California Department of Water Resourecs-CW3E Research and Operations Partnership: Highlights of a Family of Nine Atmospheric Rivers
California has the most variable precipitation in the country, driven by the presence or absence of atmospheric rivers (ARs). Climate projections indicate that ARs will become more extreme and will contribute a larger share of annual precipitation. Longer periods of dry conditions, punctuated by stronger and wetter ARs, are also predicted.
Nine atmospheric rivers made landfall over the U.S. West Coast during December 27, 2022 – January 17, 2023. Arrows represent the locations, orientation, and strength (color) or each AR during ther peak intensity over land.
A look at the last decade suggests that California is already entering this transition, with a record dry period from 2012-2016, and again from 2020-2022 affecting much of the state. AR activity (or lack thereof) during this period corresponds to these changing conditions.
Recently, a rapid transition from dry to wet occurred when a family of nine ARs hit the California coast over three weeks starting on December 27, 2022. These storms were driven by the alignment of the jet stream over the North Pacific and featured the longest period of continuous AR days since 1950. They caused enormous impacts statewide.
The following Story Map, “California Department of Water Resourecs-CW3E Research and Operations Partnership: Highlights of a Family of Nine Atmospheric Rivers,” was developed to delve into the dynamics and characteristics of these storms with the goal of further improving forecast skill. CW3E, in partnership with CA DWR, has made great strides in AR forecast skill (increasing lead time by a full day in just 5 years). Continued improvements are made possible by better understanding, and thus better predicting, the factors that contribute to AR landfall direction, timing, duration, and intensity.
The Story Map covers the characteristics, dynamics, forecast skill and impacts of the nine ARs that impacted the coast from December 26, 2022 to January 17, 2023, the key role of AR observations (reconnaissance program), and future research needs.