Tag Archives: EP15

Typhoon Koguma Intensifies to Equivalent of a Major Hurricane

Typhoon Koguma intensified to the equivalent of a major hurricane east of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Koguma was located at latitude 20.5°N and longitude 153.5°E which put the center about 640 miles (1035 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 961 mb.

Typhoon Koguma intensified to the equivalent of a major hurricane on Friday as it was completing an eyewall replacement cycle.  A new larger eye was forming at the center of Koguma’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  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.

Even though Typhoon Koguma was completing an eyewall replacement cycle, the circulation around Koguma was still small for a typhoon over the Western North Pacific Ocean.  Winds to typhoon force extended out 45 miles (75 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6.  The Hurricane Size Index (HSI) is 16.2 and the Hurricane Wind Intensity Size Index (HWISI) is 36.8.  Typhoon Koguma is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.

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 northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo continued to weaken gradually far to the southeast of Japan.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Nolo was located at latitude 29.7°N and longitude 147.6°E which put the center about 635 miles (1025 km) southeast of Tokyo, Japan.  Nolo was moving toward the northwest at 13 m.p.h. (21 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 991 mb.

Koguma Strengthens to a Typhoon

Former Tropical Storm Koguma strengthened to a typhoon over the Western North Pacific Ocean east of the Northern Marianas on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Koguma was located at latitude 18.4°N and longitude 157.1°E which put the center about 810 miles (1310 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 14 m.p.h. (22 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 980 mb.

Former Tropical Storm Koguma strengthened to a typhoon on Thursday.  The inner end of a rainband wrapped around the southern side of the center of Koguma’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  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.

The distribution of wind speeds in Typhoon Koguma was fairly symmetrical.  Winds to typhoon force extended out 30 miles (50 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.  Koguma could strengthen to the equivalent of a major hurricane during the weekend.

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 west-northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo was weakening gradually far to the southeast of Japan.

At 5:00 p.m. EDT on Thursday the center of Tropical Storm Nolo was located at latitude 28.1°N and longitude 150.6°E which put the center about 855 miles (1380 km) east-southeast of Tokyo, Japan.  Nolo was moving toward the west-northwest at 17 m.p.h. (28 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 991 mb.

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.

Nolo Strengthens Back to a Major Hurricane

Hurricane Nolo strengthened back to a major hurricane as it moved over the Central North Pacific Ocean far to the west of Hawaii on Saturday.

At 11:00 p.m. EDT on Saturday the center of Hurricane Nolo was located at latitude 23.4°N and longitude 175.1°W which put the center about 200 miles (320 km) south-southwest of Lisianski Island.  Nolo 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 135 m.p.h. (215 km/h).  The minimum surface pressure was 957 mb.

Hurricane Nolo strengthened back to a major hurricane on Saturday.  However, Nolo appeared to be in the middle of an eyewall replacement cycle on Saturday night.  The inner end of a rainband wrapped around the existing eye and eyewall.  The eye was no longer seen on satellite images.  Bands of showers and thunderstorms were revolving around the core of Nolo’s circulation.  Storms near the core of Nolo generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease on Saturday.

The distribution of wind speeds in Hurricane Nolo was relatively symmetrical.  Winds to hurricane force extended out 30 miles (50 km) from the center of Nolo’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Hurricane Nolo.

The Hurricane Intensity Index (HII) for Hurricane Nolo is 20.6.  The Hurricane Size Index (HSI) is 11.6 and the Hurricane Wind Intensity Size Index (HWISI) is 32.2.  Hurricane Nolo is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Hurricane Nolo will move through an environment favorable for intensification during the next 24 hours.  Nolo 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.  Hurricane Nolo could weaken during the next few hours until the eyewall replacement cycle is completed.  Nolo is likely to intensify again after the eyewall replacement cycle is completed.

Hurricane 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-northwest during the next 24 hours.  On its anticipated track, Hurricane Nolo will move across the International Date Line on Sunday.

Elsewhere, Hurricane Rachel continued to spin south of Baja California.

At 11:00 p.m. EDT on Saturday the center of Hurricane Rachel was located at latitude 20.0°N and longitude 112.8°W which put the center about 275 miles (440 km) southwest of the southern tip of Baja California.  Rachel was moving toward the west-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 970 mb.

