Hurricane (Typhoon) — Saipan, Guam

2023-05-23 to 2023-05-25 · Saipan, Guam

Event narrative

On May 17th a circulation that had been over the area for a few days was classified as Invest 97W by JTWC. 97W was located to the west-southwest of Chuuk at that time. Scatterometer data showed a west-wind burst south of the circulation with winds up to 30 knots. On the morning of May 18th, 97W was located near 6N147E. At this time strong convection was located to the southeast of the center with cloud-top temperatures down to -83C. These temperatures correspond to cloud tops up

to 56k feet. The circulation continued to organize over the next few days. Scatterometer satellite imagery shows a well-defined circulation center surrounded by 20 to 25-knot winds by the 20th of May. On the afternoon of May 20th, the circulation was classified as Tropical Depression 02W. The tropical depression was located near 5.6N 149.0E or about 235 miles west-southwest of Chuuk with maximum sustained

winds of 30 mph. 02W continued to intensify and by the morning of the 21st of May it became Tropical Storm Mawar. Mawar was located near 5.9N 149.2E at about 185 miles west-southwest of Chuuk. Winds were up to 40 mph. Mawar continues to intensify and by the morning of the 22nd of May, it became a typhoon. At that time Typhoon Mawar was located near 8.3N 148.1E, or about 260 miles west-northwest of Chuuk with maximum sustained winds of 80 mph.

Mawar continued to intensify as it moved towards the Marianas and by the evening of May 23rd it was located near 12.1N 146.3E or about 205 miles south-southeast of Tinian, and 210 miles south of Saipan. By that time Mawar had winds up to 155 mph.

In the Northwest Pacific, a typhoon with winds of 150 mph or higher is classified as a super typhoon.

During the morning of the 24th radar and satellite imagery detected the eye was deteriorating slightly. It was determined that Mawar was undergoing an eyewall replacement. During an eyewall replacement cycle(ERC) winds near the eye

usually decrease briefly. This also happened to Mawar and later that morning it was estimated to have decreased from 155 mph to 140 mph.

By the early afternoon of the 24th of May, Mawar was located near 13.2N 145.E or only about 125 miles south of Tinian, and about 135 miles south of Saipan. Later that afternoon Mawar was passing near northern Guam and was near 13.6N 145.2E or about south of Tinian, and 110 miles south-southwest of Saipan. At this time the typhoon had maximum sustained winds of 140 mph. Mawar started to move away from the CNMI during the morning of the 24th.

The ASOS at the Saipan International Airport recorded winds of 37 mph with a gust to 52 mph. A private weather station on Wireless Ridge in Saipan gusted to 70 mph

An automated Sutron on Tinian observed winds of 35mph with a gust to 52 mph.

The lowest SLP at the Tinian Sutron was 998.2 mb, on Saipan AMME Garapan Saipan CNMI NPS 1000.3 mb and Saipan International Airport CNMI ASOS 1001.3 mb.

Mawar impacts across Tinian and Saipan impacts were consistent with tropical storm wind conditions. For these two islands, many banana trees were felled, along with many large branches and some uprooted trees that blocked some secondary roads. Lighter-constructed buildings saw some damage with some tin roofs being peeled up. On Saipan, a few non-residential wood and tin structures were blown apart.

Wider weather episode

Mawar developed over the Northwest Pacific Ocean in the second half of May. It moved northwestward from near Chuuk to eventually cross the Mariana Islands near Guam and Rota.

Source: NOAA Storm Events Database, event_id 1120094. Narrative written by the NWS forecast office that issued the report.