Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Strengthening Typhoon Nesat Nearing Taiwan

Strengthening Typhoon Nesat moved nearer to Taiwan on Friday.   At 5:00 p.m. EDT on Friday the center of Typhoon Nesat was located at latitude 22.0°N and longitude 123.3°E which put it about 275 miles (440 km) south-southeast of Taipei, Taiwan.  Nesat was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 973 mb.

Typhoon Nesat has a very well organized circulation.  A ring of thunderstorms almost completely surrounds the eye.  There is a small gap in the ring on the northeastern rim of the eye.  Numerous additional bands of showers and thunderstorms are occurring in the southern half of the circulation.  There are fewer bands of showers and thunderstorms in the northern part of the circulation.  Thunderstorms in the core of Typhoon Nesat are producing upper level divergence which is pumping out mass.  Winds to typhoon force extend out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extend out about 145 miles (230 km) from the center.

Typhoon Nesat will be moving through an environment favorable for intensification until it reaches Taiwan.  Nesat will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge centered west of Japan is producing east-northeasterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear, but they are not strong enough to keep Typhoon Nesat from strengthening.  Typhoon Nesat is likely to intensify for another 12-18 hours until it reaches Taiwan.  When it Nesat reaches Taiwan, the mountains will disrupt the circulation.

Typhoon Nesat is being steered toward the west-northwest by a subtropical ridge to its north.  A general west-northwesterly or northwesterly motion is expected to continue until Nesat makes landfall in Taiwan.  On its anticipated track Typhoon Nesat will make landfall on the east coast of Taiwan in 12 to 18 hours.  Neast will bring strong winds and heavy rain to Taiwan.  The heavy rain is likely to cause flash floods in the mountains.

Typhoon Noru Approaches Iwo To From Northeast

Typhoon Noru approached Iwo To from the northeast on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Noru was located at latitude 27.6°N and longitude 143.0°E which put it about 220 miles (355 km) north-northeast of Iwo To.  Noru was moving toward the southwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (150 km/h).  The minimum surface pressure was 975 mb.

Typhoon Noru retains a well organized circulation.  An eyewall wraps about three quarters of the way around the eye.  There is a break in the ring of thunderstorms on the northeastern rim of the eye.  Bands of showers and thunderstorms are occurring north and east of the center of circulation.  There are fewer showers and thunderstorms south and west of the center of the typhoon.  Thunderstorms near the center are generating some upper level divergence.  The circulation of Typhoon Noru is fairly large.  Winds to tropical storm force extend out about 200 miles (320 km) from the center of circulation.

Typhoon Noru will be moving through an environment that is marginally favorable for intensification.  Noru will move over water where the Sea Surface Temperature (SST) is near 29°C.  An upper level ridge centered west of Japan is producing northeasterly winds which are blowing toward the top of the circulation.  Those northeasterly winds are creating moderate vertical wind shear, which is limiting the upper level divergence to the north of the typhoon.  The wind shear is not strong enough to weaken Typhoon Noru, but it is strong enough to inhibit intensification.  Typhoon Noru may undergo small changes in intensity during the next several days, but it could maintain its status as a typhoon.

The ridge west of Japan is also steering typhoon Noru toward the southwest and that general motion is expected to continue for another day or so.  In 24 to 48 hours Noru is forecast to reach and area where the steering winds are weak and it could stall near Iwo To.  On its anticipated path Typhoon Noru could bring an extended period of strong gusty winds and heavy rain to Iwo To.

Tropical Storm Nesat Forms Southeast of Taiwan

Tropical Storm Newsat formed southeast of Taiwan on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Nesat was located at latitude 18.0°N and longitude 127.5°E which put it about 620 miles (1000 km) southeast of Taipei, Taiwan.  Nesat was moving toward the north at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 988 mb.

A well organized surface circulation formed in an area of thunderstorms southeast of Taiwan on Wednesday.  A strong cluster of thunderstorms formed south of the center of circulation.  Additional bands of showers and thunderstorms developed in the western and southern portions of Tropical Storm Nesat.  There were few thunderstorms in the eastern half of the circulation.  More thunderstorms appeared to be forming near the core of the circulation in recent hours.  The thunderstorms in the core were generating upper level divergence which was pumping out mass.

