 The storm originated over the Pacific Ocean and crashed into the Northwest Pacific coast with damaging gale @-@ force winds on January 8 , 1975 . By January 9 it had cleared the Rocky Mountains and began to redevelop and strengthen . At the same time , Arctic air was being drawn southward from Canada into the Great Plains , and large amounts of warm tropical air from the Gulf of Mexico were being pulled northward into much of the eastern U.S. The storm was a classic Panhandle Hook which moved from Colorado into Oklahoma before turning northward towards the Upper Midwest . It produced record low barometric pressure readings in the Midwest , with the pressure falling to an estimated 28 @.@ 38 in ( 961 mb ) just north of the Minnesota border in Canada . 
