According to Daniel Swain, California is currently in the midst of one of its wettest winters on record.
Swain is a climate scientist, postdoctoral fellow at the University of California, Los Angeles and owner of the California Weather Blog.
Swain emphasized that, “All of this water is severely taxing California’s water storage, conveyance and flood protection systems.”
This is interesting, because until this fall, California was experiencing its driest period in 1,000 years if one considers its record high temperatures.
According to the California Department of Water Resources, the northern Sierra and Cascades this water year are also on track to be the wettest year on record.
The north state is on course to eclipse the water years 1997-1998 and 1982-1983, the previous record holders. The latter years were El Nino years, when northern California usually gets its most precipitation.
This year is not an El Nino year and yet this area is poised to break the regional precipitation record.
Conversely, last year, 2015-2016, was a very strong El Nino year and yet the region received very little precipitation.
Go to bit.ly/1CK8D7z to track ongoing precipitation.
Snowfall this year
Even though the storms this year have been from the tropics, and thus wet and relatively warm, a lot of snow has fallen.
However, most of this snow has already melted and added to the rain runoff.
To see the current estimate of the amount of snow in the Sierras, visit the interactive map at bit.ly/2lwCwEJ.
The jet stream this year
Winds are primarily from the west in this area, though they can vary from northwest to southwest as storms from the Pacific Ocean move through the area.
High winds, like the region experienced last Monday, occur when the jet stream, also moving from west to east, moves directly overhead.
The jet stream on Monday was directly over Plumas County, bringing 100-plus mph winds to high elevations and wreaking havoc on local communications.
Swain noted that climates in California are exhibiting wider swings between dry and wet conditions since 1948. Extremely dry years are happening more frequently in recent decades and the wettest years seem to be becoming more frequent as well.
This increase in extremes in weather patterns is consistent with what most climatologists believe should be expected with climate warming.
California’s unique vulnerability
Swain pointed out that California is relatively unique in that two-thirds of the state’s precipitation typically comes from just a few storms between the months of December and March.
Summers are usually dry, with less than 5 percent of the state’s precipitation coming during summer months.
Swain pointed out, “This striking dependence of California’s entire water supply upon the occurrence of just a few atmospheric river events each winter means that a surplus or deficit of just one or two such storms can quickly increase the risk of flood or drought in any given year.”
An increased frequency and intensity of weather extremes will impact agriculture, the state’s infrastructure, the forests and, directly or indirectly, all California residents.