Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Saola Moves Back Toward Northern Luzon

Typhoon Saola moved back toward northern Luzon on Monday. At 11:00 p.m. EDT on Monday the center of Typhoon Saola was located at latitude 18.8°N and longitude 123.3°E which put it about 115 miles (185 km) east-northeast of Aparri, Philippines. Saola was moving toward the northwest at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h). The minimum surface pressure was 951 mb.

Two concentric eyewalls formed in the core of Typhoon Saola on Monday. A small eye was at the center of Saola’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. A second, slightly larger ring of storms surrounded the inner eyewall. Bands of showers and thunderstorms were revolving around the concentric eyewalls. Storms in the eyewalls generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Saola was small even with the two concentric eyewalls. Winds to typhoon force extended out 25 miles (40 km) from the center of Saola’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Saola was 20.6. The Hurricane Size Index (HSI) was 9.5 and the Hurricane Wind Intensity Size Index (HWISI) was 30.1. Typhoon Saola was similar in size and intensity to Hurricane Zeta when Zeta hit Louisiana in 2020.

Typhoon Saola will move through an environment favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move through a region where the upper level ridge winds are weak and there will be little vertical wind shear. Typhoon Saola could intensify during the next 24 hours.

Typhoon Saola will move around the southwestern side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Saola toward the northwest during the next 24 hours. On its anticipated track, Typhoon Saola will move between Luzon and Taiwan in 24 hours.

Typhoon Saola will bring strong winds and heavy rain to the islands north of Luzon. Saola could also drop heavy rains over parts of northern Luzon. Heavy rain is likely to cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Damrey moved quickly away from Japan and Tropical Storm Haikui formed south of Iwo To. At 11:00 p.m. EDT on Monday the center of Tropical Storm Damrey was located at latitude 41.2°N and longitude 152.3°E which put it about 285 miles (460 km) east-southeast of Hamanaka, Japan. Damrey was moving toward the east at 25 m.p.h. (40 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 990 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Haikui was located at latitude 19.2°N and longitude 137.6°E which put it about 450 miles (725 km) south-southwest of Iwo To. Haikui was moving toward the west-northwest at 17 m.p.h. (28 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 995 mb.

Typhoon Saola Churns East of Luzon

Typhoon Saola continued to churn over the Western North Pacific Ocean east of Luzon on Sunday. At 11:00 p.m. EDT on Sunday the center of Typhoon Saola was located at latitude 17.0°N and longitude 124.4°E which put it about 200 miles (320 km) east-southeast of Aparri, Philippines. Saola was moving toward the northeast at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h). The minimum surface pressure was 941 mb.

Microwave satellite images showed that the inner end of a rainband was wrapping around the existing eye and eyewall at the center of Typhoon Saola. If the inner end of the rainband wraps completely around the existing eye and eyewall, then a second, larger outer eyewall would form. The formation of two concentric eyewalls would mark the start of an eyewall replacement cycle. An eyewall replacement cycle would cause Typhoon Saola to weaken.

There was still a small circular eye at the center of Typhoon Saola. The small eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Storms near the center of Saola’s circulation generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Saola was small. Winds to typhoon force extended out 20 miles (30 km) from the center of Saola’s circulation. Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Saola was 25.1. The Hurricane Size Index (HSI) was 6.9 and the Hurricane Wind Intensity Size Index (HWISI) was 32.0. Typhoon Saola was similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Typhoon Saola will move through an environment favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move through a region where the upper level ridge winds are weak and there will be little vertical wind shear. However, an eyewall replacement cycle is likely to cause Typhoon Saola to weaken during the next 24 hours.

Typhoon Saola will move around the southwestern side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Saola back toward the north during the next 24 hours. On its anticipated track, Typhoon Saola will move parallel to the coast of northeastern Luzon. Saola could move toward southern Taiwan later this week.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Damrey was passing east of Japan. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Damrey was located at latitude 38.9°N and longitude 145.3°E which put it about 225 miles (360 km) southeast of Misawa, Japan. Damrey was moving toward the north-northeast at 14 m.p.h. (22 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 979 mb.

Typhoon Saola Strengthens to Equivalent of a Major Hurricane

Typhoon Saola strengthened to the equivalent of a major hurricane over the Western North Pacific Ocean near northern Luzon on Saturday morning. At 5:00 a.m. EDT on Saturday the center of Typhoon Saola was located at latitude 17.8°N and longitude 123.3°E which put it about 100 miles (160 km) east-southeast of Aparri, Philippines. Saola was moving toward the south at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 953 mb.

Typhoon Saola rapidly intensified to the equivalent of a major hurricane during the past 24 hours. A small circular eye with a diameter of 12 miles (19 km) was at the center of Saola’s circulation. The eye was surrounded by a 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 Typhoon Saola. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon.

