Typhoon Mireille

September 1991

In 1990 the Joint Typhoon Warning Center Guam revised its list of names for Western North Pacific tropical cyclones and added the name Mireille. The list is published in the 1990 Annual Tropical Cyclone Report available from the National Technical Information Service acquisition number AD A239910, and in PDF format. Mireille Bouchard was the daughter of one of the typhoon forecasters at the Joint Typhoon Warning Center, Guam. She was named for her mother's classmate - Mireille Marquis of Van Buren, Maine. Van Buren is located in extreme northeastern Maine on the St. John River which separates Maine from the Canadian province of New Brunswick.

In 1991 Typhoon Mireille (Joint Typhoon Warning Center, Guam classified it as a Super Typhoon, but the term Super Typhoon is not widely recognized, see the Hong Kong link) was one of the worst typhoons to strike Japan. The death and destruction were so terrible that the name Mireille was retired, never to be used to name another typhoon. An exhaustive treatment of Typhoon Mireille can be found in the 1991 Annual Tropical Cyclone Report available from National Technical Information Service acquisition number AD 251952, and PDF format.

(The following is from the 1991 Annual Tropical Cyclone Report
Capt. Dan Mundell, USAF and Mr. Frank Wells, Eds.)



    The second super typhoon in the Northwest Pacific of the year. Mireille became the worst storm to strike Japan in three decades. Mireille outgrew its early midget size and reached super typhoon intensity several days before threatening Okinawa. Recurving just to the southwest of Okinawa, the typhoon accelerated, cutting a path across western Kyushu and Honshu. Then over the Sea of Japan, Mireille transitioned into an intense extratropical cyclone which slammed into northern Honshu. Mireille was part of a three storm outbreak in September - first with Tropical Storm Luke (20W) and Typhoon Nat(22W), and later with Typhoons Nat and Orchid(23W).


    Mireille was first described as a poorly organized area of cloudiness in the monsoon trough over the southern Marshall Islands. The disturbance was mentioned on the 130600Z Significant Tropical Weather Advisory. An increase in the amount of the tropical disturbance's deep convection prompted a Tropical Cyclone Formation Alert at 151200Z. Assuming normal development, forecasters issued the first warning for a 30-kt (15-m/s) system at 160000Z. However, this was not to be a normal system. This was reflected in the 160600Z warning which upgraded the intensity to 45 kts (23 m/s) and identified the system as very compact and rapidly intensifying. For several days the tropical system drifted to the west-northwest under the influence of the subtropical ridge. On the evening of 17 September, Mireille began to track to the west-southwest, creating some concern that it would target Guam, but 24 hours later the typhoon acquired a westward track and passed 12 nm (20 km) north of Saipan on 19 September as a midget typhoon. Then, on 21 September, the typhoon began interacting with Typhoon Nat (22W). This binary interaction resulted in the temporary capture of the smaller typhoon, Nat, and its subsequent movement southward in the South China Sea. After releasing Nat, Mireille recurved under increasing southwesterly mid-tropospheric winds, and accelerated northeastward past Okinawa. Extratropical transition occurred in the Sea of Japan and the intense baroclinic storm continued northeastward, first passing over the extreme northern section of Honshu and then moving over southern Hokkaido.

    The tropical cyclone initially peaked at 75 kt (39 m/s) on 16 September and remained at moderate typhoon intensity until 21 September when it commenced a second deepening episode enroute to super typhoon intensity. This second episode was associated with decreasing upper-level wind shear from Tropical Storm Luke (20W) as that system weakened and accelerated northward. After peaking at 130 kt (65 m/s) for a day (221200Z to 230600Z), Mireille began to slowly weaken.

    Mireille's size, which was determined by the diameter of its outer-most closed isobar, began gradually to increase after an intensity of 80 kt (40 m/s) was reached, and continued through subtropical transition.

