MIAMI, Nov 30 (Reuters) - U.S. weather experts posthumously upgraded Tropical Storm Karen to a hurricane as the 2007 Atlantic storm season drew to a close on Friday, making the year a near-average one for hurricane activity.

The U.S. National Hurricane Center, in a post-season analysis of Karen, said the storm briefly reached hurricane intensity on Sept. 26, with winds of 65 knots, equal to 74.8 mph (120 kph) or just over the threshold at which tropical storms become hurricanes.

The upgrade of Karen took the 2007 season's hurricane toll to six, bang on the long-term average. The 14 named storms that formed exceeded the long-term average of around 10 for a six-month Atlantic hurricane season.