The "atmospheric river" weather occurrences that hit California with storms from the end of December to the end of January may have regained 37 percent of the five-year snow water deficit inside the state. The data is provided by the University of Colorado Boulder and employed NASA satellite data.

Scientists at the university's Center for Water Earth Science and Technology approximate that two powerful storms that occurred recently accumulated approximately 17.5-million acre feet of water on the range of Sierra Nevada in January.

California Atmospheric River, Notable Occurrence

Compared to the averages from the pre-drought satellite record, the quantity represents more than 120 percent of the usual annual quantity of snow accumulated in this geographic range. The snowmelt represents a vital source of water for the agriculture of the state, as well as for the municipal water supplies and hydropower generation.

Snow-water deficit is explained as the shortage in the water stored in snowpack, or slow-melting packed snow, compared with the yearly average water stored in snowpack before the onset of the drought in 2012. California went through an approximately 10.8-million acre feet deficit of snow water every year from 2012 to 2016, and the total deficit over this period is approximately 54 million acre feet.

However, due to the recent storms, the total deficit was reduced by approximately 37 percent in less than a month.

An atmospheric river is a relatively narrow region in the atmosphere responsible for the majority of the horizontal transport of water vapor outside of the tropics. Atmospheric rivers can be very different from one another, but the ones containing the largest amounts of water vapor and the stronger winds can produce extreme rainfall and flood.

Among the consequences of these events, disrupting travel, inducing mud slides and catastrophic damage to life and property are generally associated with the phenomenon. However, some of the atmospheric rivers, which are weaker, can be beneficial for the water supply of the area. On average, approximately 30 to 50 percent of the annual precipitation in the states located on the west coast takes place in a small number of atmospheric rivers.

Atmospheric rivers have the capacity to produce a large amount of precipitation, as they are very rich in vapor, associated with strong winds making the water vapor to rise to mountain sides. Once there, the water vapor condenses and can form precipitation.

Since 1986, when the consequences of atmospheric rivers were first described, in regard to northern and central California, numerous notable events have occurred, gaining the scientists' attention.

A Large Step Toward The Normal Amount Of Precipitation

Throughout January 2017, the better part of the higher elevations in northern California were confronted with more than 10 feet of snow in a little over two weeks, while some areas were confronted with more than 20 feet of snow.

At the beginning of the storm cycle that occurred in January, the lower mountain elevations received some rain. However, most of the precipitation on the mountain has come as snow.

Five years back, when the snowing stopped, the state was forced to use the groundwater reserves to function properly and, while this year's weather alone will not have the power to completely make up for that, it balances the quantity.

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