Tag Archives: HWISI

Norma Prompts Hurricane Warning for Baja California

The potential risk posed by Hurricane Norma prompted the issuance of a Hurricane Warning for the southern part of Baja California. At 11:00 p.m. EDT on Thursday the center of Hurricane Norma was located at latitude 18.2°N and longitude 108.1°W which put it about 345 miles (555 km) south-southeast of Cabo San Lucas, Mexico. Norma was moving toward the north at 7 m.p.h. (11 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. (220 km/h). The minimum surface pressure was 948 mb.

A Hurricane Warning was in effect for the portion of the coast from Todos Santos to Los Barriles, Mexico. The Hurricane Warning included Cabo San Lucas. A Tropical Storm Watch was in effect for Los Islas Marias. Tropical Storm Watches were also in effect for the portions of the coast from Todos Santos to Santa Fe, Mexico and from Los Barriles to La Paz, Mexico.

Hurricane Norma weakened slowly on Thursday evening. An upper level trough west of Baja California was producing southwesterly winds that were blowing toward the top of Norma’s circulation. Those winds were causing the vertical wind shear to increase. The eye at the center of Hurricane Norma was less distinct on satellite images. Bands of showers and thunderstorms were revolving around the core of Norma’s circulation. Storms near the core generated upper level divergence that pumped mass away from the hurricane.

Winds to hurricane force extended out 35 miles (55 km) from the center of Hurricane Norma. Winds to tropical storm force extended out 150 miles (240 km) from the center of Norma’s circulation. The Hurricane Intensity Index (HII) for Hurricane Norma was 22.1. The Hurricane Size Index (HSI) was 12.5 and the Hurricane Wind Intensity Size Index (HWISI) was 34.6. Hurricane Norma was similar in size and intensity to Hurricane Delta when Delta hit southwest Louisiana in 2020.

Hurricane Norma will move through an environment unfavorable for intensification during the next 24 hours. Norma will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level trough west of Baja California will continue to produce southwesterly winds that will blow toward the top of Norma’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will cause Hurricane Norma will to weaken during the next 24 hours.

Hurricane Norma will move around the western part of a high pressure system over Mexico. The high pressure system will steer Norma toward the north during the next 24 hours. On its anticipated track, Hurricane Norma could approach the southern end of Baja California on Friday night. Norma will bring strong winds and locally heavy rain to the southern end of Baja California. Heavy rain is likely to cause flash floods in some locations.

Norma Rapidly Intensifies to a Major Hurricane

Hurricane Norma rapidly intensified to a major hurricane over the Eastern North Pacific Ocean on Thursday morning. At 8:00 a.m. EDT on Thursday the center of Hurricane Norma was located at latitude 17.0°N and longitude 107.5°W which put it about 430 miles (690 km) south-southeast of Cabo San Lucas, Mexico. Norma was moving toward the north at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 950 mb.

A Hurricane Watch was in effect for the portion of the coast from Todos Santos to Los Barriles, Mexico. The Hurricane Watch included Cabo San Lucas.

Hurricane Norma rapidly intensified to a major hurricane on Thursday morning. A circular eye with a diameter of 23 miles (37 km) was at the center of Norma’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 Hurricane Norma. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane.

Winds to hurricane force extended out 25 miles (40 km) from the center of Hurricane Norma. Winds to tropical storm force extended out 150 miles (240 km) from the center of Norma’s circulation. The Hurricane Intensity Index (HII) for Hurricane Norma was 23.6. The Hurricane Size Index (HSI) was 10.6 and the Hurricane Wind Intensity Size Index (HWISI) was 34.2. Hurricane Norma was similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Hurricane Norma will move through an environment favorable for intensification during the next 12 hours. Norma will move over water where the Sea Surface Temperatures are near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Hurricane Norma could continue to intensify during the next 12 hours. An upper level trough west of Baja California will approach Norma later on Thursday. The upper level trough will produce southwesterly winds that will blow toward the top of Norma’s circulation. Those winds will cause the vertical wind shear to increase. Hurricane Norma will start to weaken when the wind shear increases.

