Subtropical Storm Alberto's pelting rain and brisk winds rain roiled the seas as it neared the U.S. Gulf Coast on Monday, keeping white sandy beaches emptied of their usual Memorial Day crowds. Forecasters warned of life-threatening surf conditions as Alberto approached expected landfall along the Florida Panhandle. A few brief tornadoes were possible in much of Florida and parts of Georgia, South Carolina and Alabama. But forecasters said flash flooding from heavy rain was the biggest threat for most areas. The National Hurricane Center in Miami said at 2 p.m. EDT Monday that Alberto was centered about 30 miles (50 kilometers) south-southwest of Panama City, Florida. Landfall was expected later Monday. The storm had maximum sustained winds of 50 mph (85 kph) and was moving north at 8 mph (13 kph). However, once Alberto's center heads inland — deprived of the warm waters that fuel tropical weather systems — the storm was expected to steadily weaken. A subtropical storm like Alberto has a less defined and cooler center than a tropical storm, and its strongest winds are found farther from its center. Rough conditions were whipping up big waves off the eastern and northern Gulf Coast region, and officials warned swimmers to stay out of the surf through Tuesday due to life-threatening swells and rip currents. The hurricane center said a tropical storm warning was in effect from the Suwannee River in Florida to the Alabama-Florida state line. Between four and eight inches (10-25 centimeters) of rain could pummel Florida Panhandle, eastern and central Alabama, and western Georgia before the storm moves on. Isolated deluges of 12 inches (30 centimeters) were possible. Several inches (centimeters) were also possible from Tennessee east through the Carolinas. Lifeguards posted red flags along the white sands of Pensacola Beach, where swimming and wading were banned. Some tourists said the rainy weather would not dampen their vacations. Jason Powell said he was seeking to keep his children entertained until Alberto blows through his Florida Panhandle vacation spot. "So far we've seen a lot of wind and the ocean is really high, covering up the entire beach," Powell said, adding, "we're not letting it ruin our vacation ... we're going to watch some movies inside and a little TV, and hopefully maybe even get into the pool" despite the rain. Janet Rhumes said her group of friends from Kansas had been planning their Memorial Day weekend on Navarre Beach since October, and no tropical storm could deter them. They stocked up on groceries and planned to play card games. "We've never seen one before and we're here celebrating a friend's 20th birthday," Rhumes told the Northwest Florida Daily News. "So how often can you say you rode a storm out?" Rhumes said her group. The mayor of Orange Beach, on Alabama's Gulf Coast, said Alberto brought rain and aggravation — and dashed hopes for record crowds. Red flags flew on Alabama beaches and officers patrolled, making sure no one entered the water. Elsewhere, Florida's Division of Emergency Management said, about 2,600 customers were without power in northwestern Florida on Monday morning. Scarlett Rustemeyer, a barista at the Fosko Coffee Barre in Pensacola Beach, said she always frets about power outages whenever storms come through Florida. "My boyfriend and I usually try to go to the store and stock up on lots of bottled water, and get like canned goods and things that won't go bad if our power goes out," she said. The National Oceanic and Atmospheric Administration released a hurricane season forecast Thursday that calls for 10 to 16 named storms, with five to nine hurricanes. One to four hurricanes could be "major" with sustained winds of at least 111 mph (178 kph). If that forecast holds, it would make for a near-normal or above-normal season. An average hurricane season produces 12 named storms, of which six become hurricanes, including three major hurricanes. ____ Kay reported from Miami. Associated Press writer Kate Brumback in Atlanta contributed to this story.