Tag Archives: Big Island

Tropical Storm Calvin Brings Gusty Winds and Rain to Hawaii

Tropical Storm Calvin brought gusty winds and rain to Hawaii on Wednesday. At 8:00 a.m. EDT on Wednesday the center of Tropical Storm Calvin was located at latitude 17.7°N and longitude 155.6°W which put it about 160 miles (260 km) south of Hilo, Hawaii. Calvin was moving toward the west at 20 m.p.h. (32 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 1003 mb.

A Tropical Storm Warning was in effect for Hawaii County.

After Tropical Storm Calvin strengthened late on Tuesday, it started to weaken again on Wednesday morning. An upper level trough northwest of Hawaii was producing southwesterly winds that were blowing toward the top of Calvin’s circulation. There were strong easterly winds in the lower levels of the atmosphere. The combination of southwesterly winds in the upper troposphere and easterly winds in the lower levels of the atmosphere caused strong vertical wind shear. The winds in the upper troposphere blew the top part of Tropical Storm Calvin toward the northeast. The strong easterly winds near the surface pushed the lower part of Calvin quickly toward the west.

The strong vertical wind shear caused Tropical Storm Calvin to weaken on Wednesday morning. The center of Calvin at the surface was passing south of the Big Island of Hawaii. Bands revolving around the center at the surface consisted primarily of showers and lower clouds. Thunderstorms were occurring in bands in the northern side of Tropical Storm Calvin where the wind was pushing air up the eastern slopes of the Hawaiian Islands. Winds to tropical storm force extended out 140 miles (220 km) in the northern side of Calvin’s circulation. Winds in the southern part of Calvin were blowing at less than tropical storm force.

Tropical Storm Calvin will move through an environment unfavorable for intensification during the next 24 hours. Calvin will move over water where the Sea Surface Temperatures are near 26˚C. However, the upper level trough northwest of Hawaii will continue to cause strong vertical wind shear. Tropical Storm Calvin will weaken to a tropical depression during the next 24 hours.

Tropical Storm Calvin will continue to produce gusty winds and locally heavy rain in Hawaii during the next 24 hours. The strongest wind gusts will occur at higher elevations. Calvin could cause isolated minor wind damage. Locally heavy rain could cause flooding in some locations. Flood Watches are in effect for the Big Island of Hawaii, Maui, Molokai, Lanai, and Kahoolawe.

Tropical Storm Calvin Speeds Toward Hawaii

Tropical Storm Calvin sped toward Hawaii on Tuesday. At 2:00 p.m. EDT on Tuesday the center of Tropical Storm Calvin was located at latitude 17.6°N and longitude 150.5°W which put it about 330 miles (640 km) east-southeast of Hilo, Hawaii. Calvin was moving toward the west at 22 m.p.h. (35 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1002 mb.

A Tropical Storm Warning was in effect for Hawaii County.

Tropical Storm Calvin appeared to be getting stronger on Tuesday afternoon. More thunderstorms formed near the center of Calvin’s circulation. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. Even though Tropical Storm Calvin appeared to be strengthening, the vertical structure of Calvin’s circulation seemed to tilt a little to the north in the middle and upper levels of the troposphere. Winds to tropical storm force extended out 105 miles (165 km) in the northern side of Tropical Storm Calvin. Winds to tropical storm force extended out 25 miles (40 km) in the southern side of Calvin.

Tropical Storm Calvin will move through an environment that will be somewhat favorable for intensification during the next 24 hours. Calvin will move over water where the Sea Surface Temperatures will increase to 26˚C. It will move through a region where the upper level winds are blowing from the south. Those winds are not very strong, but they will cause some vertical wind shear. Tropical Storm Calvin could strengthen during the next 24 hours in spite of the vertical wind shear.

Tropical Storm Calvin will move around the southern part of a subtropical high pressure system over the Eastern and Central Pacific Ocean. The high pressure system will steer Calvin toward the west during the next several days. On its anticipated track, Tropical Storm Calvin will move near the Big Island of Hawaii on Tuesday night. Calvin will bring gusty winds and locally heavy rain to Hawaii on Tuesday night and Wednesday. Flood Watches are in effect for the Big Island of Hawaii, Maui, Molokai, Lanai, and Kahoolawe.

Hurricane Olivia Causes Tropical Storm Watches for Hawaii

The potential impacts of Hurricane Olivia caused the issuance of Tropical Storm Watches for Hawaii on Sunday night.  Tropical Storm Watches were issued for Oahu, Maui County including Maui, Molokai, Lanai, and Kahoolawe, and Hawaii County.  At 11:00 p.m. EDT on Sunday the center of Hurricane Olivia was located at latitude 21.4°N and longitude 146.1°W which put it about 595 miles (960 km) east-northeast of Hilo, Hawaii.  Olivia was moving toward the west at 12 m.p.h. (19 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 988 mb.

Hurricane Olivia maintained its intensity and structure on Sunday.  A circular eye persisted at the center of circulation and a ring of thunderstorms surrounded the eye.  The strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Olivia.  Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 125 miles (200 km) from the center.

Hurricane Olivia will move through a less favorable environment during the next several days.  Olivia will move over water where the Sea Surface Temperature is near 26°C.  So, there will be enough energy in the upper ocean to support a hurricane.  However, an upper level trough north of Hawaii will produce southwesterly winds which will blow toward the top of Hurricane Olivia.  Those winds will cause more vertical wind shear and Hurricane Olivia could weaken to a tropical storm as it approaches Hawaii.

Hurricane Olivia will move south of a subtropical high pressure system over the Central Pacific Ocean.  The high is forecast to strengthen and it will steer Olivia on a west-southwesterly track.  On its anticipated track Olivia could approach Hawaii late on Tuesday.  Olivia will bring gusty winds and it could cause power outages.  Locally heavy rain and the potential for flash floods are greater risks.