The origins of Mireille were from a poorly-organized area of convection, or thunderstorms, associated with the monsoon trough near the Marshall Islands on September 13.
That day, the Japan Meteorological Agency (JMA) began tracking the system as a tropical depression.
The system moved westward, developing a large increase in thunderstorms over the center on September 15.
That day, the Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert, and issued their first advisory on Tropical Depression 21W at 00:00 UTC, estimating 1‑minute sustained winds of 55 km/h (35 mph).
About six hours later, the agency upgraded the depression to Tropical Storm Mireille, after satellite imagery indicated the storm was very compact and intensifying quickly.
The JTWC later determined in a post-storm analysis that Mireille had attained tropical storm status 12 hours earlier on the previous day.
Also at the time of it attaining tropical storm status, Mireille was one of three storms in the basin, along with Tropical Storm Luke to the northwest and Typhoon Nat to the west in the South China Sea.

Only 12 hours after the JTWC issued the first warning, Mireille attained typhoon status at 12:00 UTC on September 16, and several hours later reached an initial peak intensity of 135 km/h (85 mph).
The small storm moved west-northwestward due to the influence of the subtropical ridge to the north.
On September 17, the track shifted to the west-southwest, threatening Guam.
The small typhoon turned more to the west, passing about 20 km (12 mi) north of Saipan on September 19, part of the Northern Marianas Islands north of Guam.
For several days, Mireille failed to intensify due to wind shear from the larger Tropical Storm Luke to the north.
After Luke weakened and progressed northward, Mireille was able to strengthen more gradually, as well as increase in size.
On September 22, the typhoon strengthened into a super typhoon, which is an unofficial category used by the JTWC for storms reaching 1‑minute winds of at least 240 km/h (150 mph).
According to the JMA, Mireille attained 10‑minute winds of 185 km/h (115 mph) on September 23.

Around the time of reaching peak intensity, Mireille turned more to the northwest along the southwestern periphery of the subtropical ridge.
The increasing size began to impart wind shear in Typhoon Nat to the west, and the two storms underwent the Fujiwhara effect, in which Nat turned sharply southward while Mireille progressed toward the Ryukyu Islands of Japan.
After maintaining peak winds for about 30 hours, Mireille began weakening, passing just east of Miyako-jima on September 26 with 10‑minute winds of 165 km/h (105 mph), according to the JMA.
That day, the typhoon accelerated to the northeast due to increasing mid-level winds from the southwest, passing west of Okinawa.
According to the JMA, Mireille re-intensified slightly on September 27 to a secondary peak of 175 km/h (110 mph), aided by unusually warm water temperatures in the East China Sea.
The typhoon made landfall at that strength at 07:00 UTC between Saikai and Nagasaki along southwest Kyushu.
The pressure at landfall was 940 mbar (28 inHg), the lowest in the country since Typhoon Trix in 1971.

The typhoon quickly weakened while continuing northeastward through Kyushu and western Honshu, and started to become an extratropical cyclone; during the process, the wind field expanded, aided by moist air from the southwest and cold air from the northwest.
It accelerated further over the Sea of Japan, and late on September 27, Mireille made a second landfall in Japan along southwestern Hokkaido at 22:00 UTC, with 10‑minute winds of 150 km/h (90 mph) still at typhoon status.
Crossing the island, the typhoon weakened to tropical storm status early on September 28, and shortly thereafter became fully extratropical in the Sea of Okhotsk.
The powerful remnants of Mireille continued eastward, crossing the Aleutian Islands on September 29 and crossed the International Date Line shortly thereafter.
That day, a pressure of 954 mb (hPa; 28.17 inHg) was obser
The origins of Mireille were from a poorly-organized area of convection, or thunderstorms, associated with the monsoon trough near the Marshall Islands on September 13. That day, the Japan Meteorological Agency (JMA) began tracking the system as a tropical depression. The system moved westward, developing a large increase in thunderstorms over the center on September 15. That day, the Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert, and issued their first advisory on Tropical Depression 21W at 00:00 UTC, estimating 1‑minute sustained winds of 55 km/h (35 mph). About six hours later, the agency upgraded the depression to Tropical Storm Mireille, after satellite imagery indicated the storm was very compact and intensifying quickly. The JTWC later determined in a post-storm analysis that Mireille had attained tropical storm status 12 hours earlier on the previous day. Also at the time of it attaining tropical storm status, Mireille was one of three storms in the basin, along with Tropical Storm Luke to the northwest and Typhoon Nat to the west in the South China Sea.
Only 12 hours after the JTWC issued the first warning, Mireille attained typhoon status at 12:00 UTC on September 16, and several hours later reached an initial peak intensity of 135 km/h (85 mph). The small storm moved west-northwestward due to the influence of the subtropical ridge to the north. On September 17, the track shifted to the west-southwest, threatening Guam. The small typhoon turned more to the west, passing about 20 km (12 mi) north of Saipan on September 19, part of the Northern Marianas Islands north of Guam. For several days, Mireille failed to intensify due to wind shear from the larger Tropical Storm Luke to the north. After Luke weakened and progressed northward, Mireille was able to strengthen more gradually, as well as increase in size. On September 22, the typhoon strengthened into a super typhoon, which is an unofficial category used by the JTWC for storms reaching 1‑minute winds of at least 240 km/h (150 mph). According to the JMA, Mireille attained 10‑minute winds of 185 km/h (115 mph) on September 23.
Around the time of reaching peak intensity, Mireille turned more to the northwest along the southwestern periphery of the subtropical ridge. The increasing size began to impart wind shear in Typhoon Nat to the west, and the two storms underwent the Fujiwhara effect, in which Nat turned sharply southward while Mireille progressed toward the Ryukyu Islands of Japan. After maintaining peak winds for about 30 hours, Mireille began weakening, passing just east of Miyako-jima on September 26 with 10‑minute winds of 165 km/h (105 mph), according to the JMA. That day, the typhoon accelerated to the northeast due to increasing mid-level winds from the southwest, passing west of Okinawa. According to the JMA, Mireille re-intensified slightly on September 27 to a secondary peak of 175 km/h (110 mph), aided by unusually warm water temperatures in the East China Sea. The typhoon made landfall at that strength at 07:00 UTC between Saikai and Nagasaki along southwest Kyushu. The pressure at landfall was 940 mbar (28 inHg), the lowest in the country since Typhoon Trix in 1971.
The typhoon quickly weakened while continuing northeastward through Kyushu and western Honshu, and started to become an extratropical cyclone; during the process, the wind field expanded, aided by moist air from the southwest and cold air from the northwest. It accelerated further over the Sea of Japan, and late on September 27, Mireille made a second landfall in Japan along southwestern Hokkaido at 22:00 UTC, with 10‑minute winds of 150 km/h (90 mph) still at typhoon status. Crossing the island, the typhoon weakened to tropical storm status early on September 28, and shortly thereafter became fully extratropical in the Sea of Okhotsk. The powerful remnants of Mireille continued eastward, crossing the Aleutian Islands on September 29 and crossed the International Date Line shortly thereafter. That day, a pressure of 954 mb (hPa; 28.17 inHg) was obser
Typhoon Mireille