Hurricane Norma will move around the western part of a high pressure system over Mexico. The high pressure system will steer Norma toward the north during the next 24 hours. On its anticipated track, Hurricane Norma could approach the southern end of Baja California on Friday night. Norma will bring strong winds and locally heavy rain to the southern end of Baja California. Heavy rain is likely to cause flash floods in some locations.

Typhoon Bolaven Passes East of Iwo To

Typhoon Bolaven passed east of Iwo To on Thursday evening. At 11:00 p.m. EDT on Thursday the center of Typhoon Bolaven was located at latitude 26.2°N and longitude 147.8°E which put it about 350 miles (570 km) east of Iwo To. Bolaven was moving toward the northeast at 23 m.p.h. (37 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (285 km/h). The minimum surface pressure was 928 mb.

Concentric eyewalls developed at the center of Typhoon Bolaven on Thursday. The inner end of a rainband wrapped around the existing small eye and eyewall. The larger outer eyewall surrounded the inner eye and eyewall. Bands of showers and thunderstorms revolved around the concentric eyewalls. Storms near the eyewalls generated upper level divergence that pumped mass away to the northeast of the typhoon.

The size of Typhoon Bolaven increased when the concentric eyewalls developed. Winds to typhoon force extended out 60 miles (95 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 265 miles (425 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 29.9. The Hurricane Size Index (HSI) was 21.3 and the Hurricane Wind Intensity Size Index (HWISI) was 51.2.

Typhoon Bolaven will move through an environment that will become more unfavorable for a powerful typhoon during the next 24 hours. Bolaven will move over water where the Sea Surface Temperatures are near 27°C. It will move under the eastern side of an upper level trough near Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Bolaven’s circulation. Those winds will cause the vertical wind shear to increase. Typhoon Bolaven is likely to weaken during the next 24 hours as it goes through an eyewall replacement cycle and the vertical wind shear increases. Bolaven could make a transition to a strong extratropical cyclone when it moves over cooler water south of Alaska.

The upper level trough near Japan will steer Typhoon Bolaven quickly toward the northeast during the next 24 hours. On its anticipated track, Typhoon Bolaven will pass far to the east of Japan on Friday. Bolaven could move south of the Aleutian Islands during the weekend.

Typhoon Bolaven Gets Even Stronger

Typhoon Bolaven got even stronger on Wednesday morning. At 11:00 a.m. EDT on Wednesday the center of Typhoon Bolaven was located at latitude 19.3°N and longitude 142.9°E which put it about 420 miles (675 km) south-southeast of Iwo To. Bolaven was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 180 m.p.h. (290 km/h) and there were wind gusts to 220 m.p.h. (355 km/h). The minimum surface pressure was 904 mb.

Typhoon Bolaven grew even more powerful on Wednesday morning. A circular eye with a diameter of 16 miles (26 km) was at the center of Bolaven’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 Bolaven. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass caused the surface pressure to decrease to 904 mb.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 45 miles (65 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 195 miles (315 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 42.2. The Hurricane Size Index (HSI) was 18.4 and the Hurricane Wind Intensity Size Index (HWISI) was 60.6. Typhoon Bolaven was similar in intensity to Hurricane Dorian in 2019. Bolaven was bigger than Dorian was.

Typhoon Bolaven will move through an environment favorable for a very powerful typhoon during the next 24 hours. Bolaven 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. Typhoon Bolaven could maintain its intensity during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north during the next 24 hours. On its anticipated track, the Typhoon Bolaven will move closer to Iwo To.

Typhoon Bolaven Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Tuesday evening. At 11:00 p.m. EDT on Tuesday the center of Typhoon Bolaven was located at latitude 17.5°N and longitude 143.8°E which put it about 245 miles (390 km) north-northwest of Guam. Bolaven was moving toward the north-northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 920 mb.

Typhoon Warnings were in effect for Rota, Tinian and Saipan. Tropical Storm Warnings were in effect for Agrihan, Pagan and Alamagan.

