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Atmospheric rivers as drought busters on the U.S. west coast

Journal of Hydrometeorology

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DOI: 10.1175/JHM-D-13-02.1

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Abstract

Atmospheric rivers (ARs) have, in recent years, been recognized as the cause of the large majority of major floods in rivers all along the U.S. West Coast and as the source of 30%–50% of all precipitation in the same region. The present study surveys the frequency with which ARs have played a critical role as a common cause of the end of droughts on the West Coast. This question was based on the observation that, in most cases, droughts end abruptly as a result of the arrival of an especially wet month or, more exactly, a few very large storms. This observation is documented using both Palmer Drought Severity Index and 6-month Standardized Precipitation Index measures of drought occurrence for climate divisions across the conterminous United States from 1895 to 2010. When the individual storm sequences that contributed most to the wet months that broke historical West Coast droughts from 1950 to 2010 were evaluated, 33%–74% of droughts were broken by the arrival of landfalling AR storms. In the Pacific Northwest, 60%–74% of all persistent drought endings have been brought about by the arrival of AR storms. In California, about 33%–40% of all persistent drought endings have been brought about by landfalling AR storms, with more localized low pressure systems responsible for many of the remaining drought breaks.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Atmospheric rivers as drought busters on the U.S. west coast
Series title:
Journal of Hydrometeorology
DOI:
10.1175/JHM-D-13-02.1
Volume
14
Issue:
6
Year Published:
2013
Language:
English
Publisher:
American Meteorological Society
Contributing office(s):
National Research Program - Western Branch
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Hydrometeorology
First page:
1721
Last page:
1732
Country:
United States
State:
California;Oregon;Washington