Even as Hurricane Isaac weakens to a tropical depression bringing heavy rain and flash floods in Mississippi and the lower Ohio River valley, Hurricane Kirk, the fifth hurricane of the Atlantic hurricane season advances toward the north east at 26 km per hour, a National Weather Service Bulletin said.

Kirk, which started as a tropical depression in the Atlantic was elevated to hurricane category Tuesday, but has been on a wane since Friday. The system is expected to gather momentum by Saturday; however, the category one hurricane is not expected to be a major threat anymore.

The maximum speed of sustained winds has decreased to 80 mph and the NOAA bulletin forecast expects Kirk to become a post-tropical cyclone in about 48 hours. The minimum central pressure is 988 mb.

Another tropical storm Leslie, the twelfth storm of the season continues to move west-northwestward and is expected to pass north of the Leeward Islands this weekend. The maximum wind speed is 65 km per hour with an estimated minimum central pressure of 999 mb.

The average number of named tropical storms in the Atlantic tropical hurricane season is 11. With Leslie, the average number of tropical storms has been surpassed in the first half of the season itself. An updated hurricane season bulletin issued by the NOAA on Thursday forecasts an even busier second half.

The NOAA bulletin has issued a tornado watch for Isaac in portions of northeastern Arkansas, southeastern Missouri and extreme western Tennessee and flood and flash flood watches and warnings for the areas of Arkansas, Southern Mississippi and southeastern Louisiana. The slow-moving hurricane is expected to enter Ohio River Valley by Saturday night.