Description

The National Seasonal Assessment workshop was held in mid April for Alaska. The initial fire potential predictions made for the 2009 Alaska season all indicated a lower than average number of acres would be burned. The AICC Predictive Services group, the Alaska Center for Climate Assessment and Policy, and a private Meteorologist all predicted a slow Alaskan fire season. Each of these forecasts used different techniques, but all were based on climate indices. Though there have been great improvements in long term forecasting over the past 10 years, the extremely dry July in the Interior and Southeast Alaska was not forecast, and this dry weather was the major factor in a busy 2009 fire season. In April, the climate indices showed a La Nina pattern, which means cooler than normal sea surface temperatures in the Eastern Pacific along the equator. This has most frequently been associated with slower than normal fire seasons in Alaska. Early spring forecasts showed the weak La Nina pattern persisting through the summer. In fact, the La Nina pattern transitioned rapidly in early summer to an El Nino, with warmer sea temperatures. It is likely that the feedback from these changes led to the difference in Alaska's fire weather. The first fire number of the season was issued for a CGF downed powerline fire on 1/21/09. The second was issued to SWS on 3/18/09 for a fire estimated at 25' x 75-100' smoldering in a large rock slide debris field, located adjacent to the Iditarod trail. This fire continued to burn all summer and grew to 1,000 acres. There were no more fire numbers issued until April, which proved to be the beginning of the 2009 fire season with a total of 34 fires. Fires on the Kenai Peninsula in the old bug-killed spruce continued to be a problem. This fuel complex has a matted grass understory with dead and down spruce. A brief period of drying is all that is needed for the fine fuels to be available to burn, and when combined with winds can lead to rapid fire spread. Warm and dry weather at the start of May brought Duff Moisture Codes (DMCs) to above normal to record dry levels on the Kenai Peninsula. Fuels were extremely dry across much of eastern Alaska through August. Canadian Fine Fuel Moisture Code values reached very high to extreme values in early June with Buildup Index (BUI) values reaching critical levels by June 10 across most of eastern Alaska. It wasn't until the first week of August that rainfall and cooler weather finally drove BUI indices down below critical levels and kept them there through the end of the month. By the end of July, Alaska had 468 fires (115% of normal) that burned 2,081,295 acres, which is 186% of normal. By the end of August, 511 fires had burned 2,934,455 acres which is 171% of normal. In November, a 5 acre fire was discovered in the Galena Area. In December, a brush fire on Military land was the last fire of the season. The final acreage for the year was 2,951,592.9 acres with 527 fires.