Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Nyatoh Strengthens to a Typhoon West of the Marianas

Former Tropical Storm Nyatoh strengthened to a typhoon west of the Marianas on Wednesday. At 10:00 a.m. EST on Wednesday the center of Typhoon Nyatoh was located at latitude 15.5°N and longitude 135.6°E which put it about 580 miles (935 km) west-northwest of Guam. Nyatoh was moving toward the north-northwest 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. (145 km/h). The minimum surface pressure was 981 mb.

Former Tropical Storm Nyatoh continued to strengthen over the Western North Pacific Ocean west of the Marianas on Wednesday. The inner end of a rainband wrapped around the center of Typhoon Nyatoh and microwaves satellite images indicated that an eye was forming. The developing eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Nyatoh. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 35 miles (55 km) from the center of Nyatoh. Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation.

Typhoon Nyatoh will move through an environment mostly favorable for intensification during the next 24 hours. Nyatoh will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the western part of the axis of an upper level ridge centered near the Marianas. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Clockwise flow around a high pressure system centered over eastern Asia will transport drier air toward the northwestern part of Nyatoh’s circulation. The drier air is likely to remain northwest of Typhoon Nyatoh during the next 24 hours. Nyatoh could intensify more rapidly once the eye and eyewall become fully formed. Typhoon Nyatoh will continue to strengthen and it could intensify to the equivalent of a major hurricane during the next 24 hours. An upper level trough west of Japan will produce southwesterly winds that will begin to affect Nyatoh later this week. Those winds will create more vertical wind shear and the shear will cause Typhoon Nyatoh to weaken.

Typhoon Nyatoh will move around the western part of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer Nyatoh toward the north during the next 24 hours. The upper level trough will steer Typhoon Nyatoh toward the northeast after Nyatoh moves around the western end of the high pressure system. On its anticipated track Tropical Storm Nyatoh will remain west of the Marianas during the next 24 hours. Nyatoh could approach Iwo To in 48 hours.

Tropical Storm Nyatoh Strengthens West of the Marianas

Tropical Storm Nyatoh strengthened over the Western North Pacific Ocean west of the Marianas on Tuesday. At 4:00 p.m. EST on Tuesday the center of Tropical Storm Nyatoh was located at latitude 13.4°N and longitude 136.7°E which put it about 510 miles (825 km) west of Guam. Nyatoh was moving toward the west-northwest at 7 m.p.h. (11 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 991 mb.

Tropical Storm Nyatoh continued to strengthen west of the Marianas on Tuesday. The inner end of a rainband wrapped around the northern and western sides of the center of Nyatoh. Additional bands of showers and thunderstorms were revolving around the center of Tropical Storm Nyatoh. Storms near the center of circulation generated strong upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 130 miles (210 km) from the center of Nyatoh’s circulation.

Tropical Storm Nyatoh will move through an environment mostly favorable for intensification during the next 24 hours. Nyatoh will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of the axis of an upper level ridge centered east of the Marianas. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Clockwise flow around a high pressure system centered over eastern Asia could transport drier air toward the northwestern part of Nyatoh’s circulation. The drier air is likely to remain northwest of Tropical Storm Nyatoh during the next 24 hours. Nyatoh could intensify more rapidly once the inner end of the rainband wraps around the center of circulation and a core with an eye and an eyewall develops. Tropical Storm Nyatoh will continue to strengthen and it will intensify to a typhoon during the next 24 hours.

Tropical Storm Nyatoh will move around the western part of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer Nyatoh toward the north during the next 24 hours. Nyatoh could move toward the northeast after it moves around the western end of the high pressure system. On its anticipated track Tropical Storm Nyatoh will remain west of the Marianas during the next 24 hours.

TD 27W Strengthens to Tropical Storm Nyatoh West of Guam

Former Tropical Depression 27W strengthened to Tropical Storm Nyatoh west of Guam on Monday night. At 10:00 p.m. EST on Monday the center of Tropical Storm Nyatoh was located at latitude 13.0°N and longitude 138.7°E which put it about 370 miles (600 km) west of Guam. Nyatoh was moving toward the west 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 surface pressure was 1000 mb.

