Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Hinnamnor Moves South of Okinawa

Typhoon Hinnamnor moved south of Okinawa on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Typhoon Hinnamnor was located at latitude 24.4°N and longitude 127.3°E which put it about 115 miles (185 km) south of Okinawa. Hinnamnor was moving toward the west-southwest at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 175 m.p.h. (280 km/h). The minimum surface pressure was 929 mb.

Concentric eyewalls developed at the center of Typhoon Hinnamnor on Tuesday night. The original eye with a diameter of 10 miles (16 km) was still present at the center of Hinnamnor. The inner end of a rainband wrapped around the original eye and eyewall. An outer eye with a diameter of 60 miles (95 km) surrounded the original eye and eyewall. Typhoon Hinnamnor weakened slightly as the winds in the inner eyewall decreased slightly. The core of Hinnamnor still generated strong upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Hinnamnor increased when the concentric eyewalls developed. Winds to typhoon force extended out 35 miles (55 km) from the center of Hinnamnor. Winds to tropical storm force extended out 120 miles (195 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 29.9. The Hurricane Size Index (HSI) was 13.4 and the Hurricane Wind Intensity Size Index (HWISI) was 43.3. Hinnamnor was capable of causing regional severe damage.

Typhoon Hinnamnor will move through an environment capable of supporting a strong typhoon during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Even though it will be in a favorable environment, Typhoon Hinnamnor will weaken as the inner eyewall weakens because of the eyewall replacement cycle. More of the low level inflow will become concentrated in the outer eyewall. Hinnamnor could strengthen again after the eyewall replacement cycle is completed.

Typhoon Hinnamnor will interact with Tropical Depression 13W that is located southeast of Okinawa during the next 24 hours. At 11:00 a.m. EDT on Wednesday morning center of Tropical Depression 13W was located at at latitude 22.6°N and longitude 131.6°E which put it about 400 miles (640 km) southeast of Okinawa. The tropical depression was moving toward the north-northwest at 14 m.p.h. (22 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 1000 mb.

Typhoon Hinnamnor will moved toward the southwest during the next 24 hours as it moves around the western side of Tropical Depression 13W. On its anticipated track, Typhoon Hinnamnor will move south of the southern Ryukyu Islands. The much stronger circulation around Typhoon Hinnamnor will eventually absorb the weaker tropical depression. Hinnamnor could be in an area where the steering winds are weak after it absorbs the tropical depression. Typhoon Hinnamnor could meander near the southern Ryukyu Islands later this week.

Typhoon Hinnamnor Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Hinnamnor intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale over the Western North Pacific Ocean near Minami Daito Jima on Tuesday afternoon. At 5:00 p.m. EDT on Tuesday the center of Typhoon Hinnamnor was located at latitude 26.1°N and longitude 131.2°E which put it about 55 miles (90 km) east-northeast of Minami Daito Jima and about 255 miles (410 km) east of Okinawa. Hinnamnor was moving toward the west at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h). The minimum surface pressure was 915 mb.

Powerful Typhoon Hinnamnor was the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Tuesday afternoon. A circular eye with a diameter of 10 miles (16 km) was at the center of Hinnamnor’s circulation. 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 core of Typhoon Hinnamnor. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large quantities of mass allowed the surface pressure to decrease.

The circulation around Typhoon Hinnamnor contracted in size when the typhoon intensified to Category 5. Winds to typhoon force extended out 25 miles (40 km) from the center of Hinnamnor. Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 35.0. The Hurricane Size Index (HSI) was 8.8 and the Hurricane Wind Intensity Size Index (HWISI) was 43.8. Hinnamnor was capable of causing regional catastrophic damage.

Typhoon Hinnamnor will move through an environment capable of supporting a strong typhoon during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Typhoon Hinnamnor could maintain much of its intensity during the next 24 hours, if the inner end of rainband does not wrap around the existing eye and eyewall. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Hinnamnor could to weaken temporarily.

Typhoon Hinnamnor will interact with Tropical Depression 13W that formed southeast of Okinawa during the next 24 hours. At 5:00 p.m. EDT on Tuesday morning center of Tropical Depression 13W was located at at latitude 20.5°N and longitude 133.0°E which put it about 555 miles (895 km) southeast of Okinawa. The tropical depression was moving toward the north at 5 m.p.h. (8 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 1000 mb.

