In the foothills of the Rocky Mountains, buzzing chainsaws interrupt the serenity. Crews are hustling to remove charred trees and other debris that have been washing down the mountainsides in the wake of the largest wildfire in New Mexico’s recorded history, choking rivers and streams.
Heavy equipment operators are moving boulders dislodged by the daily torrential summer rains that have followed the flames.
A team led by Kristen Guirguis, a climate researcher at Scripps Institution of Oceanography at UC San Diego, found evidence that the risk of hazardous weather is increasing in the Southwest.
The researchers investigated the daily relationships among four major modes of weather affecting California. How they interact governs the formation of weather events such as atmospheric rivers capable of bringing torrential rains and Santa Ana winds that can spread devastating wildfires.
“This study suggests that weather patterns are changing in a way that enhances hot, dry Santa Ana winds, while reducing precipitation frequency in the Southwest,” said Guirguis. “These changes in atmospheric circulation are raising the risk of wildfires during California winters.”
A team led by Kristen Guirguis, a climate researcher at Scripps Institution of Oceanography at UC San Diego, found evidence that the risk of hazardous weather is increasing in the Southwest.
The researchers investigated the daily relationships among four major modes of weather affecting California. How they interact governs the formation of weather events such as atmospheric rivers capable of bringing torrential rains and Santa Ana winds that can spread devastating wildfires.
“This study suggests that weather patterns are changing in a way that enhances hot, dry Santa Ana winds, while reducing precipitation frequency in the Southwest,” said Guirguis. “These changes in atmospheric circulation are raising the risk of wildfires during California winters.”
The study, “Winter wet—dry weather patterns driving atmospheric rivers and Santa Ana winds provide evidence for increasing wildfire hazard in California,” was published in the journal Climate Dynamics July 17, 2022.
Dillard Road is flooded near the Hwy 99 off ramp, located south of Elk Grove, California. Photo credit: Florence Low / California Department of Water Resources.The basis of the research was an examination of the dominant atmospheric circulation patterns over the North Pacific Ocean, known as Baja-Pacific, Alaskan-Pacific, Canadian-Pacific, and Offshore-California modes. What distinguishes them from each other are the relative positions of ridges and troughs in the atmosphere.
The research team identified 16 recurring weather patterns that are created daily as these modes interact with each other. One product of the work was a summary of California weather patterns from 1949 to 2017. The patterns associated with the formation of dry gusty Santa Ana winds that often stoke Southern California fires are becoming more frequent. Patterns associated with what might be considered “normal” rainfall are decreasing in the Southwest thus promoting drought, but patterns associated with extreme precipitation and strong atmospheric river episodes have remained steady over the study period. The researchers noted that while the patterns associated with heavy precipitation and strong atmospheric rivers have not changed in frequency, a warmer atmosphere is capable of holding more water so these storms are becoming more damaging.
The results suggest an increasing probability of compounding environmental hazards during California winters, said the research team. Though winter atmospheric rivers are the antithesis of hot, dry Santa Ana wind conditions, sequences of wildfires followed by strong atmospheric rivers often compound the damage from fires when they trigger flash floods and destructive debris flows from burn scars.
Photo of the Thomas Fire taken from a Santa Barbara beach. Photo credit: Carsten Schertzer / iStock.“This spells challenges for wildfire and water resource management and provides observational support to our previous results projecting that California will increasingly have to depend on potentially hazardous atmospheric rivers and floodwater for water resource generation in a warming climate,” said study co-author Alexander Gershunov, a Scripps Oceanography climate scientist.
Study authors say this work is helping to inform an experimental subseasonal-to-seasonal (S2S) forecast product being developed at Scripps Oceanography’s Center for Western Weather and Water Extremes (CW3E) that predicts extreme weather in California including atmospheric river landfalls, Santa Ana winds, drought, and heat waves.
The U.S. Department of the Interior via the Bureau of Reclamation and the Southwest Climate Adaptation Science Center, the California Department of Water Resources, and the Regional Integrated Sciences and Assessments (RISA) California—Nevada Climate Applications Program and the International Research Applications Program of the National Oceanic and Atmospheric Administration funded the study. Additional funding was provided by the University of California Office of the President MRPI grant.
High water levels on the Tuolumne River close River Road in the city of Modesto, California, part of Stanislaus County. Photo credit: Dale Kolke / California Department of Water Resources.The San Diego County Water Authority has a partnership with the Scripps Institution of Oceanography at UC San Diego to better predict atmospheric rivers and improve water management before, during and after seasonal storms.
(Editors Note: Study co-authors include Benjamin Hatchett of the Desert Research Institute in Nevada; Tamara Shulgina, Michael DeFlorio, Rosana Aguilera, achel Clemesha, Tom Corringham, Luca Delle Monache, and Marty Ralph of CW3E at Scripps Oceanography; Aneesh Subramanian and David Reynolds of the University of Colorado Boulder; Janin Guzman-Morales of the University of California Santa Barbara; and Alex Tardy and Ivory Small of the National Weather Service.)
As the drought punishing California drags on, water is a top — and growing — worry for residents of our parched state, outpacing wildfires and climate change, according to a new poll about environmental issues.
With reservoirs and snowpack shrinking, Californians listed the state’s water supply as their number one environmental worry, with 68% of adults saying it’s a big problem — up from 63% a year ago.
Lake Siskiyou is beautiful this time of year.
About 200 miles north of Sacramento, the artificial reservoir — formed by a dam on the Sacramento River — is ringed by quiet beaches that offer a cool respite from triple-digit heat. The views of Mt. Shasta are spectacular. When I visited last week, I saw double-crested cormorants, ospreys and great blue herons soaring over the water and ducklings swimming with their mother.
California’s forests are in rapid retreat, which bodes ill for the future.
Using satellite data, researchers from the University of California, Irvine found that trees in the state’s mountainous regions declined 6.7 percent between 1985 and 2021 thanks to wildfires, drought and other climate-related sources of stress.
The U.S. national drought early-warning information system, called NIDIS, gave a rundown Thursday on when much of the Southwest will experience conditions that heighten the potential for wildfire.
Drought is one of the main drivers because less water means drier soils, drier plants and drier air, all conditions that fuel wildfire.
California likely will have an energy shortfall equivalent to what it takes to power about 1.3 million homes when use is at its peak during the hot and dry summer months, state officials said Friday.
Threats from drought, extreme heat and wildfires, plus supply chain and regulatory issues hampering the solar industry will create challenges for energy reliability this summer, the officials said. They represented the California Public Utilities Commission, the California Energy Commission, and the California Independent System Operator, which manages the state’s energy grid.
Flood, fire, and drought fueled by climate change could take a massive bite out of the U.S. federal budget per year by the end of the century, the White House said in its first ever such assessment on Sunday.
The Office of Management and Budget assessment, tasked by President Joe Biden last May, found the upper range of climate change’s hit to the budget by the end of the century could total 7.1% annual revenue loss, equal to $2 trillion a year in today’s dollars.
Already diminished by drought and extreme heat, California’s water supply will face yet another peril as wildfires continue to incinerate ever larger areas of forested land, according to new research.
In a UCLA-led study published Monday in the journal Proceedings of the National Academy of Sciences, researchers determined that increasing forest fire activity is “unhinging” western U.S. stream flow from its historical predictability. In areas where more than a fifth of the forest had burned, stream flow increased by an average of 30% for six years after the fire.
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