    JTWC Best Track


    As Mireille passed the Mariana Islands, it was difficult to determine how much the thin extension of the subtropical ridge would affect the cyclone's track. The first indications of a possible west-southwestward track excursion toward Guam came from the Beta-Advection Models. OTCM locked onto a west-southwest track after the turn had started. However, both FBAM and OTCM overemphasized the southward excursion which lasted only day.
    After the system had passed the Marianas, recurvature forecasts wer premature. The NOGAPS model underestimated teh strength and teh duration of the subtropical ridge, and as a result all of the dynamic objective aids indicated early recurvature. The underestimation may have been the model's response to receiving three simultaneous tropical cyclone boguses in the basin corresponding to three storms. Also, the bogus, initializing the NOGAPS model, overplayed the size of Mireille, which in turn overemphasized the storm's weakening influence on the ridge.


    As Mireille approached the Mariana Islands, the wobble of its track and subsequent adjustment of the forecast to the north and back to the west, resulted in a flurry of disaster perparedness preparations on Guam northward through Saipan. When the midget typhoon passed north of Saipan, no reports of deaths or injuries were received. However, the island did suffer 70-80% crop damage, in addition to trees being uprooted, and coral roads seriously eroded. Most damage was confined to the north end of the island. Okinawa experienced 27 hours with winds greater than 50 kt (25 m/s) and Kadena AB recorded a peak gust of 82 kt (41m/s). The island also recorded a total rainfall of 10.14 inches, and as a result, was able to cancel water rationing for the remainder of the year. Press reports from Japan indicated that 52 deaths were associated with the typhoon, including all ten crew memebers of a South Korea freighter that capsized while in port at Hakata on the island of Kyushu. Press reports also indicated 777 injuries, the flooding of approximately 10,000 homes, and power outages affecting naerly 6 million homes. Japanese crop damage was estimated at US$ 3 billion, with the apple crop being particularly hard hit. Nagasaki (WMO 47855) reported winds of 72 kt (37 m/s) gusting to 118 kt (61 m/s). On northern Honshu, Misawa AB recorded the most destructive winds since the U.S. started record-keeping for the base in 1946. For more than 5 hours the winds wer 50 kt (25 m/s) or greater and included a peak gust to 82 kt (41 m/s). The previous all-time record for the base was 70 kt (35 m/s) in March of 1987. The resulting wind damage was estimated to be between 0.5 to 1.5 million dollars. Several warehouse roofs were torn off, storage sheds were reportedly knocked off their foundations, and trees were blown down. The The Pacific Stars and Stripes reported: "Base officials credit the Joint Typhoon Warning Center in Guam with early storm forecasts that allowed them to warn the base population and get million-dollar aircraft into hardened shelters."


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Glossary of Terms
Beta Advection Model
Numerical forecasting model which primarily drives tropical cyclones by means of the advection of Beta which is the change in the Coriolis parameter (f) with latitude.
Binary Interaction
Also known as Fujiwhara Effect
When two tropical cyclones are within 750 nm (1390 km) of begin to track around a central point between the two.
See Brand, S., 1970: Interaction of Binary Tropical Cylones of the Western North Pacific Ocean. Jrnl. Appl. Met., V.9, pp. 433-441.
Artificial data.
Extratropical Cyclone
Describes a former tropical cyclone that has lost its tropical characteristics, but may still have strong winds associated it with it.
One-Way Influence Tropical Cyclone Model
A numerical model which uses a grid system into which a tropical cyclone is inserted (bogussed) before the model is run.
Super Typhoon
A term used by JTWC for Western North Pacific tropical cyclones with maximum sustained surface wind speeds of 130 kt (65 m/s) or greater.
Tropical cyclones in the Western North Pacific with maximum sustained winds speeds greater than 63 kt (33 m/s).
Tropical depression
Tropical cyclone with maximum sustained surface winds less than 34 kt (17 m/s).
Tropical Storm
Tropical cyclones with maximum sustained surface winds between 34 and 63 kt.
World Meteorological Organization.