Tropical Storm Nesat will be moving through an area that is favorable for intensification.  Nesat will move over water where the Sea Surface Temperature is near 31°C.  Tropical Storm Nesat is beneath the northeastern part of an upper level ridge.  The ridge is producing northeasterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear and the shear could be the reason for the asymmetrical distribution of thunderstorms.  Tropical Storm Nesat could move under the axis of the upper level ridge where the winds are weaker.  In that case the shear would be less and Nesat could intensify more quickly.  Tropical Storm Nesat is likely to intensify into a typhoon during the next 24 hours.

Tropical Storm Nesat is moving around a weak area in a subtropical ridge, which is allowing the tropical storm to move toward the north.  The ridge is forecast to strengthen and when that happens it will steer Nesat more toward the west.  On its anticipated track Tropical Storm Nesat could approach Taiwan in about three days.  Nesat could be a strong typhoon when it nears Taiwan.

Elsewhere in the Western North Pacific Typhoon Noru has turned back toward the west.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Noru was located at latitude 30.6°N and longitude 151.2°E which put it about 770 miles (1240 km) east-northeast of Iwo To.  Noru was moving toward the west at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (150 km/h).  The minimum surface pressure was 978 mb.

A subtropical ridge north of Typhoon Noru is steering the typhoon toward the west.  A general westerly motion is forecast to continue for several more days.  Noru could reach an area of weaker steering winds in a few days and its motion may slow.  On its anticipated track Typhoon Noru could approach Iwo To in three or four days.

Tropical Storm Sonca Near Landfall in Vietnam.

Tropical Storm Sonca neared a landfall on the coast of Vietnam on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Sonca was located at latitude 16.7°N and longitude 108.2°E which put it about 60 miles (95 km) east-northeast of Hue, Vietnam.  Sonca was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 991 mb.

The circulation of Tropical Storm Sonca is fairly small.  Winds to tropical storm force only extend out about 60 miles (95 km) from the center of circulation.  A subtropical ridge north of Sonca is steering the tropical storm toward the west and that general motion is expected to continue for another 24 to 36 hours.  On its anticipated track the center of Tropical Storm Sonca will make landfall north of Hue, Vietnam in a few hours.

Tropical Storm Sonca will bring gusty winds, locally heavy rain and the potential for floods when it makes landfall.  Sonca will continue to move inland over central Vietnam, central Laos and northeastern Thailand.  Sonca could continue to produce locally heavy rain over those areas as it moves inland and weakens.

Elsewhere in the Western North Pacific the circulations of Typhoon Noru and Tropical Storm Kulap are interacting east-southeast of Japan.  At 11:00 p.m. EDT on Monday the center of Typhoon Noru was located at latitude 25.9°N and longitude 157.0°E which put it about 1330 miles (2150 km) east-southeast of Tokyo, Japan.  Noru was moving toward the east at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 95 m.p.h. (155 km/h) and there were gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 966 mb.

At 11:00 p.m. EDT the center of Tropical Storm Kulap was located at latitude 32.9°N and longitude 155.8°E which put it about 1095 miles (1765 km) east-southeast of Tokyo, Japan.  Kulap was moving toward the west at 15 m.p.h. (24 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 1000 mb.

Typhoon Noru and Tropical Storm Kulap are close enough to each other to rotate cyclonically around a point between them in what is called the Fujiwhara effect.  Typhoon Noru is the much larger and stronger circulation and upper level outflow from Noru is causing vertical wind shear over Tropical Storm Kulap.  If the two tropical cyclones move closer to each other, it is possible that the circulation of Kulap could be absorbed by the larger, more powerful circulation of Typhoon Noru.

Tropical Storm Roke Close to Landfall Near Hong Kong

Tropical Storm Roke is close to making a landfall near Hong Kong.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Roke was located at latitude 22.4°N and longitude 114.1°E which put it about 35 miles (55 km) east of Hong Kong.  Roke was moving toward the west-northwest at 14 m.p.h. (22 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 sutface pressure was 1002 mb.

Tropical Storm Roke will make landfall on the coast of China near Hong Kong during the next few hours.  Roke will bring gusty winds and locally heavy rainfall as it move inland over eastern China.  Flash flooding could occur in places that receive heavy rain.

Elsewhere, there are three more tropical storms over the Western North Pacific Ocean.  Tropical Storm 08W is the only other imminent threat to land.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm 08W was located at latitude 17.6°N and longitude 111.5°E which put it about 85 miles (135 km) southeast of Hainan Island.  It was moving toward the west at 4 m.p.h. (6 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 999 mb.

At 11:00 p.m. EDT on Saturday the center of Tropical Storm Noru was located at latitude 28.3°N and longitude 151.3°E which put it about 920 miles (1485 km) east-southeast of Tokyo, Japan.  Noru was moving toward west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 997 mb.

