Predicting weather

Associated Press

SEATTLE – Weather experts hope they soon will be able to do a better job of predicting precipitation.

How much moisture will fall has always been tough to forecast, even with the best methods and when experts know snow and rain is on its way. It’s especially tricky in the wet Northwest, which is prone to flooding.

About 100 scientists and technicians are taking part in a four-week effort to study mountain storms like never before. It started last week with an airborne exhibition over the Cascade Mountains in a P-3 aircraft called “hurricane hunter.”

In the five-hour flight, scientists gathered the most comprehensive data ever on what happens when clouds collide with mountains and moisture falls from the sky, The News Tribune of Tacoma reported Monday.

“This is very practical stuff, not ivory tower research,” said Nick Bond, a research meteorologist at the University of Washington and the National Oceanic and Atmospheric Administration. “We’re trying to do things that directly help forecast precipitation.”

Bond is one of the participants in the study. He and several colleagues flew along the spine of the Central Oregon Cascades, while a UW research plane also made its way through the same storm.

Teams of researchers in the foothills below released weather balloons that took measurements as they floated up through the clouds. In addition, scientists on the ground pointed radars into the sky, while others in four-wheel-drive vehicles caught snow flakes and examined them on chilled microscope slides before they melted.

“It’s an amazing collection of observational assets never brought together before,” said UW meteorologist Cliff Mass, who is overseeing the project.

By studying how precipitation falls, scientists hope to improve weather and flood forecasts.

“Right now, it’s very hard for us to predict how much rain is going to fall, how much snow is going to fall,” said Bradley Colman, the National Weather Service’s Seattle science officer. “This should help us figure out what we’re doing wrong.”

The P-3 hurricane hunter is operated by the National Oceanic and Atmospheric Administration. The crew, based in Tampa, Fla., chases tropical storms and hurricanes in the Pacific Ocean all summer. The rest of the year, the plane goes where the weather is worst.

The seats have industrial-strength seat belts and shoulder harnesses, but it can still be a rocky ride, said veteran pilot Capt. Dave Tennesen. A steel pipe runs along the cabin roof, serving as a handrail for passengers to grab when the plane hits turbulence. During Hurricane Hugo several years ago, a life raft broke loose and slammed into the pipe, making an impressive dent.

“We left it there to remind folks what a hurricane can do to you,” Tennesen said.

Meteorologists use computer models for weather forecasts. The models have improved over the last 10 years, but it’s still not easy to predict precipitation amounts, Colman said.

Precipitation in the Northwest typically starts out as snow, released from clouds as they’re forced up and over mountain ranges, he said. The P-3 tracks the entire process, flying a series of 100-mile-long north/south passes as the front approaches, then crosses, the peaks. The air crew calls the grid-like pattern “mowing the pasture.”