SEATTLE (AP) - Long droughts and more winter rain than snow could become common in the Northwest and threaten the region's water supply, fish and more, climate scientists here said Friday.

The Cascades are in trouble if climate projections from new studies for the coming decades are accurate, said Edward Miles, leader of the Climate Impacts Group at the University of Washington.

Northwest temperatures will increase by about 3 to 6 degrees Fahrenheit by the 2040s, and the Cascades snowpack will decline by 59 percent by 2050, Miles said.

"If you think about this in terms of risk management, it's past time to buy some insurance," Miles said in reporting the findings at the annual meeting of the American Association for the Advancement of Science.

"And the insurance is planning. It takes 20 years to change a water supply system, so time's a-wastin'."

"These results are more dramatic than past results because we have more improved models that include much greater climate detail," Miles said in an interview.

He also reported on a new University of Washington study with scientists from the University of Colorado that examined 800 snowpack records from 1950 to 2000 for the entire West.

Although he declined to give details because the findings have not been published, Miles said both computer models and direct observations tell the same story about the past half-century: About 75 percent of the West has seen declines in spring snowpack in excess of 30 percent in low to middle elevations.

He added that the Cascades have been particularly hard-hit, along with mountain ranges in Northern California.

Philip Mote, research scientist with the University of Washington Climate Impacts Group, and Martin Clark of the University of Colorado found that the Cascades' average April 1 snowpack had decreased by 60 percent between 1950 and 2000.

"I was expecting to see only a zero to 30-percent decline," Mote said in an interview.

They also found that average temperatures had increased by between 2.5 and 3.5 degrees Fahrenheit at many sites throughout Oregon and Washington since 1920.

"What these observations emphasize in surprising detail is that the projections for the future are already coming true," said Mote, who is the Washington state climatologist.

Mote said that the largest snowpack declines in the West are projected to be in the Cascades, where they have been for 50 years.

Miles and his colleagues attribute the snowpack losses primarily to temperature increases. The Northwest has had a 1.5 degree increase in average annual temperature in the past century, nearly a half-degree more than the global temperature increase.

In addition, the scientists project that summer drought seasons will lengthen by about a month to six weeks.

"Spring flow peaks will come earlier and won't be as large," Miles said, which will put more demands on water from the Columbia and other rivers.