The circulation around former Tropical Depression 27W continued to strengthen on Monday night and the Japan Meteorological Agency upgraded the system to Tropical Storm Nyatoh. More thunderstorms developed near the center of circulation and in the bands revolving around the center of Nyatoh. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 125 miles (200 km) from the center of Tropical Storm Nyatoh.

Tropical Storm Nyatoh will move through an environment mostly favorable for intensification during the next 36 hours. Nyatoh will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of the axis of an upper level ridge centered east of the Marianas. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Clockwise flow around a high pressure system centered over eastern Asia could transport drier air toward the northwestern part of Nyatoh’s circulation. The drier air is likely to remain northwest of the core of Tropical Storm Nyatoh during the next 36 hours. Tropical Storm Nyatoh will continue to strengthen and it could intensify to a typhoon during the next 36 hours.

Tropical Storm Nyatoh will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high pressure system will steer the tropical depression toward the northwest during the next 36 hours. On its anticipated track Tropical Storm Nyatoh will move farther away from the Marianas and Yap.

Tropical Depression Forms Southwest of the Marianas

A tropical depression formed southwest of the Marianas on Monday morning. At 7:00 a.m. EST on Monday the center of Tropical Depression 27W was located at latitude 11.8°N and longitude 141.1°E which put it about 270 miles (435 km) west-southwest of Guam. The tropical depression was moving toward the west-northwest 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 1003 mb.

The circulation around a low pressure system west-southwest of Guam exhibited more organization on Monday morning and the Japan Meteorological Agency designated the system as a tropical depression. The circulation around Tropical Depression 27W was gradually becoming more organized. A distinct low level center of circulation was evident on conventional and microwave satellite images. More thunderstorms were beginning to develop near the center of circulation. Storms near the center began to generate upper level divergence that pumped mass away from the tropical depression. Additional thunderstorms were forming in bands revolving around the center of the depression.

Tropical Depression 27W will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of the axis of an upper level ridge centered east of the Marianas. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Tropical Depression 27W will strengthen gradually and it is likely to intensify to a tropical storm during the next 24 hours.

Tropical Depression 27W will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer the tropical depression toward the west-northwest during the next day or so. On its anticipated track Tropical Depression 27W will move farther away from the Marianas. It will pass north of Yap.

Typhoon Malou Brings Strong Winds, Rain to Ogasawara Islands

Typhoon Malou brought strong winds and heavy rain to the Ogasawara Islands on Thursday morning. At 5:00 a.m. EDT on Thursday the center of Typhoon Malou was located at latitude 25.6°N and longitude 141.2°E which put it about 15 miles (25 km) east of Iwo To. Malou was moving toward the north-northeast at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 100 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h). The minimum surface pressure was 967 mb.

The strong inner core of Typhoon Malou passed directly over Iwo To on Thursday morning. An eye with a diameter of 35 miles (55 km) was at the center of Malou. The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Winds to typhoon force extended out 70 miles (110 km) from the center of Malou. Winds to tropical storm force extended out 175 miles (280 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Malou was 16.5. The Hurricane Size Index (HSI) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 37.1.

An upper level trough near Japan will steer Typhoon Malou toward the northeast during the next several days. On its anticipated track Malou will move away from the Ogasawara Islands. Typhoon Malou will pass well to the southeast of the larger islands of Japan.

Typhoon Malou will move into an environment unfavorable for tropical cyclones during the next few days. Malou will move over water where the Sea Surface Temperatures are cooler. The upper level trough near Japan will produce stronger southwesterly winds that will blow toward the top of Malou’s circulation. The vertical wind shear will increase as the upper level winds get stronger. The combination of cooler water and stronger vertical wind shear will cause Typhoon Malou to weaken. The cooler water and stronger shear will also cause Malou to make a transition to an extratropical cyclone during the next few days.

Typhoon Malou Nears Iwo To

Typhoon Malou neared Iwo To on Wednesday night. At 11:00 p.m. EDT on Wednesday the center of Typhoon Malou was located at latitude 24.2°N and longitude 141.3°E which put it about 100 miles (160 km) south-southwest of Iwo To. Malou was moving toward the north-northeast at 14 m.p.h. (22km/h). The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 970 mb.

