Tag Archives: Johnston Island

Tropical Storm Iselle Spins Southwest of Baja California

Tropical Storm Iselle was spinning southwest of Baja California on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Iselle was located at latitude 20.1°N and longitude 118.6°W which put the center about 590 miles (950 km) west-southwest of the southern tip of Baja California.  Iselle was moving toward the northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 988 mb.

Tropical Storm Iselle strengthened on Monday.  More thunderstorms developed near the center of Iselle’s circulation.  Bands of showers and thunderstorms were also revolving around the center of Tropical Storm Iselle.  Storms near the center of Iselle generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

Wind to tropical storm force extended out 195 miles (315 km) from the center of Tropical Storm Iselle.

Tropical Storm Iselle will move through an environment that will become unfavorable for intensification during the next 24 hours.  Iselle will move over water where the Sea Surface Temperatures are near 27°C.  It will move under the southern part of an upper level trough that is west of the West Coast of the U.S  The upper level trough will produce southwesterly winds that will blow toward the top of Iselle’s circulation.  Those winds will cause the vertical wind shear to increase on Tuesday.  In addition, Iselle will move into a mass of drier air that is west of Baja California.  Tropical Storm Iselle is likely to start to weaken on Tuesday because of the effects of the increased vertical wind shear and the drier air.

Tropical Storm Iselle will move around the southwestern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Iselle toward the west-northwest during the next 24 hours.  On its anticipate track, Tropical Storm Iselle will move farther away from Baja California.

Elsewhere, former Tropical Storm Moke weakened to a tropical depression south of Hawaii and Tropical Storm Lala weakened gradually far to the northwest of Hawaii.

At 11:00 p.m. EDT on Monday the center of Tropical Depression Moke was located at latitude 16.0°N and longitude 163.0°W which put the center about 435 miles (695 km) east of Johnston Island.  Moke was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1005 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Lala was located at latitude 34.3°N and longitude 175.6°W which put the center about 435 miles (705 km) north-northeast of Kure Atoll.  Lala 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 992 mb.

Hurricane Dora Passes South of Johnston Island

Hurricane Dora passed south of Johnston Island early on Thursday. At 5:00 a.m. EDT on Thursday the center of Hurricane Dora was located at latitude 12.1°N and longitude 169.8°W which put it about 320 miles (510 km) south of Johnston Island. Dora was moving toward the west at 22 m.p.h. (35 km/h). The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 950 mb.

The structure of Hurricane Dora showed signs of changing early on Thursday. The eye at the center of Dora’s circulation got smaller and the eye was more difficult to see on infrared satellite images. Several new bands of thunderstorms developed in the eastern and northern parts of Hurricane Dora. Dora was still a powerful hurricane. Storms near the center of Dora generated upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Dora increased a little as its structure began to change. Winds to hurricane force extended out 30 miles (50 km) from the center of Dora’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation. The Hurricane Intensity Index (HII) was 28.3. The Hurricane Size Index (HSI) was 9.9 and the Hurricane Wind Intensity Size Index (HWISI) was 38.2. Hurricane Dora was similar in size and intensity to Hurricane Charley when Charley hits southwest Florida in 2004.

Hurricane Dora will move through an environment that will be favorable for a major hurricane during the next 24 hours. Dora 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 Dora could be starting an eyewall replacement cycle. If an eyewall replacement cycle is beginning, then Dora is likely to weaken during the next 24 hours, even though the hurricane will be in a favorable environment. Since the circulation around Hurricane Dora is so small, any changes in the environment will have large effects on the intensity of Dora.

Hurricane Dora will move south of a subtropical high pressure system over the North Pacific Ocean. The high pressure system will steer Dora toward the west-northwest during the next 24 hours. On its anticipated track, Hurricane Dora will be move west of the International Date Line on Friday.

Hurricane Dora Passes South of Hawaii

Hurricane Dora passed south of Hawaii on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Hurricane Dora was located at latitude 11.4°N and longitude 160.1°W which put it about 700 miles (1125 km) south-southwest of Honolulu, Hawaii. Dora was moving toward the west at 23 m.p.h. (37 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 953 mb.

Hurricane Dora changed very little on Tuesday. The structure of Dora continued to be very symmetrical. An eye with a diameter of 12 miles (19 km) was still at the center of Hurricane Dora. 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 Dora’s circulation. Storms near the core generated upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Dora did not change much on Tuesday either. Winds to hurricane force extended out 30 miles (50 km) from the center of Dora’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation. The Hurricane Intensity Index (HII) was 25.1. The Hurricane Size Index (HSI) was 9.9 and the Hurricane Wind Intensity Size Index (HWISI) was 35.0.

Hurricane Dora will move through an environment that will be favorable for a major hurricane during the next 24 hours. Dora 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. Hurricane Dora has been in equilibrium with its environment during the past 24 hours. The intensity of Dora may not change much during the next 24 hours. Since the circulation around Hurricane Dora is so small, any changes in the environment will have large effects on the intensity of Dora.

Hurricane Dora will move south of a subtropical high pressure system over the North Pacific Ocean. The high pressure system will steer Dora toward the west during the next 24 hours. On its anticipated track, Hurricane Dora will be near Johnston Island on Thursday.