Will high-pressure ridge leave Rockies high and dry?

Will high-pressure ridge in Pacific cause Rockies to stay dry ’til January?

Chilling new evidence of link to melting Arctic sea

by Allen Best

GLENWOOD SPRINGS, Colo. – Might it be a dry Christmas in Colorado, Utah and perhaps other locations, the result of yet again a high-pressure ridge that has formed off the West Coast?

That’s one possibility suggested by Eric Kuhn after examining two stories out of California posted on Tuesday. Kuhn is in the final months as general manager of the Colorado River Water Conservation District, but he continues to monitor the news that affect water users on the upper Colorado River.

Eric Kuhn

The two, overlapping postings concern formation of a high-pressure ridge off the West Coast that causes moisture-laden storms to go northward. Whistler has been getting hammered with snow. Mammoth? No, not all that much.

One posting forecasts a “remarkably persistent weather pattern will begin to develop across North America and adjacent oceanic regions.” The writer, Daniel Swain, writing on Weathewest.com, pointed out that “patterns like this have a tendency to become self-reinforcing, lasting for much longer than more typical transient weather patterns and leading to prolonged stretches of unusual weather.”

The result: “an extended, multi-week warm and dry spell” in California while “much of the East Coast shivers through repeated blasts of cold, Arctic air.” Swain expects this pattern to last “at least two weeks” but suggests possibly longer.

The posting, based largely on a peer-reviewed paper published earlier this year in the Journal of Geophysical Research, runs 2,400 words. It is well worth reading. Swain, the writer, coined the phrase “ridiculously resilient ridge” in 2014, during the drought in California.

Kuhn points out that when this stubborn high-pressure ridge forms off the West Coast, it has always produced problems for California and sometimes for the Rocky Mountains, too. He would have you imagine a clock, the storms moving across the top of the clock and down to the right, just as some of these storms have slid down into the Great Plains and others down the spine of the Rocky Mountains.

Will the weather be like clock-work this year? Forecasts of more than a week or two, if improving, remain subject to a great deal of variability, he points out.

That same posting by Swain in Weatherwest.com discusses the link between disappearing Arctic sea ice and the formation of the high-pressure ridge off the West Coast.

“The Arctic is warming more than twice as fast as the rest of the world, and sea ice has been disappearing at a greater rate than had projected by climate models—a rapid rate of change…” Swain writes. He goes on to say that there is no clear link between the vanishing sea ice and the persistent high-pressure ridge but that does not discount the possibility.

However, on the same day, a study conducted by scientists from the Lawrence Livermore Laboratory in California claims to have found evidence of this link.

The Los Angeles Times summarized the study in this way: “Using complex new modeling, the scientists have found that rapidly melting Arctic sea ice now threatens to diminish precipitation over California by as much as 15% within 20 to 30 years.”

The story goes on to say that the study, published in the journal Nature Communications “provides compelling evidence of the link between the disappearance of sea ice in the Arctic and the buildup of high ridges of atmosphere pressure over the Pacific Ocean. Those ridges push winter storms away from the state, causing drought.”

Kuhn, from his purview in Colorado, extends the story inland. “To me, it’s a potentially troublesome for both California and Colorado and the states between.”

The result of that high-pressure ridge was devastating to California in 2012 and 2013 and, to a lesser extent, in 2014 and 2015. Colorado fared better, as storms tracked down the spine of the Rockies. But that weather system left Utah more exposed. “We had one winter where Colorado was in decent shape, but Utah was in bad shape.”

Lake Mead from Hoover Dam in late 2016. Photo/Allen Best

This new research will undoubtedly be discussed next week in the hallways of Caesar’s Palace, site of the annual Colorado River Water Users Association. The story during the 21st century in the Colorado River Basin has been of the effects of rising temperatures but also the effects of that high-pressure ridge along the West Coast and its impact on states from Wyoming to Arizona.

Mountain towns in Colorado and other interior states are less directly affected than those of the Sierra Nevada. Even in drought years, headwater valleys usually get water. But Powell, Mead and other reservoirs of the Colorado River Basin have been slowly ebbing.

About 70 percent of all the water in the Colorado River at Lee’s Ferry, at the head of the Grand Canyon, below Lake Powell, comes from Colorado, mostly as a result of snow. Very little water is added to the river below Lee’s Ferry. In this way, ski towns are directly connected to the vegetable fields of California’s Imperial Valley and Yuma, Ariz., source of the winter veggies their restaurants will be serving Christmas week.

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About Allen Best

Allen Best is a Colorado-based journalist. He publishes a subscription-based e-zine called Mountain Town News, portions of which are published on the website of the same name, and also writes for a variety of newspapers and magazines.
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6 Responses to Will high-pressure ridge leave Rockies high and dry?

  1. paul says:

    Ski Canada

  2. rg says:

    OK. I live south of Wilson. Last winter we were buried. I spent far more time with my butt in the seat of my plow truck than I did on skis.
    If I had written an article generalizing last winter’s experience, and declaring that a new ice age was upon us, Here’s what I would have been told:
    -“Short term weather isn’t climate”.
    However, some folks can parley an early winter dry spell into “Oh My God We’re Going To Dry Up Blow Away Burn Up Run Out Of Water Forever.
    Yawn. FYI, in my forty-odd years living here I’ve experienced these blocking highs regularly in early winter. Check the records from 1976-77, that was a doozie. That was forty one years ago.

  3. rg says:

    P. S.
    Central Rockies had an extremely wet fall. Snowpack data in my area (headwaters of the Snake River) indicates 130% of 30 year average water content snowpack. Adjacent area (Headwaters of the Green/Colorado) is 125% today. It rained/snowed all fall. I know, I was out hunting elk in it for nearly two months.
    And last winter was epic. Plenty of that water went into Powell. I rafted Stillwater/Labyrinth in April at an extremely high level, and the San Juan at the end of May at 9K, which is like pre-Navajo Dam runoffs.
    Can we talk about any of this?

  4. rg says:

    The photo in your article is from December 2016. Any chance you can post a photo from the same location July 2017? I think that would be very instructive.

  5. Allen Best says:

    Yes, lots of snow early on from the Winds north this year. Lots of snow last winter in lots of places, including Telluride and elsewhere—especially California. And lots of winters with a late start in Colorado during the 65 winters in my rear-view mirror. But I don’t think that’s the point of the story. Two points to this story: 1) The high-pressure ridge is blocking, at least for now, arrival of snow. Moments ago talked with somebody who crossed Vail Pass this afternoon. “How much snow did you see?” None, she said. No. 2) Lawrence Livermore has this modeling study linking melting sea ice in the Arctic to formation of this high-pressure ridge and predicting that it will become more frequent in 20 to 30 years. Will it? Who knows. Maybe other modeling studies will punch holes in this study. Or maybe other studies will find it was too cautious. But it’s worth paying attention to, I think.

  6. Michael Rose says:

    Hi I’m a retired Meteoroloist here on the west coast . I’m beginnign
    To think that last years way above average precipitation, was the odd guy out if you will. Of the last 10 years of data shows very few of those were above average , most were well below and in the case of here in Ca. It turned out to be devestating . The pattern is very similair to our driest years on record and once a pattern sets up like this Mother Nature doesn’t like change . The Rockies may end up in the plus catogory as the long range forecast shows the persistent high will retrograde west and allow for a few potent storms to spill over the top of the ridge . Here on the west coast that is not good news . Because a pattern like this just reinforces the dry conditions although it will be colder then average under this pattern and a few storms may clip the sierra with occasional snow

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