Tag Archives: HWISI

Bermuda Issues Tropical Storm Warning Because of Hurricane Sam

Bermuda issued a Tropical Storm Warning because of the potential effects of Hurricane Sam. At 5:00 p.m. EDT on Thursday the center of Hurricane Sam was located at latitude 23.6°N and longitude 60.9°W which put it about 645 miles (1040 km) south-southeast of Bermuda. Sam was moving toward the northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 170 m.p.h. (280 km/h). The minimum surface pressure was 938 mb.

A Tropical Storm Warning was in effect for Bermuda.

Hurricane Sam continued to be a powerful hurricane on Thursday. Sam was rated at Category 4 on the Saffir-Simpson Scale. A circular eye with a diameter of 28 miles (44 km) was present at the center of Hurricane Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving round the core of Sam’s circulation. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane.

The size of the circulation around Hurricane Sam was increasing in size as it moved farther to the north. Winds to hurricane force extended out 60 miles (95 km) from the center of Sam. Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 29.8. The Hurricane Size Index (HSI) was 17.5 and the Hurricane Wind Intensity Size Index (HWISI) was 47.3.

Hurricane Sam will move through an environment capable of maintaining a major hurricane during the next 36 hours. Sam 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 during the next 24 hours. An upper level trough east of the U.S. will produce southwesterly winds that will start to affect Hurricane Sam later on Friday. Those winds will blow toward the top of Sam’s circulation and they will cause more vertical wind shear. The wind shear will cause Hurricane Sam to start to weaken.

Hurricane Sam will move around the western end of a high pressure system over the Atlantic Ocean during the next 24 hours. The high will steer Sam toward the north during that time period. The upper level trough east of the U.S. will start to steer Hurricane Sam toward the northeast later on Friday. On its anticipated track Hurricane Sam will pass east of Bermuda on Friday night. The western fringes of Sam could bring gusty winds and locally heavy rain to Bermuda, which is why the Tropical Storm Warning was issued.

Elsewhere over the Atlantic Ocean, Tropical Storm Victor strengthened a little southwest of the Cabo Verde Islands. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Victor was located at latitude 9.9°N and longitude 30.0°W which put it about 585 miles (940 km) southwest of the Cabo Verde Islands. Victor was moving toward the west-northwest at 14 m.p.h. (22 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 1003 mb.

Typhoon Mindulle Passes South of Tokyo

Typhoon Mindulle passed south of Tokyo on Thursday. At 5:00 p.m. EDT on Thursday the center of Typhoon Mindulle was located at latitude 31.1°N and longitude 140.0°E which put it about 340 miles (545 km) south of Tokyo, Japan. Mindulle was moving toward the northeast at 17 m.p.h. (28 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 969 mb.

The core of Typhoon Mindulle passed well to the south of Tokyo on Thursday. However, the circulation around Typhoon Mindulle was so large, that bands of showers and thunderstorms on the northern periphery of Mindulle were bringing gusty winds and rain to parts of Honshu. Winds to typhoon force extended out 130 miles (210 km) on the eastern side of Typhoon Mindulle. Winds to typhoon force extended out 75 miles in the western half of Mindulle. Winds to tropical storm force extended out 310 miles (500 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 13.9. The Hurricane Size Index (HSI) was 37.6 and the Hurricane Wind intensity Size Index (HWISI) was 51.5.

Typhoon Mindulle weakened as it moved over cooler water and into a region where westerly winds in the upper levels caused more vertical wind shear. A larger eye was present at the center of Mindulle, but breaks were developing in the ring of thunderstorms around the eye. The upper level westerly winds in the middle latitudes were beginning to affect the structure of Typhoon Mindulle. Those winds were blowing toward the top of Mindulle’s circulation and they were causing increasing vertical wind shear. The strongest thunderstorms were occurring in bands north and east of the center of the typhoon. Bands south and west of the center consisted primarily of showers and lower clouds. The combination of cooler water and more wind shear was causing Typhoon Mindulle to start a transition to an extratropical cyclone.

The westerly winds in the upper levels will steer Typhoon Mindulle quickly toward the northeast during the next 48 hours. On its anticipated track the core of Mindulle will pass well to the east of Honshu and Hokkaido. Bands on the northern side of Typhoon Mindulle could bring gusty winds and heavy rain to coastal parts of northern Honshu and eastern Hokkaido. Big waves will affect shipping southeast of Japan. Mindulle will weaken gradually during the next 48 hours while it makes a transition to an extratropical cyclone.

