Tag Archives: Tropical Storm Koguma

Typhoon Nolo Passes North of Wake Island

Typhoon Nolo passed north of Wake Island on Tuesday evening.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Nolo was located at latitude 25.5°N and longitude 162.9°E which put the center about 445 miles (720 km) north of Wake Island.  Nolo was moving toward the west at 25 m.p.h. (40 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 977 mb.

Typhoon Nolo weakened on Tuesday.  The eye was no longer visible at the center of Nolo’s circulation.  The distribution of thunderstorms in Typhoon Nolo became more asymmetrical on Tuesday.  Thunderstorms were still occurring in bands in the southern and eastern parts of Nolo’s circulation.  Bands in the northern and western parts of Typhoon Nolo consisted primarily of showers and lower clouds.  Storms near the center of Nolo generated less upper level divergence that pumped less 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 Tuesday.

The circulation around Typhoon Nolo was still large.  Winds to typhoon force extended out 75 miles (120 km) from the center of Nolo’s circulation.  Winds to tropical storm force extended out 205 miles (335 km) from the center of Typhoon Nolo.

Typhoon Nolo will move through an environment that will be unfavorable for intensification during the next 24 hours.  Nolo 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 Nolo’s circulation.  Those winds will cause moderate vertical wind shear.  Typhoon Nolo will continue to weaken gradually on Wednesday because of the moderate vertical wind shear.

Typhoon Nolo 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 Nolo toward the west during the next 24 hours.  On its anticipated track, Typhoon Nolo will move northwest of Wake Island on Wednesday.

Elsewhere over the Western North Pacific Ocean, Typhoon Choi-wan was making a transition to a strong extratropical cyclone east of Japan and Tropical Storm Koguma was gradually intensifying south of Wake Island.

At 5:00 p.m. EDT on Tuesday the center of Typhoon Choi-wan was located at latitude 37.9°N and longitude 151.3°E which put the center about 530 miles (855 km) east-southeast of Misawa, Japan.  Choi-wan was moving toward the northeast at 35 m.p.h. (55 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 959 mb.

At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Koguma was located at latitude 15.5°N and longitude 163.6°E which put the center about 325 miles (525 km) south-southwest of Wake Island.  Koguma was moving toward the northwest at 11 m.p.h. (17 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 996 mb.

Typhoon Nolo Moves Northeast of Wake Island

Typhoon Nolo moved northeast of Wake Island on Monday evening.  At 11:00 p.m. EDT on Monday the center of Typhoon Nolo was located at latitude 25.7°N and longitude 172.0°E which put the center about 600 miles (970 km) northeast of Wake Island.  Nolo was moving toward the west at 17 m.p.h. (28 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 955 mb.

Typhoon Nolo did not change much on Monday.  A circular eye with a diameter of 30 miles (50 km) was at the center of Nolo’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 Typhoon Nolo.  Storms near the center of Nolo generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure did not change much on Monday.

The distribution of wind speeds around Typhoon Nolo was fairly symmetrical.  Winds to typhoon force extended out 50 miles (80 km) from the center of Nolo’s circulation.  Winds to tropical storm force extended out 155 miles (250 km) from the center of Typhoon Nolo.

The Hurricane Intensity Index (HII) for Typhoon Nolo is 22.1.  The Hurricane Size Index (HSI) is 16.1 and the Hurricane Wind Intensity Size Index (HWISI) is 38.2.  Typhoon Nolo is similar in size and intensity to Hurricane Milton, when Milton hit Florida in 2024.

Typhoon Nolo will move through an environment that will be somewhat unfavorable for intensification during the next 24 hours.  Nolo 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 northeasterly winds that will blow toward the top of Nolo’s circulation.  Those winds will cause moderate vertical wind shear.  Typhoon Nolo is likely to weaken gradually on Tuesday because of the moderate vertical wind shear.

Typhoon Nolo 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 Nolo toward the west during the next 24 hours.  On its anticipated track, Typhoon Nolo will pass north of Wake Island on Tuesday.

Elsewhere over the Western North Pacific Ocean, Typhoon Choi-wan weakened gradually northeast of Iwo To and Tropical Storm Koguma strengthened slowly north of Kwajalein.

At 11:00 p.m. EDT on Monday the center of Typhoon Choi-wan was located at latitude 30.8°N and longitude 146.3°E which put the center about 440 miles (710 km) northeast of Iwo To.  Choi-wan was moving toward the north at 16 m.p.h. (26 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 945 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Koguma was located at latitude 13.2°N and longitude 166.7°E which put the center about 295 miles (475 km) north of Kwajalein. Koguma was moving toward the northwest at 11 m.p.h. (17 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 Choi-wan Passes East of Iwo To

Typhoon Choi-wan passed east of Iwo To on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Choi-wan was located at latitude 25.7°N and longitude 146.4°E which put the center about 325 miles (525 km) east of Iwo To.  Choi-wan was moving toward the northwest at 12 m.p.h. (19 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 916 mb.