Typhoon Hinnamnor will move toward the west-southwest during the next 24 hours when its circulation interacts with the tropical depression. On its anticipated track the core of Typhoon Hinnamnor will be near Minami Daito Jima in a few hours. Hinnamnor could cause catastrophic wind damage on Minami Daito Jima. Very heavy rain could cause flash floods. Typhoon Hinnamnor will also cause a significant storm surge along the coast of Minami Daito Jima. Widespread electrical outages are likely. The center of Hinnamnor could be southeast of Okinawa in 12 hours.

Typhoon Hinnamnor will eventually absorb the circulation around the tropical depression. Hinnamnor could move slowly around the southern Ryukyu Islands while it absorbs the depression. A prolonged period of strong winds and heavy rain could affect the southern Ryukyu Islands later this week.

Powerful Typhoon Hinnamnor Moves Toward Okinawa

Powerful Typhoon Hinnamnor moved toward Okinawa on Tuesday morning. At 11:00 a.m. EDT on Tuesday the center of Typhoon Hinnamnor was located at latitude 26.4°N and longitude 132.8°E which put it about 360 miles (575 km) east of Okinawa. Hinnamnor was moving toward the west at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 910 mb.

Powerful Typhoon Hinnamnor was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Tuesday morning. A circular eye with a diameter of 10 miles (16 km) was at the center of Hinnamnor’s circulation. 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 core of Typhoon Hinnamnor. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon.

The circulation around Typhoon Hinnamnor increased in size when the typhoon intensified. Winds to tropical storm force extended out 40 miles (65 km) from the center of Hinnamnor. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 31.6. The Hurricane Size Index (HSI) was 15.3 and the Hurricane Wind Intensity Size Index (HWISI) was 46.9. Hinnamnor was capable of causing regional severe damage.

Typhoon Hinnamnor will move through an environment capable of supporting a strong typhoon during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Typhoon Hinnamnor could intensify during the next 24 hours, if the inner end of rainband does not wrap around the existing eye and eyewall. Hinnamnor could strengthen to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Hinnamnor could to weaken temporarily.

Typhoon Hinnamnor will interact with a tropical depression that formed southeast of Okinawa during the next 24 hours. At 11:00 a.m. EDT on Tuesday morning the tropical depression was centered at latitude 19.7°N and longitude 133.1°E which put it about 585 miles (945 km) southeast of Okinawa. The tropical depression was moving toward the west at 6 m.p.h. (10 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 1000 mb.

Typhoon Hinnamnor will move toward the west-southwest during the next 24 hours when its circulation interacts with the tropical depression. On its anticipated track Typhoon Hinnamnor will be near Minami Daito Jima in 12 hours. Hinnamnor could cause severe wind damage on Minami Daito Jima. Very heavy rain could cause flash floods. Typhoon Hinnamnor will also cause a significant storm surge along the coast of Minami Daito Jima. Widespread electrical outages are likely. The center of Hinnamnor could be south of Okinawa in 24 hours.

Typhoon Hinnamnor will eventually absorb the circulation around the tropical depression. Hinnamnor could move slowly around the southern Ryukyu Islands while it absorbs the depression. A prolonged period of strong winds and heavy rain could affect the southern Ryukyu Islands later this week.

Typhoon Hinnamnor Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Hinnamnor rapidly intensified to the equivalent of a major hurricane on Monday morning. At 11:00 a.m. EDT on Monday the center of Typhoon Hinnamnor was located at latitude 27.3°N and longitude 140.4°E which put it about 835 miles (1345 km) east of Okinawa. Hinnamnor was moving toward the west at 20 m.p.h. (32 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. (230 km/h). The minimum surface pressure was 956 mb.

Typhoon Hinnamnor rapidly intensified to the equivalent of a major hurricane in a very favorable environment over the Western North Pacific Ocean northwest of Chichi Jima. A small circular eye was at the center of Hinnamnor’s circulation. 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 core of Typhoon Hinnamnor. Storms near the core generated strong upper level divergence that pumped mass away from the typhoon. The removal of large quantities of mass allowed the surface pressure to decrease rapidly.