Hurricane Rachel Spins South of Baja California

Hurricane Rachel was spinning over the Eastern North Pacific Ocean south of Baja California on Friday night.

At 11:00 p.m. EDT on Friday the center of Hurricane Rachel was located at latitude 19.4°N and longitude 111.5°W which put the center about 265 miles (425 km) south-southwest of the southern tip of Baja California.  Rachel was moving toward the west at 5 m.p.h. (8 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 966 mb.

Hurricane Rachel weakened gradually on Friday.  Rachel move over cooler water that was mixed to the surface by the passage of Hurricane Polo last week.  The cooler water caused some of the thunderstorms, especially on the northern side of Rachel’s circulation to weaken.

The circulation around Hurricane Rachel was still well organized even though Rachel was a little weaker than it was yesterday.  A circular eye was still present at the center of Rachel’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were also occurring in bands in the southern half of Hurricane Rachel.  Bands in the northern side of Rachel’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Rachel generated less upper level divergence that pumped less mass away from the hurricane.  The removal of mass in he upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure to increased on Friday.

The distribution of winds speeds in Hurricane Rachel was fairly symmetrical . Winds to hurricane force extended out 45 miles (75 km) from the center of Rachel’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Hurricane Rachel.

Hurricane Rachel will move through an environment unfavorable for intensification during the next 24 hours.  Rachel will move over water where the Sea Surface Temperatures are near 27°C. It will move under the southern side of an upper level ridge that is over Baja California.  The upper level ridge will produce northeasterly winds that will blow toward the top of Rachel’s circulation.  Those winds will cause moderate vertical wind shear.  Hurricane Rachel is likely to continue to weaken on Saturday because of the moderate vertical wind shear.

Hurricane Rachel will move around the southern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Rachel toward the west during the next 24 hours.  On its anticipated track, Hurricane Rachel will continue to move farther away from Baja California.

Elsewhere, former Tropical Storm Nolo strengthened back to a hurricane far to the west of Hawaii.

At 11:00 p.m. EDT on Friday the center of Hurricane Nolo was located at latitude 23.4°N and longitude 168.5°W which put the center about 145 miles (230 km) west-southwest of French Frigate Shoals.  Nolo was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 978 mb.

A Tropical Storm Warning is in effect for the Papahanaumokuakea Marine National Monument from French Frigate Shoals to Lisianaki Island including Maro Reef.

Rachel Strengthens to a Major Hurricane

Hurricane Rachel strengthened to a major hurricane over the Eastern North Pacific Ocean south of Baja California on Thursday afternoon.

At 5:00 p.m. EDT on Thursday the center of Hurricane Rachel was located at latitude 19.4°N and longitude 109.5°W which put the center about 245 miles (390 km) south of the southern tip of Baja California.  Rachel was moving toward the west at 3 m.p.h. (5 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 950 mb.

Hurricane Rachel intensified to a major hurricane on Thursday afternoon.  The inner end of a rainband wrapped around the center of Rachel’s circulation.  A circular eye with a diameter of 12 miles (19 km) was at the center of Rachel’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 Rachel’s circulation.  Storms near the core of Rachel generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The distribution of winds speeds in Hurricane Rachel was fairly symmetrical.  Winds to hurricane force extended out 40 miles (65 km) from the center of Rachel’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Hurricane Rachel.

The Hurricane Intensity Index (HII) for Hurricane Rachel is 22.1.  The Hurricane Size Index (HSI) is 14.0 and the Hurricane Wind Intensity Size Index (HWISI) is 36.1.  Hurricane Rachel is similar in size and intensity to Hurricane Milton when Milton hit Florida in 2024.

Hurricane Rachel will move through an environment favorable for intensification during the next 24 hours.  Rachel 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 Rachel will intensify during the next 24 hours.  Rachel will move over cooler water during the weekend.  Hurricane Rachel will start to weaken when it moves over the cooler water.

Hurricane Rachel will move around the western part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will Rachel toward the west during the next 24 hours. On its anticipated track, Hurricane Rachel will gradually move farther away from Baja California.

Elsewhere, Tropical Storm Nolo started to intensify again far to the west of Hawaii.

