A Gulf low or Texas Low is a low pressure area that forms or intensifies over the Gulf of Mexico and moves northeast on the western side of the Appalachian Mountains and sometimes on the Atlantic coast to become a nor'easter. Because they move from over or near the Gulf of Mexico, these storm systems are capable of transporting copious amounts of moisture with them. At their strongest, these storm systems are even more potent snowfall producers than panhandle hooks, primarily because of the mixing of Atlantic Ocean moisture into the storm system once they cross the Appalachian Mountains. Because of the general west to east movement of weather systems in the mid latitudes of the northern hemisphere, Gulf Lows rarely affect areas west of the Mississippi River. One such exception was the Halloween Blizzard of 1991.