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.