Update at 11 a.m. Sunday:
Sam continued to strengthen on Saturday afternoon and evening, reaching a Category 4 intensity during Saturday’s 5 p.m. advisory. Sam had sustained winds of 145 mph on Sunday morning. Its intensity is expected to fluctuate, but the Hurricane Center forecast maintains Sam as a major hurricane – Category 3 or above – over the coming week.
Any model simulations that compromise the U.S. and European ensemble now predict that Sam will miss the northern Leeward Islands on Wednesday and Thursday, when the storm is likely to be on its closest approach. A more north-northwest turn is expected on Friday, which would keep the storm well south of Bermuda during this time.
The southeast coast of the United States is unlikely to experience any direct impact from Sam, but increasing swells could start to hit Atlantic beaches from Florida to the Carolinas on Thursday. The swell is expected to increase on Friday until next weekend. Swimmers and visitors to Atlantic beaches next weekend should take this into account and check the forecast later in the week.
Two other disturbances closer to the African coast have a chance of becoming tropical depressions in the middle or at the end of the week.
Original Saturday Afternoon Story:
Hurricane Sam reached Category 3 status late Saturday morning, becoming the fourth Atlantic hurricane to achieve major hurricane status in 2021.
As of noon Saturday, Sam was located just under 1,100 miles east of the Lesser Antilles with sustained winds of 120 mph. It is moving west-northwest at around 10 mph. The National Hurricane Center predicts Sam will hit a Category 4 intensity on Sunday, slow his forward movement and look further northwest on Monday. The hurricane itself is compact: hurricane-force winds extend outward up to 25 miles from the center, and tropical storm-force winds extend 105 miles from Sam’s eye.
The predicted track will keep an eye on Hurricane Sam north and east of the Leeward Islands by Thursday. It is still unclear how close the center will approach these islands, but there is still a chance of peripheral effects from the hurricane. Almost all of the global models and their sets predict that Sam will look north and stay over the open Atlantic for the week to come. It’s not possible to say for sure whether Sam will miss the US coastline, but longer-term models favor this scenario.
A strong hurricane over the Atlantic almost always generates swells, much like Hurricane Larry did earlier in the month. The most recent simulations of the US world model show a long period swell reaching the Atlantic coast of the United States next weekend. Those planning to enter the Atlantic Ocean next weekend to swim or surf should watch the forecast later this week, as reverse currents could become a concern.
Subtropical storm Teresa formed late Friday afternoon north of Bermuda. It weakened into a subtropical depression on Saturday morning and will move out to sea off the Atlantic. The remainder of what was once Tropical Storm Peter has a small chance to regenerate well south of Bermuda early in the coming week, but it should not threaten land areas. Finally, another tropical wave is expected to move off the African coast on Monday. It has a good chance of becoming the next tropical depression of the season midweek over the tropical Atlantic.