SPOKANE — The National Weather Service has issued a flash flood watch from Saturday morning through Sunday evening on the east side of the Washington Cascades while Spokane and the Columbia Basin are under a fire warning due to potential lightning strikes.
Forecasters say thunderstorms could drop heavy rain in places. It could cause mudslides, especially in areas that have recently been burned by wildfires. The watch area includes Winthrop, Omak, Chelan, Wenatchee and Ellensburg.
An intense thunderstorm last Sunday evening in Wenatchee caused street flooding and mudslides.
In Spokane, the potential for thunderstorms arrives at 5 p.m. and continues through 11 p.m. on Sunday.
An upper-level low pressure area along the coast of Oregon is expected to draw waves of moisture into the region, triggering thunderstorms as warm and moist air at ground level rises into cooler air aloft. The storms will start out mostly dry, but as moisture from the south works its way northward, the storms will start producing rain.
Spokane has a 20 percent chance of thunderstorms tonight, increasing to 50 percent by Saturday night and Sunday.
The incoming waves of storminess will be different from the low pressure area that brought steady rain over a broad area of the region last week. Rather than widespread rain, the weekend storms will move as distinct clusters with breaks between them, forecasters said.
Temperatures under a southerly to southwesterly flow will remain warm, and humidity will be on the increase. Storminess will linger into early next week, forecasters said.
Highs should be near 90 and lows will be in the lower 60s.