Typhoon Mindulle Strengthens Back to Equivalent of a Major Hurricane

Typhoon Mindulle strengthened back to the equivalent of a major hurricane west-southwest of Iwo To on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Typhoon Mindulle was located at latitude 23.0°N and longitude 135.6°E which put it about 390 miles (630 km) west-southwest of Iwo To. Mindulle was moving toward the north at 7 m.p.h. (11 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 950 mb.

Typhoon Mindulle strengthened back to the equivalent of a major hurricane after it completed several Eyewall Replacement Cycles. A large circular eye with a diameter of 45 miles (75 km) was present at the center of Typhoon Mindulle. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Mindulle. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Mindulle grew even larger after it completed the Eyewall Replacement Cycles. Winds to typhoon force extended out 70 miles (110 km) from the center of Mindulle. Winds to tropical storm force extended out 235 miles (380 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 22.1. The Hurricane size Index (HSI) was 27.4 and the Hurricane Wind Intensity Size Index (HWISI) was 49.5.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 29˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle could strengthen gradually during the next 36 hours.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next 48 hours. The high pressure system will steer Mindulle toward the north during the next 24 hours. Typhoon Mindulle will start to move toward the northeast after it moves around the western end of the high. On its anticipated track Typhoon Mindulle will pass west of Iwo To during the next 24 hours. Mindulle cold be south of Tokyo in 48 hours.

Hurricane Sam Strengthens Back to Cat. 4

Hurricane Sam strengthened back to Category 4 on the Saffir-Simpson Scale on Tuesday morning. At 11:00 a.m. EDT on Tuesday the center of Hurricane Sam was located at latitude 17.5°N and longitude 54.3°W which put it about 580 miles (935 km) east of the Northern Leeward Islands. Sam moving toward the northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 954 mb.

Hurricane Sam strengthened back to Category 4 after completing several Eyewall Replacement Cycles. The Eyewall Replacement Cycles also resulted in an increase in the size of Hurricane Sam. A larger circular eye with a diameter of 40 miles (65 km) was present at the center of Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Hurricane Sam. Storms near the core generated upper level divergence that pumped mass away from the hurricane.

The circulation around Hurricane Sam was larger after the completion of the Eyewall Replacement Cycles. Winds to hurricane force extended out 40 miles (65 km) from the center of Sam. Winds to tropical storm force extended out 140 miles (225 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 25.1. The Hurricane Size Index (HSI) was 14.2 and the Hurricane Wind Intensity Size Index (HWISI) was 39.3.

Hurricane Sam will move through an environment capable of sustaining a major hurricane during the next 48 hours. Sam 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 Sam could strengthen in the favorable environment.

Hurricane Sam will move around the southwestern part of a subtropical high pressure system over the Atlantic Ocean. The high will steer Sam toward the northwest during the next 48 hours. On its anticipated track Hurricane Sam could pass northeast of the Northern Leeward Islands on Thursday. Sam could be southeast of Bermuda by Friday.

Hurricane Sam Peaks Just Shy of Cat. 5

Hurricane Sam peaked just shy of Category 5 on the Saffir-Simpson Scale on Sunday. At 11:00 p.m. EDT on Sunday the center of Hurricane Sam was located at latitude 14.7°N and longitude 50.8°W which put it about 850 miles (1365 km) east-southeast of the Northern Leeward Islands. Sam moving toward the northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 170 m.p.h. (280 km/h). The minimum surface pressure was 943 mb.

The National Hurricane Center indicated that the maximum sustained wind speed in Hurricane Sam may have peaked at 155 m.p.h. (250 km/h) on Sunday afternoon before an Eyewall Replacement Cycle halted intensification. The inner end of a rainband wrapped around the existing small eye and eyewall at the center of Hurricane Sam. There were two concentric eyewalls for a period of time and then the inner eyewall began to dissipate. Low level convergence became primarily concentrated on the outer eyewall. The outer eyewall had a diameter of 16 miles (26 km). The western side of the outer eyewall was weaker and the rainbands on the western side of Hurricane Sam were also weaker.

The size of the circulation around Hurricane Sam only increased slightly as a result of the Eyewall Replaement Cycle. Winds to hurricane force extended out 30 miles (50 km) from the center of Sam. Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation. The Hurricane Intensity Index (HII) was 29.9. The Hurricane Size Index (HSI) was 9.8 and the Hurricane Wind Intensity Size Index (HWISI) was 39.7.