Typhoon Malou strengthened as it moved closer to Iwo To on Wednesday night. A very large eye with a diameter of 90 miles (145 km) was at the center of Malou. Several smaller counterclockwise circulations were rotating within the eye. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the large core of Typhoon Malou. Storms near the core generated upper level divergence that pumped mass away to the northeast of the typhoon.

The size of Typhoon Malou’s circulation increased on Wednesday. Winds to typhoon force extended out 60 miles (95 km) from the center of Malou. Winds to tropical storm force extended out 175 miles (280 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Malou was 13.9. The Hurricane Size Index (HSI) was 14.6 and the Hurricane Wind Intensity Size Index (HWISI) was 28.5.

Typhoon Malou will move through an environment favorable for intensification during the next 18 hours. Malou will move over water where the Sea Surface Temperatures are near 28˚C. An upper level trough near Japan will produce southwesterly winds that will blow toward the top of Malou’s circulation. However, the winds in the lower levels of the atmosphere will also blow from the southwest and so there will not be a lot of vertical wind shear. Typhoon Malou is could strengthen during the next 18 hours. The upper level winds will get stronger on Friday and the vertical wind shear will increase. Malou is likely to weaken and to begin a transition to an extratropical cyclone when the wind shear increases.

An upper level trough over Japan will steer Typhoon Malou toward the north-northeast during the next 24 hours. On its anticipated track Typhoon Malou could make a direct hit on Iwo To in a few hours. Typhoon Malou will bring strong winds and heavy rain to Iwo To. The eyewall with the strongest winds is likely to pass over Iwo To. The wind could blow at tropical storm force or greater for several hours. Malou will be capable of causing serious damage on Iwo To. In addition, heavy rain could also cause flash floods.

Malou Strengthens to a Typhoon South-southwest of Iwo To

Former Tropical Storm Malou strengthened to a typhoon over the Western North Pacific Ocean south-southwest of Iwo To on Tuesday night. At 11:00 p.m. EDT on Tuesday the center of Typhoon Malou was located at latitude 21.0°N and longitude 139.4°E which put it about 310 miles (500 km) south-southwest of Iwo To. Malou was moving toward the north-northeast at 3 m.p.h. (5 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. 145 km/h). The minimum surface pressure was 981 mb.

Former Tropical Storm Malou intensified to a typhoon on Tuesday night. The inner end of a rainband wrapped around the center of Typhoon Malou and an eye appeared intermittently on satellite images. A broken ring of thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Malou’s circulation. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 80 miles (130 km) from the center of Malou. Winds to tropical storm force extended out 165 miles (270 km) from the center of circulation.

Typhoon Malou will move through an environment favorable for intensification during the next 24 hours. Malou will move over water where the Sea Surface Temperatures are near 29˚C. It will move under an upper level ridge south of Japan. The upper level winds are weak in the ridge and there will be little vertical wind shear. The upper level ridge will enhance divergence which will cause the surface pressure to decrease. Typhoon Malou is likely to strengthen during the next 24 hours. Malou could intensify rapidly if an inner core with an eye and a complete eyewall develops.

An upper level trough over Japan will steer Typhoon Malou toward the north-northeast during the next 24 hours. On its anticipated track Typhoon Malou could make a direct hit on Iwo To in 24 hours. Typhoon Malou will bring strong winds and heavy rain to Iwo To. Malou will be capable of causing serious damage on Iwo To. Heavy rain could also cause flash floods.

Tropical Storm Malou Forms West of the Marianas

Tropical Storm Malou formed west of the Marianas on Sunday night. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Malou was located at latitude 16.5°N and longitude 138.1°E which put it about 515 miles (830 km) west-northwest of Saipan. Malou was moving toward the north-northwest at 17 m.p.h. (28 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 1003 mb.