Typhoon Bolaven rapidly intensified to the equivalent of a Category 5 hurricane west of the Marianas on Tuesday evening. A small circular eye with a diameter of 14 miles (22 km) was at the center of Bolaven’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 Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Bolaven was very symmetrical. Winds to typhoon force extended out 25 miles (40 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 35.0. The Hurricane Size Index (HSI) was 11.5 and the Hurricane Wind Intensity Size Index (HWISI) was 46.5.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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. Typhoon Bolaven could continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. If concentric eyewalls form, then an eyewall replacement cycle could cause Typhoon Bolaven to weaken.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north-northwest during the next 24 hours. On its anticipated track, the Typhoon Bolaven will stay west of the Marianas during the next 24 hours.

Hurricane Lidia Hits Mexico Near Puerto Vallarta

Powerful Hurricane Lidia hit the coast of Mexico near Puerto Vallarta on Tuesday evening. At 8:00 p.m. EDT on Tuesday the center of Hurricane Lidia was located at latitude 20.1°N and longitude 105.5°W which put it about 35 miles (55 km) south-southwest of Puerto Vallarta, Mexico. Lidia was moving toward the east-northeast at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 942 mb.

A Hurricane Warning was in effect for the portion of the coast from Manzanillo to El Roblito, Mexico. A Hurricane Warning was in effect for Las Islas Marias. A Tropical Storm Warning was in effect for the portion of the coast from El Roblito to Mazatlan, Mexico. A Tropical Storm Warning was also in effect for the portion of the coast from Manzanillo to Punta San Telmo, Mexico.

Hurricane Lidia rapidly intensified to Category 4 on the Saffir-Simpson Scale prior to making landfall on the west coast of Mexico. Winds to hurricane force extended out 30 miles (50 km) from the center of Lidia. Winds to tropical storm force extended out 140 miles (220 km) from the center of circulation. The Hurricane Intensity Index (HII) was 28.3. The Hurricane Size Index (HSI) was 9.8 and the Hurricane Wind Intensity Size Index (HWISI) was 38.1. Hurricane Lidia was similar in size and intensity to Hurricane Charley when Charley hit Southwest Florida in 2004.

An upper level trough west of Baja California will steer Hurricane Lidia toward the northeast during the next 24 hours. On its anticipated track, Hurricane Lidia will move quickly inland over Jalisco. Lidia will weaken steadily as it moves farther inland. Even though it will weaken, Hurricane Lidia be capable of causing severe damage. Lidia will bring strong, gusty winds and locally heavy rain. Regional outages of electricity are likely. Heavy rain will fall in Jalisco and Nayarit. The heavy rain is likely to cause flash floods in some locations. Hurricane Lidia could cause a storm surge of up to 13 feet (4 meters) along the coast of Jalisco.

Typhoon Bolaven Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Bolaven rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean north of Guam on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Typhoon Bolaven was located at latitude 16.4°N and longitude 144.3°E which put it about 100 miles (160 km) northwest of Tinian. Bolaven was moving toward the north-northwest at 11 m.p.h. (17 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 959 mb.

A Typhoon Warning was in effect for Rota, Tinian and Saipan. A Typhoon Watch was in effect for Guam. A Tropical Storm Warning was in effect for Guam.

Typhoon Bolaven brought strong winds and heavy rain to Guam, Rota, Tinian and Saipan. The center of Bolaven passed between Rota and Tinian and the strongest winds likely occurred in those places. A weather station in Saipan reported a sustained wind speed of 49 m.p.h. (79 km/h) and a wind gust of 68 m.p.h. (110 km/h). A weather station at Guam International Airport reported a sustained wind speed of 32 m.p.h. (52 km/h) and a wind gust of 46 m.p.h. (74 km/h). That weather station also measured 4.54 inches (115.3 mm) of rain.

