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Mass evacuation as atmospheric river brings floods

Mass evacuation as atmospheric river brings floods

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A car is submerged in floodwaters after heavy rain moved through the area on January 9 in Windsor, California. Photo: Justin Sullivan/Getty Images

The most powerful in a “merciless parade” of atmospheric rivers hits california tuesday through wednesday. It brought with it widespread flash floods, river floods, mudslides and staggeringly high mountain snowfalls.

The big picture: The latest deadly storm prompted evacuations and closures of schools and roads across California due to the threat of “heavy rain, widespread flooding, rapidly rising water, mudslides and mudslides with possible debris flows, heavy mountain snow and gusty winds,” according to the National Weather Service.

  • Authorities have called off the search for a 5-year-old boy who was swept away by floodwaters near Paso Robles in central coastal California as the death toll from a barrage of strong storms rose to 14 on Monday. AP reports.

By the numbers: The NWS issued flood watches Monday for more than 34 million Californians — about 90 percent of the state’s population.

  • Almost all of California has received a total of 400% to 600% above average rainfall over the past few weeks, the National Weather Service noted in forecast discussion.
  • Santa Barbara County Kachuma Reservoir has risen nearly five feet in 24 hours — and the San Marcos Pass has seen more than 12 inches of rainfall during that period, warns NWS coordinating meteorologist Eric Boldt said at a briefing. “As far as we know, this is a historical record,” he added.

Meanwhile, an appreciated 63,600 customers were without power Monday night.

Between the lines: The whiplash from a dry state to a flood-prone state is a demonstration of how human-caused climate change is accentuating California’s naturally erratic rainfall patterns.

  • While flooding, power outages and landslides threaten Californians in the short term, these storms are raising reservoir levels badly depleted by The Southwest Megadrought.
Mass evacuation as atmospheric river brings floods
Photo: Ventura County Fire Department Public Information Office/Twitter. Firefighters also rescued 18 people from a river in the county Monday — some by the department’s rescue helicopter and others using a ladder they lowered from an overpass, the office said.

Current status: Amid the evacuation orders issued in answer to the storm was one for the whole city from Montecito in Santa Barbara County, on the fifth anniversary of the mudslide that killed 23 people there, of AP.

  • Flash flood warnings were issued for Santa Cruz and counties in the state, such as the California Highway Patrol reported water rescue operations in Santa Cruz and other areas.
  • NWS meteorologist Eric Boldt said at a press conference with Santa Barbara County officials Monday that parts of the county’s mountain and foothills could see total rainfall of nearly a foot.
A screenshot of a CHP Santa Cruz tweet stating
Photo: California Highway Patrol Santa Cruz/Twitter

Threat Level: These storms have caused debris flows and flash flooding in areas where the ground has been weakened by recent wildfires, with multiple flash flood warnings issued across Central California.

  • They also prepare the slopes of the Sierra Nevada mountains for avalanches.
  • Snowfall totals through Tuesday are expected to exceed 6 feet for elevations above 7,000 feet, according to the NWS. Some places have already received 100 inches in the past two weeks.
  • The NWS Weather Prediction Center notes that there is more than a 50 percent chance that flash flood thresholds will be exceeded from Sacramento to the hills of Southern California.
  • Severe thunderstorms were possible overnight Tuesday from San Francisco to Los Angeles, a rarity for this region. These storms can contain damaging winds, hail and very heavy rainfall that can lead to more flooding.
A screenshot of a CHP Santa Cruz tweet stating
Photo: California Highway Patrol Santa Cruz/Twitter

What we watch: The threat of flooding Tuesday was more concentrated in Southern California, with up to a foot of rain falling on the hills of Los Angeles, Santa Barbara and Ventura counties.

  • A rare flash flood attention was issued in southwest Los Angeles County until midnight local time as forecasters warned that downtown Los Angeles could see up to 5 inches of rain by Wednesday morning.

For the record: President Biden approved late Sunday California’s request for a storm emergency declaration, allowing federal aid to flow to the state.

What are they saying: “The timing, duration and timing between each of potentially four more storms will be key to how flood impacts intensify and how drought conditions develop,” Michael Anderson, state climatologist at the California Department of Water Resources, told Axios via e-mail.

  • “While each individual storm may not be unusually large, the impacts will be greater because of the number of storms and how quickly they arrive,” he said.
  • Anderson said there is enough reservoir in the Sacramento River system to absorb the rainfall, but streams and creeks will rise and there will be higher water along the Sacramento.
  • “Forecasts for incoming storms indicate increased impacts to the San Joaquin Valley and Monterey County,” Anderson said, noting that the state’s flood operations center is closely monitoring the situation.

Context: The hydrologic whiplash from the depths of the worst long-term drought in more than a millennium to the flooding showcases California’s capricious history of extreme rainfall.

  • This is consistent with what studies warn of years—human-induced climate change amplifies the effects of these extremes, making dry years drier and wet periods wetter.
  • Climate change is making the swings wider.
  • At the same time, the portion of California’s annual precipitation that comes from atmospheric rivers is expected to increase as the climate warms, according to Julie Kalansky of the Scripps Center for Western Weather and Extreme Waters.

What next: There is no end in sight to these storms until the end of the month.

Editor’s note: This post has been updated with additional developments.

Rebecca Falconer contributed reporting.

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