For people living in and traveling through the mountain regions in the western United States, winter weather can be unpredictable. This week, the National Oceanic and Atmospheric Administration begins a month-long research project to learn more about snow and rain in mountain areas with the ultimate goal of improving future winter weather forecasts.

The Intermountain Precipitation Experiment is a field project designed to improve the understanding, analysis and prediction of precipitation and precipitation processes in complex terrain. Thirty scientists from several NOAA organizations and the Universities of Utah and Oklahoma will gather data from Jan. 31 to Feb. 25 in the Wasatch Range of northern Utah based out of the National Weather Service Forecast Office in Salt Lake City.

The major scientific objectives of IPEX are to understand the causes and variation in mountain precipitation and to study lake-effect precipitation downwind of the Great Salt Lake. The researchers will use the data they gather to validate precipitation estimates produced by Doppler weather radars located at high elevation. Ultimately, what the scientists learn during IPEX will be used to improve computer-based forecast models employed by forecasters in mountainous regions.

"During the past nine years, the fastest growing states have been Nevada, Arizona, Idaho and Utah. The steep terrain in this area makes it one of the most difficult places to forecast snow and rain," said project co-lead scientist Dr. David Schultz, research meteorologist with NOAA's National Severe Storms Laboratory in Norman, Okla. "Future analysis of the data we collect during IPEX should allow scientists to develop better understanding of the structure and evolution of these weather systems, eventually leading to better forecasts."

A variety of sophisticated atmospheric observing platforms will be used during the experiment. The NOAA P-3 research aircraft, equipped with meteorological instrumentation and radars, will fly into the storms. On the ground, scientists will release instrumented weather balloons from two NSSL mobile laboratories. Three mobile Doppler weather radars and a stationary microwave radiometer will be deployed throughout northern Utah to map areas of clouds and precipitation.

Weather balloons will be released three to eight times a day at National Weather Service sites near Boise, Idaho; Grand Junction, Colo.; Salt Lake City; Elko and Las Vegas, Nev. These measurements will enhance an existing surface observing system known as the Mesowest Cooperative Networks coordinated by the University of Utah.

The impact of IPEX will be far-reaching.

"The results from IPEX will have positive scientific and scio-economic benefits for the intermountain west, including Salt Lake City, host of the 2002 Winter Olympics," said Dr. James Steenburgh, meteorology professor at the University of Utah and IPEX co-lead scientist. "Local forecasters will use the data on a real-time basis during the experiment and the results will be used in future weather forecasts."

IPEX is lead by Schultz and Steenburgh; Dr. Jeff Trapp, NOAA/NSSL, Boulder, Colo.; and Dr. David Kingsmill, Desert Research Institute, Reno, Nev. Organizations collaborating on the project are the University of Utah and the National Weather Service Forecast Office in Salt Lake City; National Severe Storms Laboratory and Storm Prediction Center in Norman, Okla.; the NWS Hydrometeorological Prediction Center in Camp Springs, Md.; and flight crew members from NOAA's Aircraft Operations Center at MacDill Air Force Base in Florida. The scientists will be joined by 20 meteorological students from the Universities of Utah and Oklahoma.

Additional funding for the project was provided by the Utah Department of Transportation to purchase surface observing systems for IPEX observation sites.