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Tropical Storm Philippe Prompts Watches for Antigua and Barbuda

A potential risk caused by Tropical Storm Philippe prompted the issuance of Tropical Storm Watches for Antigua and Barbuda on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Philippe was located at latitude 16.6°N and longitude 59.1°W which put it about 155 miles (245 km) east of Guadeloupe. Philippe was moving toward the west-northwest at 5 m.p.h. (8 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 998 mb.

Tropical Storm Watches were in effect for Antigua and Barbuda.

Tropical Storm Philippe did not move much on Sunday. The circulation around Philippe also did not change much on Sunday. An upper level ridge over the eastern Caribbean Sea continued to produce northwesterly winds that blew toward the top of Philippe’s circulation. Those winds caused strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the southeastern part of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the other parts of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 170 miles (275 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region that will be unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level ridge over the eastern Caribbean Sea will continue to cause strong vertical wind shear. The wind shear is likely to prevent intensification of Tropical Storm Philippe on Monday.

Tropical Storm Philippe will move around the southwestern part of a high pressure system over the Atlantic Ocean. The high pressure system will steer Philippe toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could move a little closer to Antigua and Barbuda on Monday.

Elsewhere over the Atlantic Ocean, former Tropical Storm Rina weakened to a tropical depression northeast of the Leeward Islands. At 11:00 p.m. EDT on Sunday the center of Tropical Depression Rina was located at latitude 27.1°N and longitude 55.4°W which put it about 785 miles (1265 km) northeast of the Northern Leeward Islands. Rina was moving toward the north at 13 m.p.h. (21 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1010 mb.

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Tropical Storm Philippe Drifts East of the Leeward Islands

Tropical Storm Philippe drifted over the Atlantic Ocean east of the Leeward Islands on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Philippe was located at latitude 16.1°N and longitude 57.0°W which put it about 430 miles (690 km) east-southeast of the Northern Leeward Islands. Philippe was moving toward the southwest at 5 m.p.h. (8 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 999 mb.

Tropical Storm Philippe continued to drift slowly east of the Leeward Islands on Saturday. The circulation around Tropical Storm Philippe did not change much on Saturday. An upper level ridge over the eastern Caribbean Sea produced northwesterly winds that blew toward the top of Philippe’s circulation. Those winds caused strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the southeastern part of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the other parts of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 150 miles (240 km) in the eastern side of Philippe’s circulation. Winds to tropical storm force extended out 90 miles (145 km) in the western side of Tropical Storm Philippe.

Tropical Storm Philippe will move through a region that will become marginally favorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level ridge will continue to cause strong vertical wind shear during the first half of Sunday. The upper level winds could weaken later on Sunday. If the upper level winds weaken, then the strong wind shear will decrease and Tropical Storm Philippe could start to intensify.

Tropical Storm Philippe will move around the southwestern part of a high pressure system over the Atlantic Ocean. The high pressure system will steer Philippe toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could move a little closer to the Northern Leeward Islands on Sunday.

Elsewhere over the Atlantic Ocean, Tropical Storm Rina weakened northeast of Tropical Storm Philippe. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Rina was located at latitude 23.5°N and longitude 52.8°W which put it about 760 miles (1220 km) east-northeast of the Northern Leeward Islands. Rina was moving toward the northwest at 14 m.p.h. (22 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 1004 mb.

Tropical Storm Philippe Meanders East of the Leeward Islands

Tropical Storm Philippe meandered over the Atlantic Ocean east of the Leeward Islands on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Philippe was located at latitude 17.6°N and longitude 55.8°W which put it about 480 miles (775 km) east of the Northern Leeward Islands. Philippe was moving toward the southwest at 3 m.p.h. (5 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 1002 mb.

Tropical Storm Rina moved around formed the northeastern periphery of Tropical Storm Philippe on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Rina was located at latitude 20.4°N and longitude 48.8°W which put it about 945 miles (1520 km) east-northeast of the Northern Leeward Islands. Rina was moving toward the northwest at 12 m.p.h. (19 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 999 mb.

The circulations around Tropical Storm Philippe and Tropical Storm Rina continued to interact on Friday. Philippe and Rina revolved around a point between the centers of the two tropical storms in a motion called the Fujiwhara effect. An upper level trough over the Atlantic Ocean east of Bermuda produced westerly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western half of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 140 miles (220 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

The circulation around Tropical Storm Philippe was also affecting Tropical Storm Rina. Upper level divergence from Philippe was adding to the westerly winds blowing toward the top of Rina’ circulation. Those winds caused strong vertical wind shear in Tropical Storm Rina. The wind shear also caused the distribution of thunderstorms in Rina to be asymmetrical. Most of the thunderstorms in Tropical Storm Rina were in bands in the southern and eastern parts of Rina’s circulation. Bands in the northern and western parts of Rina consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 140 miles (220 km) in the eastern part of Rina’s circulation. Winds in the western side of Rina were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level trough east of Bermuda will continue to cause strong vertical wind shear. The strong wind shear is likely to keep Tropical Storm Philippe from intensifying on Saturday.

The interaction between Tropical Storm Philippe and Tropical Storm Rina will continue on Saturday. Philippe and Rina will continue their counterclockwise loop around a point in between the two tropical storms. On its anticipated track, Tropical Storm Philippe will move slowly toward the southwest during the next 24 hours. Tropical Storm Rina is forecast to move toward the northwest during the next 24 hours.

Tropical Storm Philippe Stalls East of the Leeward Islands

Tropical Storm Philippe stalled east of the Leeward Islands on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Philippe was located at latitude 18.3°N and longitude 55.0°W which put it about 530 miles (855 km) east of the Northern Leeward Islands. Philippe was moving toward the west-southwest at 5 m.p.h. (8 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 1004 mb.

