Champi Strengthens to a Typhoon East of Guam

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Former Tropical Storm Champi strengthened to a typhoon east of Guam on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Champi was located at latitude 12.0°N and longitude 149.6°E which put the center about 375 miles (610 km) east-southeast of Guam.  Champi was moving toward the west-northwest at 15 m.p.h. (24 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 984 mb.

Typhoon Warnings are in effect for Guam and Rota,

Tropical Storm Warnings are in effect for Tinian and Saipan.

Former Tropical Storm Champi strengthened to a typhoon on Friday.  The inner end of a rainband wrapped around the center of Typhoon Champi.  A small circular eye formed at the center of Champi’s circulation.  Bands of showers and thunderstorms were revolving around the the center of Typhoon Champi.  Storms near the center of Champi generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the northern side of Typhoon Champi.  Winds to typhoon force extended out 30 miles (50 km) in the northern half of Champi’s circulation.  Winds to tropical storm extended out 100 miles (160 km) from the center of Typhoon Champi.

Typhoon Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the southern part of an upper level ridge that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear. The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Typhoon Champi will intensify during the next 24 hours.  Champi could strengthen to the equivalent of a major hurricane on Saturday.

Typhoon Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Champi will reach Guam in 24 hours.

Typhoon Champi is could be the equivalent of a major hurricane when it reaches Guam.  Champi is likely to bring strong winds and heavy rain to Guam, Rota, Tinian and Saipan.  The strongest winds and heaviest rain are likely to affect Guam and Rota.  Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian and Saipan.

Trudy Intensifies to a Major Hurricane

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Hurricane Trudy intensified to a major hurricane on Thursday night as it moved over the Eastern North Pacific Ocean south of Mexico.  At 8:00 a.m. EDT on Friday the center of Hurricane Trudy was located at latitude 14.5°N and longitude 102.5°W which put the center about 240 miles (385 km) southwest of Acapulco, Mexico.  Trudy was moving toward the northwest at 6 m.p.h. (15 km/h). The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 956 mb.

A Hurricane Watch is in effect for the portion of the coast from Punta San Telmo to Cabo Corrientes, Mexico.

A Tropical Storm Warning is in effect for the portion of the coast from Manzanillo to Zihuatanejo, Mexico.

Hurricane Trudy intensified to a major hurricane on Thursday night.

A circular eye with a diameter of 17 miles (28 km) was at the center of Hurricane Trudy.  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 Trudy’s circulation.  Storms near the core of Trudy generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

Winds to hurricane force extended out 30 miles (50 km) from the center of Hurricane Trudy.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Trudy’ circulation.

The Hurricane Intensity Index (HII) for Hurricane Trudy is 22.1.  The Hurricane Size Index (HSI) is 20.3 and the Hurricane Wind Intensity Size Index (HWISI) is 42.4.  Hurricane Trudy is similar in intensity to Hurricane Milton when Milton hit Florida in 2024.  Trudy is not quite as large as Milton was.

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

Hurricane Trudy will move around the western side of a high pressure system that is over Mexico.  The high pressure system will steer Trudy toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Trudy will move closer to the coast of southwestern Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Simon was weakening south of Baja California.  At 5:00 a.m. EDT on Friday the center of Tropical Storm Simon was located at latitude 20.0°N and longitude 108.8°W which put the center about 210 miles (335 km) south-southeast of Cabo San Lucas, Mexico.  Simon was moving toward the northwest at 9 m.p.h. (15 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 1002 mb.

Tropical Storm Champi Forms east of Guam

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Tropical Storm Champi formed over the Western North Pacific Ocean east of Guam on Thursday.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Champi was located at latitude 11.6°N and longitude 155.8°E which put the center about 795 miles (1285 km) east of Guam.  Champi was moving toward the west-northwest at 12 m.p.h. (19 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 999 mb.

Typhoon Watches are in effect for Guam, Rota, Tinian, and Saipan.

A low pressure system over the Western North Pacific Ocean east of Guam strengthened on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Champi.

Even though Tropical Storm Champi was strengthening on Thursday, the distribution of thunderstorms in Champi was asymmetrical.  Thunderstorms were occurring in bands in the western and southern parts of Champi’s circulation.  Bands in the eastern and southern parts of Tropical Storm Champi consisted primarily of showers and lower clouds.  Storms near the center of Champi began to generate upper level divergence that pumped mass away to the west of the tropical storm.  The removal of mass caused the surface pressure to start to decrease.

