Weather: California Nears All-Time High Atmospheric Pressure

Newport Beach, CA

With California on the cusp of breaking all-time high-pressure readings, approaching Pacific rainstorms are being deflected northward to give the state a chance to dry out after a series of early season storms that caused five deaths and widespread flooding.

The high-pressure structure is centered over northern Utah, but its massive zone stretches about 400 miles to form high-pressure ridges that are acting like an atmospheric shield across the Great Plains to about 200 miles off the West Coast.

California was hammered by winter weather during mid-January as an extreme atmospheric low acted like a vacuum to suck in a moisture-laden “Pineapple Express” from Hawaii that brought about three times the average January rainfall across the state.

With a 100 year average annual rainfall of 18.51 inches, California suffered 5 years of drought with rainfall averaging less than six inches. But this year, most of the state saw almost that much precipitation in January.

At Mammoth Mountain’s Main Lodge at an altitude of 8,909 feet in the Sierra’s, the recent storms brought 35 inches of new snow in a five-day period. By the time the weather cleared, annual snowfall at America’s most popular ski area stood at 350 inches and the current snow pack stands at 180 inches.

With Shasta Lake in Northern California filling at a rate of 57,000 cubic feet per second, the U.S. Bureau of Reclamation on January 12 opened all 5 of the huge drain pipes on the face of the 521-foot-high Shasta Dam for the first time in six years. But at a maximum discharge rate of 36,000 cubic feet per second, some local authorities feared the risk of uncontrolled flooding if the lake continued to rise and go over the spillway at the top of the dam.

California’s 12 major reservoirs due to runoff are now at about 120 percent of their historical average levels and most are discharging higher water flows. The San Joaquin River is currently pouring into California’s Delta at a rate of 20,000 cubic feet per second. At its peak last year, the river was only flowing at about 4,000 cubic feet per second.

The U.S. Interior Department’s Bureau of Reclamation has been offering $1.1 billion to raise the height of Shasta Dam by 18.5 feet to increase water storage by 14 percent. But the Obama Administration killed the project in 2014 by filing a 349-page report claiming any expansion would threaten salmon under the Endangered Species Act.

But Obama’s outgoing Interior Secretary Sally Jewell did issue a Secretarial Order on January 4 directing the Bureau of Reclamation and U.S. Fish and Wildlife Service “to allocate available resources” to complete Governor Jerry Brown’s $15 billion twin tunnels under the Delta as part of his California WaterFix.

Interior Secretary Nominee Ryan Zinke told a Senate confirmation hearing this week that “our states, local governments, and Indian nations need a partner who can restore trust in Washington as a responsible steward of our federally owned lands.”

Zinke pointed out that the federal government now owns an incredible 20 percent of the land in the United States after President Obama added 29 new national monuments and 553 million acres of land and water across the U.S. to the jurisdiction of the Interior Department’s National Parks system.

As part of Donald Trump’s campaign promise to make America “energy independent,” his Administration is expected to open up drilling on federal lands after the Obama Administration cut the number of wells drilled on federal lands by 50 percent since 2008. Any big expansion of drilling is usually coupled to an expansion of water storage.

The current high-pressure ridge is expected to break up over the next six days and clear the way for more rains. The heaviest period of precipitation during California’s annual water year is mid-January through late early April, so there is plenty of time for extreme flooding over the state’s already soggy soil.