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.

Wildfire in WATERVILLE PLATEAU, WASHINGTON
From 08-SEP-12 20:00:00 to 19-SEP-12 00:00:00 (PST-8)
Property damage: 600.00K
Reported by: Other Federal Agency

The Barker Canyon Complex was located along the western banks of Banks Lake. This complex was composed of two wildfires: the Barker Canyon Fire and Leahy Fire. Both wildfires grew rapidly during a windy period on September 10th through the 11th. The Barker Canyon Fire initially threatened the towns of Grand Coulee and Coulee Dam. Total acreage of both fires grew to 91,162 acres before they were contained on September 19th.  The fires destroyed three homes and nine outbuildings and burned through two power stations.  Total damage was estimated.

Wildfire in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 08-SEP-12 21:00:00 to 30-SEP-12 23:59:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

The Okanogan wildfire complex composed of three fires that burned on the hillsides along the Methow Valley.  Dry conditions resulted in these fires burning into the month of October.  By the end of September, these fires had consumed a total acreage of 6,169 acres.  Road closures were included on Gold Creek Road (FS4340-100) and Forest Service Road 4330-100.

Wildfire in EAST SLOPES NORTHERN CASCADES, WASHINGTON
From 08-SEP-12 18:00:00 to 30-SEP-12 23:59:00 (PST-8)
Property damage: 1.50K
Reported by: Park/Forest Service

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.