The circulation around Typhoon Hinnamnor was small. Winds to typhoon force extended out 30 miles (50 km) from the center of Hinnamnor. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 20.6. The Hurricane Size Index (HSI) was 9.2 and the Hurricane Wind Intensity Size Index (HWISI) was 29.8.

Typhoon Hinnamnor will move through an area favorable for intensification during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Typhoon Hinnamnor is likely to continue to intensify rapidly during the next 24 hours. Hinnamnor could strengthen to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.

Typhoon Hinnamnor will move around the southwestern part of a high pressure system that extends over Japan. The high pressure system will steer Hinnamnor toward the west during the 48 hours. On its anticipated track Typhoon Hinnamnor could approach the Ryukyu Islands in 48 hours. Hinnamnor will continue to produce strong gusty winds and locally heavy rain on Chichi Jima during the next few hours until it moves farther away. Typhoon Hinnamnor is likely to be the equivalent of a major hurricane when it approaches the Ryukyu Islands.

Hinnamnor Rapidly Intensifies to a Typhoon Near Chichi Jima

Former Tropical Storm Hinnamnor rapidly intensified to a typhoon near Chichi Jima on Monday morning. At 5:00 a.m. EDT on Monday the center of Typhoon Hinnamnor was located at latitude 27.4°N and longitude 142.2°E which put it about 30 miles (50 km) north of Chichi Jima. Hinnamnor was moving toward the west at 22 m.p.h. (35 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. (165 km/h). The minimum surface pressure was 967 mb.

Former Tropical Storm Hinnamnor rapidly intensified to a typhoon in a favorable environment over the Western North Pacific Ocean near Chichi Jima. A small circular eye formed at the center of Hinnamnor’s circulation. 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 core of Typhoon Hinnamnor. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Hinnamnor was small. Winds to typhoon force extended out 25 miles (40 km) from the center of Hinnamnor. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 12.7. The Hurricane Size Index (HSI) was 7.8 and the Hurricane Wind Intensity Size Index (HWISI) was 20.5.

Typhoon Hinnamnor will move through an area favorable for intensification during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Typhoon Hinnamnor is likely to continue to intensify rapidly during the next 24 hours. Hinnamnor could strengthen to the equivalent of a major hurricane.

Typhoon Hinnamnor will move around the southwestern part of a high pressure system that extends over Japan. The high pressure system will steer Hinnamnor toward the west during the 48 hours. On its anticipated track Typhoon Hinnamnor could approach the Ryukyu Islands in 48 hours. Hinnamnor will continue to produce strong gusty winds and locally heavy rain on Chichi Jima during the next few hours until it moves farther away. Typhoon Hinnamnor could be the equivalent of a major hurricane when it approaches the Ryukyu Islands.

Tropical Storm Hinnamnor Forms East of Iwo To

Tropical Storm Hinnamnor formed east of Iwo To on Sunday morning. At 5:00 a.m. EDT on Sunday the center of Tropical Storm Hinnamnor was located at latitude 26.2°N and longitude 148.8°E which put it about 510 miles (825 km) east-northeast of Iwo To. Hinnamnor was moving toward the north-northwest at 14 m.p.h. (22 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 997 mb.

The circulation around a low pressure system east of Iwo To strengthened on Sunday morning and the Japan Meteorological Agency designated the system as Tropical Storm Hinnamnor. The circulation around Hinnamnor was still organizing. The inner end of a rainband wrapped around the western and southern sides of the center of circulation. Other bands of showers and thunderstorms were revolving around the center of Tropical Storm Hinnamnor. 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 140 miles (225 km) on the eastern side of Hinnamnor’s circulation. Winds to tropical storm force extended out 75 miles (120 km) on the western side of the circulation.

Tropical Storm Hinnamnor will move through an area favorable for intensification during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region between an upper level trough over Japan, a small upper level low northwest of the Marianas, and a larger upper level low east of the Marianas. The upper level winds are weak in the region between the upper level trough, and the two upper level lows. Tropical Storm Hinnamnor will be in a region where there is little vertical wind shear during the next 24 hours and it is likely to intensify.