Typhoon Bolaven began to intensify rapidly as it moved west of the Marianas. A small circular eye with a diameter of 14 miles (22 km) developed at the center of Bolaven’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 Bolaven. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Bolaven increased when it intensified on Tuesday. Winds to typhoon force extended out 25 miles (40 km) from the center of Bolaven’s circulation. Winds to tropical storm force extended out 185 miles (295 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Bolaven was 20.6. The Hurricane Size Index (HSI) was 11.5 and the Hurricane Wind Intensity Size Index (HWISI) was 32.1.

Typhoon Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven 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. Typhoon Bolaven will intensify during the next 24 hours. Bolaven could intensify rapidly at times. Typhoon Bolaven could strengthen to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.

Typhoon Bolaven will move around the western part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the north-northwest during the next 24 hours. On its anticipated track, the Typhoon Bolaven will stay west of the Marianas during the next 24 hours.

Lidia Rapidly Intensifies to a Major Hurricane Southwest of Puerto Vallarta

Hurricane Lidia rapidly intensified to a major hurricane over the Eastern North Pacific Ocean southwest of Puerto Vallarta on Tuesday afternoon. At 2:00 p.m. EDT on Tuesday the center of Hurricane Lidia was located at latitude 19.2°N and longitude 107.2°W which put it about 155 miles (255 km) southwest of Puerto Vallarta, Mexico. Lidia was moving toward the east-northeast at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 135 m.p.h. (220 km/h). The minimum surface pressure was 959 mb.

A Hurricane Warning was in effect for the portion of the coast from Manzanillo to El Roblito, Mexico. A Hurricane Warning was in effect for Las Islas Marias. A Tropical Storm Warning was in effect for the portion of the coast from El Roblito to Mazatlan, Mexico. A Tropical Storm Warning was also in effect for the portion of the coast from Manzanillo to Punta San Telmo, Mexico.

Hurricane Lidia rapidly intensified to a major hurricane on Tuesday. A U.S. Air Force Reserve Hurricane Hunter plane reported a circular eye with a diameter of 17 miles (28 km) was present at the center of Lidia’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 center of Hurricane Lidia. Storms near the center generated upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Lidia increased on Tuesday. Winds to hurricane force extended out 30 miles (50 km) from the center of Lidia. Winds to tropical storm force extended out 125 miles (200 km) from the center of circulation. The Hurricane Intensity Index (HII) was 20.6. The Hurricane Size Index (HSI) was 8.5 and the Hurricane Wind Intensity Size Index (HWISI) was 29.1. Hurricane Lidia was similar in size and intensity to Hurricane Zeta when Zeta made landfall in Louisiana in 2020.

Hurricane Lidia will move through an environment favorable for intensification during the next few hours. Lidia will move over water where the Sea Surface Temperatures are near 30°C. It will move under the eastern side of an upper level trough that is west of Baja California. The upper level trough will produce southwesterly winds that will blow toward the top of Lidia’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be strong enough to prevent intensification. Hurricane Lidia will intensity during the next few hours. Lidia could continue to intensify rapidly.

The upper level trough west of Baja California will steer Hurricane Lidia toward the northeast during the next 24 hours. On its anticipated track, the center of Hurricane Lidia will make landfall near Puerto Vallarta on Tuesday evening. Lidia will be a major hurricane when it makes landfall. Hurricane Lidia will bring strong, gusty winds and locally heavy rain. The strong winds will be capable of causing major damage. Regional outages of electricity are likely. Heavy rain will fall in Jalisco and Nayarit. The heavy rain is likely to cause flash floods in some locations. Hurricane Lidia could cause a storm surge of up to 13 feet (4 meters) along the coast of Jalisco.

Typhoon Koinu Lingers Near Hong Kong

Typhoon Koinu lingered over the Western North Pacific Ocean near Hong Kong on Saturday. At 11:00 p.m. EDT on Saturday the center of Typhoon Koinu was located at latitude 21.4°N and longitude 114.4°E which put it about 65 miles (105 km) south-southeast of Hong Kong. Koinu was moving toward the west-northwest at 4 m.p.h. (6 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 968 mb.

