Hurricane (Typhoon) — Saipan, Guam

2018-10-24 to 2018-10-25 · Saipan, Guam

Event narrative

A tropical disturbance was noted just northwest of Kosrae on the morning of October 21 near 8N160E. By the morning of October 22 the system had become Tropical depression 31W and was 130 miles north-northwest of Pohnpei. 31W continued to intensify through the day and by the afternoon of the 22nd became Tropical Storm Yutu. Yutu continued to strengthen and became a typhoon on the afternoon of October

23rd.

Yutu continued to intensify and on the afternoon of the 24th it became a Super Typhoon. A Super Typhoon is a Joint Typhoon Warning Center's designation placed on a system if wind speeds in the typhoon equal or exceed 150 mph. At that time, Yutu was less than 200 miles to the east of the Marianas.

The 20 mile wide eye of Super Typhoon Yutu crossed over Tinian between midnight and 0400 ChST on October 25th. Saipan is not too far away from Tinian and the southern part of the island had the destructive eye wall pass over it. The highest wind gust recorded on Saipan was 90 knots (104 mph) at 24/1444Z. Weather instruments on Tinian and Saipan were either destroyed or damaged and this was most likely not the highest winds that occurred. Ground based storm assessment estimated maximum sustained winds were 170 mph with wind gust to 200 mph. A Saipan resident recorded a wind gust to 168 mph plus another anemometer had a peak wind of 133 mph. On Guam, Andersen AFB saw a gust to 50 knots (58 mph) at 24/1554Z and 24/1603Z. Over central Guam the National Weather Service Office observed a peak gust to 46 knots(53 mph) 24/1624.

Only 2.66 inches of rain was observed at the Saipan airport, but most likely was well below what actually fell. A University of Guam professor on Saipan had set up a rain gage and recorded 10 inches of rain fall, but he was located 3 miles northeast of the eye. Below are rainfall amounts recorded on Guam.

24 25

NWS Tiyan Guam 0.56 0.56

Geomag Observatory Rain Gage, Andersen AFB 0.86 0.62

Umatac Rain Gage at Umatac, Guam 0.42 0.54

Almagosa Rain Gage nr Santa Rita 0.72 0.58

Fena RG at Res. 0.95 0.57

Windward Hills Rain Gage 0.91 0.53

Dededo Rain Gage 0.56 1.00

Mt. Santa Rosa 0.62 0.88

A 44 year old woman died after she sought shelter from the storm in an abandoned building in Chalan Kanoa Saipan. Strong winds caused the wall of the structure to fall on the lady. A second woman died on Saipan in Susupe. She was found dead in a building and died from carbon monoxide poisoning from a portable generator. 121 injuries were reported at least 1000 structures were damage or destroyed across the Commonwealth of the Northern Marianas. The power plant on both Tinian and Saipan were destroyed.

Wider weather episode

Super Typhoon Yutu passed through the Marianas October 24th to 25th. Yutu was classified as the second most powerful storm to hit the U.S.A.

Source: NOAA Storm Events Database, event_id 816106. Narrative written by the NWS forecast office that issued the report.