The circulation around a low pressure system over the Western North Pacific Ocean west of the Marianas strengthened on Sunday night and the Japan Meteorological Agency designated the system as Tropical Storm Malou. The circulation around Tropical Storm Malou was still organizing. There was a broad center of circulation, but there were not many thunderstorms near the center of Malou. Several long rainbands were revolving around the broad center of circulation. The strongest winds were occurring in the eastern half of Malou. Winds to tropical storm force extended out 185 miles (295 km) on the eastern side of Malou. The winds in the western half of Malou’s circulation were blowing at less than tropical storm force.

Tropical Storm Malou will move through an environment favorable for intensification during the next 48 hours. Malou will move over water where the Sea Surface Temperatures are near 29˚C. It will move under an upper level ridge near the Marianas. The upper level winds are weak in the ridge and there will be little vertical wind shear. Tropical Storm Malou is likely to intensify steadily during the next 48 hours. Malou could strengthen to a typhoon in 48 hours.

Tropical Storm Malou will move around the western end of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Malou toward the west-northwest during the next 48 hours. Tropical Storm Malou will turn toward the northeast after it moves around the western end of the ridge. On its anticipated track Malou could approach Iwo To in three days. Malou could be a typhoon when it approaches Iwo To.

Namtheun Strengthens to a Typhoon North of Wake Island

Former Tropical Storm Namtheun strengthened to a typhoon over the Western North Pacific Ocean north of Wake Island on Saturday morning. At 5:00 a.m. EDT on Saturday the center of Typhoon Namtheun was located at latitude 31.4°N and longitude 165.6°E which put it about 800 miles (1290 km) north of Wake Island. Namtheun was moving toward the north-northeast at 18 m.p.h. (29 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 979 mb.

Former Tropical Storm Namtheun passed over water where the Sea Surface Temperatures are near 27˚C during the past 24 hours and it was able to extract enough energy to strengthen to a typhoon. A small eye formed at the center of Typhoon Namtheun. The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Storms near the center of Namtheun generated upper level divergence that pumped mass away from the typhoon. The circulation around Typhoon Namtheun was relatively small. Winds to typhoon force extended out 20 miles (30 km) from the center of Namtheun. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation.

An upper level trough east of Japan will steer Typhoon Namtheun toward the north-northeast during the weekend. On its anticipated track Namtheun will move toward the Aleutian Islands. Typhoon Namtheun will move into an environment unfavorable for intensification during the weekend. Namtheun will move over much cooler water. The upper level trough east of Japan will produce strong southwesterly winds that will blow toward the top of Namtheun’s circulation. Those winds will cause moderate vertical wind shear. The combination of cooler water and more vertical wind shear will cause Typhoon Namtheun to make a transition to an extratropical cyclone as it moves toward the Aleutian Islands.

Tropical Storm Namtheun Spins Southeast of Japan

Tropical Storm Namtheun was spinning southeast of Japan on Friday morning. At 5:00 a.m. EDT on Friday the center of Tropical Storm Namtheun was located at latitude 26.6°N and longitude 161.9°E which put it about 495 miles (800 km) east-northeast of Minami Tori Shima. Namtheun was moving toward the east-northeast at 18 m.p.h. (29 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 994 mb.

Tropical Storm Namtheun was the only current tropical cyclone on Friday morning as it churned over the Western North Pacific Ocean between Japan and Hawaii. Namtheun intensified during the past 24 hours as it moved well to the east of the main islands of Japan. The inner end of a rainband wrapped around the center of Tropical Storm Namtheun. A broken ring of thunderstorms was around the center of circulation. The strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Namtheun. Storms near the core generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation.

Tropical Storm Namtheun will move through an environment somewhat favorable for intensification during the next 24 hours. Namtheun will move over water where the Sea Surface Temperatures are near 27˚C. An upper level trough southeast of Japan will produce southwesterly winds that will blow toward the top of Namtheun’s circulation. Those winds will cause some vertical wind shear and the wind shear will inhibit intensification. Tropical Storm Namtheun could strengthen during the next 24 hours. Namtheun will move over colder water during the weekend. It will also move in a region where the upper level winds will be stronger. Tropical Storm Namtheun will weaken during the weekend.

The upper level trough southeast of Japan will steer Tropical Storm Namtheun toward the northeast during the next several days. On its anticipated track Namtheun will move farther away from Japan.