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Gulf of Alaska Storms

© Keith C. Heidorn

As summer wanes and the sun's influence on high Northern Hemisphere latitudes diminishes, the prime global breeding grounds for northern winter storms renew their vigour. One can be found in the North Atlantic Ocean between the coasts of Greenland and Iceland, the appropriately named Icelandic Low. The second lies in the North Pacific off the coast of Alaska between the Aleutian Islands archipelago and the southern Alaska coast. It goes by the names the Aleutian Low and the Gulf of Alaska Low. These low pressure zones are semipermanent features of the global weather map and general circulation patterns that diminish in extent and depth during the warm season and intensify during the cold months.

The Aleutian Low and the eastern North Pacific High found to the south have a cyclic relationship during the course of the year which impacts the weather along the west coasts of Canada and the United States and into the northern portions of the western Cordilleran. Since this is also a prime source region for Pacific maritime air masses, the weather patterns across the continent are also affected. Within the subpolar zone, warm air moving north from the tropics and cold air moving south from the Arctic clash, a conflict that is strongest during the cold half of the year and weakest during the warm season months.

After an active winter, the Aleutian Low diminishes slightly in March and by April is sending fewer storms outward. The feature virtually disappears in July, appearing as a trough of low pressure rather than a tight low-pressure cell. As solar energy falling on the arctic regions diminishes, the Aleutian Low again strengthens in September, ready to produce a litter of winter storms.

The clash between cold and mild air generates spinning, low-pressure cells that grow to energetic youth over the Gulf of Alaska. As a result, meteorologists call the region a "center of action" for North Pacific maritime and coastal storms. The Aleutian Low region is characterized by barometric pressure readings of 101.3 kPa or less, high humidity, and generally complete cloud covers. When a newly born storm spins up, the region experiences strong winds and heavy precipitation, most falling as rain, despite the high latitude. By November, the Aleutian Low average surface pressure has dropped to 100.2 kPa, a level it maintains for much of the winter.

The Gulf of Alaska lies in the arched bite of the State, south of Anchorage between the Kenai Peninsula and Kodiak Island and the eastern panhandle. The northern coast of the gulf is fortressed by the Wrangell/St Elias Mountains - one of the world's highest mountain ranges which continues to grow at a geologically-hyper speed of 4 cm per year - that effectively block most storms from entering eastern Alaska and the Yukon Territory. The Gulf of Alaska is the most common entry point for the northeastern Pacific storm track that sends stormy weather to the North American coast.

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