ARs in the Air

January 7, 2017

Rain-to-drizzle-to-rain again this Saturday morning on the storm-tossed northern California coast — under the sweep of several ‘atmospheric rivers’ for the next week to 10 days.
According to the NWS, those storms will bring ‘copious amounts of moisture‘ to our area, from tonight through next Thursday — 5.5-to-12-inches of rain for Humboldt County, depending on your location. We’re getting really wet.

Statewide, a punch to the drought — Bill Patzert, a research scientist and oceanographer at NASA’s Jet Propulsion Laboratory in Pasadena, waxes enthusiastic about our current weather: ‘“You get this once in a decade. It’s a conveyor belt….For water and snow aficionados, when the polar jet stream and an atmospheric river merge and take aim on California, it’s like winning the Powerball and Super Lotto Plus in the same week.”

(Illustration: ‘Rain,’ by Brad Sharp, found here)

Apparently, nothing but rain for awhile. We’re forecast for maybe a half-inch here along the shoreline today, but from the looks of it already, the totals will be much higher.
We’re under a ‘Flood Watch’ until tomorrow at least, and it’s going to get gnarly.

Our weather is based on a couple of contributing factors — from the San Jose Mercury News this morning:

After five years of historic drought, conditions in the Pacific Ocean are lining up in drenching ways not seen since at least 2010, with new storms forming off California’s coast that will continue to bring rain throughout next week, even after this weekend’s powerful system is gone.

First, the huge mass off offshore high-pressure air, dubbed the “Ridiculously Resilient Ridge,” which blocked dozens of storms over the past three years from coming ashore to California is now gone.
Scientists don’t know exactly why it stayed so long, or why it went away.
Second, now there are two other ridges — one off the Aleutian Islands in Alaska, and one off Baja, Mexico — that are funneling storms toward California.
The Alaska ridge is pushing the polar jet stream south, where it is connecting with a series of atmospheric river storms that are being generated in warm waters in the subtropical Pacific.
Such fast-moving storms, often called “Pineapple Express” systems, are 200 miles wide, driven by high winds and can carry 20 times as much water as the Mississippi River where it flows into the Gulf of Mexico, acting as a meteorological fire hose over the West Coast.

Storms this week already have boosted the Sierra Nevada snowpack enormously. On Monday, it was 70 percent of the historic average. By Friday it was 103 percent. The warm storms this weekend could melt some of the snow, causing the flood risk, although the runoff will fill reservoirs around the state.

At least, we’re wet for a reason…

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