Gradually cooler storms have been moving through western Washington this week. After being well above normal with our daytime highs earlier in the month, the past week has run close to our normal highs in the upper 40s.
Snow levels in the mountains have run close to the 3,000 foot, starting to give us our winter snowpack. It has also allowed Mt. Baker, Crystal Mt. and Stevens Pass to get open to start the ski season.
We will continue to see fronts move through the state into the weekend with daily highs close to normal and more snow in the mountains. One of these will move in Saturday night with a good round of rain in the lowlands and snow in the mountains. The air behind it will be cooler, dropping Sunday's snow levels down to 1,500 feet Sunday afternoon. The showers should decrease during the afternoon.
Early Monday morning another system will move down the British Columbia coast and swing inland over the state. This will bring in some moisture and even colder air, possibly bringing snow levels down to near sea level. But as is so often the case with lowland snow here, as the cold air moves in, the air mass is drying. So even though snow levels will drop, there is no guarantee there will still be enough moisture left for snow.
So at this point, all we can say is, "There is a chance of lowland snow" on Monday morning.
This is all further complicated by our terrain. This far out from the event, our computer models have only a crude representation of our topography. As we get into the weekend, Monday morning will come within range of our models that have realistic terrain. Also overall, the models will be more accurate, so we will be able to refine that "chance" into more details.
One thing we can say for sure is that it will be our coldest air we have had this fall. Skies will clear later Monday, and Tuesday should be sunny and cold. Highs both days may only be in the 30s in a lot of places and the lows on Tuesday morning should be in the 20's and 30's. Time to bring in any plants you have been nursing along outside in our mild November weather!
Rich Marriott - KING5 Meteorologist