At 5:00 a.m. EDT on Thursday the center of Tropical Storm Nolo was located at latitude 22.3°N and longitude 165.5°W which put the center about 120 miles (195 km) south-southeast of French Frigate Shoals.  Nolo was moving toward the northwest at 6 m.p.h. (10 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 993 mb.

A Tropical Storm Warning is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to Maro Reef including French Frigate Shoals.

A Tropical Storm Watch is in effect for the Papahanaumokuakea Marine National Monument from Maro Reef to Lisianski Island.

Rachel Intensifies to a Hurricane Southwest of Mexico

Former Tropical Storm Rachel intensified to a hurricane over the Eastern North Pacific Ocean southwest of Mexico on Tuesday night.

At 8:00 a.m. EDT on Wednesday the center of Hurricane Rachel was located at latitude 17.8°N and longitude 107.6°W which put the center about 220 miles (350 km) southwest of Cabo Corrientes, Mexico.   Rachel was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 979 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Punta San Telmo to Playa, Perula, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from Playa Perula to Cabo Corrientes, Mexico.

Former Tropical Storm Rachel intensified to a hurricane on Tuesday night.  Tall thunderstorms formed near the center of Hurricane Rachel.  Bands of showers and thunderstorms were revolving around the center of Rachel’s circulation.  Storms near the center of Rachel 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 eastern side of Hurricane Rachel.  Winds to hurricane force extended out 25 miles (40 km) in the eastern side of Rachel’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) from the center of Hurricane Rachel.

Hurricane Rachel will move through an environment that will be favorable for intensification during the next 24 hours.  Rachel 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 Rachel will intensify during the next 24 hours.  Rachel could intensify rapidly at times.  Hurricane Rachel could strengthen to a major hurricane during the next day or so.

Hurricane Rachel will move around the western part of a high pressure system that is over northern Mexico.  The high pressure system will Rachel toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Rachel will move parallel to the coast of southwestern Mexico.

Bands in the eastern periphery will bring gusty winds and locally heavy rain to the coast of southwestern Mexico on Wednesday.  Heavy rain could cause flash floods in some locations.

Elsewhere, Former Hurricane Nolo weakened to a tropical storm far to the west of Hawaii.

At 8:00 a.m. EDT on Wednesday the center of Tropical Storm Nolo was located at latitude 22.2°N and longitude 164.8°W which put the center about 150 miles (240 km) southeast of French Frigate Shoals.  Nolo was moving toward the west at 6 m.p.h. (10 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 991 mb.

A Tropical Storm Warning is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals.

A Tropical Storm Watch is in effect for the Papahanaumokuakea Marine National Monument from French Frigate Shoals to Maro Reef.

Nolo Strengthens to a Major Hurricane

Hurricane Nolo strengthened to a major hurricane as it moved over the Central North Pacific Ocean south of Hawaii on Sunday.

At 5:00 p.m. EDT on Sunday the center of Hurricane Nolo was located at latitude 16.2°N and longitude 159.3°W which put the center about 365 miles (585 km) south-southwest of Honolulu, Hawaii.  Nolo was moving toward the west at 12 m.p.h. )19 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. (215 km/h).  The minimum surface pressure was 966 mb.

A Hurricane Watch is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals.

Hurricane Nolo intensified to a major hurricane on Sunday.  A circular eye with a diameter of 35 miles 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 Hurricane Nolo.  Storms near the center of Nolo generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The distribution of wind speeds around Hurricane Nolo was fairly symmetrical.  Winds to hurricane force extended out 35 miles (55 km) from the center of Nolo’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Hurricane Nolo.

The Hurricane Intensity Index (HII) for Hurricane Nolo is 20.6.  The Hurricane Size Index (HSI) is 14.0 and the Hurricane Wind Intensity Size Index (HWISI) is 34.6.  Hurricane Nolo is similar in size and intensity to Hurricane Delta when Delta hit Southwest Louisiana in 2020.

Hurricane Nolo will move through an environment that will be favorable for intensification during the next 24 hours.  Nolo 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.  Hurricane Nolo will intensify during the next 24 hours.

Hurricane Nolo will move around the southwestern part of a high pressure system that is over the Central North Pacific Ocean.  The high pressure system will steer Nolo toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Nolo will stay southwest of Hawaii on Monday.