Atmospheric river storms carry as much water as more than dozen Mississippi Rivers, and when oriented right, they can drop prodigious amounts of water in short periods of time. Parts of the California coast have received more than 10 inches of rain in the past day or two, and more rain is falling. Cities in the Bay Area have more than 3 inches thus far, and the flooding has been intense, as the news reports are showing. It didn't help matters that the storm included gale-force winds that brought down trees and caused power outages. Ours was out for an hour this morning.
Those numbers might seem paltry to my friends in rainy environments, but our local environment is a near desert that is surrounded by mountain ranges that exert a distinct rain-shadow effect. Our average yearly rainfall is only 12 inches. And our valley floor is flat. Really, really flat. We don't have effective storm drain systems to handle such storm events. In general, the storm drains don't have enough gradient to reach nearby rivers, so we have depended on dry wells to divert the storm runoff into our groundwater supply. This works most of the time, but when the rain exceeds an inch or so, large lakes and ponds will develop that fill streets, lawns and parking lots. It may take days for the water to seep underground. Storms of today's magnitude can develop dangerous conditions for drivers.
My neighborhood is lucky. I live east of the flattest valley floor, at an elevation of 125 feet (Modesto is closer to 65 feet). I also live only a mile from the Tuolumne River. A decade ago the city completed a storm drain that connects directly with the river, so we don't get the horrible ponding that once took place.
The rain will be falling through the day on Friday, and we'll have a break until Monday when another storm will move in. We appreciate the moisture so much, but a bit of it at a time, please!
The birds in my neighborhood took things in stride. Here is an Anna's Hummingbird that sheltered in our backyard for awhile today.