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Public Information Statement
National Weather Service Spokane WA
226 PM PDT Sat May 10 2025

Tuesday through Friday: The Inland Northwest will remain under the influence of the northern branch of a deep upper-level trough on Tuesday as it shifts southeast into the Great Basin, while subtle ridging builds into western Washington. Ensemble cluster analysis shows good agreement on these synoptic-scale features, but highlights some disagreement among global models regarding the exact placement and strength of the trough from Tuesday through Thursday. For Tuesday, model agreement is good enough to support higher confidence in continued showers across much of eastern Washington and north Idaho through the afternoon. 
Whether this showery pattern persists into Thursday is less certain. Around 70 percent of ensembles favor a slightly weaker and faster moving trough, which would support continued mountain showers on Wednesday with a distinct dry period on Thursday as a ridge builds in. The remaining 30 percent suggest a deeper, slower moving trough that would keep conditions more unsettled, though showers would likely be confined to the mountains for Thursday. Temperatures in both scenarios only differ by a few degrees, with the more progressive pattern bringing slightly warmer conditions. Regardless of the outcome, continued onshore flow would support breezy afternoon winds through the Cascade gaps and into the western Columbia Basin.
By Friday and Saturday, ensemble guidance leans toward another trough digging into the region from the northwest, likely keeping the weather unsettled into the weekend. /vmt