Tropical Storm Hinnamnor will move around the southwestern part of a high pressure system that extends over Japan. The high pressure system will steer Hinnamnor toward the west during the several days. On its anticipated track the center of Tropical Storm Hinnamnor could be north of Iwo To in 36 hours.

Tropical Storm Ma-on Makes Landfall in Southeast China

Tropical Storm Ma-on made landfall in southeast China on Thursday morning. At 5:00 a.m. EDT on Thursday the center of Tropical Storm Ma-on was located at latitude 22.0°N and longitude 109.2°E which put it about 80 miles (130 km) east of Qinzhou. Ma-on was moving toward the west-northwest at 20 m.p.h. (32 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 Ma-on made landfall on the coast of southeastern China between Dianbai and Zhanjiang on Thursday morning. The center of Ma-on made landfall near Wuchuan. Ma-on was a strong tropical storm at the time of landfall. The maximum sustained wind speed was 65 m.p.h. (105 km/h). The distribution of thunderstorms and heavy rain in Tropical Storm Ma-on was asymmetrical. Many of the thunderstorms with heavy rain were occurring in the southern half of Ma-on’s circulation. The strongest winds were occurring over the South China Sea. Winds to tropical storm force extended out 130 miles (210 km) from the center of Tropical Storm Ma-on.

Tropical Storm Ma-on will move around the southwestern part of a high pressure system over the Western North Pacific during the next 36 hours. The high pressure system will steer Ma-on toward the west-northwest. On its anticipated track Tropical Storm Ma-on will move inland over southeastern China and northern Vietnam. Ma-on will drop locally heavy rain over parts of southeastern China and northern Vietnam. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Tokage was weakening as it sped away from Japan. At 5:00 a.m. EDT on Thursday the center of Tropical Storm Tokage was located at latitude 41.3°N and longitude 153.9°E which put it about 610 miles (985 km) east of Misawa, Japan. Tokage was moving toward the northeast at 25 m.p.h. (40 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 987 mb.

Tropical Storm Ma-on Moves over South China Sea

Tropical Storm Ma-on moved over the South China Sea southeast of Hong Kong on Wednesday morning. At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Ma-on was located at latitude 20.0°N and longitude 116.1°E which put it about 245 miles (395 km) southeast of Hong Kong. Ma-on was moving toward the west-northwest at 12 m.p.h. (19 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 984 mb.

Tropical Storm Ma-on maintained its intensity as it moved over the South China Sea southeast of Hong Kong on Wednesday morning. The inner end of a rainband wrapped around the southern and eastern sides of the center of Ma-on’s circulation. However, the distribution of thunderstorms in the rest of Tropical Storm Ma-on was asymmetrical. The strongest thunderstorms were occurring in bands in the southern and western parts of Ma-on. Bands in the eastern and northern parts of the circulation consisted primarily of showers and lower clouds. An upper level ridge over China was producing east-northeasterly winds that were blowing toward the top of Tropical Storm Ma-on. Those winds were causing moderate vertical wind shear and the wind shear was causing the asymmetrical distribution of thunderstorms.

Tropical Storm Ma-on will move through an environment somewhat favorable for intensification during the next 24 hours. Ma-on will move over water where the Sea Surface Temperatures are 29˚C. The upper level ridge over China will continue to cause vertical wind shear. If the vertical wind shear does not increase, then Tropical Storm Ma-on could strengthen during the next 24 hours. There is a chance Ma-on could strengthen to a typhoon.

Tropical Storm Ma-on will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Ma-on toward the west-northwest during the next 36 hours. On its anticipated track Tropical Storm Ma-on could be south of Hong Kong in 12 hours. The center of Ma-on could make landfall on the south coast of China near Yangjiang and Dianbai in 24 hours. Tropical Storm Ma-on will bring gusty winds and locally heavy rain to southern China. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Typhoon Tokage was passing east of Japan. At 5:00 a.m. EDT on Wednesday the center of Typhoon Tokage was located at latitude 35.8°N and longitude 149.4°E which put it about 475 miles (770 km) east of Tokyo, Japan. Tokage was moving toward the north-northeast at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h). The minimum surface pressure was 961 mb.

