Hurricane Katia strengthened to a powerful category three hurricane in the Atlantic Monday, but was still too far from any land to pose an immediate risk to life or property, US officials said. But the storm, with sustained winds clocked at nearly 115 miles (185 kilometers) per hour, was being closely monitored for a possible collision into the US east coast in several days' time, forecasters said. At 2100 GMT, the center of Katia was about 795 kilometers (495 miles) south of Bermuda, and further strengthening was expected, the Miami-based national Hurricane Center said. "Interests in Bermuda should monitor the progress of Katia," the NHC added. Forecast models vary, but several tracks show the hurricane taking aim at the US eastern seaboard, parts of which are still suffering the crippling effects of Hurricane Irene, which slammed the densely populated region last week. Katia, the 11th named storm of the Atlantic season, had been downgraded to a tropical storm last week, but regained hurricane status after passing over warmer water.