Eos, Transactions American Geophysical Union

El Niño-induced flooding in the U.S. West: What can we expect?



Ocean conditions in the tropical Pacific seem to be signaling the emergence of another El Niño event. Even though it is uncertain what will happen in the next two to three seasons, climate forecasting centers are beginning to advise planners in ENSO-sensitive regions to review their contingency plans. Here, we examine the potential for floods in the western United States as measured by the annual maximum flood in the region.

The timing (figure 1) and causes of the annual maximum flood vary across the western United States. Nevertheless, correlations of the annual maximum flood with January-April averages of the NIN03 and Pacific Decadal Oscillation (PDO) indices are statistically significant over large, contiguous areas in the region, irrespective of the dominant season of occurrence and the operative climate mechanism.