1. Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, portions of the Bahamas, and southeastern Newfoundland through midweek. 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, portions of the Bahamas, and southeastern Newfoundland through midweek. These swells could cause life threatening surf and rip current conditions. Please consult products from your local weather office.

At 300 AM GMT (0300 UTC), the center of Hurricane Sam was located near latitude 47.7 North, longitude 40.2 West. Sam is moving toward the north northeast near 29 mph (46 km/h). This general motion should continue overnight with a decrease in forward speed. A slow east northeastward motion is forecast to begin by late today, and a northeastward motion is expected Wednesday and Wednesday night. Maximum sustained winds have decreased to near 85 mph (140 km/h) with higher gusts. Although gradual weakening is forecast during the next few days, Sam is expected to transition into a powerful post tropical cyclone over the north Atlantic within the next 6 12 hours. Hurricane force winds extend outward up to 80 miles (130 km) from the center and tropical storm force winds extend outward up to 460 miles (740 km). The estimated minimum central pressure is 965 mb (28.50 inches).

Sam's extratropical transition is well underway. The central core convection has decreased over the past several hours, with the telltale elongated cloud pattern forming on the northwestern side of the circulation. Still, AMSU-microwave data just before 00Z was very clear it is still has a healthy warm core, so advisories will continue. The initial wind speed is decreased to 75 kt, a bit above the satellite estimates.

An approaching mid-latitude trough should cause Sam to quickly transition into a powerful extratropical cyclone within the next 6-12 hours while maintaining hurricane-force winds for about the next day. A slow weakening is expected after that time as Sam loses its baroclinic forcing. The only significant change from the last advisory is that models are in better agreement that Sam will become absorbed by another extratropical low in about 3 days, rather than be the dominant center, so the 96 h forecast is now dissipated.

Sam is moving north-northeastward or 030/25 kt. The system is forecast to slow down as it merges with the mid-latitude trough. By late Tuesday, the post-tropical cyclone should turn east- northeastward before it moves northward and northwestward around the eastern portion of another trough/cut-off low over the north Atlantic. The latest NHC forecast is very close to the last one and the model consensus.