Typhoon Choi-wan intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Sunday.  An eyewall replacement cycle appeared to be starting in Typhoon Choi-wan.  A circular eye with a diameter of 20 miles (32 km) was at the center of Choi-wan’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  The inner end of a rainband wrapped around the existing eye and eyewall.  A larger outer eyewall appeared to be forming around the existing eye and eyewall.  Bands of showers and thunderstorms were revolving around the core of Typhoon Choi-wan.  Storms near the core of Choi-wan generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Choi-wan was large.  Winds to typhoon force extended out 80 miles (130 km) from the center of Choi-wan’s circulation.  Winds to tropical storm force extended out 355 miles (575 km) from the center of Typhoon Choi-wan.

The Hurricane Intensity Index (HII) for Typhoon Choi-wan is 31.6.  The Hurricane Size Index (HSI) is 27.4 and the Hurricane Wind Intensity Size Index (HWISI) is 59.0.  Typhoon Choi-wan is similar in intensity to Hurricane Laura when Laura hit Southwest Louisiana in 2020.  Typhoon Choi-wan is much larger than Hurricane Laura was.

Typhoon Choi-wan will move through an environment that will be favorable for intensification during the next 24 hours.  Choi-wan 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.  Even though Typhoon Choi-wan will move through a favorable environment, Choi-wan is likely to weaken during the next 24 hours because of the eyewall replacement cycle.

Typhoon Choi-wan will move around the western end of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Choi-wan toward the north during the next 24 hours.  On its anticipated track, the center of Typhoon Choi-wan will pass east of Japan during the next few days.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Koguma formed north of Kwajalein and former Hurricane Nolo moved west of the International Date Line.  Nolo is now designated as Typhoon Nolo because it is over the Western North Pacific Ocean.

At 11:00 p.m. EDT on Sunday the center of Tropical Storm Koguma was located at latitude 10.8°N and longitude 168.0°E which put the center about 125 miles (200 km) north of Kwajalein. Koguma was moving toward the northeast 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 1002 mb.

At 11:00 p.m. EDT on Sunday the center of Typhoon Nolo was located at latitude 25.0°N and longitude 178.6°W which put the center about 315 miles (510 km) southwest of Midway Island.  Nolo was moving toward the west-northwest at 18 m.p.h. (30 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 955 mb.

Tropical Storm Koguma Nears Vietnam

The center of Tropical Storm Koguma moved closer to northern Vietnam on Saturday. At 11:00 a.m. EDT on Saturday the center of Tropical Storm Koguma was located at latitude 20.2°N and longitude 106.9°E which put it about 115 miles (185 km) southeast of Hanoi, Vietnam. Koguma was moving toward the northwest at 20 m.p.h. (32 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 997 mb.

The circulation around former Tropical Depression 05W strengthened slightly on Saturday and the system was upgraded to Tropical Storm Koguma. Even though the circulation around the former tropical depression was a little stronger, the distribution of thunderstorms around Tropical Storm Koguma was still asymmetrical. The strongest thunderstorms were occurring in bands southwest of the center of Koguma. Bands in the other parts of the tropical storm consisted primarily of showers and lower clouds. An upper level ridge centered over southern China was producing moderate northeasterly winds that were blowing toward the top of the depression. Those winds were causing moderate vertical wind shear and they were also causing the asymmetrical distribution of thunderstorms.

Tropical Storm Koguma will move into an environment only marginally favorable for intensification during the next few hours. Koguma will move over an area where the Sea Surface Temperatures are near 30°C. However, the upper level ridge over southern China will continue to produce moderate vertical wind shear. The moderate wind shear will keep Tropical Storm Koguma from strengthening significantly before it reaches Vietnam. The circulation around Koguma will weaken after the center moves over Vietnam.

Tropical Storm Koguma will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer Koguma toward the northwest. On its anticipated track the center of Tropical Storm Koguma will make landfall on the coast of northern Vietnam south of Haiphong in a few hours. Koguma will bring gusty winds to parts of northern Vietnam. Since the heaviest rain is falling southwest of the center of Tropical Storm Koguma, heavy rain is already falling over parts of northern Vietnam, northern Laos and extreme northeastern Thailand. The heavy rain could cause flash floods in some locations.