Synoptic Summary Archive

December 2012 Synoptic Summary

The pattern of circulation over Alaska in December was quite similar to that of November. Vigorous low pressure systems were in the Gulf of Alaska and high pressure was over the Arctic for most of December. There was an important difference: three low pressure systems emerged from the North Pacific and moved overland into southwest Alaska.

November 2012 Synoptic Summary

A series of strong low pressure systems remained over the Gulf of Alaska for nearly all of November. High pressure over the Arctic and the Interior combined with the low pressure systems. Persistent northeast flow over the mainland ensued. The onshore flow over the Arctic coast brought well above normal precipitation and above normal temperatures to the region, and well below normal precipitation in the lee of the Brooks Range, especially northwest Alaska.

October 2012 Synoptic Summary

The path of incoming North Pacific low pressure systems shifted to lay over the eastern Bering Sea for a good part of October. These lows brought a series of coastal storms to the west coast of Alaska during the first week of October. By October 10, the pattern was rearranged. High pressure built over the mainland of Alaska and Siberia. This allowed a series of lows passage through Alaskan Arctic waters to the Beaufort Sea. There was heavy surf on the Arctic coast of Alaska during the second week of October.

September 2012 Synoptic Summary

Stronger than normal high pressure aloft held over the northeast Pacific for a good part of September. This displaced the storm track – the path along which north Pacific low pressure systems move from the western north Pacific toward North America – northward over the Aleutians and the Gulf of Alaska...and at times over the mainland of Alaska. Although there were some periods of quiet weather during September, these came between storms, mainly during its first and third weeks.

August 2012 Synoptic Summary

As can be expected, August had more active weather than July. Gales blew somewhere in Alaskan waters on 24 days of the month. Three significant low pressure systems affected Alaska during August, arriving at ten day intervals, on July 5, 15 and 25. Quite consistently, these low pressure systems affected Northwest Alaska far more that the rest of the realm. The Northwest had a rough, disagreeable month indeed. In contrast, marine weather in the Gulf of Alaska was abnormally quiet.