MIAMI (AP) — Tropical storm warnings have been issued for the Southeast coast from north Florida to South Carolina as a cluster of thunderstorms was gathering strength early Saturday and expected to become Tropical Storm Beryl over the Memorial Day weekend.

The National Weather Service said that the storm's maximum sustained winds were at 45 mph. But they are expected to increase as the storm moves over the waters of the Atlantic.

The system was about 285 miles (460 kilometers) from Charleston, S.C., at 2 a.m. and swirling toward the Southeast coast.

Tropical storm warnings were issued for the Volusia/Brevard County line in Florida to Edisto Beach, S.C., and watches from Edisto Beach to the Santee River. The storm is expected to eventually move southwest and the Georgia coast and northern Florida could see heavy rains starting Sunday and into next week.

Higher than normal tides will be crashing against the Southeastern coast and may cause flooding. Heavy rain is forecast and dangerous surf was expected along the coasts of northeastern Florida, Georgia and South Carolina over the holiday weekend.

Forecasters are classifying the storm as Subtropical Storm Beryl, which has more to do with how the center of the storm is forming, not wind speed, according to Weather Underground's website. It is the second named Atlantic storm of the hurricane season that doesn't officially begin until June 1.

Often when subtropical storms remain over warm water for several days, they become tropical because thunderstorms start building close to the center.

Forecasters were not indicating that the storm would become a hurricane.

Check out the photos below of storm clouds seen around the world:
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  • Rain clouds sweep over the desert plains on the Birdsville Track June 9, 2005 near Marree, Australia. (Photo by Ian Waldie/Getty Images)

  • A storm cloud passes over as the US space shuttle Discovery sits on Pad 39A on November 3, 2010 at Kennedy Space Center in Florida. (TIMOTHY A. CLARY/AFP/Getty Images)

  • A girl gathers flowers of rapeseed (brassica napus) in a field some 300 km from Kiev prior to heavy rain on May 10, 2010. (SERGEI SUPINSKY/AFP/Getty Images)

  • Rain clouds sweep over the desert plains on the Birdsville Track June 9, 2005 near Marree, Australia. (Photo by Ian Waldie/Getty Images)

  • Clouds hang over the Hong Kong skyline on May 22, 2011. (Ed Jones/AFP/Getty Images)

  • The cathedral of Strasbourg, eastern France is pictured on September 18, 2011 as the sun sets on a cloudy sky. (PATRICK HERTZOG/AFP/Getty Images)

  • Simon Buret, the singer of French band Aaron, performs during the second day of the 36th edition of the Paleo festival on July 20, 2011 in Nyon. (FABRICE COFFRINI/AFP/Getty Images)

  • A cumulonimbus cloud as seen from a commercial airliner on May 28, 2009. (KAREN BLEIER/AFP/Getty Images)

  • Rainclouds cover the buildings in the central business district of Bangkok on June 16, 2008. (PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)

  • Huge rainclouds gather on the horizon beyond Belarabon Station May 17, 2007 in Cobar, Australia. (Photo by Getty Images)

  • Rain clouds loom over the city skyline November 23, 2005 in Sydney, Australia. (Photo by John Pryke/Getty Images)

  • Villagers walk against a backdrop of cyclone clouds on the outskirts of the eastern temple city Bhubaneswar on May 25, 2009. (ASIT KUMAR/AFP/Getty Images)

  • Dark rainclouds loom before a heavy downpour, which delayed the start of the IPL Twenty20 cricket match between Pune Warriors India and Royal Challengers Bangalore at The Subroto Roy Sahara Stadium in Pune on May 11, 2012. (INDRANIL MUKHERJEE/AFP/GettyImages)

  • Indian walk along Juhu Beach in Mumbai on July 22, 2008 as monsoon rainclouds gather overhead. (SAJJAD HUSSAIN/AFP/Getty Images)

  • Storm Clouds gather during day 3 of the Fifth Test between South Africa and England on January 23 2005 at Centurion Cricket Ground, Pretoria, South Africa (Photo by Tom Shaw/Getty Images)

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