Extreme rainfall could top 20 inches in California
By
Jake Sojda, AccuWeather meteorologist
Updated Jan 27, 2021 4:26 PM EDT
Relentless rain and mountain snow are expected to pound California for days this week as a more potent system will take aim at the region. AccuWeather meteorologists say it will bring a deluge of nearly two feet of rain — and up to 10 feet of snow to the Golden State. Even though precipitation is greatly needed across the drought-stricken state, the storm will bring too much all at once and lead to serious flooding and mudslide concerns as snowfall could shut down travel through the passes.
The week already got off to a stormy start as a system with locally drenching rain and mountain snow with low freezing levels slid southeastward from California to the Four Corners region on Monday. On Tuesday, the majority of the storm focused on the Four Corners states of Utah, Colorado, Arizona and New Mexico.
However, forecasters say this first storm will pale in comparison with the new storm on the way this week, which could not only be a drought-buster but may evolve into a historic and perhaps life-threatening event.
"A storm with copious amounts of moisture is expected to move into California from Tuesday night to Friday," said AccuWeather Senior Meteorologist Adam Douty. "This storm is expected bring very heavy snow into the mountains and torrential rain into the lower elevations."
The storm will stall just off of the Northwest coast this week. That will aim what is known as an "atmospheric river" directly at California, where it will persist for days.
"The storm system will 'wobble' at times as it spins just off the coast. This will cause a plume of the greatest moisture to shift at times, shifting where the heaviest rain and snow is directed through the week," Douty said.
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This could lead to a widespread flooding threat, as large portions of the state will spend time under the plume of heavy rainfall. The greatest rainfall amounts will be along the west- and southwest-facing coastal ranges of Northern and Central California, as well as in the western foothills of the Sierra, below the snow line.
Widespread rainfall totals of 4-8 inches are anticipated in these areas. Rainfall amounts of 8-12 inches will be possible where the heavy rain is more persistent, with an AccuWeather Local StormMax™ of 20 inches. The heaviest rain may occur from just south of San Francisco to just north of Los Angeles.
"Not only can this lead to a significant threat for flash flooding, but in
the many burn scars across the state, mudslides and debris flows would be a significant threat as well," Douty said.
Forecasters say some of the areas of greatest concern are with the burn scars associated with the SCU Lightning Complex and Creek Fire in Central California, August and North Complexes in Northern California and the Bobcat Fire in Southern California.
As the storm will drench lower elevations, the higher ground will see prolific snowfall. Accumulations of 3-6 feet are expected from Tuesday night through Friday in elevations over 4,000 feet, with an AccuWeather Local StormMax™ of 10 feet. At times, snow levels are expected to be as low as 2,000 feet in Northern California and 2,000 to 4,000 feet across the Sierra Nevada Mountains, which will be low enough to impact nearly all passes and cause significant travel delays.
There is the potential for all of the major passes in California and southern Oregon to be shut down at about the same time from this storm this week, according to AccuWeather Senior Meteorologist Alex Sosnowski said.
"Travel along Interstate 80 through Donner Pass could completely come to a halt this week as snow heaps up and gusty winds whip [it around]," said AccuWeather Senior Meteorologist Danny Pydynowski.
Blizzard warnings have been hoisted for part of the Sierra Nevada where the heavy snow will be accompanied by wind gusts over 70 mph. People in Lake Tahoe and Mammoth Lakes should brace for the potential for long-lasting blizzard conditions.
Heavy snow is forecast to fall at intermediate elevations in Northern California from the storm. Redding, California, is one of several locations that can be hit with more than 6 inches of snow.
"With so much snow on the way in a relatively short period of time, the risk for avalanches will greatly increase in the Sierra as well," Douty explained.
In Southern California, snow levels are expected to be higher with the storm from Wednesday to Friday, which should keep the majority of accumulating snow above pass levels. However, snow can still be heavy across the higher elevations, adding even more to the snowpack at some mountain resorts in the region.
Gusty winds are also forecast to accompany the new storm this week. However, while winds are not expected to raise the fire risk due to rain and snow accompanying the system, there will still be strong enough gusts to lead to sporadic to regional power outages. Gusty crosswinds can add to the difficult driving conditions caused by the rain and snow.
As of early Wednesday morning, more than 350,000 utility customers were without power in California, according to poweroutage.us.
Even though forecasters warn that this storm will be no joke and will bring some serious threats to California, the precipitation is also much needed.
As of Wednesday, Jan. 23, 2021, the mountain snow drought was serious in parts of the Southwest, according to the National Weather Service. The amount of water locked up in existing snow was less than 50% of the 30-year average from 1980 to 2010.
According the United States Drought Monitor, 78% percent of the state of California is in moderate drought or worse, with nearly 40% in severe or extreme drought. This storm will likely help to put a huge dent in the drought in the area, and could completely erase it for some.
"As beneficial as the stormy pattern will be for shutting off the wildfire threat and boosting snow depth over the high country, which later feeds runoff into streams and rivers during the spring and summer and replenishes the water supply in the region, rounds of heavy rain over low elevations are likely to be too much for the landscape to handle without problems," Sosnowski warned.
"Motorists should be prepared for substantial delays on the highways with the risk of some roads being closed from flooding, mudslides and snowfall," he said.
The next storm this week will largely set its sights on California, but the entire Southwest will face chances for active weather into early February.
"The storms will keep coming in the Southwest," said AccuWeather Lead Long-Range Meteorologist Paul Pastelok. "More snow and rain will fall across the Southwest, leading to some flooding and slippery travel in the higher elevations into the first few days of February."
