Atmospheric rivers (ARs) effect inland hydrological impacts related to
extreme precipitation. However, little is known about the possible
coastal hazards associated with these storms. Here we elucidate
high-tide floods (HTFs) and storm surges during ARs through a
statistical analysis of data from the US West Coast during 1980-2016.
HTFs and landfalling ARs co-occur more often than expected from random
chance. Between 10%-63% of HTFs coincide with landfalling ARs,
depending on location. However, only 2%-15% of ARs coincide with HTFs,
suggesting that ARs typically must co-occur with anomalously high tides
or mean sea levels to cause HTFs. Storm surges during ARs are
interpretable in terms of local wind, pressure, and precipitation
forcing. Meridional wind and barometric pressure are the primary drivers
of the storm surge. This study highlights the relevance of ARs to
coastal impacts, clarifies the drivers of storm surge during ARs, and
identifies future research directions.