Multiyear predictability of flood frequency along the U.S. Southeast Coast from Atlantic Meridional Overturning Circulation variability

Observations have shown a significant increase in flood frequency along the U.S. Southeast Coast (USSEC) since the year 2010. This increased flooding is driven both by increases in storm frequency and rising background sea level due to increasing greenhouse gases and internal low-frequency variabilities. While background sea levels are the primary factor driving the increase in flooding events, storms are responsible for the most extreme flooding events and play a crucial role in determining the maximum flood intensity. We describe here multiyear predictability of USSEC flood frequency, where much of the predictive skill originates from predictable decadal scale variations in the Atlantic Meridional Overturning Circulation (AMOC) which impact regional sea level. Using a 1/12o regional ocean model along with AMOC predictions from the Geophysical Fluid Dynamics Laboratory (GFDL) global decadal prediction system, we generate skillful flood frequency predictions along the USSEC with significant skill three years in advance. AMOC-driven sea-level variability provides a source of multiyear predictability for increasing post-2010 flood frequency along the US Southeast Coast up to three years ahead, according to a study using a regional ocean model and decadal AMOC predictions