May 28 (Reuters) - The first tropical storm to threaten the United States this year is expected to slam into the coast of South Carolina during the Memorial Day weekend, bringing heavy rain and strong winds, federal officials said on Saturday.
The system, a tropical depression, is forecast to strengthen into a tropical storm later in the day, at which time it will take the name Bonnie, the National Hurricane Center in Miami said in a bulletin.
The center warned at 11 a.m. ET that within 24 hours tropical storm conditions could make landfall anywhere from the Savannah River north to the Little River Inlet along coastal South Carolina.
Tropical storms are defined as a cyclonic weather systems packing winds with sustained surface speeds ranging from 39 to 73 miles per hour (63 to 119 kilometers per hour).
Take a look back at the damage from Hurricane Alex:
The system, now designated Tropical Depression Two, is carrying maximum sustained winds of 35 mph (55 kph), the bulletin said.
The system's forward speed is expected to slow on Saturday and Sunday as it nears the coast.
The formation of Bonnie will mark the second such weather system of 2016, following one that grew into Hurricane Alex in the far eastern Atlantic in January, according to the center.
Alex, a rare wintertime storm that threatened the Azores island group far off the coast of Portugal, never came near the United States.
The depression's center on Saturday morning was 195 miles (310 km) south-southeast of Charleston, South Carolina. The weather system is expected to produce one to three inches (3 to 8 cm) of rainfall along parts of the South Carolina coast.
Tidal storm surge flooding of one to two feet (30 to 60 cm) above ground level also is expected in the storm warning area, the Hurricane Center said.
U.S. meteorologists have predicted an increase in the number of named storms this hurricane season compared with below-average numbers during the past three years.
The National Oceanic and Atmospheric Administration forecast a 70 percent likelihood of 10 to 16 named storms in the upcoming hurricane season. By comparison, 11 named storms occurred in 2015, including four hurricanes, of which two were major, according to federal data.
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