The entire Mid-Columbia is under a red flag fire warning Wednesday morning through late Thursday night because of possible thunderstorms.
A 30 percent chance of showers and thunderstorms is forecast for the Tri-Cities Wednesday, according to the National Weather Service.
That increases to a 90 percent chance of showers Thursday with a possible thunderstorm.
A low pressure system spinning off the Oregon and Washington coasts will send surges of moisture and energy east of the Cascade Mountains through Thursday morning, according to the weather service.
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The thunderstorms are expected to bring heavy rain, but they also could bring lightning outside the rainy areas that could start fires, according to the weather service.
Some cooler weather is in the forecast with highs dropping as low as 77 to 78 degrees Thursday and Friday in the Tri-Cities.
However, highs could be back to the low to mid 80s by the weekend and back to about 90 degrees early in the next work week.