The distribution of wind speeds in Tropical Storm Champi was also asymmetrical.  Winds to tropical storm force extended out 85 miles (135 km) in the southern half of Champi’s circulation.  The winds in the northern part of Tropical Storm Champi were blowing at less than tropical storm force.

Tropical Storm Champi will move through an environment that will be favorable for intensification during the next 24 hours.  Champi will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the southern part of an upper level ridge that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Champi’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear will inhibit intensiciation, but the wind shear will not be enough to prevent intensification.  Tropical Storm Champi will intensify during the next 24 hours.  Champi could strengthen to a typhoon by Friday night.

Tropical Storm Champi will move around the southern side of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Champi toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Champi will move toward the Marianas.  Champi could reach the Marianas in 48 hours.

Tropical Storm Champi is likely to be a typhoon when it reaches the Marianas.  Champi is likely to bring strong winds and heavy rain to Guam, Rota, Tinian and Saipan.  Heavy rain is likely to cause flash floods in some locations.

Trudy Strengthens to a Hurricane

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Former Tropical Storm Trudy strengthened to a hurricane on Wednesday night as it moved over the Eastern North Pacific Ocean south of Mexico.  At 5:00 a.m. EDT on Thursday the center of Hurricane Trudy was located at latitude 12.9°N and longitude 101.6°W which put the center about 300 miles (480 km) south-southwest of Acapulco, Mexico.  Trudy was moving toward the northwest at 9 m.p.h. (15 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 989 mb.

Former Tropical Storm Trudy strengthened to a hurricane on Wednesday night.

Tall thunderstorms were occurring near the center of Hurricane Trudy.  Thunderstorms were also occurring in bands revolving around the center of Trudy’s circulation.  Storms near the center of Trudy generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the northern side of Hurricane Trudy.  Winds to hurricane force extended out 25 miles (40 km) in the northern side of Trudy’s circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Hurricane Trudy.

Hurricane Trudy will move through an environment that will be favorable for intensification during the next 24 hours.  Trudy will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Trudy will intensify during the next 24 hours.  Trudy could rapidly intensify to a major hurricane by early on Friday.

Hurricane Trudy will move around the western side of a high pressure system that is over Mexico.  The high pressure system will steer Trudy toward the west-northwest during the next 24 hours.  On its anticipated track, Hurricane Trudy will move closer to the coast of southwestern Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Simon was still meandering west of Mexico.  At 5:00 a.m. EDT on Thursday the center of Tropical Storm Simon was located at latitude 19.2°N and longitude 108.5°W which put the center about 200 miles (320 km) west-southwest of Cabo Corrientes, Mexico.  Simon was stationary.  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 996 mb.

Hurricane Simon Meanders West of Mexico

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Hurricane Simon meandered over the Eastern North Pacific Ocean west of Mexico on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Simon was located at latitude 20.1°N and longitude 107.6°W which put the center about 125 miles (200 km) west of Cabo Corrientes, Mexico.  Simon was moving toward the west at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 965 mb.

A Hurricane Watch is in effect for Las Islas Marias.

Hurricane Simon strengthened on Tuesday evening as it meandered just to the west of Mexico.

A very small circular eye with a diameter of 6 miles (10 km) was at the center of Hurricane Simon.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Short bands of showers and thunderstorms were revolving around the core of Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels was greater than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure decreased on Tuesday evening.

The circulation around Hurricane Simon was very small.  Winds to hurricane force extended out 15 miles (25 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 35 miles (55 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 19.2.  The Hurricane Size Index (HSI) is 4.7 and the Hurricane Wind Intensity Size Index (HWISI) is 23.9.  Hurricane Simon is similar in intensity to Hurricane Zeta when Zeta hit Louisiana in 2020.  Simon is much smaller than Zeta was.

Hurricane Simon will move through an environment favorable for intensification during the next 12 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Simon could intensify back to a major hurricane during the next 12 hours.  Simon could meander back over cooler water it has mixed to the surface later on Wednesday.  If Simon meanders over that cooler water, then it is likely to weaken, because it will extract less energy from the ocean.

Hurricane Simon will be in an area where the steering winds are weak during the next 24 hours.  On its anticipated track, Hurricane Simon will continue to meander slowly west of Mexico on Wednesday.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Trudy formed south of Mexico.

At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Trudy was located at latitude 20.1°N and longitude 107.6°W which put the center about 440 miles (705 km) south-southeast of Acapulco, Mexico.  Trudy was moving toward the northwest at 10 m.p.h. 165 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 1004 mb.

