The U.S. territorial island of Guam in the western Pacific has to prepare annually for tropical cyclones. These storms can approach the island from multiple directions and intensities. Knowing this information is key to predicting storm surge impacts and preparing the island’s community.
When storm surge specialists at NOAA’s National Hurricane Center start developing a new storm surge “basin,” which is the foundation of the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model, the first step is to perform an intensive climatological assessment to see the directions and intensities of storms that have typically approached the coast. Using the Historical Hurricane Tracks tool, modelers quickly searched the historical record for Guam, finding that most storms approached the island from the east or southeast. But there are several outliers that show up in the results, such as Olive in 1963 and Andy in 1989, that approached the island from a more southerly direction. Therefore, in addition to including hypothetical tracks that come from the typical east and southeast directions, modelers also included directions such as south and southwest.
By using the Historical Hurricane Tracks tool, modelers determined that storms of all categories, up to and including category 5, have impacted the island in the past and may continue to do so in the future. Therefore, the SLOSH model data should be developed for all storm intensities, ensuring modelers they’re including the most relevant directions and intensities of tropical cyclones. Communities can then trust they’re using the best data when considering future development and community planning. (2022)