PORTLAND, Ore. (KOIN) — Though “atmospheric river” (AR) may not be a household term, the concept is fairly basic: a corridor of concentrated moisture that sits in the atmosphere. Essentially, an AR is a river in the sky that can help scientists measure how much rain or snow could make landfall at any given time.

AR’s can carry an equivalent of about 25 times the amount of water in the Mississippi River as water vapor, according to the National Oceanic and Atmospheric Administration (NOAA). Strong winds can create extreme rainfall and floods, often stalling over watersheds vulnerable to flooding.


So to proactively study these large bodies of moisture, NOAA routinely employs what are known as atmospheric river reconnaissance flights. These missions entail a crew flying up into the AR’s and gathering data from the inside of a storm.

“In case people wonder how on earth do you get four feet of snow or five feet of snow in the cascades in one day? How is that possible? Well, it’s because of these rivers of moisture that come all the way from deep in the tropics all the way up to the Pacific Northwest,” said NOAA Flight Director Henning.

KOIN 6 News’ Chief Meteorologist Natasha Stenbock recently hopped aboard a reconnaissance flight up and over the Pacific Ocean and the Aleutian Islands of Alaska — an eight-hour, 4,000-mile journey that all happened at about 600 miles per hour at 45,000 feet!

Dr. Forrest Cannon of UC San Diego’s Scripps Institution of Oceanography said of the Pacific Ocean, “It’s a large expansive region and we really don’t have any other observations other than from satellites that can tell us about where this weather system currently is, how it’s evolving.”

The crew flew on top of the AR and released foot long tubes packed with instruments called “dropsondes,” which measures several characteristics of an AR. The information recorded gets transmitted to the ground, undergoes quality control, and is then ingested into computer models that forecast our weather.

“On its way down, it is collecting temperature, humidity, winds and pressure,” said Dr. Cannon. “And from that, the information can go back into the global scale models.”

These efforts go into the global weather models the KOIN 6 Weather Team uses to bring you the most accurate forecast in the region.

“It could mean the difference between a catastrophic flooding or not necessarily getting anything to be worried about,” said Dr. Cannon.