Significant Early Fall Anchorage Wind Storm

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Monday, 3 February 2014
Hall C3 (The Georgia World Congress Center )
James A. Nelson Jr., NOAA/NWS, Anchorage, AK

A strong low pressure system moved through the Aleutian Island chain and into Bristol Bay Alaska on the 4th and 5th of September 2012. Wind gusts in excess of 70 mph for 12 hours were not uncommon during this event. In fact, one member of the public reported a gust over 120 mph. The event was one of the most significant and damaging wind storms to affect the city of Anchorage in 30 years. Two antecedent factors raised the level of impact were saturated soils and full foliage trees. These antecedent conditions combined with the strong winds led to downed trees, fences, other small structures, as well as excessive power outages. Some areas did not receive power for days after the event due to debris. The fascinating and uniqueness of the event was the duration of strong wind speeds as well as the early season strength of the storm.

Although the high impact event was well advertised, wind duration was not well represented. Output from a high resolution WRF model as well as reanalysis and observational data will be used to explain the details of the duration and breadth of the strong winds in the complex terrain of the Chugach Mountains of South Central Alaska.