The National Weather Service has issued a Red Flag Warning covering all of Grant County, in effect from 2 p.m. Thursday to 11 p.m. Friday.
A trough of low pressure will lift northeast and slowly move through the area over the next few days, according to a weather service press release.
Scattered thunderstorms will develop as early as Wednesday evening along the east slopes of the Oregon Cascades. Thunderstorms will be slow to move east, beginning to impact the Ochoco-John Day Highlands and Blue Mountains of Oregon Thursday afternoon, before spreading into the Washington Blue Mountains and Wallowa County Thursday evening.
The chance of thunderstorms will linger through late Thursday evening in central Oregon, and until Friday evening for the northeast Oregon mountains and Blue Mountains in Washington. Gusty and erratic winds up to 45 mph are expected, and any fires that develop will likely spread rapidly.
At this time, most of the thunderstorm activity is expected to produce lightning activity levels up to three, but level 4 cannot be ruled out, especially on Thursday. The thunderstorms may start off drier Wednesday, before becoming much wetter Thursday afternoon through Friday. Some storms could produce greater than a quarter inch of rain in the core.