Typhoon Koguma Continues to Weaken

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Typhoon Koguma continued to weaken on Monday as it moved over the Western North Pacific Ocean east of Japan.  At 11:00 p.m. EDT on Monday the center of Typhoon Koguma was located at latitude 34.6°N and longitude 152.6°E which put the center about 690 miles (1110 km) east of Tokyo, Japan.  Koguma was moving toward the northeast at 28 m.p.h. (45 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 979 mb.

Typhoon Koguma started to make a transition to a strong extratropical cyclone on Monday.  Thunderstorms were still occurring in bands in the eastern and northern parts of Koguma’s circulation.  Bands in the western and southern parts of Typhoon Koguma consisted primarily of showers and lower clouds.  Storms near the center of Koguma generated upper level divergence that pumped mass away to the northeast of the typhoon.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Monday.

Even though Typhoon Koguma started a transition to an extratropical cyclone on Monday, the distribution of wind speeds was still fairly symmetrical.  Winds to typhoon force extended out 60 miles (95 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Koguma.

Typhoon Koguma will move through an environment that will be unfavorable for intensification of a typhoon during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 22°C.  It will move under the eastern side of an upper level trough that is east of Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause strong vertical wind shear.  Typhoon Koguma will continue to weaken on Tuesday as it makes a transition to a strong extratropical cyclone.

The upper level trough that is east of Japan will steer Typhoon Koguma quickly toward the northeast during the next 24 hours.  On its anticipated track, Typhoon Koguma will move farther away from Japan.

Hurricane Simon Stalls Just West of Mexico

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Hurricane Simon stalled just west of Mexico on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Hurricane Simon was located at latitude 20.2°N and longitude 106.8°W which put the center about 75 miles (120 km) west of Cabo Corrientes, Mexico.  Simon was moving toward the west-northwest at 3 m.p.h. (5 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 969 mb.

A Hurricane Warning is in effect for Las Islas Marias.

A Hurricane Watch is in effect for the portion of the coast from Cabo Corrientes to Bahia Tempehuaya, Mexico.  The Hurricane Watch includes Puerto Vallarta.

Hurricane Simon weakened gradually as it stalled on Monday.

Even though Hurricane Simon weakened on Monday, a very small circular eye was still present at the center of Simon’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 Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Monday.

The circulation around Hurricane Simon was very small.  Winds to hurricane force extended out 15 miles (25 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 45 miles (75 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 16.5.  The Hurricane Size Index (HSI) is 4.4 and the Hurricane Wind Intensity Size Index (HWISI) is 20.9.  Hurricane Simon is similar in intensity to Hurricane Idalia when Idalia hit Florida in 2023.  Simon is smaller than Idalia was.

Hurricane Simon will move through an environment marginally favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  However, Hurricane Simon will pull some drier air that is over Mexico into its circulation because Simon will remain very close to Mexico.  The drier air will inhibit the formation of new thunderstorms in the eastern and northern parts of Simon’s circulation.  Hurricane Simon is likely to continue to weaken gradually on Tuesday because of the effects of the drier air.  Simon could intensify on Wednesday when it is little farther away from the coast of Mexico.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon slowly toward the northwest during the next 24 hours.  On its anticipated track, the core of Hurricane Simon will pass west of the Islas Marias on Tuesday night.

The core of Hurricane Simon will pass west of Las Islas Marias on Tuesday night.  Simon will bring strong winds and heavy rain to those islands on Tuesday and Wednesday.  Flash floods are likely to occur in some locations.  Hurricane Simon could cause a storm surge of up to 10 feet (3 meters) along parts of coast of Las Islas Marias.

Typhoon Koguma Weakens

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Typhoon Koguma weakened on Sunday as it moved over the Western North Pacific Ocean southeast of Japan.  At 11:00 p.m. EDT on Sunday the center of Typhoon Koguma was located at latitude 29.0°N and longitude 147.6°E which put the center about 655 miles (1060 km) southeast of Tokyo, Japan.  Koguma was moving toward the north at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 115 m.p.h. (1850 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 954 mb.

Typhoon Koguma weakened on Sunday, but the structure of Koguma was still intact.  A large circular eye with a diameter of 45 miles (75 km) was at the center of Koguma’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 revolved around the center of Koguma’s circulation.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Sunday.

