MIAMI, Sept 26 (Reuters) - Tropical Storm Karen gained strength on Wednesday and could soon become a hurricane in the open Atlantic while a new tropical storm was expected to form in the Gulf of Mexico, U.S forecasters said. Karen, the 11th named Atlantic storm of the year, was located around 1,225 miles (1,970 km) east of the Windward Islands by 11 a.m. (1500 GMT) and had top sustained winds of 70 miles per hour (110 km per hour), the U.S. National Hurricane Center said. The storm could become a hurricane later on Wednesday with winds in excess of 74 mph (119 kph), the hurricane center said, but its most likely track would take it well north of the Caribbean islands and out over open ocean, potentially toward Bermuda. A developing tropical system in the Gulf of Mexico, however, was expected to strike land within three days although computer models indicated that important U.S. and Mexican oil installations in the region were not at risk. The tropical depression, which would be named Lorenzo once it reaches tropical storm strength with winds of at least 39 mph (63 kph), was around 205 miles (335 km) east-southeast of Tampico, Mexico, and around 155 miles (250 km) east of Tuxpan. Its top winds were near 35 mph (55 kph) and it was expected to drift aimlessly for a while before coming ashore in central Mexico at below hurricane strength. None of the computer models used to forecast storm tracks and intensity showed the system heading north toward areas near Texas and Louisiana where the United States gets a third of domestic crude output and 15 percent of its natural gas. The 2007 Atlantic storm season has generated three hurricanes so far, including Hurricane Humberto, which startled coastal residents of Texas and Louisiana in mid-September by unexpectedly strengthening into a hurricane before landfall, and two ferocious maximum-strength Category 5 hurricanes. One of the Category 5 hurricanes, Dean, swiped Jamaica and then plowed into Mexico's Yucatan Peninsula. The other, Felix, tore into Central America. It was the first time since records began in 1851 that two top-ranked hurricanes on the five-step Saffir-Simpson scale made landfall in the Atlantic basin in the same season, which begins June 1 and runs to the end of November. Weather experts have forecast an above-average 16 named storms this year. Record-busting 2005 saw 28 storms form, of which 15 strengthened into hurricanes, including Hurricane Katrina, the storm that swamped New Orleans.
