Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Hurricane Rachel Churns West

Hurricane Rachel churned westward over the Eastern North Pacific Ocean southwest of Baja California on Monday evening.  At 11:00 p.m. EDT on Monday the center of Hurricane Rachel was located at latitude 20.4°N and longitude 117.9°W which put the center about 540 miles (870 km) west-southwest of the southern tip of Baja California.  Rachel was moving toward the west at 9 m.p.h. (15 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 973 mb.

A large circular eye with a diameter of 60 miles (96 km) was at the center of Hurricane Rachel.

The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were occurring in bands in the eastern and southern part of Rachel’s circulation.  Bands in the western and northern parts of Hurricane Rachel consisted primarily of showers and lower clouds.  Storms near the center of Rachel still generated upper level divergence that pumped mass away from the hurricane.  However, 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 slowly on Monday.

The distribution of wind speeds in Hurricane Rachel did not change much on Monday.  Winds to hurricane force extended out 40 miles (65 km) from the center of Rachel’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Hurricane Rachel.

Hurricane Rachel will move through an environment that will be unfavorable for intensification during the next 24 hours.  Rachel will move over water where the Sea Surface Temperatures are near 26°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, Rachel will continue to move through a mass of drier air that is west of Baja California.  Hurricane Rachel is likely to continue to weaken gradually on Tuesday because of the effects of the drier air.

Hurricane Rachel will move around the southern side 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.

Hurricane Rachel Still South of Baja California

Hurricane Rachel was still spinning over the Eastern North Pacific Ocean south of Baja California on Sunday evening.  At 11:00 p.m. EDT on Sunday the center of Hurricane Rachel was located at latitude 20.2°N and longitude 114.8°W which put the center about 365 miles (590 km) west-southwest of the southern tip of Baja California.  Rachel was moving toward the west-northwest at 7 m.p.h. (11 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 967 mb.

Although Hurricane Rachel strengthened earlier on Sunday, Rachel appeared to be weakening again on Sunday.  Hurricane Rachel was moving into a large mass of drier air.  The drier air caused many of the thunderstorms in the northern side of Rachel’s circulation to dissipate.  Thunderstorms were still occurring in bands in the southern half of Hurricane Rachel.  Storms near the center of Rachel still generated upper level divergence that pumped mass away from the hurricane.  However, 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 started to increase again.

The distribution of wind speeds in Hurricane Rachel was still fairly symmetrical on Sunday evening.  Winds to hurricane force extended out 40 miles (65 km) from the center of Rachel’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Hurricane Rachel.

Hurricane Rachel will move through an environment that will be 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 through a region where the upper level winds are weak and there will be little vertical wind shear.  However, Rachel will continue to move through the mass of drier air.  Hurricane Rachel is likely to weaken on Monday because of the effects of the drier air.

Hurricane Rachel will move around the southern side 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 move farther away from Baja California.

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.

Hurricane Polo Hits Sonora

Hurricane Polo hit Sonora on Tuesday morning after crossing the southern part of Baja California on Monday night.

At 8:00 a.m. EDT on Tuesday the center of Hurricane Polo was located at latitude 26.9°N and longitude 111.7°W which put the center about 90 miles (145 km) south-southwest of Guaymas, Mexico.  Polo was moving toward the northeast at 10 m.p.h. (16 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 981 mb.

A Hurricane Warning is in effect for the portion of the west coast of Baja California from Punta Abreojos to Santa Fe, Mexico.

A Hurricane Warning is in effect for the portion of the east coast of Baja California from  Loreto to Bahia San Juan Bautista, Mexico.

A Hurricane Warning is in effect for the portion of the coast from Bahia Kino to Huatabampito, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Loreto to San Evaristo, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Huatabampito to Topolobampo, Mexico.

A large upper level trough over the western U.S. was producing strong southwesterly winds that were blowing toward the top of Hurricane Polo.  Those winds were causing strong vertical wind shear.  Those winds were also blowing the upper part of Polo’s circulation to the northeast of the lower level circulation.  The upper part of Hurricane Polo was already over Sonora.  The lower part of Polo’s circulation was near the coast south of Guaymas.

Hurricane force winds extended out 30 miles (50 km) from the center of the surface circulation around Hurricane Polo.  Tropical storm force winds extended out 90 miles from the center of the surface circulation.

The upper level trough over the western U.S. will steer Hurricane Polo toward the northeast during the next 24 hours.  On its anticipated track, Hurricane Polo will move across northern Mexico toward New Mexico.

The strong vertical wind shear and the mountains in northern Mexico will cause the surface circulation around Hurricane Polo to weaken quickly.  The upper part of Hurricane Polo could reach southern New Mexico on Tuesday night.

Hurricane Polo will continue to produce strong winds and heavy rain over Sonora during the next few hours.  Heavy rain will cause flash floods in some locations.

Hurricane Polo could also drop locally heavy rain over parts of northern Mexico and New Mexico.

Flood Watches are in effect for much of New Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Rachel was gradually getting better organized.

At 8:00 a.m. EDT on Tuesday the center of Tropical Storm Rachel was located at latitude 15.1°N and longitude 104.8°W which put the center about 370 miles (595 km) south of Cabo Corrientes, Mexico.   Rachel was moving toward the west-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 992 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.

Hurricane Polo Brings Wind and Rain to Baja California

Hurricane Polo brought wind and rain to the southern part of Baja California on Monday night.

