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Extreme Atmospheric Rivers: What will California’s Strongest Storms Look Like in a Warming Climate?

/in , , /by /WeatherWestby Daniel Swain

Atmospheric rivers (ARs)—long, sinuous corridors of water vapor in motion in the lower half of Earth’s atmosphere—are a key aspect of California’s cool-season climate. ARs are in many cases pretty unremarkable when they’re out over the open ocean, visible on satellite as a narrow ribbon of cloudiness and (usually) light precipitation. But when these moisture plumes attach themselves to wintertime low pressure systems and make landfall along the California coast, the consequences can be dramatic—prolonged heavy rain and mountain snow often result, along with sometimes powerful winds.

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Future Precipitation Increase from Very High Resolution Ensemble Downscaling of Extreme Atmospheric River Storms in California

/in , , /by /ScienceAdvances (AAAS)by Xingying Huang, Daniel L. Swain, and Alex D. Hall

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often inadequately resolved by global climate models. In this analysis, we develop a framework involving targeted dynamical downscaling of historical and future extreme precipitation events produced by a large ensemble of a global climate model. This framework is applied to extreme “atmospheric river” storms in California.

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Early April Precipitation is Expected to be Below Normal Where it is Most Needed in Northern California

/in , , /by /Los Angeles Timesby Paul Duginski

April showers may be more scarce than normal north of Point Conception in California, according to an outlook produced by the National Oceanic and Atmospheric Administration.

This area where the probability of precipitation is below normal includes virtually all of Northern California and the crucial northern Sierra Nevada, where the state’s largest reservoirs are located.

While snow cover has increased thanks to a series of March storms, the Northern Sierra 8-Station Index stands at 56% of normal for the season. As of March 24, another 29.25 inches would be needed to reach the season normal of 54.52 inches.

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