Atmospheric River on EARTH Magazine

Rivers in the sky: Improving predictions of atmospheric rivers to reduce risk

Fri, 03 Aug 2018 11:29:41 -0400

Atmospheric rivers are long, narrow weather systems that carry large amounts of moisture from the tropics into the midlatitudes. This NOAA illustration of a system stretching from the tropics around Hawaii to the U.S. West Coast, with darker blue shades representing greater amounts of precipitable water, depicts an atmospheric river that drenched Northern California in April 2018. Credit: NOAA National Environmental Satellite, Data, and Information Service.

In early February 2017, authorities in Northern California ordered more than 180,000 residents around the Oroville Dam to evacuate over concerns that heavy rains might cause the dam’s spillway to fail. The rains were brought by an atmospheric river (AR) — a long, narrow system of moist, tropical air that can deposit enormous amounts of water — adding to an already wet season for the U.S. West Coast. ARs occur around the planet, but certain regions — including western North America, where moisture from the tropics near Hawaii is repeatedly delivered by recurring “Pineapple Express” events — are especially prone.

Comment: Atmospheric rivers increase water supply in California — but only to a point

Fri, 10 Feb 2017 14:26:42 -0500

Atmospheric rivers are concentrated bands of water vapor that can stretch thousands of kilometers across the ocean, bringing tremendous amounts of moisture to the U.S. West Coast. Credit: NOAA ESRL.

December and January were very wet months in California, together landing in the top five of wettest two-month periods on record in Northern California. The abundant precipitation has restored soil moisture, refilled reservoirs and caused minor flooding. This is a big — and welcome — change from the past five years of record drought. Much of the improvement can be attributed to the return of atmospheric rivers flowing in from the Pacific: unique storms that are both a blessing and challenge for California water managers.

Sahara dust brings rain and snow to California

Thu, 28 Feb 2013 19:10:41 -0500

Researchers flying over the Sierra Nevada during winter storms in 2009, 2010 and 2011 collected data on the chemical composition of particles suspended in the air from a plane and on the ground, and then combined those data with cloud and particle data from satellites. Courtesy of Kimberly Prather

Ready for takeoff. Scientists flew through storms to measure aerosols to determine if and how aerosols affect winter precipitation in California. Courtesy of Kimberly Prather

One of the field sites in the Sierra Nevadas where researchers sampled winter precipitation. Courtesy of Kimberly Prather

What triggers the mountain rain and snow that are vital to California’s water and energy needs? The answer, according to new research, is blowing in the wind: dust and bacteria from as far away as Africa’s Sahara Desert.

Hazardous Living: Preparing for the storm of the century

Thu, 05 Jan 2012 06:41:58 -0500

A 'Pineapple Express' (known scientifically as an atmospheric river) over the Pacific in December 2010. NASA GOES Project, Dennis Chesters

Megan Sever (pictured at Yellowstone) writes Hazardous Living for EARTH. Megan Sever

They’re calling it “California’s Other Big One” — the giant storm that could drop more than two meters of rain on California and cause massive flooding, landslides, levee failures and general catastrophic chaos. It’s probably not that hard to imagine this year for water-weary Californians who have been hit hard by heavy rains and subsequent floods and landslides since early winter. But for now, the “other big one” is just a “what if” scenario put forth this week by researchers and government officials in order to help Californians know what to expect and how to react if and/or when such a storm does hit.