1. Swells generated by Sam will impact the Northern Leeward Islands and the Greater Antilles, including Puerto Rico, during the next few days. Swells are expected to reach Bermuda and the Bahamas by Friday, and then spread to the United States east coast by this weekend. These swells could cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

2. Tropical storm conditions are possible on Bermuda beginning Friday night or early Saturday, and a Tropical Storm Watch has been issued for that island.

CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Watch is in effect for...
- Bermuda A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area, please monitor products issued by your national meteorological service.

Key messages for Sam can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC, and on the web at hurricanes.gov/graphics_at3.shtml?key_messages.

WIND: Tropical storm conditions are possible on Bermuda beginning Friday night or early Saturday.

SURF: Swells generated by Sam will impact the northern Leeward Islands and the Greater Antilles, including Puerto Rico, during the next few days. Swells are expected to reach Bermuda and the Bahamas by Friday, and then spread to the United States east coast by this weekend. These swells could cause life threatening surf and rip current conditions. Please consult products from your local weather office.

At 1100 AM AST (1500 UTC), the center of Hurricane Sam was located near latitude 22.6 North, longitude 60.0 West. Sam is moving toward the northwest near 13 mph (20 km/h), and a turn toward the north northwest with an increase in forward speed is expected tonight. A turn toward the north is anticipated by late Friday, and a northeastward motion is forecast to begin on Saturday. On the forecast track, the core of Sam will pass to the east of Bermuda early Saturday. Maximum sustained winds are near 145 mph (230 km/h) with higher gusts. Sam is a category 4 hurricane on the Saffir Simpson Hurricane Wind Scale. Some fluctuations in intensity are expected during the next couple of days, but Sam is forecast to remain a major hurricane through Saturday, with more significant weakening anticipated later in the weekend. Hurricane force winds extend outward up to 60 miles (95 km) from the center and tropical storm force winds extend outward up to 150 miles (240 km). The estimated minimum central pressure is 937 mb (27.67 inches).

Sam continues to look quite impressive on satellite images, with a 20-25 n mi wide eye surrounded by very deep convection. The system's convective banding features and upper-level anticyclonic outflow also remain well-defined, with particularly strong outflow to the northwest and north. Subjective and objective Dvorak intensity estimates have not changed significantly since earlier this morning, so the advisory intensity will remain at 125 kt. Interestingly, aircraft observations show that Sam has been a little stronger than indicated by satellite-derived intensity estimates, which underscores the value of aerial reconnaissance of tropical cyclones. Another Air Force Hurricane Hunter aircraft is scheduled to investigate the hurricane later today.

Sam should continue to move over waters of high oceanic heat content and within a low-shear atmospheric environment for the next 24 hours or so. Thus, it could still strengthen a little today and tonight. By 48 hours, decreasing SSTs and increasing shear should lead to a gradual weakening trend. Around day 5, global model fields suggest that Sam will be merging with a baroclinic zone and transition into a large and powerful extratropical cyclone over the north Atlantic. The official intensity forecast is in good agreement with the HCCA corrected consensus model prediction.

The hurricane is moving a little faster toward the northwest, or at about 320/11 kt. During the next couple of days, a gradual turn toward the north is likely as Sam rounds the western end of a large subtropical anticyclone over the eastern and central Atlantic. Thereafter, Sam is forecast to move generally northeastward in the flow between the anticyclone and a trough near Atlantic Canada. The NHC forecast is very similar to a consensus of the typically reliable GFS and ECMWF predictions, with a little bit of smoothing around days 3-4.

Although the core of Sam is forecast to pass east of Bermuda early Saturday, the tropical-storm-force wind field is forecast to expand and could pass very close to the island beginning late Friday night or early Saturday. Therefore, a Tropical Storm Watch is in effect for Bermuda.