Plentiful sunshine is expected today across the Willamette Valley with warm temperatures reaching the upper 80s, influenced by fair weather aloft and onshore flow at lower levels. Winds will be out of the north at 10 to 15 mph, creating conditions similar to those observed yesterday.
Looking ahead to Wednesday, we anticipate increasing confidence in an upper-level pattern change as a broad trough moves southward into Oregon. This change will likely lead to a deepening of the marine layer, pushing deeper clouds into southwest Washington and the northern Willamette Valley. Daytime highs in the inland valleys will cool slightly into the upper 70s to low 80s, while coastal areas will see highs in the 60s and the Cascades in the 70s.
Toward the latter part of this week, some model uncertainty remains regarding temperature trends for Thursday and Friday. Guidance is split between the mid-week trough lingering or a return of ridging in the upper levels of the atmosphere. If the trough persists, cooler or near-average temperatures would be more likely, but if a more progressive pattern develops, a warming trend with highs returning into the mid to upper 80s is possible, potentially reaching 90 degrees Friday and continuing through Sunday…