An excellent article about it from Cal Matters.
“We were flying about 200 nautical miles off the coast of California when a voice over the headset reported a strong smell of fuel in the back of the plane.
“I was in the cockpit with the U.S. Air Force’s “Hurricane Hunters,” who spend the summer and fall flying into the eyes of hurricanes. On a Tuesday at the end of January, though, we flew out of Travis Air Force Base in California toward a different kind of storm: an atmospheric river that was moving east across the North Pacific, toward the West Coast.
“All right, you have my attention,” pilot Lt. Colonel Jeff Ragusa said through his headset.
“Talk to me, Goose.”
“The smell, it turned out, was a false alarm: a maintenance bucket that one of the crew had converted into a trashcan was contaminated with traces of fuel. “The crew is a little gun shy,” Ragusa told me. A fuel leak had forced them to end their last flight early.
“The mission was to investigate an atmospheric river, a massive stream of water vapor and wind that condenses into rain and snow when it rises to flow over mountains. Just a few of these winter storms drop up to half of California’s yearly precipitation and have ended more than a third of the state’s persistent droughts.
“But atmospheric rivers are also estimated to have caused about $43 billion of flood damage across the West over the past 40 years — including the $1.1 billion disaster when the Oroville Dam spillway crumbled under a deluge in 2017.
“Knowing where and when these storms are going to hit and how much rain or snow they’re likely to drop is key in a region that reels between too much water and not nearly enough. Especially since climate change is expected to make these devastating cycles of drought and floods even worse.
“That’s why scientists like Anna Wilson, field research manager with the Center for Western Weather and Water Extremes at Scripps Institution of Oceanography, have teamed up with the Hurricane Hunters and the National Oceanic and Atmospheric Administration to collect data during atmospheric river fly-overs.
“The presence or absence of atmospheric rivers can mean the difference between a drought year or a non-drought year,” said Wilson, who followed the Hurricane Hunters’ flight from the ground. But, she said, “Too many, or too strong, you can get into hazards. It’s crucial to understand them for California, and the whole West Coast.”
“The Hurricane Hunters’ mission is part of a five-year state, federal, and local effort to improve forecasts of these storms, so dam operators and emergency responders know whether to prepare for dangerous flooding or store water for a dry spell.
“On this flight, the crew was tasked with shooting oblong scientific instruments called dropsondes into the atmospheric river, where they collect information about temperature, pressure, humidity, and wind as the tubes parachute to the ocean’s surface.
“The dropsondes radio a stream of data back to the crew on the plane; from there, it goes out via satellite to the National Hurricane Center and weather databases around the world. But less than two hours after the phantom fuel false alarm, we were turning around before firing a single dropsonde into the atmospheric river.
“One of the crew had spotted actual fuel streaming past the right wing. An extra tank had sprung a leak, ending the mission early. I asked Ragusa, the pilot, how it felt. “Terrible,” he said. “It’s showing up for a sporting event and hearing that your team is forfeiting. It’s just, we don’t like to do it.”
“A simultaneous Hurricane Hunters flight out of Hawaii managed to complete a similar circuit over the western end of the atmospheric river. And a few days later, the crew flying out of Travis successfully shot 24 dropsondes into the storm. Within hours, the research was helping shape forecasts of the atmospheric river that days later hammered Washington with rain, leaving flooding and landslides in its wake.
“Mother Nature doesn’t usually work that way.”
“Right now, forecasters can see an atmospheric river coming a few days ahead of time, according to Marty Ralph, Wilson’s colleague and director of Scripps’ Center for Western Weather and Water Extremes. But the details are foggier.
“The forecast’s location, for instance, can miss the mark by around 200 miles, Ralph said. That means flooding expected on the Russian River, which wanders south through wine country before taking a turn toward the Pacific Ocean, can instead hit the Eel River, which flows northwest from Lake County.
“The goal is to narrow forecasts of the future by improving observations of the present. If you want to predict an atmospheric river, Ralph said, “We need to know where it is at the beginning.”
“The idea is that more accurate forecasts and longer lead times could help reservoir managers better gauge whether to store water for a dry spell or make room for floods.
“Like the Goldilocks syndrome, we want just the right amount,” said Jay Jasperse, chief engineer and director of groundwater management with Sonoma Water. “Not too much, because then we’re dealing with flood, and not too little — because then we’re dealing with droughts. But Mother Nature doesn’t usually work that way.”
“It’s a balancing act that scientists predict will only become more challenging as climate change worsens the state’s wet and dry extremes and shrivels the snowpack — a natural reservoir socked away on mountainsides rather than behind dams. This year’s snowpack was only 49 percent of normal on Feb. 24, California’s Department of Water Resources reported.
“Atmospheric river research from the sky already helps that balancing act through a pilot project at Lake Mendocino, the Mendocino County reservoir that resulted from the completion of the Coyote Valley Dam in 1958.
“Lake Mendocino is one of 36 dams the U.S. Army Corps of Engineers owns and operates in California, according to Nick Malasavage, chief of the operations and readiness division for the U.S. Army Corps of Engineers San Francisco District.”
Retrieved February 26, 2020 from https://calmatters.org/environment/2020/02/california-drought-floods-atmospheric-rivers-reservoir-management-hurricane-hunters/