Tag Archives: Tropical Depression 27W

Tropical Storm Fengshen Forms East of Northern Marianas

Tropical Storm Fengshen formed east of the Northern Marianas on Tuesday.  At 4:00 p.m. EST on Tuesday the center of Tropical Storm Fengshen was located at latitude 17.1°N and longitude 157.1°E which put it about 805 miles (1300 km) east of Saipan.  Fengshen was moving toward the west-northwest at 18 m.p.h. (30 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 1000 mb.

More thunderstorms developed near the center of a cluster of thunderstorms east of the Northern Marianas on Tuesday and the Japan Meteorological Society designated the system as Tropical Storm Fengshen.  The distribution of thunderstorms around Tropical Storm Fengshen was asymmetrical.  Stronger thunderstorms were occurring in bands in the western half of the circulation.  Bands in the eastern half of the tropical storm consisted primarily of showers and lower clouds.  Fengshen was moving south of an upper level ridge over the Western North Pacific Ocean.  The ridge was producing easterly winds which were causing moderate vertical wind shear.  The wind shear was contributing to the asymmetrical distribution of thunderstorms.

Tropical Storm Fenshen will move through an environment favorable for intensification during the next several days.  Fengshen will move over water where the Sea Surface Temperature is near 29°C.  The upper level ridge will continue to cause vertical wind shear.  The wind shear will inhibit intensification, but the shear will not be strong enough to prevent intensification.  Tropical Storm Fengshen will intensify gradually and it could strengthen into a typhoon during the next two to three days.

Tropical Storm Fengshen will move around the western end of the ridge over the Western North Pacific.  The ridge will steer Fengshen toward the west-northwest during the next 24 to 36 hours.  Tropical Storm Fengshen will move more toward the north in about 36 hours when it reaches the western end of the ridge.  On its anticipated track Fengshen will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 27W developed east of Luzon.  At 4:00 p.m. EST on Tuesday the center of Tropical Depression 27W was located at latitude 12.1°N and longitude 130.9°E which put it about 315 miles (510 km) east of Laoang, Philippines.  The depression was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1004 mb.

Typhoon Lan Brings Wind and Rain to Japan

Typhoon Lan brought wind and rain to parts of Japan on Sunday.  At 5:00 p.m. EDT on Sunday the center of Typhoon Lan was located at latitude 35.2°N and longitude 139.1°E which put it about 50 miles southwest of Tokyo, Japan.  Lan was moving toward the northeast at 37 m.p.h. (60 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 960 mb.

Typhoon Lan weakened significantly before it reached Japan.  Lan moved over cooler water south of Japan.  Strong upper level westerly winds caused strong vertical wind shear.  The circulation of Lan pulled drier air into the western half of the circulation.  The combination of cooler water, strong shear and drier air caused the significant weakening.  In addition the shear was strong enough to push the heavier rain to the northeast of the center of Typhoon Lan.

Lan was still a typhoon when it made landfall in Honshu despite the unfavorable environment.  A weather station at the Tokyo International Airport reported a wind speed of 56 m.p.h. (90 km/h).  Some areas in eastern Honshu experienced periods of heavy rain and gusty winds.  The drier air will limit the rainfall after the center of the typhoon passes a given location.

The strong westerly winds will steer Typhoon Lan rapidly toward the northeast.  Lan will move east of Honshu in a few hours.  The strong vertical wind shear and cooler, drier air will cause Typhoon Lan to transition to a strong extratropical cyclone east of Japan.

While Typhoon Lan races across eastern Japan, Tropical Depression 27W organized southeast of Guam.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression 27W was located at latitude 9.3°N and longitude 147.4°E which put it about 360 miles (580 km) southeast of Guam.  It was moving toward west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gust to 45 m.p.h.  The minimum surface pressure was 1004 mb.

Tropical Depression 27W will move through an environment that will be somewhat favorable for development during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge centered northeast of the Marianas is producing easterly winds which are blowing over the top of the depression.  Those winds are causing moderate vertical wind shear.  The shear is inhibiting the organization of the circulation and it is slowing the development of the depression.  The shear is forecast to decrease during the next several days and the depression could strengthen into a tropical storm if a distinct low level center forms.

Tropical Depression 27W is near the southwestern end of the ridge to its northeast.  The ridge is currently steering the depression toward the west.  It is forecast to move around the end of the ridge and turn more toward the north during the next few days.  On its anticipated track the depression could be near Guam in about 24 hours.  It could be a tropical storm at that time.

Tropical Depression 27W Forms Southeast of Pohnpei

A center of circulation formed in an area of thunderstorms southeast of Pohnpei and the system was designated Tropical Depression 27W (TD 27W).  At 10:00 p.m. EST on Monday the center of Tropical Depression 27W was located at latitude 4.7°N and longitude 162.3°E which put it about 360 miles (585 km) east-southeast of Pohnpei.  TD 27W was moving to the west at 17 m.p.h. (27 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1001 mb.

The circulation of TD 27W is still organizing.  A clearly defined low level center of circulation formed near the northern edge of an area of thunderstorms.  However, most of the stronger thunderstorms are southwest of the center.  Those storms are generating upper level divergence that is expanding south and west of the center.

Tropical Depression 27W is in an environment that favors further intensification.  It is over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of TD 27W is producing light easterly winds over the top of the depression.  The vertical wind shear is modest, and it should only slow the rate of intensification.  Intensification could be slow initially as a stronger inner core forms around the center of circulation.  Once the core of the circulation consolidates, then intensification could occur more quickly.  TD 27W could become a tropical storm within 24 to 36 hours and it could be a typhoon in three or four days.

A subtropical ridge north of TD 27W is steering the depression toward the west.  A gradual turn toward the west-northwest is expected and that general motion is expected to continue for much of the week.  On its anticipated track TD 27W could be near Pohnpei in about 24 hours and it could bring tropical storm force winds and heavy rain.  The tropical cyclone could be approaching Guam by the end of the week and it could be a typhoon by that time.