At 11:00 p.m. EDT the center of Tropical Storm Kulap was located at latitude 30.8°N and longitude 166.8°E which put it about 790 miles (1270 km) north of Wake Island.  Kulap was moving toward the west-northwest at 13 m.p.h. (20 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 1000 mb.

Tropical Storm Noru Forms Southeast of Japan

Tropical Storm Noru formed southeast of Japan on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Noru was located at latitude 28.3°N and longitude 157.0°E which put it about 1145 miles (1850 km) east-southeast of Tokyo, Japan.  Noru was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 40 m.p.h. (64 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1003 mb.

Tropical Storm Noru had a complicated development.  Noru began as a cold front that became stationary southeast of Japan.  The front stalled over water where the Sea Surface Temperature (SST) was near 30°C.  Transfers of internal energy from the ocean to the atmosphere warmed the air and the temperature difference between the two sides of the front gradually diminished.  A surface low pressure system developed along the dissipating front.  An upper level low initially near the front caused strong vertical wind shear over the surface low.  The wind shear kept blowing the tops off thunderstorms that started to develop near the surface low.  Eventually, the upper low moved far enough to the northwest of the surface low for the vertical wind shear to decrease and thunderstorms were able to develop near the surface low.  The low gradually began to exhibit tropical characteristics and the Japan Meteorological Agency designated the system as Tropical Storm Noru.

The circulation of Tropical Storm Noru is still not well organized.  Although there is a definite center of circulation at the surface most of the showers and thunderstorms are forming in bands in the eastern half of the circulation.  There are few showers and thunderstorms in the western half of the circulation.  Thunderstorms on the eastern side of Noru are generating some upper level divergence which is pumping mass away to the east of the tropical storm.

Tropical Storm Noru is an environment that is somewhat favorable for intensification.  Noru is moving over water where the SST is near 30°C.  However, the upper low northwest of Noru and an upper level ridge near Noru are generating moderate vertical wind shear.  The wind shear may be part of the reason for the asymmetrical distribution of thunderstorms.  Tropical Storm Noru is likely to intensify but the vertical wind shear will slow the rate of intensification.

A subtropical ridge to the north of Noru is steering the tropical storm toward the northwest.  The northwesterly motion is expected to continue for another day or two.  The steering currents are expected to weaken in 36 to 48 hours an Noru could meander southeast of Japan during the weekend.

Tropical Storm Talas Makes Landfall in Vietnam

Tropical Storm Talas made landfall on the coast of Vietnam on Sunday.  Talas was bringing gusty winds and heavy rainfall to parts of Vietnam, Laos and Thailand.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Talas was located at latitude18.6°N and longitude 105.5°E which put the center near Vinh, Vietnam.  Talas was moving toward the west at 17 m.p.h. (27 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 984 mb.

Tropical Storm Talas strengthened before it made landfall in Vietnam.  A primary band wrapped around the western and southern sides of the center of circulation.  Thunderstorms formed near the center of Talas as the tropical storm approached the coast of Vietnam.  The strongest winds in Tropical Storm Talas were occurring in thunderstorms over the South China Sea.  Tropical Storm Talas will weaken as it moves farther inland.

Tropical Storm Talas was bringing gusty winds and heavy rain to parts of Vietnam, Laos and Thailand.  Locally heavy rain could cause flooding, which will be the greatest risk as Tropical Storm Talas moves farther inland.

Tropical Storm Talas Forms East of Vietnam

Tropical Storm Talas formed east of Vietnam on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Talas was located at latitude 17.3°N and longitude 110.1°E which put it about 170 miles (270 km) east-northeast of Da Nang, Vietnam.  Talas was moving toward the west 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 996 mb.

A large area of showers and thunderstorms persisted over the South China Sea for the past several days.  A distinct center of circulation began to develop in the northern part of the area of thunderstorms.  The Japan Meteorological Agency classified the system as Tropical Storm Talas on Saturday.

The circulation of Tropical Storm Talas is still organizing.  The center of rotation was near the northwestern edge of the area of thunderstorms.  Additional thunderstorms were beginning to form near the center of circulation.  Several bands of showers and thunderstorms were southwest of the center.  Bands of lighter showers were occurring in the remainder of Tropical Storm Talas.  Thunderstorms forming near the center of circulation were beginning to generate strong upper level divergence which was pumping out mass.

