Tag Archives: Northern Leeward Islands

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.

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.

Subtropical Storm Teresa Develops North of Bermuda

Subtropical Storm Teresa developed north of Bermuda on Friday afternoon. At 5:00 p.m. EDT on Friday the center of Subtropical Storm Teresa was located at latitude 34.5°N and longitude 64.5°W which put it about 155 miles (245 km) north of Bermuda. Teresa moving toward the 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 1008 mb.

A distinct low level of circulation was evident under an upper level low pressure system north of Bermuda and the National Hurricane Center designated the system as Subtropical Storm Teresa. The structure of Subtropical Storm Teresa was complex. There was a distinct low level center of circulation under the western side of the upper level low. A long band of showers and thunderstorms arced around the eastern and northern side of the larger circulation. Winds to tropical storm force extended out 70 miles (110 km) in the northeastern quadrant of Subtropical Storm Teresa. Winds in the other parts of Teresa were blowing at less than tropical storm force.

Subtropical Storm Teresa will move through an environment that is only marginally favorable for intensification during the next 24 hours. Teresa will move over water where the Sea Surface Temperatures are near 27˚C. However, the circulation around the upper level low will cause vertical wind shear over the low level center of Teresa. The wind shear will inhibit intensification. Subtropical Storm Teresa could get a little stronger during the next 24 hours. Teresa is forecast to be absorbed by a larger extratropical cyclone by the end of the weekend.

An upper level trough over the eastern U.S. will steer Subtropical Storm Teresa toward the northeast during the weekend. On its anticipated track, Teresa will move farther away from Bermuda. Subtropical Storm Teresa is forecast to be absorbed by an extratropical cyclone south of Nova Scotia on Sunday.

Elsewhere, Hurricane Same strengthened over the tropical Atlantic Ocean. At 5:00 p.m. EDT on Friday the center of Hurricane Sam was located at latitude 12.1°N and longitude 44.8°W which put it about 1290 miles (2075 km) east-southeast of the Northern Leeward Islands. Sam moving toward the west at 12 m.p.h. (19 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 986 mb. Hurricane Sam is forecast to strengthen to a major hurricane during the weekend.

Sam Strengthens to a Hurricane

Former Tropical Storm Sam strengthened to a hurricane over the Tropical Atlantic Ocean early on Friday. At 5:00 a.m. EDT on Friday the center of Hurricane Sam was located at latitude 11.5°N and longitude 42.2°W which put it about 1470 miles (2365 km) east-southeast of the Northern Leeward Islands. Sam moving toward the west at 15 m.p.h. (24 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 993 mb.

Former Tropical Storm Sam strengthened to a hurricane early on Friday. The inner end of a rainband wrapped around the eastern side of the center of Hurricane Sam. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated 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 20 miles (30 km) from the center of Sam. Winds to tropical storm force extended out 60 miles (95 km) from the center of circulation.

Hurricane Sam will move through an environment very favorable for intensification 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 will continue to intensify during the next 48 hours. Sam could intensify rapidly after an inner core with an eye and an eyewall fully form. Hurricane Sam could intensify to a major hurricane during the weekend.

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 approach the Northern Leeward Islands by the middle of next week. Sam could be a major hurricane at that time.

Tropical Storm Sam Strengthens over Eastern Atlantic

Tropical Storm Sam strengthened over the eastern Atlantic Ocean on Thursday morning. At 11:00 a.m. EDT on Thursday the center of Tropical Storm Sam was located at latitude 10.9°N and longitude 38.1°W which put it about 1745 miles (2805 km) east-southeast of the Northern Leeward Islands. Sam moving toward the west at 16 m.p.h. (26 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.

Former Tropical Depression Eighteen strengthened to Tropical Storm Sam on Thursday morning. Tropical Storm Sam was organizing quickly. The inner end of a rainband wrapped around the center of Sam . An eye appeared to be forming at the center of circulation. Bands of showers and thunderstorms were revolving around the center of Tropical Storm Sam. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 45 miles (75 km) from the center of Sam.

Tropical Storm Sam will move through an environment very favorable for intensification during the next 48 hours. Sam will move over water where the Sea Surface Temperatures are near 28˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Sam will continue to intensify during the next 36 hours. Sam could strengthen to a hurricane by Friday. Sam could intensify rapidly after an inner core with an eye and an eyewall forms. Sam could intensify to a major hurricane during the weekend.

Tropical Storm 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 Tropical Storm Sam could approach the Northern Leeward Islands next week. Sam could be a major hurricane by that time.

Tropical Depression 16 Forms East of Northern Leeward Islands

Tropical Depression Sixteen formed east of the Northern Leeward Islands on Saturday night. At 11:00 p.m. EDT on Saturday the center of Tropical Depression Sixteen was located at latitude 16.4°N and longitude 53.1°W which put it about 670 miles (1080 km) east of the Northern Leeward Islands. The tropical depression was moving toward the west-northwest at 15 m.p.h. (24 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 1008 mb.

More thunderstorms developed near the center of a low pressure system east of the Northern Leeward Islands on Saturday night and the National Hurricane Center designated the system as Tropical Depression Sixteen. Thunderstorms were also developing in bands in the eastern and northern parts of the tropical depression. Bands in the southern and western parts of the circulation consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away to the north of the tropical depression.

Tropical Depression Sixteen will move through an environment somewhat favorable for intensification during the next 24 hours. The depression will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of an upper level ridge. The ridge will produce southerly winds that will blow toward the top of the tropical depression. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Depression Sixteen is likely to strengthen to a tropical storm on Sunday. The tropical depression will move closer to an upper level trough northeast of Puerto Rico on Monday. The upper level trough will produce strong southwesterly winds that will blow toward the top of the tropical depression. Those winds will cause moderate vertical wind shear, which is likely to weaken the tropical depression.

Tropical Depression Sixteen will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The high pressure system will steer the depression toward the west-northwest during the next 24 hours. On its anticipated track Tropical Depression Sixteen could be northeast of the Northern Leeward Islands by Monday morning.

Elsewhere over the Atlantic Ocean, Tropical Storm Odette made a transition to an extratropical cyclone south of Nova Scotia. At 5:00 p.m. EDT on Saturday the center of former Tropical Storm Odette was located at latitude 39.1°N and longitude 65.1°W which put it about 385 miles (625 km) south-southwest of Halifax, Nova Scotia. Odette was moving toward the east-northeast at 18 m.p.h. (29 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 1001 mb.