At 11:00 p.m. EDT on Monday the center of Hurricane Polo was located at latitude 25.9°N and longitude 112.5°W which put the center about 75 miles (120 km) north of Cabo San Lazaro, Mexico.  Polo was moving toward the northeast at 13 m.p.h. (21 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 963 mb.

A Hurricane Warning is in effect for the portion of the west coast of Baja California from Punta Abreojos to Santa Fe, Mexico.

A Hurricane Warning is in effect for the portion of the east coast of Baja California from  Loreto to Bahia San Juan Bautista, Mexico.

A Hurricane Warning is in effect for the portion of the coast from Bahia Kino to Huatabampito, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Punta Eugenia to Punta Abreojos, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from ; Loreto to San Evaristo, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Huatabampito to Topolobampo, Mexico.

Hurricane Polo was still a major hurricane on Monday night.  Winds to hurricane force extended out 40 miles (65 km) from the center of Polo’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Hurricane Polo.

he Hurricane Intensify Index (HII) for Hurricane Polo is 20.6.  The Hurricane Size Index (HSI) is 13.3 and the Hurricane Wind Intensity Size Index (HWISI) is 33.9.  Hurricane Polo is similar in size and intensity to Hurricane Zeta when Zeta hit Louisiana in 2020.

An upper level trough over the western U.S. will steer Hurricane Polo toward the northeast during the next 24 hours.  On its anticipate track, the center of Hurricane Polo will move across the southern part of Baja California during the next few hours.  The center of Polo’s circulation could pass between Loreto and Santa Rosalia.

Hurricane Polo will bring strong winds and heavy rain to southern Baja California. Heavy rain is likely to cause flash floods in some locations.  Hurricane Polo will be capable of causing major damage.

Hurricane Polo will weaken as it moves across the southern part of Baja California.  However, Polo could still be a hurricane when it reaches the west coast of Mexico.  The center of Hurricane Polo will make a landfall on the west coast of Mexico near Guaymas early on Tuesday.

Hurricane Polo will also bring strong winds and locally heavy rain to parts of Sonora.  Heavy rain is likely to cause flash floods in some locations there as well.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Rachel was strengthening gradually.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Rachel was located at latitude 14.3°N and longitude 102.5°W which put the center about 345 miles (555 km) south-southeast of Manzanillo, Mexico.   Rachel was moving toward the west-northwest at 10 m.p.h. (16 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 997 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.

 

Hurricane Polo Nears Southern Baja California

Hurricane Polo moved nearer to the coast of southern Baja California on Sunday evening.

At 11:00 p.m. EDT on Sunday the center of Hurricane Polo was located at latitude 22.8°N and longitude 114.0°W which put the center about 175 miles (280 km) southwest of Cabo San Lazaro, Mexico.  Polo was moving toward the north at 12 m.p.h. (19 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 951 mb.

A Hurricane Warning is in effect for the portion of the west coast of Baja California from Punta Abreojos to Santa Fe, Mexico.

A Hurricane Warning is in effect for the portion of the east coast of Baja California from  Loreto to Santa Rosalia, Mexico.

A Hurricane Warning is in effect for the portion of the coast from Guaymas to Huatabampito, Mexico.

A Tropical Storm Warning and a Hurricane Watch  is in effect for the portion of the coast from Punta Eugenia to Punta Abreojos, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from ; Loreto to San Evaristo, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Santa Rosalia to Bahia San Juan Bautista, Mexico

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Guaymas to Bahia Kino, Mexico.

A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Huatabampito to Topolobampo, Mexico.

Hurricane Polo was still a major hurricane on Sunday evening.  A circular eye with a diameter of 17 miles (28 km) was present at the center of Polo’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 Polo.  Storms near the center of Polo generated upper level divergence that pumped mass away from the hurricane.  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 Sunday.

The distribution of wind speeds in Hurricane Polo was fairly symmetrical.  Winds to hurricane force extended out 45 miles (75 km) from the center of Polo’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Hurricane Polo.

The Hurricane Intensify Index (HII) for Hurricane Polo is 23.4. The Hurricane Size Index (HSI) is 14.6 and the Hurricane Wind Intensity Size Index (HWISI) is 38.0.  Hurricane Polo is similar in size and intensity to Hurricane Milton when Milton hit Florida in 2024.

Hurricane Polo will move through an environment that will be unfavorable for intensification during the next 24 hours.  Polo will move over water where the Sea Surface Temperatures are near 28°C.  However, Polo will move under the southern part of an upper level trough that is near the West Coast of the U.S.  The upper level trough will produce southwesterly winds that will blow toward the top of Polo’s circulation.  Those winds will cause the vertical wind shear to increase on Monday.  Hurricane Polo will weaken during the next 24 hours because of more vertical wind shear.

The upper level trough near the West Coast of the U.S. will pull Hurricane Polo toward the northeast during the next 24 hours.  On its anticipated track, the center of Hurricane Polo will make landfall on the coast of southwest Baja California north of Cabo San Lazaro on Monday afternoon.

Hurricane Polo will bring strong winds and heavy rain to southern Baja California. Heavy rain is likely to cause flash floods in some locations.

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

At 11:00 p.m. EDT on Sunday the center of Tropical Storm Rachel was located at latitude 12.9°N and longitude 99.8°W which put the center about 275 miles (445 km) south-southwest of Acapulco, Mexico.  Rachel was moving toward the west at 7 m.p.h. (11 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 1003 mb.

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

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.