The circulation around Typhoon Saola was small. Winds to typhoon force extended out 30 miles (50 km) from the center of Saola’s circulation. Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Saola was 22.1. The Hurricane Size Index (HSI) was 10.9 and the Hurricane Wind Intensity Size Index (HWISI) was 33.0. Typhoon Saola was similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Typhoon Saola will move through an environment favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move through a region where the upper level ridge winds are weak and there will be little vertical wind shear. Typhoon Saola is likely to intensify during the next 24 hours.

Typhoon Saola will move around the western side of a large counterclockwise monsoon gyre east of the Philippines. The monsoon gyre will pull Saola toward the southeast during the next 24 hours. A high pressure system over the Western North Pacific Ocean will start to steer Saola back toward the northwest by the end of the weekend. On its anticipated track, Typhoon Saola is forecast to make a slow counterclockwise loop east of Luzon.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Damrey was southeast of Japan. At 5:00 a.m. EDT on Saturday the center of Tropical Storm Damrey was located at latitude 26.9°N and longitude 152.1°E which put it about 1020 miles (1645 km) southeast of Tokyo, Japan. Damrey was moving toward the north-northwest at 25 m.p.h. (40 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 987 mb.

Saola Intensifies to a Typhoon Near Northern Luzon

Former Tropical Storm Saola intensified to a typhoon over the Western North Pacific Ocean near northern Luzon on Friday morning. At 5:00 a.m. EDT on Friday the center of Typhoon Saola was located at latitude 19.5°N and longitude 124.0°E which put it about 170 miles (280 km) east-northeast of Aparri, Philippines. Saola was moving toward the southwest at 2 m.p.h. (3 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.

Typhoon Saola was continuing to intensify on Friday morning. A small circular eye was at the center of Saola’s circulation on microwave satellite images. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Storms near the eye generated upper level divergence that pumped mass away from the typhoon. Bands of showers and thunderstorms were in the southern and eastern parts of Typhoon Saola. Bands in the northern and western parts of Saola’s circulation consisted primarily of showers and lower clouds.

The circulation around Typhoon Saola was small. Winds to typhoon force extended out 24 miles (40 km) from the center of Saola’s circulation. Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation.

Typhoon Saola will move through an environment mostly favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southeastern part of an upper level ridge over South Asia and Southeast Asia. The ridge will produce northerly winds that will blow toward the top of Saola’s circulation. Those winds will cause some vertical wind shear and the wind shear will inhibit intensification. The vertical wind shear will probably not be enough to prevent intensification and Typhoon Saola is likely to intensify during the next 24 hours.

Typhoon Saola will move around the western side of a large counterclockwise monsoon gyre east of the Philippines . The monsoon gyre will pull Saola toward the south during the next 24 hours. On its anticipated track, Typhoon Saola is forecast to make a slow counterclockwise loop east of Luzon.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression 08W strengthened to Tropical Storm Damrey southeast of Japan. At 5:00 a.m. EDT on Friday the center of Tropical Storm Damrey was located at latitude 20.8°N and longitude 155.5°E which put it about 300 miles (485 km) southeast of Minami Tori Shima. Damrey was moving toward the northeast at 20 m.p.h. (33 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 995 mb.

Tropical Storm Saola Forms Northeast of Luzon

Tropical Storm Saola formed over the Western North Pacific Ocean northeast of Luzon during Wednesday night. At 5:00 a.m. EDT on Thursday the center of Tropical Storm Saola was located at latitude 20.5°N and longitude 124.5°E which put it about 250 miles (400 km) northeast of Aparri, Philippines. Saola was moving toward the northwest at 5 m.p.h. (8 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 998 mb.

A small low pressure system northeast of Luzon strengthened during Wednesday night and the Japan Meteorological Agency designated the system as Tropical Storm Saola. The circulation around Saola was small. Winds to tropical storm force extended out 30 miles (50 km) in the southern side of Saola’s circulation. The winds win the northern side of the circulation were blowing at less than tropical storm force.

More thunderstorms were forming near the center of Tropical Storm Saola. Storms near the center began to generate upper level divergence that pumped mass away from the tropical storm. Bands of showers and thunderstorms developed around Tropical Storm Saola. The bands were beginning to revolve around the center of Saola’s circulation.

Tropical Storm Saola will move through an environment mostly favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern part of an upper level ridge over South Asia and Southeast Asia. The ridge will produce easterly winds that will blow toward the top of Saola’s circulation. Those winds will cause some vertical wind shear and the wind shear will inhibit intensification. The vertical wind shear will probably not be enough to prevent intensification and Tropical Storm Saola is likely to intensify during the next 24 hours.

