Forecasting Seasonal Sea Level Changes for Pacific Islands

With higher relative sea levels, minor coastal flooding is occurring more often during periods of large astronomical tides. If combined with above-normal seasonal sea levels, often associated with climate-driven variability in the ocean, coastal flooding becomes more severe. Many Pacific islands including Hawaii and parts of Micronesia have experienced recurrent flooding since the end of strong El Niño in 2016. Such total high water events expose coastlines to potentially damaging storm-related flooding, yet seasonal prediction of coastal high water is in an early development stage. Advancements forecasting seasonal climate variability using state-of-the-art coupled ocean-atmosphere models, which have the ability to assimilate and predict sea level, provides the opportunity to predict the potential for future high water events several months in advance. By compiling monthly sea level anomaly predictions from multiple models, which are typically skillful out to at least 6 months in the tropical Pacific, improved future outlooks are achieved. At the University of Hawaii Sea Level Center, we are delivering a real-time forecasting product of monthly mean sea level anomalies that is being served online to the Pacific island community. The goal is to reduce the residual between predicted tides and observed water levels by forecasting relative sea level changes. Here, a recap of forecasting recent high sea level events in the tropical Pacific will be reported.