High pressure ridge ensures calm weather; Fog predicted in basins and valleys

DRY AND COOL NIGHT

Today (Tuesday):
A shortwave trough exits the Pacific Northwest, leaving behind a northwesterly flow. Expect low clouds over the foothills of the Blue Mountains and parts of central Oregon, with some clearings in the Columbia Basin and north-central Oregon.
Tonight until Thursday:
Morning fog will likely return, particularly in the Columbia Basin, Kittitas and Yakima valleys, where visibility could drop to below a quarter mile. Travel early in the morning may be affected, so plan ahead.
Conditions will remain dry, although low clouds and fog are likely in the morning (>60% chance).
Snow:
Snow levels will drop from 3,000 to 4,000 feet today to about 1,500 to 1,900 feet by Thursday. Due to dry conditions, snow accumulation along the Cascade ridge will be minimal (<0.1 inches).

Friday to Sunday:
A High pressure comb will dominate and bring calm, dry weather. Light showers could move across the Cascade ridge and northern Blue Mountains on Friday, but the chance is low. Widespread Nebula and Stratus are expected in basins and valleys, especially in the morning.
Monday and Tuesday:
The ridge is likely to remain in place and maintain conditions dry and stable. There is less chance of a frontal system bringing active weather, but any precipitation would be limited to the Cascades and northern Blue Mountains.
In summary: expect dry weather until Thursday, with morning Fog and low clouds be the main concern. Long term, calm and stable conditions will last until early next week.