National Weather Service United States Department of Commerce

Atmospheric River Impacting California

A major winter storm with an active atmospheric river is inundating California the next few days with a tremendous amount of moisture. Heavy to excessive rainfall is likely from central to southern California that may produce flooding along with mudslides and dangerous debris flows near recent and vulnerable burn scars. A significant amount of snow is anticipated in the Sierra with feet of snow. Read More >

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Radar Legend Lightning Legend Flight Category:
VFR  MVFR
IFR  LIFR
Weather Shading:
Convective   Freezing
Winter   Smoke/Ash
Liquid   Fog/Haze


The above loop uses radar and visible/IR satellite data obtained from Aviation Weather Center (AWC), lightning (GLM) data from NOAA nowCOAST, and observations (for flight category and weather) from MesoWest. The radar, lightning, visible satellite, IR satellite, and flight categories/weather can be toggled on/off. When both the flight category and weather are displayed, the flight category icon will be on the inside and the partially-transparent weather color on the outside. Clicking on the map will start/stop the loop. Left-clicking on the "Speed" area will slow the loop and right-clicking will accelerate the loop, ranging from 0.05 to 5 second interval. To toggle the lower-left menu visible/hidden, click the ≪ or ≫ button. Additional URL parameters include lt (center latitude), ln (center longitude), zm (zoom level, 0-12), nolabel (removes flight category icon ID labels), hidemenu (hides the menu options on the lower left), wide (thicken US state boundaries), county (include US counties and other political boundaries based on zoom level), hidefir (hide FIR boundary), and start (UTC start date/time, YYYYMMDDhhmm format, AWC data goes back up to 2 days, GLM data up to 5 hours). The URL should auto-update with the current settings, allowing for an easy bookmark/favorite.