1. Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the eastern United States coast and Atlantic Canada for the next couple of days. These swells could cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

There are no coastal watches or warnings in effect.

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.

SURF: Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, the eastern United States and Atlantic Canada for the next couple of days. 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 33.9 North, longitude 59.3 West. Sam is moving toward the northeast near 17 mph (28 km/h). This general track with an increase in forward speed is expected for the next few days. On the forecast track, Sam will continue to move away from Bermuda. Maximum sustained winds remain near 130 mph (215 km/h) with higher gusts. Sam is a category 4 hurricane on the Saffir Simpson Hurricane Wind Scale. Some slow weakening is forecast during the next 36 hours, followed by more significant weakening early next week. Sam could become a powerful post tropical cyclone on Tuesday. Sam is becoming a large tropical cyclone. Hurricane force winds extend outward up to 65 miles (100 km) from the center and tropical storm force winds extend outward up to 240 miles (390 km). The estimated minimum central pressure is 945 mb (27.91 inches).

Sam has been an impressive hurricane during the past several days. The latest satellite imagery shows it remains a powerful system, with a well-defined eye and symmetric cloud pattern. In fact, since the plane left overnight, the eye has actually warmed, with little change in the eyewall convection. Thus the initial intensity will stay 115 kt, above the latest satellite classifications, but consistent with the earlier aircraft data and low bias of the Dvorak technique for much of the this storm. Sam is now in the top 10 for consecutive days as a category 4 hurricane or greater in the historical record, about the same as Matthew 2016.

The hurricane is forecast to gradually lose strength during the next 36 hours or so while it remains over marginally warm waters, but in fairly light shear. In fact, some of the guidance decrease the shear overnight, which should allow Sam to keep much of its strength, provided it doesn't undertake an eyewall cycle. The new intensity forecast is higher in the first day or so, consistent with the latest model solutions. In about 2 days, Sam will cross the north wall of the Gulf Stream, and in 3 days is expected to spectacularly transition into a large hurricane-force post-tropical cyclone over the far north Atlantic. No changes were made to the end of the intensity forecast.

Sam has turned northeastward at about 15 kt. The hurricane should accelerate later this weekend due to increasing flow between a deep-layer ridge to the east and a large mid- to upper-level low over Atlantic Canada. By midweek the system is forecast to turn more to the north-northeast as it becomes a spoke in a very large extratropical low over the far North Atlantic. The new forecast has shifted somewhat eastward during the first couple of days but ends up very near the last advisory by day 5.