Atmospheric rivers are long and relatively narrow bands of water vapor that form over an ocean and flow through the sky, transporting much of the moisture from the tropics to northern latitudes.
November 21, 2025
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definition
Describes a meteorological feature that transports large amounts of atmospheric moisture and can drive heavy precipitation.
Heavy or torrential rains can cause flash flooding of streets, creeks, and streams.
November 21, 2025
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hazard
Flash flooding is a common hazard associated with intense rainfall and can affect urban and natural drainage channels.
Areas ravaged by wildfire have increased susceptibility to mudslides and debris flows during heavy rains.
November 21, 2025
high
hazard
Burned vegetation and altered soil properties reduce slope stability and increase runoff, elevating post-fire landslide and debris-flow risk when heavy precipitation occurs.