Tropical Storm Saola will move around the southwestern part of a high pressure system over the Western North Pacific during the next 12 hours. The high pressure system will steer Saola toward the northwest during that time period. A large counterclockwise monsoon gyre is forecast to develop east of the Philippines. The monsoon gyre will pull Saola back to the south during the next several days. On its anticipated track, Tropical Storm Saola is forecast to make a counterclockwise loop east of Luzon.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 08W was east of the Marianas. At 5:00 a.m. EDT on Thursday the center of Tropical Depression 08W was located at latitude 16.5°N and longitude 149.2°E which put it about 225 miles (365 km) east of Anatahan. Tropical Depression 08W was moving toward the west at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1000 mb. Tropical Depression 08W is forecast to slowly strengthen.

Tropical Storm Lan Moves over the Sea of Japan

Tropical Storm Lan moved over the Sea of Japan on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Lan was located at latitude 38.7°N and longitude 135.8°E which put it about 220 miles (355 km) west-southwest of Akita, Japan. Lan was moving toward the north-northeast at 14 m.p.h. (22 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 989 mb.

Tropical Storm Lan moved over the Sea of Japan on Tuesday after it crossed Honshu near Osaka. Lan weakened to a tropical storm as it crossed over Honshu. The distribution of thunderstorms in Tropical Storm Lan was asymmetrical on Tuesday night. Most of the thunderstorms were occurring in bands in the northern half of Lan’s circulation. Bands in the southern half of the circulation consisted primarily of showers and lower clouds. Storms in the northern half of Lan generated upper level divergence that pumped mass away to the north of the tropical storm. Winds to tropical storm force extended out 150 miles (240 km) from the center of Tropical Storm Lan.

Tropical Storm Lan will move through an environment that will be unfavorable for intensification during the next 36 hours. Lan will move over water where the Sea Surface Temperatures are near 28°C. It will move under the eastern part of an upper level trough that is northwest of Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Lan’s circulation. Those winds will cause moderate vertical wind shear. The moderate wind shear will prevent intensification of Tropical Storm Lan. Lan will begin a transition to an extratropical cyclone in a day or so when it moves over colder water.

The upper level trough that is northwest of Japan will steer Tropical Storm Lan toward the northeast during the next 36 hours. On its anticipated track, The center of Tropical Storm Lan will pass west of Hokkaido in 24 hours. Lan could approach Sakhalin Island in 36 hours.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Dora weakened to a tropical depression north-northeast of Wake Island. At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Dora was located at latitude 25.0°N and longitude 168.4°E which put it about 380 miles (610 km) north-northeast of Wake Island. Dora was moving toward the north-northeast at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1008 mb.

Typhoon Lan Makes Landfall in Honshu

Typhoon Lan made landfall in Honshu on Monday. At 5:00 p.m. EDT on Monday the center of Typhoon Lan was located at latitude 33.7°N and longitude 135.9°E which put it about 15 miles (25 km) north of Shingu, Japan. Lan was moving toward the northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h). The minimum surface pressure was 970 mb.

The center of Typhoon Lan made landfall in Wakayama Prefecture near Shingu on Monday. A circular eye with a diameter of 50 miles (80 km) was at the center of Lan’s circulation. 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 Typhoon Lan.

There was still a large circulation around Typhoon Lan. Winds to typhoon force extended out 70 miles (110 km) from the center of Lan’s circulation. Winds to tropical storm force extended out 145 miles (235 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Lan was 13.9. The Hurricane Size Index (HSI) was 23.0 and the Hurricane Wind Intensity Size Index (HWISI) was 36.9. Typhoon Lan was capable of causing widespread serious damage.

Typhoon Lan 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 Lan toward the north-northwest during the next 24 hours. On its anticipated track, Typhoon Lan will move across Honshu during the next 24 hours. The center of Lan’s circulation will pass near Osaka in a few hours. The center of circulation will also pass west of Kyoto before Lan moves over the Sea of Japan.

Although Typhoon Lan will weaken as it moves across Honshu, Lan will produce strong gusty winds and locally heavy rain over parts of Honshu. Lan will drop heavy rain over Wakayama, Nara, Osaka, Shiga, Kyoto, Hyogo, Tottori, Okayama and Fukui Prefectures. Heavy rain could cause flash floods in some locations. Wind and rain are also likely to cause loss of electricity in widespread areas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Dora continued to weaken east of Wake Island. At 5:00 p.m. EDT on Monday the center of Tropical Storm Dora was located at latitude 20.9°N and longitude 168.3°E which put it about 145 miles (235 km) east of Wake Island. Dora was moving toward the north-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 1004 mb.

Typhoon Lan Approaches Honshu

Typhoon Lan was approaching Honshu on Sunday night. At 11:00 p.m. EDT on Sunday the center of Typhoon Lan was located at latitude 32.1°N and longitude 137.2°E which put it about 120 miles (195 km) south-southeast of Shingu, Japan. Lan was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 959 mb.