Typhoon Koinu weakened gradually on Saturday as it lingered near Hong Kong. Since Koinu moved very slowly, the strong winds in the lower atmosphere mixed cooler water to the surface of the ocean. Koinu was unable to extract as much energy from the cooler water and the typhoon weakened. Thunderstorms in Typhoon Koinu did not rise quite as high into the atmosphere.

Even though Typhoon Koinu weakened on Saturday, it still exhibited a well organized circulation. A very small eye was present at the center of Koinu’s circulation. The inner end of a rainband wrapped around the existing eye and eyewall, and concentric eyewalls could be developing. Bands of showers and thunderstorms revolved around the small core of Typhoon Koinu. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Koinu decreased as Koinu gradually weakened. Winds to typhoon force extended out 25 miles (40 km) from the center of Koinu’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 Koinu was 16.5. The Hurricane Size Index (HSI) was 8.6. and the Hurricane Wind Intensity Size Index (HWISI) was 25.1.

Typhoon Koinu will move through an environment somewhat unfavorable for intensification during the next 24 hours. Koinu will move over water where the Sea Surface Temperatures are near 27°C. It will move under axis of an upper level ridge over China. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. However, strong winds in the lower atmosphere will continue to mix cooler water to the surface of the ocean. In addition, the circulation around the northern side of Typhoon Koinu could draw in some drier air from China. Typhoon Koinu is likely to continue to weaken gradually during the next 24 hours due to the mix of cooler water to the surface of the ocean.

Typhoon Koinu will move will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu slowly toward the west during the next 24 hours. On its anticipated track the center Typhoon Koinu will move south of Hong Kong on Sunday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 15W strengthened to Tropical Storm Bolaven east-southeast of Guam. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Bolaven was located at latitude 9.6°N and longitude 152.9°E which put it about 630 miles (1020 km) east-southeast of Guam. Bolaven was moving toward the west-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1000 mb. Typhoon Watches were in effect for Guam, Rota, Tinian and Saipan.

Typhoon Koinu Moves Southeast of Hong Kong

Typhoon Koinu moved southeast of Hong Kong on Friday night. At 11:00 p.m. EDT on Friday the center of Typhoon Koinu was located at latitude 21.1°N and longitude 115.3°E which put it about 115 miles (185 km) southeast of Hong Kong. Koinu was moving toward the west-southwest at 4 m.p.h. (6 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 952 mb.

Typhoon Koinu intensified back to the equivalent of a major hurricane over the South China Sea southeast of Hong Kong on Friday. A circular eye with a diameter of 12 miles (19 km) was at the center of Koinu’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 core of Typhoon Koinu. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

Wins to typhoon force extended out 40 miles (65 km) from the center of Typhoon Koinu. Winds to tropical storm force extended out 285 miles (460 km) in the northeast quadrant of Koinu’s circulation. Winds to tropical storm force extended out 130 miles (210 km) in the other parts of Typhoon Koinu. The Hurricane Intensity Index (HII) for Typhoon Koinu was 22.1. The Hurricane Size Index (HSI) was 14.9 and the Hurricane Wind Intensity Size Index (HWISI) was 37.0. Typhoon Koinu was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon Koinu will move through an environment somewhat favorable for a strong typhoon during the next 24 hours. Koinu 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 over China. The ridge will produce easterly winds that will blow toward the top of Koinu’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification. The circulation around the northern side of Typhoon Koinu could draw in some drier air from China. Typhoon Koinu could maintain its intensity during the next 24 hours if the drier air does not reach the inner core of the circulation. Koinu is likely to weaken if the drier penetrates to the core of the circulation.

Typhoon Koinu will move will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu slowly toward the west-southwest during the next 24 hours. On its anticipated track the center Typhoon Koinu will move south of Hong Kong on Saturday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 15W formed east-southeast of Guam. At 11:00 p.m. EDT on Friday the center of Tropical Depression 15W was located at latitude 9.9°N and longitude 154.2°E which put it about 700 miles (1130 km) east-southeast of Guam. The tropical depression was moving toward the west-northwest at 13 m.p.h. (21 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 1003 mb.