The 2 storm fronts directed streams of wetness from north of Hawaii toward the West Coast in long, narrow bands of moisture referred to as climatic rivers. Climatic rivers account for approximately 50 percent of all rain and snow that falls in the western United States.
The parade of storms brought high winds and extreme precipitation that splashed wildfires and brought some relief from severe drought to Central and Northern California. But the occasions also caused power outages, flooding, landslides, and mud and particles flows that rinsed roads.
The animation above programs a design of the movement of total precipitable water vapor over the eastern Pacific Ocean from October 10-25, 2021 Green locations represent the greatest quantities of wetness. Keep in mind the fingers of white to light green that repeatedly flow into the Pacific Northwest of North America. Keep in mind also how locations in the tropics are typically saturated with moisture that can ultimately huddle into middle latitudes.
Overall precipitable water vapor is a measurement of the amount of water in a column of the atmosphere if all the water vapor in that column were condensed into liquid. Not all precipitable water vapor actually falls as rain.
October 25, 2021.
The simulated natural-color image above, acquired on October 25 by NOAAs Geostationary Operational Environmental Satellite 17 (GOES-17) reveals an arc of clouds stretching throughout the Pacific– a visible manifestation of the atmospheric river putting moisture into the Pacific Northwest. GOES-17 is operated by the National Oceanic and Atmospheric Administration (NOAA); NASA helps release the goes and develop series of satellites.
The Center for Western Weather and Water Extremes ranked the October 24-25 climatic river as a category-5 occasion for the San Francisco Bay Area. The 1 to 5 scale thinks about the longevity and the quantity of water vapor carried by these rivers of damp air that take a trip ahead of cold fronts.
In Marin County, the National Weather Service (NWS) reported that Mount Tamalpais got a 48-hour total of 16.55 inches of precipitation by the morning of October 25. Downtown San Francisco recorded 4.02 inches on October 24 alone, making it the wettest October day the city has seen considering that record keeping began.
In Blue Canyon, California, 10.4 inches of rain fell in a 24-hour-period on October 24-25, breaking a record of 9.33 inches set in 1964, according to the NWS. Over the same period, downtown Sacramento saw 5.44 inches of rain, breaking a record embeded in 1880. Just one week previously, Sacramento had broken another severe record for the longest drought, marking 212 days without quantifiable rain.
On October 24, the NWS released flash flood cautions for 13 burn scar areas in California from wildfires that happened in between 2018 and 2021. The cautions included the Caldor fire burn scar near Lake Tahoe, where numerous more inches of rain were anticipated to fall on October 25.
Up and down the California coast, NWS released high surf cautions for swells of 16 to 24 feet on west to northwest dealing with beaches. At the same time, winter storm warnings were in effect in the Sierra Nevada, where multiple feet of snow were anticipated at high elevations. Residues of the storm were anticipated to reach Southern California late on October 25.
NASA Earth Observatory image and video by Joshua Stevens, using GOES 17 images thanks to NOAA and the National Environmental Satellite, Data, and Information Service (NESDIS) and GEOS-5 information from the Global Modeling and Assimilation Office at NASA GSFC.
One of the most intense extratropical cyclones ever to strike the Pacific Northwest drew an equally historic quantity of wetness onto the West Coast of North America on October 24-25, 2021. The storm off the coast of Washington– with a main pressure of 942.5 millibars, comparable to a category 4 hurricane– was the 2nd severe low-pressure storm in the North Pacific in a week. Overall precipitable water vapor is a measurement of the quantity of water in a column of the atmosphere if all the water vapor in that column were condensed into liquid. Not all precipitable water vapor actually falls as rain. Remnants of the storm were expected to reach Southern California late on October 25.
October 10– 25, 2021
One of the most intense extratropical cyclones ever to strike the Pacific Northwest drew an equally historical quantity of wetness onshore.
One of the most extreme extratropical cyclones ever to strike the Pacific Northwest drew an equally historical quantity of wetness onto the West Coast of North America on October 24-25, 2021. The storm off the coast of Washington– with a central pressure of 942.5 millibars, equivalent to a classification 4 cyclone– was the second extreme low-pressure storm in the North Pacific in a week. Both displayed pressure drops of more than 24 millibars in 24 hours, making them “bomb cyclones.”
By Sara E. Pratt, NASA Earth Observatory
October 26, 2021