Water Level Verification of Versions 1 and 2 of the Extratropical Surge and Tide Operational Forecast System for the Middle Texas Coast

Accurate water level guidance forecasts are important to decision makers who live or interact within the land-sea interface. When water levels are anomalously high along the Middle Texas Coast, significant impacts occur which affect thousands of people. Flooded properties, closed beaches, and closed coastal roads are just some of the impacts that can result. Given these impacts, National Weather Service Corpus Christi marine forecasters must understand verification of marine model water level guidance in order to produce the most accurate forecast possible for decision makers.

Version 1 of the Extratropical Surge and Tide Operational Forecast System (ESTOFS) was first implemented on 18 September 2012. On 25 April 2017, the ESTOFS was upgraded to version 2. This upgrade increased its native grid resolution from 3 kilometers to 200 meters and also increased the resolution from 55 kilometers to 13 kilometers of the Global Forecast System (GFS) input used by the ESTOFS. Verification results from both versions of the ESTOFS will be presented in this study for all coastal flooding events that were observed along the Middle Texas Coast between the summers of 2015 and 2018. Coastal flooding in this study is defined as water levels reaching at or above 2 feet above mean sea level as measured at Bob Hall Pier located in Corpus Christi, Texas.

Preliminary verification results indicate an improvement in water level forecasts from version 2 versus version 1 of the ESTOFS.