Hurricane Sam will move through an environment capable of sustaining a major hurricane during the next 48 hours. Sam 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. The current Eyewall Replacement Cycle will cause Hurricane Sam to weaken until the outer eyewall becomes full developed. Additional Eyewall Replacement Cycles could occur which would cause fluctuations in the intensity of Hurricane Sam.

Hurricane Sam will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The high will steer Sam toward the northwest during the next 48 hours. On its anticipated track Hurricane Sam could be east of the Northern Leeward Islands by Wednesday.

Hurricane Sam Rapidly Intensifies to Cat. 4

Hurricane Sam rapidly intensified to Category 4 on the Saffir-Simpson Scale on Saturday night. At 11:00 p.m. EDT on Saturday the center of Hurricane Sam was located at latitude 13.5°N and longitude 49.0°W which put it about 990 miles (1595 km) east-southeast of the Northern Leeward Islands. Sam moving toward the west-northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 170 m.p.h. (280 km/h). The minimum surface pressure was 943 mb.

A NOAA plane conducting a research mission in Hurricane Sam fund that Sam had rapidly intensified to Category 4 on the Saffir-Simpson Scale. A circular eye with a diameter of 12 miles (19 km) was present at the center of Hurricane Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Hurricane Sam. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane in all directions.

The circulation around Hurricane Sam was relatively small. Winds to hurricane force extended out 30 miles (50 km) from the center of Sam. Winds to tropical storm force extended out 100 miles (160 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 30.0. The Hurricane Size Index (HSI) was 9.2 and the Hurricane Wind Intensity Size Index (HWISI) was 39.2.

Hurricane Sam will move through an environment capable of sustaining a major hurricane during the next 48 hours. Sam 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. The NOAA aircraft did report that there was some drier air in the middle troposphere in the environment around Hurricane Sam. The drier air could weaken Sam if it gets pulled into the core of the circulation. In addition, if the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. An eyewall replacement cycle would cause Hurricane Sam to weaken.

Hurricane Sam will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The high will steer Sam toward the west-northwest during the next few days. On its anticipated track Hurricane Sam could be east of the Northern Leeward Islands by the middle of next week.

Typhoon Mindulle Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Mindulle rapidly intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Saturday night. At 11:00 p.m. EDT on Saturday the center of Typhoon Mindulle was located at latitude 18.7°N and longitude 136.8°E which put it about 510 miles (825 km) southwest of Iwo To. Mindulle moving toward the northwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h). The minimum surface pressure was 915 mb.

Typhoon Mindulle continued to intensify rapidly over the Western North Pacific Ocean on Saturday night. A circular eye with a diameter of 18 miles (29 km) was present at the center of Mindulle. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Mindulle. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass allowed the surface pressure to decrease rapidly.

The circulation around Typhoon Mindulle was more than twice as large as the circulation of Hurricane Sam which was over the Atlantic Ocean. Winds to typhoon force extended out 50 miles (80 km) from the center of Mindulle. Winds to tropical storm force extended out 210 miles (340 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 35.0. The Hurricane Size Index (HSI) was 19.4 and the Hurricane Wind Intensity Size Index (HWISI) was 54.4.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle may be near its peak intensity. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. That structure would start an eyewall replacement cycle that could cause Typhoon Mindulle to weaken. Typhoon Mindulle will move slowly. The strong winds in Mindulle could mix cooler water to the surface. That would also cause Mindulle to weaken.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the northwest during the next several days. On its anticipated track Typhoon Mindulle could be west of Iwo To in three days.

Typhoon Mindulle Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Mindulle rapidly intensified to the equivalent of a major hurricane on Saturday. At 11:00 a.m. EDT on Saturday the center of Typhoon Mindulle was located at latitude 18.3°N and longitude 137.3°E which put it about 525 miles (850 km) south-southwest of Iwo To. Mindulle moving toward the north-northwest at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h). The minimum surface pressure was 942 mb.

Typhoon Mindulle rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean on Saturday. A circular eye was present at the center of Mindulle. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Mindulle. Storms near the core generated upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass allowed the surface pressure to decrease rapidly.

