A “high” reaching the California coast may cross the mountains near Salt
Lake City (follow the track on the map), and then pass directly over the
belt of the Gulf States, turning northeastward and reaching the Virginia
coast; or it may move farther northward, cross the Rocky Mountains in
the State of Washington, up the Columbia River Valley, then turn east,
and finally reach the Gulf of St. Lawrence. These tracks are located
where they are by the laws of general circulation of the atmosphere and
the outline of the North American continent. This movement of the
“highs” from the middle Pacific coast to Florida or to the Gulf of St.
Lawrence is confined to the summer half of the year, that is, from April
to September. In the winter months, on the other hand, the source of the
“highs” is different, though they reach the same terminals.