The distribution of wind speeds in Typhoon Koguma was fairly symmetrical.  Winds to typhoon force extended out 65 miles (105 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 130 miles (210 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6. The Hurricane Size Index (HSI) is 19.6 and the Hurricane Wind Intensity Size Index (HWISI) is 40.2. Typhoon Koguma is similar in intensity to Hurricane Rita when Rita hit southwest Louisiana in 2005.  Koguma is not as large as Rita was.

Typhoon Koguma will move through an environment that will be unfavorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the eastern side of an upper level trough that is over Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause moderate vertical wind shear.  Moderate vertical wind shear and cooler Sea Surface Temperature will cause Typhoon Koguma to continue to weaken on Monday.

The upper level trough over Japan will steer Typhoon Koguma toward the northeast during the next 24 hours.  On its anticipated track, Typhoon Koguma will stay far to the east of Japan.

Hurricane Simon Stays Just West of Mexico

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The core of Hurricane Simon stayed just to the west of the west coast of Mexico on Sunday.  At 5:00 p.m. EDT on Sunday the center of Hurricane Simon was located at latitude 19.6°N and longitude 105.8°W which put the center about 55 miles (90 km) south of Cabo Corrientes, Mexico.   Simon was moving toward the north-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 947 mb.

A Hurricane Warning is in effect for the portion of the coast from Punta San Telmo to El Roblito, Mexico.  The Hurricane Warning includes Manzanillo and Puerto Vallarta.

A Hurricane Warning is in effect for Las Islas Marias.

A Hurricane Watch is in effect for the portion of the coast from El Roblito to Tempehuaya, Mexico.

Hurricane Simon was a Category 4 hurricane on the Saffir-Simpson Scale on Sunday afternoon.

A circular eye with a diameter of 10 miles (16 km) was at the center of Hurricane Simon.  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 Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Sunday.

The circulation around Hurricane Simon was very small.  Winds to hurricane force extended out 25 miles (40 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 60 miles (95 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 25.1.  The Hurricane Size Index (HSI) is 8.2 and the Hurricane Wind Intensity Size Index (HWISI) is 33.3. Hurricane Simon is similar in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Simon is smaller than Harvey was.

Hurricane Simon will move through an environment somewhat favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  However, Hurricane Simon is likely to pull some drier air that is over Mexico into its circulation because Simon will remain very close to Mexico.  The drier air will inhibit the formation of new thunderstorms in the eastern and northern parts of Simon’s circulation.  Hurricane Simon is likely to weaken on Monday because of the effects of the drier air.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon toward the north-northwest during the next 24 hours.  On its anticipated track, the core of Hurricane Simon will remain just to the west of Mexico on Monday.  The center of Simon’s circulation will pass just to the west of Cabo Corrientes on Sunday night.  The core of Hurricane Simon will be near Las Islas Marias on Monday afternoon.

Bands in the eastern side of Hurricane Simon will continue to bring strong winds and locally heavy rain to the west coast of Mexico.  The strongest winds and heaviest rains will occur in Colima, Jalisco and Nayarit.  Heavy rain is likely to cause flash floods in some locations.

The core of Hurricane Simon will pass near Las Islas Marias on Monday afternoon.  Simon will bring strong winds and heavy rain to those islands.  Flash floods are likely to occur in some locations.  Hurricane Simon could cause a storm surge of up to 13 feet (4 meters) along parts of coast of Las Islas Marias.

Typhoon Koguma Spins East of Iwo To

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Typhoon Koguma was spinning over the Western North Pacific Ocean east of Iwo To on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Typhoon Koguma was located at latitude 24.9°N and longitude 148.0°E which put the center about 435 miles (700 km) east of Iwo To.  Koguma was moving toward the northwest at 11 m.p.h. (17 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 944 mb.

Typhoon Koguma intensified on Saturday.  Koguma was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 23 miles (37 km) was at the center of Typhoon Koguma.  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 revolved around the center of Koguma’s circulation.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease on Saturday.

The distribution of wind speeds in Typhoon Koguma was fairly symmetrical.  Winds to typhoon force extended out 65 miles (105 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 25.1.  The Hurricane Size Index (HSI) is 19.9 and the Hurricane Wind Intensity Size Index (HWISI) is 45.0.  Typhoon Koguma is similar in intensity in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Koguma is larger than Harvey was.

Typhoon Koguma will move into an environment that will become unfavorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the upper level western winds in the middle latitudes.  The vertical wind shear will increase when Koguma moves under those upper level westerly winds.  Typhoon Koguma will start to weaken when the vertical wind shear increases.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the north during the next 24 hours.  On its anticipated track, Typhoon Koguma willmove away from Iwo To on Sunday.