Atmospheric Blocking and Other Large-Scale Precursor Patterns of Landfalling Atmospheric Rivers in the North Pacific: A CESM2 Study

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Benedict, James J., Clement, Amy C., Medeiros, Brian
• Language: unknown
• Published: 2022
• Subjects: 54 ENVIRONMENTAL SCIENCES; Pacific; Alaska; Siberia
• Online Access: http://www.osti.gov/servlets/purl/1799696; https://www.osti.gov/biblio/1799696; https://doi.org/10.1029/2019jd030790

Atmospheric rivers, narrow channels of strong winds carrying abundant moisture and spanning thousands of kilometers, often result in flooding. The broader weather patterns that precede atmospheric river formation can determine which regions the storms will impact, but our understanding of such processes remains insufficient. In this study, atmospheric river events in the North Pacific region are identified, and their precursor weather patterns are examined in observational data sets and within a global climate model. The analysis shows that when a large area of high pressure forms over Alaska and far eastern Siberia, the preferred path of storms crossing the North Pacific is diverted toward the south. The southward-shifted storms, some of which develop into atmospheric rivers, guide moist air toward the U.S. west coast and can produce extreme precipitation. The climate model performs reasonably well at representing atmospheric rivers and their associated precursor weather patterns. These results highlight important connections between atmospheric rivers and the large-scale weather patterns than can precede them by more than a week. Knowledge of such patterns has the potential to improve predictions of damaging wind and extreme precipitation events.