Extreme Temperature Diary- Monday January 9th, 2023/ Main Topic: California’s Atmospheric River Troubles

The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: California’s Atmospheric River Troubles

Dear Diary. As I’ve stated many times, California appears to have been the state most hurt by climate change related weather, at least since 2017 when I began this blog. The good news here is that California is probably going to get out of a historic drought by the end of this month, which has led to devastating fire weather year after year and adversely affected essential agriculture. The bad news is that there will be a lot of damage from flooding and high winds by the end of this week due to atmospheric rivers pouring onto the state. I first posted on this problem a few days ago:

Extreme Temperature Diary- Thursday January 5th, 2023/ Main Topic: More Weather Whiplash…California from Drought to Deluge – Guy On Climate

Today we will concentrate on news and notes from a very soggy California, but first here is another recent writeup from the New York Times, which ties in how climate change is influencing atmospheric rivers. This science is in its infancy, by the way:

How Climate Change Is Shaping California’s Winter Storms – The New York Times (nytimes.com)

How Climate Change Is Shaping California’s Winter Storms

So far, the downpours are largely in line with past storms, an official said. But their quick pace is testing the limits of the state’s infrastructure.

A flooded road in San Francisco on New Year’s Eve.Credit…Mike Kai Chen for The New York Times

Raymond Zhong

By Raymond Zhong

Jan. 3, 2023

Drenching rains forecast to pummel California on Wednesday and again over the weekend are poised to be the third and fourth major storms to march through in less than two weeks, raising the prospect of more misery in a season that has already brought flooding, debris flows and power outages to parts of the state.

Over the weekend, rescuers scoured rural areas of Sacramento County looking for people trapped in homes or cars. Levees failed near the Cosumnes River and flooded a highway.

Winter rain and snow typically provide much of the water used throughout the year in California, which has suffered several years of punishing drought. But when these storms, which are known as atmospheric rivers, are particularly severe or sweep through in rapid succession, they can do more harm than good, delivering too much water, too quickly, for the state’s reservoirs and emergency responders to handle.

So far, this winter’s storms have been largely in line with past ones except in their unrelenting pace, said Michael Anderson, California’s state climatologist. “This is where we’re getting hit this year: We’re seeing a lot of big storms fairly quickly.”

These storms get their name from their long, narrow shape and the prodigious amount of water they carry.

They form when winds over the Pacific draw a filament of moisture from the band of warm, moist air over the tropics and channel it toward the West Coast. When this ribbon of moisture hits the Sierra Nevada and other mountains, it is forced upward, cooling it and turning its water into immense quantities of rain and snow.

Climate scientists also distinguish atmospheric rivers from other kinds of storms by the amount of water vapor they carry. These amounts form the basis for a five-point scale used to rank atmospheric rivers from “weak” to “exceptional.”

As humans continue burning fossil fuels and heating the atmosphere, the warmer air can hold more moisture. This means storms in many places, California included, are more likely to be extremely wet and intense. Scientists are also studying whether global warming might be shifting the way winds carry moisture around the atmosphere, potentially influencing the number of atmospheric rivers that sweep through California each year and how long they last. They have not yet come to firm conclusions on these questions, though.

“The dominant thing that’s happening is just that, in a warmer atmosphere, there’s exponentially more potential for it to hold water vapor,” said Daniel L. Swain, a climate scientist at the University of California, Los Angeles. “And that exerts a really profound influence on things.”

Stranded vehicles on Interstate 80 at the Nevada-California border on Saturday.Credit…California Highway Patrol Truckee, via Associated Press

Atmospheric rivers are hugely influential for California’s weather and water supplies. They cause the state’s heaviest rains and feed the biggest floods. They drive its cycles of dry and wet, famine and feast. But they also cause a large share of the state’s levee breaches and debris flows.

One atmospheric river can be enough to flood homes, down power lines and wash away hillsides and highways. But when several sweep ashore in a matter of days or weeks, as appears to be happening this week, the potential damage is multiplied.

Soils already saturated with rainwater might not be able to absorb any more, leading to floods and landslides. Rivers and streams already swollen after one storm could overflow. In the high mountains, rain could fall on snow, melting it and causing water to cascade toward communities below. Emergency services could be stretched to the breaking point.

When big storms come one right after the other, it is also harder for infrastructure to channel all that water into the ground or into reservoirs where it can be kept in reserve for dry summers.

“It’s really helpful if the storms would be so kind as to space themselves out a week or two apart so we have time for water to move through the system,” said Jeanine Jones, an official with California’s Department of Water Resources.

A pile-on of wet weather caused catastrophic flooding across California and the Pacific Northwest in the winter of 1861-62, when deluges swept away homes and farms and turned valleys into vast lakes. As global warming continues, scientists say the risk of a replay of those floods is rising.

Flooding near Highway 99 in Wilton, Calif., on Sunday. Credit…Hector Amezcua/The Sacramento Bee, via Associated Press

In a study published last year, Dr. Swain and Xingying Huang of the National Center for Atmospheric Research in Boulder, Colo., estimated that California today had a roughly 1-in-50 chance each year of experiencing a storm of comparable intensity to 1861-62. Climate change has already doubled those odds compared with a century ago, they estimated.

It is still unclear how global warming might be affecting the likelihood for atmospheric rivers to crash into California in rapid-fire clusters. Another study last year found that in nearly four out of five years between 1981 and 2019, half or more of all atmospheric rivers that affected the state were part of an atmospheric river “family,” or a rapid parade of storms.

Still, the warmer atmosphere’s increased capacity for holding moisture is reason enough for California officials to prepare for more catastrophic rain events today and in the future, Dr. Swain said.

“Even if that were the only thing that’s happening,” he said, “it would act to juice up, if you will, whatever atmosphere rivers are occurring, whether it’s families of atmospheric rivers or one-offs.”

More on Atmospheric Rivers in California:

California Scrambles to Recover From Storm Before the Next One Hits

Jan. 1, 2023

Heavy Rain in California Causes Flooding but Offers Respite From Drought

Dec. 31, 2022

5 Dead as ‘Atmospheric River’ Pounds Western U.S. With Rain and Snow

Dec. 27, 2022

The Coming California Megastorm

Raymond Zhong is a climate reporter. He joined The Times in 2017 and was part of the team that won the 2021 Pulitzer Prize in public service for coverage of the coronavirus pandemic. @zhonggg

More notes:

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as some extreme precipitation reports:

Here is some new 2022 climatology:

Here is more climate and weather news from Monday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton… “The Climate Guy”

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