Two wildfires sparked by lightning in the Mendocino National Forest grew Wednesday to a combined 250 acres as fire officials struggled to find resources to fight the blazes.

The Skeleton fire, burning about four miles east of Lake Pillsbury northwest of Ukiah, grew to about 200 acres and was 40 percent contained Wednesday night, said Punky Moore, spokeswoman for the Forest Service.

Roughly 10 miles to the west, the Slides fire has burned nearly 50 acres and fire crews have achieved no containment there, Moore said. A DC-10 air tanker dropped several loads of retardant on the blaze, with each load amounting to about 11,000 gallons, she said.

The Forest Service has requested smoke jumpers and helicopters to fight the fires, but those orders have not been filled, Moore said. The resources “are just not available,” she said, due to firefighting efforts throughout the western states.

Northern California and the Bay Area were hit by several waves of thunderstorms Tuesday evening and Wednesday morning. The National Weather Service counted more than 1,700 lightning strikes in the region by early Wednesday.

Several other fires have been reported in Mendocino National Forest but details about their location and size were not available Wednesday.

The forecast Wednesday night showed a slight chance of thunderstorms, temperatures of 87 to 92 degrees and partly cloudy with light, variable winds.