Extra excessive climate situations for California as a collection of atmospheric stream occasions proceed

CNN
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California has been hit with heavy snowfall, damaging winds and flooding this week – and now another round of storms will hit the west coast this weekend.

“A relentless parade of Pacific cyclones will bring more flooding rain and mountain snow to the West Coast, with a focus on Northern California,” the Weather Prediction Center said Saturday.

Several storms will hit the west coast in the next few days. The concern isn’t just for rain, snow and wind, but there won’t be a big pause between events for the water to recede or for the cleanup to complete.

“We expect an even stronger storm to hit the state Sunday night through Tuesday than what we’ll see early weekend,” said Matt Solum, meteorologist at the National Weather Service’s western region headquarters. “We encourage everyone to take the time over the weekend to make any necessary preparations for the next storm.”

☔ Several winter storms will continue until next week. Widespread moderate rain returns this weekend, followed by a stronger storm Monday through Tuesday, bringing ongoing flooding concerns.

More storms are possible for the rest of next week. Plan ahead now! #CAwx pic.twitter.com/Cgw1hO3ysz

— NWS Sacramento (@NWSSacramento) January 6, 2023

The next storms follow a powerful cyclone that flooded streets, downed trees and knocked out power in almost all of California. Previously, a New Year’s weekend storm had also caused flooding.

This weekend, the main concerns for coastal communities will be widespread flooding, gusty winds and dangerous beach and sea conditions. There will be heavy snow and strong winds at the higher elevations, resulting in near-white conditions for all those out on the roads.

FOLLOW THE STORMS HERE >>>>

Winds are forecast at around 40-50mph in the valleys and up to 70mph in the mountains, lower than the storm earlier this week but still nothing to shake.

“Although these winds will not be of the magnitude of the previous/stronger system, it really won’t take much to knock down trees given saturated conditions and weakened trees from the last event,” the San Francisco Weather Service said on Friday.

Even 40 mph winds can do damage when the ground is so saturated from record rainfall earlier this week and the cumulative effect of new precipitation expected this weekend.

“Infrastructure impacts include, but are not limited to; River flooding, mudslides, power outages and snow load,” the forecast center said in a tweet.

Surely the most widespread concern over the next week will be flooding thanks to several atmospheric flow events. Atmospheric fluxes are a narrow band of concentrated moisture in the atmosphere.

The Center for Western Weather and Water Extremes, which monitors atmospheric flow events, is now forecasting a Level 5 atmospheric flow event — the highest possible level — over the next few days. While the focus of this event will be near Monterey and Big Sur, California, intense moisture will also spread to the surrounding areas of San Francisco and San Jose where a Level 4 atmospheric flow event is forecast.

Earlier this week, San Francisco experienced its wettest 10-day period since 1871 for the downtown area. So far it has rained more than a foot since Dec. 1, and the forecast calls for another 4 to 6 inches of rain over the next five days.

Sacramento is also expected to see significant rainfall levels of 4 to 7 inches in the valleys and 6 to 12 inches in the foothills.

“Additional rain on already saturated soil will contribute to additional flooding problems across much of the state,” Solum told CNN. “There will also continue to be an increased risk of falling rocks and mudslides in much of the state.”

More than 15 million people are under flood protection in the state of California this weekend. Also, much of northern and central California faces a slight to moderate risk of excessive precipitation on Saturday and Sunday. It rises to a more widespread moderate risk by Monday.

The weekend’s rains will once again trouble local streams, streams and rivers. Colgan Creek, Berryessa Creek, Mark West Creek, Green Valley Creek, and the Cosumnes River all have levels that are either currently above high water levels or are expected in the next few days.

“Tuesday is likely the day you will likely need to keep a very close eye on the weather as the potential for widespread river, stream, creek and road flooding, as well as urban flooding, will be at its highest next week as it will be all week Runoff and heavy precipitation combine to create a mess,” the Sacramento Weather Service Bureau said.

In addition to heavy rain, there will be significant amounts of snow in the higher elevations.

“Snow totals are expected to be 1 to 2 feet, with some of the higher elevations seeing 3 feet or more, causing significant travel impact,” the Sacramento Weather Service Office said.

We are currently in a La Nina recommendation for the winter months before transitioning back to a more neutral pattern by spring.

El Niño and La Niña forecast patterns released by the Climate Prediction Center provide guidelines on what the overall forecast may look like during a seasonal period.

“During a La Niña, conditions in the Pacific Northwest are typically wetter than normal and Southern California is drier than normal,” said Marybeth Arcodia, a postdoctoral researcher at Colorado State University. “That’s because the jet stream is being pushed further north and has a more rippled pattern. ”

The problem is that so far this year, Mother Nature hasn’t exactly followed the expected norms for a La Niña winter.

“However, for the past three months, Oregon has been a little drier than normal and California has been a little wetter than normal (the opposite of what was expected),” Arcodia told CNN. While El Niño and La Niña patterns typically have a major impact on seasonal West Coast conditions, “there are always additional factors at play,” she added.

One of these factors were several atmospheric flow events that hit California with intense amounts of moisture.

“Atmospheric flows typically form during the winter months and can occur during El Niños or La Niñas,” Arcodia said, noting that their strength, frequency and landfall may be affected by the larger patterns in the Pacific.

Michael Tippett, a professor of physics and mathematics at Columbia University, points out that the forecast patterns are not intended to be used on a daily forecast scale, but for the entire season as a whole. This is why exploring the patterns is so important.

“There’s an element of randomness that isn’t explained by the patterns,” Tippett told CNN. “That might help us understand why one year is different than the other.”