Storm Surge/Tide — Saipan, Guam

2025-07-24 to 2025-07-27 · Saipan, Guam

Event narrative

The greatest storm surge that was reported was along western shores of Saipan. Based on photos taken after the event at Micro Beach, Saipan, storm surge was roughly estimated to be around 2 to 3 feet, based on subtracting the predicted astronomical tide height of 1 foot (referenced to mean sea level) from the estimated run-up line height. The Division of Coastal Resources Management at Saipan reported the following impacts: minimal structural damage to shade structures and signage along public beaches. Notable sand loss at Micro Beach, particularly along the shoreline adjacent to the lifeguard station and reef marker areas. Uprooted and broken trees, some blocking pedestrian walkways. Temporary flooding along Beach Road, especially near low-lying crosswalks and drain outlets.

Wider weather episode

Tropical Storm Krosa (12W) produced peripheral impacts to the Marianas during the period of July 24-27 as the center kept west of the Marianas, with no fatalities or injuries reported, and only minimal damage to shade structures, signage, and a few down trees along public beaches of Saipan, caused by storm surge/tide. Krosa developed within a west-ward moving surface trough in northern Chuuk State as monitored as Invest 98W by the Joint Typhoon Warning Center on July 21st. Invest 98W passed over Guam during the overnight hours of July 23-24 and would become Tropical Depression 12W west of Guam. TD 12W would continue to intensify into a tropical storm early on July 25th and would maintain a northerly heading, keeping just west of the Marianas island chain. In the wake of Krosa, a monsoon surge wrapped around the southern and eastern sides of Krosa. Krosa would eventually become a typhoon at 7AM ChST July 28th as it left WFO Guam's area of responsibility. The minimum sea-level pressure recorded over land was 1006 mb via the ASOS on Saipan. Peak rainfall of 4.06 inches was also recorded at Saipan over a 48 hour period. The ASOS on Saipan recorded a peak wind of 19 kts (22 mph) with a peak gust of 34 kts (39 mph). Peak storm surge estimate available was at Saipan and was roughly estimated to be around 2 to 3 feet, based on subtracting the predicted astronomical tide height of 1 foot (referenced to mean sea level) from the estimated run-up line height that was based on photos taken after the event.

Source: NOAA Storm Events Database, event_id 1290128. Narrative written by the NWS forecast office that issued the report.