million acres have burned this year, the most for any Jan. 1-to-March 20 period in at least the 10 years since current record-keeping began and probably many years more, according to the National Interagency Fire Center, which coordinates state and federal wildfire efforts.

Nor does the end seem in sight: a worse-than-usual fire season, especially in the Southwest and on the central and southern Plains, was predicted last week by the National Oceanic and Atmospheric Administration, even as areas around Lake Tahoe in California were buried by up to 14 feet of snow.

In some ways, experts say, the climatic situation is less dire than in past drought years. Experience itself has helped, with states and cities across the West adopting conservation policies, new monitoring systems and information-sharing operations that allow faster responses and better planning.

The variability in the drought's punch has also helped. Places like Arizona, southern Utah and New Mexico, which are now parched, got lots of precipitation last winter, meaning the reservoirs around the region are in generally better shape than they would otherwise be. A major storm on the plains of eastern Colorado and western Kansas last October put months' worth of moisture into the soil, buffering the drought's effects there as well.

But scientists and government officials say the roller-coaster pattern has also underscored the fact that an uncertainty of water supply is becoming engrained in planning and Western life.

"When two out of three, or three out of four years are bad, the issue that's being driven home is how much competition there is for water in the West," said Michael J. Hayes, a climate impacts specialist at the National Drought Mitigation Center at the University of Nebraska-Lincoln.

Dr. Hayes said that in the ever more urbanized West, rolling water shortages highlighted all the tensions of land use and development, in issues like wildfires, endangered species protection and the conflict between recreation and agriculture in places where a reservoir can be important for tourism and equally crucial to farmers.

Those off-and-on shortages can be downright dispiriting, too. "In the Southwest, everybody was so excited about last year," Dr. Hayes said, referring to the wet winter of 2004-5. "But the cautious among them were saying it could be a blip, and now we've gone back to the dryness, so the enthusiasm is gone."

Colorado's total snowpack — a crucial measure of the West's hydrologic health, because those snows feed so many important rivers — is expected to come in below average again this year, as it has for eight of the last nine, according to federal figures. The northern mountains have lots of snow, but the southern do not.

The flow of the Colorado River, which supplies water to millions of people across the West, is also projected to be below average, though just slightly. The river has had only one year above average in the last seven, according to the Upper Colorado River Commission, an interstate agency that administers it.

Some experts think a spate of storms that occurred in early March could nudge the river's numbers toward average, but with the snow season approaching its end, much more than that is unlikely.

"We're pretty much running out of time," said Tom Ryan, a hydrologist with the federal Bureau of Reclamation in Salt Lake City.

Meteorologists say two factors have built and reinforced the current variability of climate: a weak La Niña pattern along the Equator in the eastern Pacific — water temperature slightly cooler than normal — combined with an active storm track that has brought numerous storms squarely into the northern Rockies while leaving areas to the south untouched.

The confluence of forces, they say, is fairly rare and has in the past resulted in strange and sometimes violent turns of weather, including a heightened risk of what are called tornado outbreaks, in which clusters of twisters form at once. On March 12, as many as 100 tornadoes touched down in five states from Illinois to Oklahoma, killing 10 people. On April 3-4, 1974, when the atmospheric pattern was similar, as many as 148 tornadoes struck the Midwest in a single day, by all accounts the worst outbreak in American history.

A weak La Niña combined with an active storm track can also draw moist warm air north from the Gulf of Mexico toward Colorado, Wyoming and New Mexico, creating a potential for other types of mayhem, including especially powerful thunderstorms along Colorado's Front Range, said John F. Henz, a meteorologist and senior project manager at HDR Engineering, a company that works on flood control projects and meteorological consulting. The conditions for that flow of air are now right for the first time in years.

Mr. Henz emphasized that this did not necessarily mean the flow would occur, but he said it could.

"It appears the atmosphere is ready to rock 'n' roll," he said.