Researchers with the PACJET (Pacific Landfalling Jets Experiment) released preliminary results of their flights into Pacific winter storms today at a press briefing in Monterey, Calif. Marty Ralph, PACJET's chief scientist from the Environmental Technology Laboratory in Boulder, Colo., said the experiment has already succeeded beyond what they had expected.

"We've gathered many new types of data that have not been possible before and delivered much of it in real time to National Weather Service forecasters," said Ralph. "We've tested the use of the NOAA P-3 aircraft as a Doppler weather ‘radar-in-the-sky' that can be sent into the heart of approaching storms. We are just beginning to learn how to observe the storms in the most useful ways and how to take most advantage of these data."

NOAA's WP-3D "hurricane hunter" has been the flying laboratory where much of the data have been collected. Crewed by a team of pilots, meteorologists, engineers and technicians from NOAA's Aircraft Operations Center in Tampa, Fla., the plane has been flying out of Monterey, Calif., directly into the storms. Captain Bob Maxson, NOAA Corps, director of NOAA's Aircraft Operations Center, says that "By flying directly into the storm, the P-3 can collect data that would otherwise not be available. Land-based instrumentation can't provide it - nor satellites. It takes a strong aircraft and a determined crew to go right to the heart of the storm and get those data, no matter how turbulent the wind is or how hard the rain is falling." Maxson says these data go into computer models to improve future forecasts, and also go to weather forecasters here on the West Coast so they can significantly improve their current predictions.

NWS forecasters throughout the West Coast frequently used data from the PACJET experiment in their forecasts during the last month, issuing winter storm forecasts for areas likely to experience heavy rains, high surf conditions and snowfall. "Weather forecasters rely on many data sources to issue forecasts, including numerical weather models, satellites, Doppler radar, and their unique knowledge of the topography of an area," Ralph said. "Being able to use current weather data from the P-3 aircraft and other sources used during the experiment has given forecasters the confidence to issue more timely and detailed forecasts."

Warren Blier, science and operations officer at the NWS Forecast Office in Monterey, said the data have been invaluable. "In the Feb. 12 mission, one of our objectives was to collect meteorological data over the Pacific that would aid in more accurately forecasting the powerful storm that struck Southern California later that night. As part of this effort, the aircraft flight track was designed to cut through the heart of the developing storm. As these same numerical forecasts are used throughout the United States, the potential forecast benefits of this data are enormous as they are applied to a much larger area than that of the initial region of storm landfall in Southern California."

PACJET also investigated how to better use NOAA satellite data. Scientists from NOAA's Satellite Service and the University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies conducted the GOES rapid-scan Winds Experiment, which produced greatly enhanced wind measurements over the ocean by tracking cloud motions using a special strategy for the Eastern Pacific. These wind measurements, as well as new polar-orbiting satellite products from Colorado State University's Cooperative Institute for Research in the Atmosphere, were important to mission planning and forecasting for PACJET, and will help support the post-analysis of other PACJET data.

In addition to the PACJET experiment, NOAA has also conducted a Winter Storm Surveillance Program (WSP). "The WSP has tasked the NOAA G-IV hurricane surveillance jet to fly over large regions of the Pacific Ocean to take real-time measurements of wind, temperature and moisture. The WSP will utilize these measurements to improve numerical model guidance employed in winter storm forecasts by using a new "targeting strategy" created at NOAA's Environmental Modeling Center, that indicates where data are most needed for improving the forecasts," said Zoltan Toth, lead scientist of the G-IV Winter Storm Program. Preliminary results from this winter's flights show about 70 percent of the forecasts targeted have been improved by the data from the G-IV.

According to Ralph, WSP and PACJET take differing, but highly complementary, approaches to aiding in West Coast storm prediction. "WSP focuses on the use of dropsondes targeted to improve numerical model guidance 24-48 hours before a storm reaches the coast, while PACJET focuses on providing data directly to forecasters to aid in the shorter-term forecast, up to 24 hours before a storm's landfall. PACJET also aims to improve understanding of the basic physical processes that determine the detailed rainfall and wind patterns in the storms."

These emphases require different observations. WSP uses high-altitude and fast aircraft to deploy dropsondes based on novel mathematical techniques, while PACJET uses the airborne radar capability of the P-3 and other new observing systems such as coastal wind profilers and improved satellite techniques to document conditions in the storms just offshore and as they strike the coast. The WSP and PACJET efforts will be brought together for six days at the end of February when the G-IV will fly out of Monterey in support of the PACJET experiment.

"After the PACJET experiment ends on March 3, we will begin assessing what we have learned from this winter's intensive efforts and start planning for the future," Ralph said. "This winter, we have been putting many new types of data directly into forecasters' hands for the first time."

Relevant Web sites:
PACJET: http://www.etl.noaa.gov/programs/pacjet
WSP: http://sgi62.wwb.noaa.gov:8080/ens/target/wsr2001.html