Uploaded February 2025 | Updated September 2026, 1 day ago
Since Jan. 31, NOAA satellites have been closely monitoring a series of strong atmospheric rivers bringing heavy rain and mountain snow from central California to the Pacific Northwest, the Sierra, southern Cascades, and northern Rocky mountains.
Atmospheric rivers are long, narrow bands of concentrated water vapor that transport moisture from warm tropical oceans to higher latitudes. In these regions, heat from the sun causes large amounts of water to evaporate into the atmosphere. When this humid air meets the mountains along the West Coast, the winds blow uphill, and the air cools, condenses, and precipitates, forming a torrent of rain and wind.
These systems vary in size and strength, but on average, they carry as much water vapor as the Mississippi River discharges at its mouth—and some can even transport up to 15 times that amount. When they make landfall, they unleash heavy rain or snow, accounting for roughly 30 to 50 percent of annual precipitation in the West Coast states.
NOAA and its partners utilize advanced satellite observations to study atmospheric rivers. Satellite data, combined with land-based observations, helps refine forecast models, improving predictions of atmospheric river intensity and duration to support water resource management and public safety.
Learn more:
nesdis.noaa.gov/news/noaa-satellites-track-powerful-atmospheric-rivers-impacting-the-west-coast
Credits:
NOAA, NASA, CIRA
Total Precipitable Water graphic courtesy of CIMSS
Music: “Argosy” by David Norath [BMI], Arun Ganapathy [BMI] and Victor Mercader [BMI]; Emperia Beta Publishing; Universal Production Music
Since Jan. 31, NOAA satellites have been closely monitoring a series of strong atmospheric rivers bringing heavy rain and mountain snow from central California to the Pacific Northwest, the Sierra, southern Cascades, and northern Rocky mountains.
Atmospheric rivers are long, narrow bands of concentrated water vapor that transport moisture from warm tropical oceans to higher latitudes. In these regions, heat from the sun causes large amounts of water to evaporate into the atmosphere. When this humid air meets the mountains along the West Coast, the winds blow uphill, and the air cools, condenses, and precipitates, forming a torrent of rain and wind.
These systems vary in size and strength, but on average, they carry as much water vapor as the Mississippi River discharges at its mouth—and some can even transport up to 15 times that amount. When they make landfall, they unleash heavy rain or snow, accounting for roughly 30 to 50 percent of annual precipitation in the West Coast states.
NOAA and its partners utilize advanced satellite observations to study atmospheric rivers. Satellite data, combined with land-based observations, helps refine forecast models, improving predictions of atmospheric river intensity and duration to support water resource management and public safety.
Learn more:
nesdis.noaa.gov/news/noaa-satellites-track-powerful-atmospheric-rivers-impacting-the-west-coast
Credits:
NOAA, NASA, CIRA
Total Precipitable Water graphic courtesy of CIMSS
Music: “Argosy” by David Norath [BMI], Arun Ganapathy [BMI] and Victor Mercader [BMI]; Emperia Beta Publishing; Universal Production Music
