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Forecast cloudy for coastal predictions Mail Tribune / Jim Craven Hydrologist Bill Ludwig, with the National Weather Service in Medford, stands atop Mount Ashland near a Doppler radar station. A professor in Washington says Doppler stations are needed on the coast, where weather can change in a few minutes. Tom and Denise Winter love to explore the Pacific Ocean's colorful underwater world when they dive around rocks and pinnacles off the coast of Brookings. "It's so beautiful with different corals and fish," said Tom Winter, a Central Point contractor. "It's a wonderful world." But the Rogue Valley divers never cross the Chetco bar in their 36-foot-long boat without first checking weather forecasts. On the Oregon coast, however, weather predictions may not be dependable, partly because there's no Doppler radar close to shore, a University of Washington scientist says. "Right now, we are blind offshore," said Cliff Mass, an atmospheric sciences professor who helps create forecast models used on Internet sites, newspaper weather pages and television broadcasts. "We can't see the area's precipitation and we can't determine low-level winds that are offshore because we don't have the radar coverage." Mass has been lobbying the National Weather Service to put Doppler radar systems at Florence and Westport, Wash. Right now, the closest Doppler radar systems are on Mount Ashland and Camano Island, Wash., both a mountain range away from the ocean. Part of the problem is that the Doppler on top of Mount Ashland is at 7,000 feet in elevation, said Dennis Gettman, science operations officer with the National Weather Service in Medford. Because of the angle of the radar beam and the curvature of the earth, by the time the echoes reach Brookings 53 nautical miles away, they are measuring at 14,400 feet, too high to accurately record precipitation and wind. "In the Northwest, we have shallow precipitation systems," Mass said. "Once you clear 10,000 feet, you are above most of the action. So it's very important that we see very low with the radar." Sometimes, the lack of information has a big impact on people. One stormy day in November 1996, for example, by the time the Mount Ashland Doppler beam reached the Coquille River 90 nautical miles away, it was measuring only one inch of rain at the 18,700-foot elevation. But more than 5 inches filled rain gauges on Earth, where the Coquille River had spilled its banks and stranded some residents. If Doppler doesn't properly observe the physics of the atmosphere, the computer programs that generate forecasts from its data will be wrong, Gettman said. "If the observation is inadequate, the best mathematical equations in the world won't come up with the right answer," he said. Incorrect forecasts give river dwellers less time to evacuate, said Dave McDaniel, a sheriff's sergeant and emergency manager for Coos County. "Almost all the coastal counties are very prone to flooding - the entire Coquille River Basin, along with the Coos River and Melicoma River," McDaniel said. While it may improve predictions, a Doppler won't help a tugboat pilot who's in the middle of a 2,156-nautical mile journey to Hawaii, said the dispatcher for Sause Brothers. The Coos Bay company has 31 barges and tugs that carry lumber and commodities such as boats and cars to many ports. "There's not much we can do except tell the guys, 'There's a storm coming - get ready for it,' " said dispatcher Tim Creager. Creager gets his weather information from a variety of sources, including Internet sites that show real-time pictures beamed from satellites 22,300 miles in space. He also depends on data from sea; Sause Brothers pilots are among spotters that radio information to the National Oceanic Atmospheric Administration station in Kodiak, Alaska. "It takes more than just Doppler to say, 'This storm is coming or not coming,"' Tim Creager said. "We depend on real-time reports from vessels at sea." Neither can Doppler offer boaters information about waves, said Dan Thompson, harbor master for the Port of Brookings Harbor, which has nearly 700 boats parked in its slips. "Doppler radar gives you aerial information but it doesn't tell you much about sea conditions," Thompson said. "For the mariner, we may not care whether it's overcast, raining or sprinkling. We'll work in the rain and wind. We care about sea conditions." If the federal government added a Doppler on the coast, it would be one more source of information to aid the U.S. Coast Guard station on the Chetco River in Brookings, which is responsible for search and rescue, law enforcement and marine protection from Crescent City to Cape Blanco. But nothing beats first-hand knowledge of the sea, said Boatswain Mate Chief Mike Lewis. "People need to spend time watching the ocean and learning it," Lewis said. "A boater might see the bar flat and calm and shoot across it. But then a series comes in with larger swells and they start having problems." Before he crosses the bar, Winter, the Central Point diver, checks the Internet, especially the National Weather Service's marine observations page. He can get wind speed, water temperature and swell heights collected by a NOAA buoy bobbing off the Brookings' shore near Point St. George. "You have to watch the seas, watch the wind and watch the Coast Guard flags," Winter said. "I've been out on the boat when it's been perfectly nice and clear, but when I come up from diving 40 minutes later, it's blowing and nasty out. "The weather can change that quickly on you." Radio waves key to Doppler The Doppler radar on top of Mount Ashland has an antenna that sends out radio waves. Objects in the air, such as raindrops, snow crystals, hail stones or even insects and dust, scatter or reflect some of the radio waves back to the antenna. The radar electronically converts the information into pictures showing the location and intensity of precipitation. The pictures are transmitted to computers at the National Weather Service office in Medford. The Doppler radar also measures the frequency change in returning radio waves. The computer uses the information to show direction and speed of the winds blowing around the rain drops, insects and other objects that reflect the radio waves. Scientists and forecasters use these pictures of wind motions to predict what's likely to happen in the atmosphere in the next hour or two. Source: www.usatoday.com/weather/wdoppler.htm Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.