Tropical Storm Ma-on Brings Wind and Rain to Northern Luzon

Tropical Storm Ma-on brought wind and rain to northern Luzon on Tuesday morning. At 5:00 a.m. EDT on Tuesday the center of Tropical Storm Ma-on was located at latitude 18.0°N and longitude 121.2°E which put it about 50 miles (80 km) southeast of Claveria, Philippines. Ma-on was moving toward the northwest at 12 m.p.h. (19 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 985 mb.

Tropical Storm Ma-on brought gusty winds and locally heavy rain to parts of northern Luzon on Tuesday morning. The center of Ma-on made landfall on the northeastern coast of Luzon east of Tuguegarao during Monday night. Tropical Storm Ma-on moved northwest across northern Luzon. Ma-on intensified before it made landfall and it was almost a typhoon at the time of landfall. Winds to tropical storm force extended out 120 miles (195 km) from the center of Ma-on’s circulation.

Tropical Storm Ma-on will move through an environment favorable for intensification when it moves over the South China Sea. Ma-on will move over water where the Sea Surface Temperatures are 29˚C. It will move under the southern part of an upper level ridge over China. The ridge will produce easterly winds that will blow toward the top of Ma-on’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification. Tropical Storm Ma-on is likely to strengthen to a typhoon during the next 36 hours.

Tropical Storm Ma-on will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Ma-on toward the west-northwest during the next 36 hours. On its anticipated track Tropical Storm Ma-on will move away from northern Luzon later on Tuesday. Ma-on will continue to bring gusty winds and locally heavy rain to northern Luzon until it moves farther away. Heavy rain could cause flash floods in some locations. Ma-on could be south of Hong Kong in 36 hours.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Tokage intensified to a typhoon southeast of Japan. At 5:00 a.m. EDT on Tuesday the center of Typhoon Tokage was located at latitude 30.8°N and longitude 149.6°E which put it about 670 miles (1080 km) southeast of Tokyo, Japan. Tokage was moving toward the north-northwest at 19 m.p.h. (30 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 979 mb.

Tropical Storm Ma-on Develops near Northern Luzon

Tropical Storm Ma-on developed near northern Luzon on Sunday night. At 5:00 a.m. EDT on Monday the center of Tropical Storm Ma-on was located at latitude 16.3°N and longitude 123.4°E which put it about 100 miles (160 km) southeast of Tuguegarao, Philippines. Ma-on was moving toward the west at 11 m.p.h. (17 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.

Former Tropical Depression 10W strengthened to Tropical Storm Ma-on just to the east of northern Luzon on Sunday night. The distribution of thunderstorms in Ma-on continued to be asymmetrical. Most of the thunderstorms were in bands in the southern half of Ma-on’s circulation. The bands in the northern half of the circulation consisted primarily of showers and lower clouds. A strong upper level ridge over China was producing strong northerly winds that were blowing toward the top of Tropical Storm Ma-on. Those winds were causing moderate vertical wind shear and the wind shear was causing the asymmetrical distribution of thunderstorms.

Tropical Storm Ma-on will move through an environment favorable for intensification during the next 12 hours. Ma-on will move over water where the Sea Surface Temperatures are 30˚C. The upper level ridge over China will continue to produce northerly winds that will blow toward the top of Ma-on’s circulation. However, Tropical Storm Ma-on could strengthen during the next 12 hours. Ma-on will weaken when the center passes over northern Luzon, but it could strengthen again over the South China Sea later this week.

Tropical Storm Ma-on will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Ma-on toward the west-northwest during the next 24 hours. On its anticipated track Tropical Storm Ma-on will hit northern Luzon in 12 hours. Ma-on will bring gusty winds and locally heavy rain to northern Luzon. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Tokage formed southeast of Japan. At 5:00 a.m. EDT on Monday the center of Tropical Storm Tokage was located at latitude 25.5°N and longitude 151.6°E which put it about 1010 miles (1635 km) southeast of Tokyo, Japan. Tokage was moving toward the north at 11 m.p.h. (17 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 998 mb.