Weather Synopsis for Tuesday night through Thursday
High clouds are moving into the forecast area on New Year's Day as an upper ridge flattens along the coast. The ridge will weaken further overnight allowing increasing frontal moisture to arrive in the form of thickening clouds. A shift to light westerly flow Tuesday has allowed warming temperatures under the ridge.
A cloudy day is in store for Wednesday as an offshore frontal system nears the coast. Some very light precipitation may reach the Olympics and Mt Baker area by late Wednesday afternoon.
Frontal precipitation will increase overnight Wednesday, mainly light in all areas except the Mt Baker area where significantly heavier precipitation is expected at rising freezing levels.
Moderate to heavy precipitation will spread over the area Thursday with a sharp delineation in intensities from north to south. Mt Baker area will receive heavy precipitation with only very light precipitation making its way to the Mt Hood area. Freezing levels should be at maximum levels Thursday morning before beginning to lower Thursday afternoon in the wake of a frontal passage.
It currently does not look like the easterly winds through the passes will be strong enough to save the passes from another rain event Thursday.