From tonight through Wednesday, our weather pattern will be influenced by an upper-level trough located off the coast, accompanied by a closed low off the southwest coast of Canada. These weather systems are gradually shifting eastward. Currently, a cold front associated with these systems is positioned over western Oregon and Washington, making its way toward the Cascade Range. As the evening progresses and overnight, this front will slowly traverse eastward over the Cascades, eventually exiting our forecast area by Tuesday afternoon. The sluggish movement of this front will result in a band of precipitation sweeping across the region, generally delivering between a tenth to a quarter of an inch of rainfall, with some higher elevation areas possibly experiencing up to half an inch of precipitation.

On Tuesday night, a secondary shortwave embedded within the trough will enter our region. There are some variations among weather models regarding the precise path of this system. The Global Forecast System (GFS) suggests a more southerly trajectory, which would imply a greater potential for precipitation. However, most models indicate that this shortwave will track through northern Washington, resulting in less precipitation along a frontal boundary Tuesday night through early Wednesday. Following this, expect some breezy westerly winds during Wednesday afternoon. Our forecast is based on the latter scenario.

Throughout this period, we can anticipate high temperatures to remain cooler than the seasonal norm.

The KIMA/KEPR Forecast Team