National Weather Service Southeast River Forecast Center and Office of Water Prediction’s Support of the Implementation of Flood Inundation Mapping in Puerto Rico

The National Weather Service (NWS) has developed the capabilities to provide Flood Inundation Maps (FIM) from the National Water Model (NWM) with real-time analyses of forecasted freshwater river levels nationwide. The Southeast River Forecast Center (SERFC) was included as one of the field offices to be a part of the strategic rollout of publicly available FIM services in 2024. This was the second stage of the implementation plan, where 30% of the nation’s population is able to receive publicly available FIM services. The San Juan, Puerto Rico Weather Forecast Office’s (SJU) service area was a part of this second stage of the effort and is the first office outside of the continental U.S. (OCONUS) to have publicly available FIM services.

Two flood inundation mapping services will be made public in Puerto Rico in late 2024. The NWM Latest Analysis FIM,which updates hourly, and the NWM 48-Hour FIM, which is available twice daily, will be available for viewing on the National Water Prediction Services (NWPS) website. The new services could be of considerable benefit for decision making given the limited flood forecast services available in Puerto Rico prior to the FIM release. In addition, SJU will work closely alongside both SERFC and the Water Prediction OPerations Division (WPOD) of the National Water Center for FIM assistance and interpretation during the pre-flood, flood event, and post-flood event phases.

In preparation for the rollout of publicly available FIM services in Puerto Rico, staff from the National Water Center and SERFC visited SJU for a two-day training and outreach visit in June 2024. The visit included training sessions on services available from the NWM and FIM, training partner agencies on how to use FIM in their operations, and a tabletop exercise was conducted using archived data from Hurricane Fiona to mimic and help answer potential questions that could arise during an event. The visit also featured a meeting with the Autoridado De Acueductos Y Alcantarillados (The Puerto Rico Aqueduct and Sewer Authority), which is the main provider of water supply on the island and the manager of several reservoir projects.