Tropical Storm Talas has about 24 hours to strengthen.  Talas will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of Talas is producing easterly winds which are blowing toward the top of the tropical storm.  There is some vertical wind shear, but the shear appears to have diminished during the past few hours.  Since Tropical Storm Talas will be moving through an environment of very warm water and reduced vertical wind shear, it will likely strengthen during the next 24 hours.

A subtropical ridge north of Talas is steering the tropical storm toward the west and motion a little to the north of due west is forecast.  On its anticipated track the center of Tropical Storm Talas will pass south of Hainan Island.  Tropical Storm Talas will approach the coast of Vietnam near Vinh in about 24 hours.  Tropical Storm Talas will bring gusty winds and locally heavy rain to Central Vietnam when it makes landfall.

Tropical Storm Nanmadol Nearing Kyushu

Tropical Storm Nanmadol was quickly nearing Kyushu on Monday.  At 1:00 p.m. EDT on Monday the center of Tropical Storm Nanmadol was located at latitude 31.0°N and longitude 127.4°E which put it about 215 miles (345 km) southwest of Sasebo, Japan.  Nanmadol was moving toward the north-northeast at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 986 mb.

The structure of Tropical Storm Nanmadol was still consistent with its designation of a tropical cyclone, but there were signs that it could be about to start the transition to an extratropical cyclone.  There was a core of thunderstorms around the center of circulation.  The strongest winds were occurring in the inner core which extended out about 25 miles (40 km) from the center.  Several rainbands were on the eastern side of the circulation.  There were far fewer showers and thunderstorms in the western half of the circulation.  There were some indications that Nanmadol could be pulling cooler, drier, more stable air into the western side of the tropical storm.

Tropical Storm Nanmadol has probably reached its maximum intensity and it is likely to weaken during the next two days.  Nanmadol is currently over water where the Sea Surface Temperature is near 27°C.  However, it has reached the upper level westerly in the middle latitudes and the vertical wind shear is increasing.  Nanmadol will weaken faster when it moves across Japan.

The westerly winds in the middle latitudes have turned Tropical Storm Nanmadol toward the north-northeast.  As Nanmadol moves farther north, the speed of the westerlies will increase and the tropical storm is forecast to move quickly toward the east-northeast across southern Japan.  On its anticipated track, Tropical Storm Nanmadol will reach Kyushu in a few hours.  Nanmadol will also move over Shikoku and Honshu.  Tropical Storm Nanmadol will bring a brief period of gusty winds and the potential for locally heavy rain when it moves across southern Japan.

Tropical Storm Nanmadol Brings Wind and Rain to Southern Ryukyu Islands

Tropical Storm Nanmadol brought wind and rain to the southern Ryukyu Islands on Sunday.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Nanmadol was located at latitude 24.4°N and longitude 124.7°E which put it about 40 miles (65 km) east of Ishigaki, Japan.  Nanmadol was moving toward the north-northwest at 21 m.p.h. (34 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 998 mb.

The core of Tropical Storm Nanmadol continued to organize on Sunday.  A ring of thunderstorms wrapped tightly around the center of circulation.  Additional bands of showers and thunderstorms formed outside the core.  Thunderstorms were beginning to generate more upper level divergence which was pumping out mass in all directions.  The circulation of Tropical Storm Nanmadol was fairly small.  Winds to tropical storm force only extend out about 70 miles (110 km) from the center.

Tropical Storm Nanmadol will be in an environment that is very favorable for intensification for about another 24 hours.  Nanmadol will be moving over water where the Sea Surface Temperature (SST) is near 29°C.  The circulation of Tropical Storm Nanmadol is underneath the center of an upper level ridge and the upper level winds are very weak.  Warm SSTs and almost no vertical wind shear will permit Tropical Storm Nanmadol to intensify during the next day and there could be a period of rapid intensification.  Nanmadol could strengthen into a typhoon before it reaches a less favorable environment.  The tropical storm will move over cooler SSTs and it will move into an area of stronger upper level westerly winds in a couple of days.  Nanmadol will begin to weaken when that happens.

Tropical Storm Nanmadol is moving around the western end of a subtropical ridge which is steering it toward the north.  A general northward motion is expected to continue for about another 24 hours.  Nanmadol will reach the westerly winds in the middle latitudes in about a day and those winds will turn it toward the northeast.  On its anticipated track the center of Tropical Storm Nanmadol will pass west of Okinawa.  Nanmadol could approach Kyushu in about 36 hours.  Tropical Storm Nanmadol will continue to cause gusty winds and locally heavy rain over the southern Ryukyu Islands for another 12 to 24 hours.