1. Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, 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.

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 500 PM AST (2100 UTC), the center of Hurricane Sam was located near latitude 38.6 North, longitude 52.8 West. Sam is moving toward the east northeast near 16 mph (26 km/h). A northeastward motion at a faster forward speed is expected over the next couple of days. The cyclone is forecast to slow down over the north Atlantic around midweek. Maximum sustained winds are near 100 mph (155 km/h) with higher gusts. Gradual weakening is forecast during the next few days, and Sam is expected to transition into a powerful post tropical cyclone by late Monday. Sam is a large tropical cyclone. Hurricane force winds extend outward up to 60 miles (95 km) from the center and tropical storm force winds extend outward up to 240 miles (390 km). The estimated minimum central pressure is 964 mb (28.47 inches).

Sam is a resilient hurricane despite having just crossed the 26 degrees C isotherm. An eye remains readily apparent in satellite imagery, while microwave images show a symmetrical concentric eyewall structure. Recent scatterometer data revealed that the tropical-storm-force wind field continues to expand, with these winds now extending 200 n mi or greater in all quadrants. A blend of the latest Dvorak intensity estimates from TAFB, SAB, and the UW-CIMMS ADT supports maintaining an initial advisory intensity of 85 kt.

Gradual weakening is expected over the next 36 h as Sam moves over progressively cooler waters. However, the wind field is forecast to continue expanding. On Monday, the cyclone is expected to interact with a strong mid-level trough moving off the coast of Newfoundland which should cause Sam to transition into a powerful extratropical cyclone. With a lack of baroclinic forcing once Sam becomes vertically stacked with the trough in 48 h, the extratropical cyclone is expected to steadily weaken over the northern Atlantic through late this week. The latest NHC intensity forecast is little changed from the previous one, and is near the various model consensus solutions.

Sam has begun to accelerate and is now moving 060/14 kt. A northwestward motion and continued acceleration is forecast through Monday as the cyclone gets caught in southwesterly flow ahead of the mid-level trough. Just before Sam merges with the trough in a couple of days, the cyclone should slow down as it pivots around the eastern flank of the trough. Thereafter, the merged system should continue northeastward then northward in the flow around a larger mid- to upper-level trough over the far northern Atlantic. The model guidance is in very good agreement on this track scenario, and the latest NHC track forecast remains near the previous one.