Wildfire — East Slopes Northern Cascades, Washington

2012-09-08 to 2012-09-30 · East Slopes Northern Cascades, Washington

Event narrative

Around 4,000 lightning strikes on September 8th through the 9th sparked around 100 wildfires north and west of Wenatchee. The vast size of the complex of wildfires burning across this area combined with the very dry conditions, resulted in these fires continuing to burn into the month of October. By the end of September, the wildfire complex was only about 50 percent contained and had consumed around 55,000 acres. The wildfire burned in a multitude of fuel types from grasses to shrubs to timber. One indirect fatality occurred as a firefighter grew ill as he battled the blaze. He was taken to a local hospital where he died on arrival. Around 180 evacuation orders were given for residential areas along the west side of Wenatchee soon after the fires were ignited, but no homes were reportedly lost; however, one shed was destroyed by the wildfires. The damage for the shed was estimated. Stable atmospheric conditions through much of the month of September resulted in poor ventilation of the wildfire complex and hazardous air quality for people living in and around the town of Leavenworth and Wenatchee. No injuries or fatalities were reported due to the poor air quality.

Wider weather episode

An upper level low pressure system sat just offshore of the southern Oregon coastline. Another deep low pressure system pushing into the Gulf of Alaska acted as a kicker to eject the upper level low pressure system offshore across the region. Increased southerly flow into the region ahead of the upper level low resulted in increased moisture and instability at mid-levels of the atmosphere across the east slopes of the northern Cascades during the late afternoon hours of September 8th. Thunderstorms developed across this area, which pushed eastward across eastern Washington through the overnight hours as the low ejected across the region. Dry conditions at low levels and fast moving storms resulted in dry lightning that started a total of 110 wildfires across the area.

Source: NOAA Storm Events Database, event_id 411455. Narrative written by the NWS forecast office that issued the report.