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 lifethreatening surf and rip current conditions. Please consult products from your local weather office.

At 800 AM AST (1200 UTC), the eye of Hurricane Sam was located near latitude 22.1 North, longitude 59.5 West. Sam is moving toward the northwest near 12 mph (19 km/h), and this general motion with an increase in forward speed is expected through 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 continue to pass well to the northeast of the northern Leeward Islands this morning, and 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 SaffirSimpson 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.

Hurricaneforce winds extend outward up to 60 miles (95 km) from the center and tropicalstormforce winds extend outward up to 150 miles (240 km).

The estimated minimum central pressure is 937 mb (27.67 inches).

Sam is a very impressive hurricane in infrared satellite imagery this morning. The 25-nm-wide eye remains very distinct and is surrounded by a ring of convection with cloud tops around -65C. The outflow is also well established in all quadrants. An Air Force Reserve Hurricane Hunter aircraft that performed three eyewall penetrations overnight has reported peak 700-mb flight-level winds of 139 kt in the northeastern, southeastern, and eastern eyewall, and peak SFMR surface winds of 119 kt. These data still support an initial wind speed of 125 kt. Sam's minimum pressure has fallen a few millibars since the NOAA aircraft mission last evening. The latest estimated pressure from dropsonde data gathered by the Air Force is 937 mb. NOAA buoy 41044 has recently reported a peak one-minute wind of 68 kt with a gust to 86 kt in the northeastern eyewall of Sam. The buoy has also reported peak seas of 40 ft.

Sam could still strengthen a little today as it continues to move over a warm ocean eddy and remains in low vertical wind shear conditions. After that time, difficult-to-predict eyewall cycles however, could cause some fluctuations in intensity. After 48 hours, gradually decreasing SSTs and ocean heat content are likely to cause a more definitive weakening trend, with a faster rate of weakening likely after day 3. Sam is forecast to complete its extratropical transition by day 5, and it is predicted by the global model guidance to become a large and powerful extratropical low over the north Atlantic.

Sam is moving northwestward or 320/10 kt. The track forecast reasoning is again unchanged from the previous advisory. Sam will move northwestward, and then northward around the western portion of a subtropical ridge during the next 48 hours. After that time, Sam is predicted to turn northeastward between the ridge and a large mid-latitude trough over the northeastern United States. As that trough lifts northeastward by day 3, Sam is forecast to continue on a northeastward heading, but it is not likely to accelerate as much as a typical recurving tropical cyclone over the north-central Atlantic. The dynamical model guidance remains in excellent agreement through 72 hours, but there is increasing spread after that time. The latest runs of the GFS and ECMWF models have come into somewhat better agreement at days 3 through 5, and the NHC track forecast is near the consensus of those typically reliable models.

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, the Bermuda Weather Service has issued a Tropical Storm Watch for Bermuda.