The circulation around Typhoon Mindulle was about twice as large as the circulation of Hurricane Sam which was over the Atlantic Ocean. Winds to typhoon force extended out 45 miles (75 km) from the center of Mindulle. Winds to tropical storm force extended out 160 miles (260 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 25.1. The Hurricane Size Index (HSI) was 16.0 and the Hurricane Wind Intensity Size Index (HWISI) was 41.1.

Typhoon Mindulle will move through an environment favorable for intensification during the next 24 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle will continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. That structure would start an eyewall replacement cycle that could cause Typhoon Mindulle to weaken.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the northwest during the next several days. On its anticipated track Typhoon Mindulle could be west of Iwo To in three or four days.

Sam Intensifies to a Major Hurricane

Hurricane Sam intensified to a major hurricane on Saturday morning. At 11:00 a.m. EDT on Saturday the center of Hurricane Sam was located at latitude 12.9°N and longitude 47.6°W which put it about 1095 miles (1760 km) east-southeast of the Northern Leeward Islands. Sam moving toward the west-northwest at 10 m.p.h. (16 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 960 mb.

Hurricane Sam intensified to a major hurricane over the tropical Atlantic Ocean on Saturday morning. A well formed circular eye was present at the center of Hurricane Sam. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Hurricane Sam. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane in all directions.

The circulation around Hurricane Sam was relatively small. Winds to hurricane force extended out 25 miles (40 km) from the center of Sam. Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 22.1. The Hurricane Size Index (HSI) was 7.4 and the Hurricane Wind Intensity Size Index (HWISI) was 29.5.

Hurricane Sam will move through an environment favorable for intensification during the next 24 hours. Sam 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 Sam will continue to intensify during the next 24 hours. Sam could strengthen to Category 5 on the Saffir-Simpson Scale.

Hurricane Sam will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The high will steer Sam toward the west-northwest during the next few days. On its anticipated track Hurricane Sam could be east of the Northern Leeward Islands by the middle of next week.

Elsewhere over the Atlantic Ocean, former Subtropical Storm Teresa weakened north of Bermuda. At 11:00 a.m. EDT on Saturday the center of Subtropical Depression Teresa was located at latitude 34.3°N and longitude 65.0°W which put it about 140 miles (225 km) north of Bermuda. Teresa was stationary. 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 1009 mb.

Typhoon Chanthu Moves Away from Taiwan

Typhoon Chanthu moved away from Taiwan on Sunday. At 11:00 a.m. EDT on Sunday the center of Typhoon Chanthu was located at latitude 26.8°N and longitude 122.7°E which put it about 105 miles (165 km) northeast of Taipei, Taiwan. Chanthu was moving toward the north-northeast at 12 m.p.h. (19 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 965 mb.

Typhoon Chanthu moved away from Taiwan on Sunday and the weather conditions were improving there. The core of Chanthu passed east of Taiwan and so it remained intact. A small circular eye was present at the center of Typhoon Chanthu. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Multiple bands of showers and thunderstorms were revolving around the core of Chanthu. Storms near the core generated upper level divergence that pumped mass away to the north of the typhoon.

The overall circulation of Typhoon Chanthu was larger after it moved past Taiwan. Winds to typhoon force extended out 25 miles (40 km) from the center of Chanthu. Winds to tropical storm force extended out 190 miles (305 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Chanthu was 19.2. The Hurricane Size Index (HSI) was 10.7 and the Hurricane Wind Intensity Size Index (HWISI) was 29.9. Typhoon Chanthu was capable of causing regional serious damage.

Typhoon Chanthu will move through an environment that will be mostly unfavorable for intensification during the next 36 hours. Chanthu will move over water where the Sea Surface Temperature is near 29˚C. An upper level trough over eastern China will produce southwesterly winds that will blow toward the top of Chanthu’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will likely be strong enough to cause Typhoon Chanthu to weaken gradually.

Typhoon Chanthu will move around the western side of a subtropical high pressure system over the Western North Pacific Ocean. The high will steer Chanthu toward the north during the next 24 hours. On its anticipated track Typhoon Chantu will continue to move away from Taiwan. Chanthu could approach the coast of Chine south of Shanghai in 24 hours. Typhoon Chanthu will bring gusty winds and locally heavy rain to the parts of east coast of China on Monday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression Conson weakened near the coast of Vietnam. At 11:00 a.m. EDT on Sunday the center of Tropical Depression Conson was located at latitude 15.4°N and longitude 109.1°E which put it about 70 miles (110 km) southeast of Da Nang, Vietnam. Conson was stationary. 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 1003 mb.