Rainfall amounts of a quarter to a half inch are expected through this evening over most of the Inland Northwest, the National Weather Service said.
The latest forecast calls for a 100 percent chance of rain during the day with a 100 percent chance of showers lingering through this evening.
Higher precipitation amounts are forecast for the mountains of North Idaho, Northeast Washington and the Cascades.
Forecasters said a deep fetch of Pacific moisture is pushing into the Northwest today under a low pressure system. The storm is moving eastward slowly to give the landscape a good soaking.
Even the Columbia Basin, which has been dry coming out of winter, should see accumulating rainfall, which is good news for dry land farmers.
As a cold front approaches later in the day, rainfall amounts could be heavy in some locations at times.
Rain and snow are expected above 5,000 feet elevation with snow levels dropping on Friday as showers linger in the mountains.
Wind gusts arrive in the wake of the storm Friday. Spokane could see gusts to 36 mph.
Highs today in the low 50s will go to the upper 50s on Friday, which should be mostly sunny.
Sunshine continues on Saturday with highs near 65, but a weak weather system early Sunday will cause temperatures to drop back to the upper 50s with partly sunny skies.