Tropical Storm Rina formed over the Atlantic Ocean about 550 miles (890 km) east of Tropical Storm Philippe on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Rina was located at latitude 18.4°N and longitude 46.6°W which put it about 1080 miles (1740 km) east of the Northern Leeward Islands. Rina was moving toward the northwest 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 60 m.p.h. (95 km/h). The minimum surface pressure was 1007 mb.

Tropical Storm Philippe stalled east of the Leeward Islands on Thursday when the circulation around Philippe began to interact with the circulation around Tropical Storm Rina. Philippe also weakened a little on Thursday. An upper level trough over the Caribbean Sea was producing southerly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The low level center of Tropical Storm Philippe was large and weak. The wind shear was also causing the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western half of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 140 miles (220 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

The circulation around Tropical Storm Philippe was also affecting Tropical Storm Rina. Upper level divergence from Philippe was causing vertical wind shear in Tropical Storm Rina. The wind shear was causing the distribution of thunderstorms in Rina to be asymmetrical. Most of the thunderstorms in Tropical Storm Rina were in bands in the southern and eastern parts of Rina’s circulation. Bands in the northern and western parts of Rina consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 70 miles (110 km) in the eastern part of Rina’s circulation. Winds in the western side of Rina were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough over the Caribbean Sea will continue to cause strong vertical wind shear. The strong wind shear is likely to keep Tropical Storm Philippe from intensifying on Friday.

The interaction between Tropical Storm Philippe and Tropical Storm Rina will increase on Friday. Philippe and Rina are likely to start a counterclockwise loop around a point in between the two tropical storms. The situation when two tropical cyclones loop around a point between them is sometimes called the Fujiwhara effect. On its anticipated track, Tropical Storm Philippe will move slowly toward the west-southwest during the next 24 hours. Tropical Storm Rina is forecast to move slowly toward the northwest during the next 24 hours.

Hurricane Sam Passes East of Bermuda

Hurricane Sam passed east of Bermuda on Saturday morning. At 11:00 a.m. EDT on Saturday the center of Hurricane Sam was located at latitude 33.9°N and longitude 59.3°W which put it about 335 miles (540 km) east-northeast of Bermuda. Sam was moving toward the northeast at 17 m.p.h. (28 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 945 mb.

Hurricane Sam was still a powerful hurricane when it passed east of Bermuda on Saturday morning. Sam was rated at Category 4 on the Saffir-Simpson Scale. A circular eye with a diameter of 30 miles (50 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 to the north of the hurricane.

The size of the circulation around Hurricane Sam continued to increase in size as it moved farther to the north. Winds to hurricane force extended out 65 miles (10 km) from the center of Sam. Winds to tropical storm force extended out 240 miles (390 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Sam was 25.1. The Hurricane Size Index (HSI) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 45.7.

Hurricane Sam will move through an environment capable of maintaining a major hurricane during the next 12 hours. Sam 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 during the next 12 hours. An upper level trough east of the U.S. will produce southwesterly winds that will start to affect Hurricane Sam on Sunday. Those winds will blow toward the top of Sam’s circulation and they will cause more vertical wind shear. Hurricane Sam will also move over cooler water on Sunday. The wind shear and cooler water will cause Hurricane Sam to weaken as it begins a transition to a strong extratropical cyclone.

The upper level trough east of the U.S. will steer Hurricane Sam toward the northeast later during the next several days. On its anticipated track Hurricane Sam will pass southeast of Newfoundland on Monday. Sam could be a powerful extratropical cyclone southeast of Greenland by early next week.

Elsewhere over the Atlantic Ocean, Tropical Storm Victor weakened west of the Cabo Verde Islands. At 11:00 a.m. EDT on Saturday the center of Tropical Storm Victor was located at latitude 13.1°N and longitude 37.2°W which put it about 905 miles (1455 km) west of the Cabo Verde Islands. Victor was moving toward the northwest at 12 m.p.h. (19 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 1005 mb.

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.

Tropical Storm Victor Forms South of Cabo Verde Islands

Tropical Storm Victor formed south of the Cabo Verde Islands on Wednesday afternoon. At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Victor was located at latitude 8.3°N and longitude 25.5°W which put it about 540 miles (870 km) south of the Cabo Verde Islands. Victor was moving toward the west-northwest at 13 m.p.h. (20 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 1005 mb.

The circulation around a low pressure system west of Africa strengthened on Wednesday afternoon and the National Hurricane Center designated the system as Tropical Storm Victor. There was a large circulation around Tropical Storm Victor and the circulation was still in the early stages of organization. Bands of showers and thunderstorms were revolving around the center of Victor. More thunderstorms were starting to develop near the center of circulation. The strongest thunderstorms were occurring west of the center. Storms near the center started to generate upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 60 miles in the northern half of Victor’s circulation. The winds in the southern half of the circulation were blowing at less than tropical storm force.

Tropical Storm Victor will move through an environment favorable for intensification during the next 36 hours. Victor 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. Tropical Storm Victor will strengthen gradually. Victor will intensify to a hurricane by Friday.

Tropical Storm Victor will move south of a high pressure system over the eastern Atlantic Ocean. The high will steer Victor toward the west-northwest during the next 36 hours. On its anticipated track Tropical Storm Victor will pass well to the southwest of the Cabo Verde Islands.

Elsewhere over the Atlantic Ocean, major Hurricane Sam was passing northeast of the Leeward Islands. At 5:00 p.m. EDT on Wednesday the center of Hurricane Sam was located at latitude 20.2°N and longitude 57.6°W which put it about 385 miles (620 km) east-northeast of the Northern Leeward Islands. Sam moving toward the northwest at 9 m.p.h. (15 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 945 mb.

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.