According to an authority, the current downpours are generally consistent with previous storms. However, their rapid speed is pushing the infrastructure of the state to its limit.
The third and fourth major storms in less than two weeks are expected to march through California on Wednesday and again over the weekend, pelting the state with heavy rains. This season has already caused flooding, debris flows, and power outages in some areas of the state.
Rescuers searched Sacramento County's rural regions over the weekend for anybody who could be confined to their houses or vehicles. Near the Cosumnes River, levees broke, flooding a roadway.
The majority of the water needed during the year in California, which has seen multiple years of terrible drought, is normally provided by winter rain and snow. However, when these storms, often referred to as atmospheric rivers, are exceptionally violent or move through rapidly, they can cause more harm than good by dumping too much water too soon for the state's reservoirs and first responders to handle.
Except for their relentless speed, this winter's storms have so far essentially mirrored those of previous years, according to Michael Anderson, the state climatologist of California. "We're getting slammed this year because there are so many huge storms coming through so soon,"
An atmospheric river is what?
These storms are so named because of the enormous volume of water they can transport and their long, narrow form.
They develop when winds across the Pacific Ocean guide a filament of moisture toward the West Coast from the belt of warm, wet air over the tropics. This ribbon of moisture is propelled higher as it strikes the Sierra Nevada and other mountains, chilling it and changing its water into massive amounts of rain and snow.
The quantity of water vapour that atmospheric rivers transport allows climate scientists to identify them from other storm types. The five-point scale used to rate atmospheric rivers from "weak" to "outstanding" is based on these figures.
A more severe version of them due to climate change?
As long as people keep igniting fossil fuels, the atmosphere will continue to warm and be able to store more precipitation. This means that storms are more likely to be exceptionally wet and strong in numerous regions, including California. Researchers are also looking at whether global warming is altering how moisture is carried by winds, which might have an impact on how many atmospheric rivers pass through California each year and how long they stay. However, they have not yet reached definite findings about these issues.
According to Daniel L. Swain, a climate scientist at the University of California, Los Angeles, "the dominating thing that's occurring is basically that, in a warmer atmosphere, there's exponentially more capacity for it to store water vapour." And that has a fairly significant impact on how things are.
stranded automobiles on Interstate 80 on Saturday at the California-Nevada border. Credit: Truckee, California Highway Patrol, Associated Press
How frequent are they?
The weather and water resources of California are greatly influenced by atmospheric rivers. They are to blame for the state's most intense rainfall and the largest floods. They control the hunger and feast, dry and wet cycles. However, they are also a significant contributor to the state's levee breaches and debris floods.
Homes can be flooded, electrical lines can be knocked down, and hillsides and highways can be washed away by a single atmospheric river. However, the potential harm is increased when multiple sweep ashore in a matter of days or weeks, as seems to be the case this week.
Floods and landslides may result from saturated soils that can no longer absorb more rains. After one storm, already swollen rivers and streams can flood. Rain might fall on snow in high mountains, melting it and sending water cascading into settlements below. There may not be enough resources available for emergency assistance.
It is also more difficult for infrastructure to direct all that water into the earth or into reservoirs where it may be stored in reserve for dry periods when major storms hit quickly one after the other.
The Department of Water Resources in California official Jeanine Jones stated, "It's tremendously great if the storms would so kind as to spread themselves out a week or two apart so we have time for water to travel through the system."
In the winter of 1861-62, an onslaught of rainy weather led to catastrophic floods in California and the Pacific Northwest, where torrential downpours washed away houses and farms and transformed valleys into enormous lakes. According to experts, the likelihood of a repeat of catastrophic floods is increasing as global warming persists.
Are they occurring more frequently?
Dr. Swain and Xingying Huang of the National Center for Atmospheric Research in Boulder, Colorado calculated that California currently has a roughly 1-in-50 probability of annually witnessing a storm of equal strength to the storm of 1861-62 in a research published last year. According to their estimates, the probabilities have already increased since a century ago due to climate change.
It is yet unknown how climate change may alter how frequently atmospheric rivers may concentrate and smash onto California. Another study conducted last year discovered that between 1981 and 2019, half or more of all atmospheric rivers that affected the state were a part of an atmospheric river "family," or a rapid parade of storms. This occurred in nearly four out of five of those years.
However, Dr. Swain said the greater ability of the warmer atmosphere to store moisture is sufficient justification for California policymakers to get ready for more catastrophic rain events in the present and the future.
It would function to 'juice up,' if you will, whatever atmospheric rivers are happening, whether it's families of atmospheric rivers or one-offs, he added, even if that were the only thing that was going on.
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