 Upon moving ashore , the National Hurricane Center expected the forward path of Ivan to be blocked , and accordingly forecast the hurricane to stall in the southern Appalachian Mountains before dissipating . As the hurricane crossed Mobile Bay it turned to the north @-@ northeast , and within twelve hours Ivan rapidly weakened to tropical storm status . The circulation became less @-@ defined , and early on September 17 the cyclone deteriorated into a tropical depression over northeastern Alabama . Ivan accelerated to the northeast ahead of an approaching cold front , dropping heavy rainfall along its path and also producing a widespread tornado outbreak from Alabama through Maryland . Late on September 18 , the remnants of Ivan transitioned into an extratropical low as it merged with the cold front over the Delmarva Peninsula . 