Typhoon Lan strengthened as it approached Honshu on Sunday. A large circular eye with a diameter of 60 miles (95 km) was at the center of Lan’s circulation. The eye was surrounded by a ring of 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 Lan. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

There was a large circulation around Typhoon Lan. Winds to typhoon force extended out 70 miles (110 km) from the center of Lan’s circulation. Winds to tropical storm force extended out 160 miles (260 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Lan was 16.5. The Hurricane Size Index (HSI) was 21.3 and the Hurricane Wind Intensity Size Index (HWISI) was 37.8. Typhoon Lan was capable of causing widespread serious damage.

Typhoon Lan will move through an environment favorable for intensification during the next 12 hours. Lan will move over water where the Sea Surface Temperatures are near 28°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Lan could continue to strengthen during the next 12 hours as it approaches Honshu.

Typhoon Lan 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 Lan toward the northwest during the next 24 hours. On its anticipated track, the center of Typhoon Lan will make landfall in Wakayama Prefecture south of Osaka in about 18 hours. Lan will produce strong gusty winds and locally heavy rain over parts of Honshu. Heavy rain is likely to cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Dora continue to weaken east of Wake Island. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Dora was located at latitude 19.0°N and longitude 169.7°E which put it about 235 miles (380 km) east of Wake Island. Dora was moving toward the west-northwest at 15 m.p.h. (24 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 1005 mb.

Typhoon Lan Continues to Move Toward Honshu

Typhoon Lan continued to move to Honshu on Saturday night. At 11:00 p.m. EDT on Saturday the center of Typhoon Lan was located at latitude 30.0°N and longitude 139.1°E which put it about 385 miles (625 km) south of Tokyo, Japan. Lan was moving toward the northwest at 8 m.p.h. (11 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 970 mb.

Typhoon Lan completed an eyewall replacement cyclone on Saturday. The smaller, inner eye and eyewall dissipated. A circular eye with a diameter of 70 miles (110 km) was at the center of Lan’s circulation on Saturday night. The large eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the large eye. Storms around the eye generated upper level divergence that pumped mass away from the typhoon.

The area of typhoon force winds in Typhoon Lan increased during the eyewall replacement cycle. Winds to typhoon force extended out 70 miles (110 km) from the center of Lan’s circulation. Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Lan was 11.5. The Hurricane Size Index (HSI) was 21.1 and the Hurricane Wind Intensity Size Index (HWISI) was 32.6.

Typhoon Lan will move through an environment favorable for intensification during the next 24 hours. Lan will move over water where the Sea Surface Temperatures are near 28°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Lan could strengthen during the next 24 hours, since the eyewall replacement cycle is complete.

Typhoon Lan 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 Lan toward the northwest during the next 24 hours. On its anticipated track, Typhoon Lan will approach Honshu in less than 48 hours. The center of Lan could make landfall south of Osaka. Lan will be a typhoon when it reaches Honshu.

Elsewhere over the Western North Pacific Ocean, former Hurricane Dora weakened to a tropical storm East of Wake Island. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Dora was located at latitude 18.2°N and longitude 174.7°E which put it about 570 miles (920 km) east of Wake Island. Dora was moving toward the west-northwest at 14 m.p.h. (22 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 996 mb.

Typhoon Lan Moves Toward Honshu

Typhoon Lan moved toward Honshu on Friday. At 11:00 p.m. EDT on Friday the center of Typhoon Lan was located at latitude 28.7°N and longitude 141.5°E which put it about 485 miles (785 km) south-southeast of Tokyo, Japan. Lan was moving toward the west-northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 960 mb.

Typhoon Lan was weakening on Friday night. The inner of a rainband wrapped around the existing eye and eyewall and a larger, outer eyewall formed. The formation of concentric eyewalls was disrupting the low level convergence into the inner eyewall and the inner eyewall was weakening. Since the strongest winds were occurring in the inner eyewall, the maximum wind speed decreased when the inner eyewall weakened. Bands of showers and thunderstorms were revolving around the concentric eyewalls. Storms around the concentric eyewalls 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 Typhoon Lan. Winds to tropical storm force extended out 140 miles (225 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Lan was 16.5. The Hurricane Size Index (HSI) was 11.4 and the Hurricane Wind Intensity Size Index (HWISI) was 27.9.

Typhoon Lan will move through an environment favorable for intensification during the next 24 hours. Lan will move over water where the Sea Surface Temperatures are near 28°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. However, Typhoon Lan is likely to weaken during the next 24 hours even though it will be in a favorable environment. The maximum wind speed is likely to continue to decrease as the inner eyewall dissipates.

Typhoon Lan will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Lan toward the northwest during the next 24 hours. On its anticipated track, Typhoon Lan will approach Honshu in less than 72 hours. Lan is likely to be a typhoon when it approaches Honshu.