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
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News / Winter Weather
Extreme rainfall could top 20 inches in California
By Jake Sojda, AccuWeather meteorologist
Updated Jan 27, 2021 4:26 PM EDT
Relentless rain and mountain snow are expected to pound California for days this week as a more potent system will take aim at the region. AccuWeather meteorologists say it will bring a deluge of nearly two feet of rain — and up to 10 feet of snow to the Golden State. Even though precipitation is greatly needed across the drought-stricken state, the storm will bring too much all at once and lead to serious flooding and mudslide concerns as snowfall could shut down travel through the passes.
The week already got off to a stormy start as a system with locally drenching rain and mountain snow with low freezing levels slid southeastward from California to the Four Corners region on Monday. On Tuesday, the majority of the storm focused on the Four Corners states of Utah, Colorado, Arizona and New Mexico.
However, forecasters say this first storm will pale in comparison with the new storm on the way this week, which could not only be a drought-buster but may evolve into a historic and perhaps life-threatening event.
"A storm with copious amounts of moisture is expected to move into California from Tuesday night to Friday," said AccuWeather Senior Meteorologist Adam Douty. "This storm is expected bring very heavy snow into the mountains and torrential rain into the lower elevations."
The storm will stall just off of the Northwest coast this week. That will aim what is known as an "atmospheric river" directly at California, where it will persist for days.
"The storm system will 'wobble' at times as it spins just off the coast. This will cause a plume of the greatest moisture to shift at times, shifting where the heaviest rain and snow is directed through the week," Douty said.
CLICK HERE FOR THE FREE ACCUWEATHER APP
This could lead to a widespread flooding threat, as large portions of the state will spend time under the plume of heavy rainfall. The greatest rainfall amounts will be along the west- and southwest-facing coastal ranges of Northern and Central California, as well as in the western foothills of the Sierra, below the snow line.
Widespread rainfall totals of 4-8 inches are anticipated in these areas. Rainfall amounts of 8-12 inches will be possible where the heavy rain is more persistent, with an AccuWeather Local StormMax™ of 20 inches. The heaviest rain may occur from just south of San Francisco to just north of Los Angeles.
"Not only can this lead to a significant threat for flash flooding, but in
the many burn scars across the state, mudslides and debris flows would be a significant threat as well," Douty said.
Forecasters say some of the areas of greatest concern are with the burn scars associated with the SCU Lightning Complex and Creek Fire in Central California, August and North Complexes in Northern California and the Bobcat Fire in Southern California.
As the storm will drench lower elevations, the higher ground will see prolific snowfall. Accumulations of 3-6 feet are expected from Tuesday night through Friday in elevations over 4,000 feet, with an AccuWeather Local StormMax™ of 10 feet. At times, snow levels are expected to be as low as 2,000 feet in Northern California and 2,000 to 4,000 feet across the Sierra Nevada Mountains, which will be low enough to impact nearly all passes and cause significant travel delays.
There is the potential for all of the major passes in California and southern Oregon to be shut down at about the same time from this storm this week, according to AccuWeather Senior Meteorologist Alex Sosnowski said.
"Travel along Interstate 80 through Donner Pass could completely come to a halt this week as snow heaps up and gusty winds whip [it around]," said AccuWeather Senior Meteorologist Danny Pydynowski.
Blizzard warnings have been hoisted for part of the Sierra Nevada where the heavy snow will be accompanied by wind gusts over 70 mph. People in Lake Tahoe and Mammoth Lakes should brace for the potential for long-lasting blizzard conditions.
Heavy snow is forecast to fall at intermediate elevations in Northern California from the storm. Redding, California, is one of several locations that can be hit with more than 6 inches of snow.
"With so much snow on the way in a relatively short period of time, the risk for avalanches will greatly increase in the Sierra as well," Douty explained.
In Southern California, snow levels are expected to be higher with the storm from Wednesday to Friday, which should keep the majority of accumulating snow above pass levels. However, snow can still be heavy across the higher elevations, adding even more to the snowpack at some mountain resorts in the region.
Gusty winds are also forecast to accompany the new storm this week. However, while winds are not expected to raise the fire risk due to rain and snow accompanying the system, there will still be strong enough gusts to lead to sporadic to regional power outages. Gusty crosswinds can add to the difficult driving conditions caused by the rain and snow.
As of early Wednesday morning, more than 350,000 utility customers were without power in California, according to poweroutage.us.
Related:
Even though forecasters warn that this storm will be no joke and will bring some serious threats to California, the precipitation is also much needed.
As of Wednesday, Jan. 23, 2021, the mountain snow drought was serious in parts of the Southwest, according to the National Weather Service. The amount of water locked up in existing snow was less than 50% of the 30-year average from 1980 to 2010.
According the United States Drought Monitor, 78% percent of the state of California is in moderate drought or worse, with nearly 40% in severe or extreme drought. This storm will likely help to put a huge dent in the drought in the area, and could completely erase it for some.
The current U.S. Drought Monitor map for California. (U.S. Drought Monitor)
"As beneficial as the stormy pattern will be for shutting off the wildfire threat and boosting snow depth over the high country, which later feeds runoff into streams and rivers during the spring and summer and replenishes the water supply in the region, rounds of heavy rain over low elevations are likely to be too much for the landscape to handle without problems," Sosnowski warned.
"Motorists should be prepared for substantial delays on the highways with the risk of some roads being closed from flooding, mudslides and snowfall," he said.
The next storm this week will largely set its sights on California, but the entire Southwest will face chances for active weather into early February.
"The storms will keep coming in the Southwest," said AccuWeather Lead Long-Range Meteorologist Paul Pastelok. "More snow and rain will fall across the Southwest, leading to some flooding and slippery travel in the higher elevations into the first few days of February."
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
Report a Typo