If there is so much uncertainty in forecasting the path of a disturbance at sea, how much more uncertain must it be on land? Elaborate statistics of the average daily movement of various types of storms have been officially published. The average speed of storms (not wind speeds) across the United States is 11 metres per second or 25 miles an hour. Storms travel more rapidly in winter than in summer, about half again as fast; that is, summer storms travel 20 miles, and winter storms 30 miles, an hour.

Fig. 7. Lips—The Southwest Wind

The paths vary widely; from the Gulf storms moving northeast and West Indian hurricanes recurving on the southern coast, to the storms from Alberta and the west which move south and east. Ten types of storms, classified according to the place of origin, are recognized by the official forecasters of the United States. These are North Pacific, Alberta, Northern Rocky Mountain, Colorado, Central, South Pacific, Texas, East Gulf, South Atlantic and West Indian Hurricanes. A better nomenclature would be (1) Alberta, (2) Washington, (3) Kootenay, (4) Utah, (5) Kansas, (6) California, (7) Texas, (8) Louisiana, (9) Florida, and (10) Hurricanes.