Wild weather driven by the raging Pacific, nature and warming

With a world getting used to extreme weather, 2023 is off to a crazier start than ever, with meteorologists saying it’s natural weather bizarre with a little help from man-made climate change.

Experts say much of what is causing problems around the world comes from the rough Pacific, carried by the rippling jet stream.

At least one highway in drought-ridden California was more like a river due to heavy rain from what is technically called an atmospheric river of moisture. New Year’s Day brought shirtless weather to the eastern United States and record high temperatures across Europe as the Northern Hemisphere was more than 2.6 degrees (1.4 degrees Celsius) warmer on Wednesday than the late 20th century average. And that’s after freezing air escaped from the Arctic, creating a festive mess across much of the United States.

“All ingredients are ready for two weeks of wild weather, especially in the western United States,” private meteorologist Ryan Maue wrote in an email.

Maue said the main driver is the three-year La Nina – a natural temporary cooling of the equatorial Pacific Ocean that is changing the world’s weather patterns – that just won’t go away. It creates literal waves in the weather systems that undulate around the world. And on some parts of the waves there are storms where the atmospheric pressure drops quickly and low, called bomb cyclones, which are quite wet and move on atmospheric waves that carry the weather called the jet stream.

The jet stream is now extremely undulating, said Maue and Woodwell Climate Research Center climatologist Jennifer Francis. The storms dip over the warm subtropics “and form a moisture conveyor belt that shells the west coast of the United States,” Maue said.

“I would describe the jet stream and bomb cyclones as a runaway Pacific freight train filled with moisture,” said Maue, former chief scientist for the National Oceanic and Atmospheric Administration in the Trump administration. “Climate change adds more fuel to the locomotive engine.”

More than 5 inches of rain fell in the Sacramento area on Saturday, with California bracing for larger storms on Wednesday and Thursday. On Wednesday, snow cover was the third highest in 40 years, over 170% of normal.

In addition to La Nina, Maue said another natural temporary weather phenomenon called the Madden-Julian Oscillation amplifies storms in the western Pacific.

Francis points to a “spot” of warm seawater off the Aleutian Islands, a phenomenon that happens more often, and an “insanely warm” Arctic – Wednesday was 5.8 degrees (3.2 degrees Celsius) warmer than in 1979-2000 medium – as part of what fuels the Pacific.

And with a more undulating than normal jet stream, extremes of all kinds rise and fall around the planet, Francis said.

“You can think of it as a jump rope. Once you start swinging at one end, that wave will eventually go all the way through the rope,” Francis said on Wednesday. “And it could be that the swell as such, perhaps driven in the Pacific, may be accentuating it in Europe as well.”

A weather station in Delemont, Switzerland, on the border with France, broke its January record with an average daily temperature of 18.1 degrees Celsius (nearly 65 Fahrenheit) on the first day of the year. On Tuesday in Bucharest, Romania, it broke the January record with a temperature of 17.2 degrees Celsius (63 degrees Fahrenheit) and 17.9 degrees Celsius (64.2 degrees Fahrenheit) in the Russian Republic of Dagestan, according to extreme weather website Maximiliano Herrera.

The Swiss weather service MeteoSuisse quipped on its blog: “… this turn of the new year can make you almost forget it’s the height of winter.”

There is a positive side to this extreme weather, especially as Europe’s record-breaking heat in January eased winter heating fuel woes caused by Russia’s invasion of Ukraine, said Colorado meteorologist Bob Henson of Yale Climate Connections. And California, which has been experiencing a megadrought that has been exacerbating wildfires for more than 20 years, has much-needed rain and snow — too much, actually.

Roads and levees in California were washed away earlier in the week. Schools were closed Wednesday in the San Francisco area as more than 8,000 sandbags were distributed in anticipation of widespread flooding. Flights have been cancelled.

“Excessive rainfall on already saturated soils will cause water levels to surge in creeks, streams and rivers, as well as flooding in urban areas,” forecasters wrote in the report.

With the exception of Europe’s impressive record heat, “which is yet another example of man-made climate change manifesting,” Northern Illinois University of Meteorology professor Victor Gensini said he found nothing out of the ordinary.

Weather is naturally extreme, “so the recent events we’ve seen may occur naturally,” said Weather Underground co-founder Jeff Masters, now at Yale Climate Connections. “But with the disruption of global weather patterns that climate change brings, the likelihood of unusual weather events each season increases.”

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Follow Seth Borenstein on Twitter at @borenbears

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