Tag Archives: Tropical Storm Rai

Typhoon Rai Rapidly Weakens to a Tropical Storm

Former Typhoon Rai rapidly weakened to a tropical storm south-southwest of Hong Kong on Monday. At 4:00 p.m. EST on Monday the center of Tropical Storm Rai was located at latitude 20.1°N and longitude 113.5°E which put it about 190 miles (305 km) south-southwest of Hong Kong. Rai was moving toward the northeast at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 997 mb.

A surface high pressure system over eastern Asia produced northeasterly winds that transported drier air which was pulled into the circulation of former Typhoon Rai. The drier air caused the thunderstorms in Rai’s circulation to dissipate and the circulation weakened. Bands revolving around the center of Tropical Storm Rai consisted almost entirely of showers and lower clouds. Winds to tropical storm force extended out 65 miles (105 km) from the center of circulation.

Since Tropical Storm Rai consists of a shallow circulation, it will be steered by the winds in the lower levels of he atmosphere. Rai will move around the northwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Tropical Storm Rai toward the east-northeast during the next 24 hours. On its anticipated track Tropical Storm Rai could be southwest of Taiwan in 24 hours.

Tropical Storm Rai will move through an environment unfavorable for a tropical cyclone. Rai will move over water where the Sea Surface Temperatures are near 27˚C. However, Rai will continue to be surrounded by drier air, which will prevent the formation of new thunderstorms. In addition, an upper level trough over eastern Asia will produce southwesterly winds that will blow across the top of Rai’s circulation. Those winds will cause strong vertical wind shear and the shear will also be unfavorable for intensification. Tropical Storm Rai will continue to weaken during the next 24 hours.

Tropical Storm Rai Strengthens East of Palau

Tropical Storm Rai strengthened east of Palau on Monday night. At 10:00 p.m. EST on Monday the center of Tropical Storm Rai was located at latitude 7.7°N and longitude 136.3°E which put it about 170 miles (275 km) east of Koror, Palau. Rai was moving toward the west-northwest at 21 m.p.h. (33 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 990 mb.

Tropical Storm Rai strengthened steadily over the Western North Pacific Ocean on Monday. Although Rai intensified, the distribution of thunderstorms was asymmetrical. The strongest thunderstorms were occurring in bands in the western half of Tropical Storm Rai’s circulation. The inner end of a rainband wrapped around the western and southern side of the center of Rai’s circulation. Bands in the eastern half of the tropical storm consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away to the west and north of the tropical storm. Winds to tropical storm force extended out 200 miles (320 km) from the center of Rai.

Tropical Storm Rai will move through an environment favorable for intensification during the next 48 hours. Rai will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the southern side of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds that will blow toward the top of Tropical Storm Rai’s circulation. Those winds will cause some vertical wind shear and the shear is already contributing to the current asymmetrical distribution of thunderstorms. The upper level winds are forecast to weaken, and the vertical wind shear will be too small to prevent intensification. Tropical Storm Rai will intensify and it likely to strengthen to a typhoon during the next 24 hours. Rai could strengthen more rapidly once an inner core with an eye and an eyewall forms.

Tropical Storm Rai will move south of a surface high pressure system over the Western North Pacific Ocean. The high pressure system will steer Rai toward the west-northwest during the next several days. On its anticipated track the center of Tropical Storm Rai will north of Palau during the next 12 hours. Rai could bring gusty winds and locally heavy rain to Palau. Tropical Storm Rai could approach the Philippines in 60 hours. Rai is likely to be a typhoon when it reaches the Philippines.

Tropical Storm Rai Forms Southeast of Yap

Tropical Storm Rai formed over the Western North Pacific Ocean southeast of Yap on Monday morning. At 4:00 a.m. EST on Monday the center of Tropical Storm Rai was located at latitude 5.5°N and longitude 140.5°E which put it about 355 miles (575 km) southeast of Yap. Rai was moving toward the west-northwest at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 998 mb.

The circulation around a low pressure system strengthened on Monday morning and the Japan Meteorological Agency designated the system as Tropical Storm Rai. Thunderstorms formed near the center of Tropical Storm Rai. More thunderstorms also developed in bands revolving around the center of Rai. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 150 miles (240 km) from the center of Tropical Storm Rai.

Tropical Storm Rai will move through an environment favorable for intensification during the next several days. Rai will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the southern side of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds that will blow toward the top of Tropical Storm Rai’s circulation. Those winds will cause some vertical wind shear, but the shear will be too small to prevent intensification. Tropical Storm Rai will intensify during the next several days. Rai could strengthen to a typhoon within 36 hours. It could strengthen more rapidly once an inner core with an eye and an eyewall forms.

Tropical Storm Rai will move south of a surface high pressure system over the Western North Pacific Ocean. The high pressure system will steer Rai toward the west-northwest during the next several days. On its anticipated track the center of Tropical Storm Rai will south of Yap during the next 24 hours. Rai could bring gusty winds and locally heavy rain to Yap. Tropical Storm Rai could affect Palau within 36 hours. Rai could approach the Philippines within 72 hours. Rai is likely to be a typhoon when it reaches the Philippines.