Warm weather + Threat of lightning = Very high wildfire danger

Warm weather + Threat of lightning = Very high wildfire danger
Early morning lighting on July 4th, 2013 above Richland. (Photo by YouNews user BenOliver)

A hot stretch of weather is on tap around the Northwest this week and now with a threat of thunderstorms, wildfire danger risk is on the rise.

Monday's weather will remain pleasant (compared with the rest of the week) as temperatures rise into the low to mid 90s with clear skies.

However, the weather pattern gets quite complex for Tuesday as changes in both the lower and upper levels of the atmosphere will conspire to make for a hotter day and then a potentially stormy night.

During the day, a thermal trough is expected to move into the region from Eastern Washington, which will provide an east-northeast wind along the ground. Those are the winds that warm when they sink down the Cascades and as a result, highs are expected to push into the mid 90s across Central Washington.

But high above, a weak upper level low pressure system will push in some high-level moisture in from the south that will destabilize the atmosphere and create a chance for widespread thunderstorms. The storms are expected to develop in Oregon early Tuesday then move into Washington from the south as the day progresses, potentially reaching Central Washington as early as the afternoon or evening. The bulk of the storms will be in the Cascades and Olympics but all areas have a chance of getting storms, with the peak of the storms during the overnight hours Tuesday into about late morning Wednesday before they taper off as the low moves away.

With dry air on the ground at first, some of the storms may not have any rain as it evaporates before it reaches the ground, but the lower air mass will gradually moisten, giving the air a increasingly muggy feel and allowing a little rain to reach down here. While the storms aren't expected to bring any extended rain, they could have frequent lightning.

Lightning is a concern for parts of Eastern Washington and northeastern Oregon where a Fire Weather Watch is in effect for much of the Columbia Basin due to heat, dry weather, and the threat of thunderstorms. Fire weather forecasters with the National Weather Service say the Cascades are in a little better shape since it hasn't been as dry for as long, but still a risk of wildfires under the right conditions.

The thunderstorms should taper off by midday Wednesday, but forecast models only show the temperatures rising even higher into the upper 90s across the Yakima Valley and into triple digits for the Columbia Basin.

The extended forecast computer models keep it very warm and very dry across the region through the weekend and into next week.