By now you have probably seen the multitude of snowflake icons on your favorite weather app, or you may have heard area forecasters mention the snow word. If you haven’t, let me be the first to tell you, it could snow! The chance of snow is high enough that I thought it best to write up a blog post based instead of responding individually to the influx of texts and messages I began to receive a couple of days ago asking if I think it will snow. So let me try to break it down based on the most recent model data as of Wednesday night.

For the past 6-7 days, area forecasters watched as the GFS (our North American Model) spat out a very consistent image of significant cold and snow for the northwest. If you have lived in the area for more than a couple of years, then you are probably aware that the words snow and consistency are not synonymous in the Northwest. If you are a weather enthusiast, then you are probably aware that the words snow, consistency, and the GFS are definitely not synonymous! Snow is incredibly hard to forecast in the northwest, our inconsistent terrain, microclimates, and mild marine influence make it astonishingly hard for everything to come together in the form of snow around here. Our weather models have a very hard time picking up on all of these nuances, which means that local forecasters usually don’t trust models showing snow until 24-48 hours out. So to have the GFS show this significant pattern change so far out and stick with it has been shocking to say the least.

The ECMWF (European Model) has generally been more accurate with forecasting dynamic weather events such as these in the Pacific Northwest. While the GFS was completely onboard, the ECMWF was much more hesitant, but has slowly began to align closer to the GFS in the past couple of days.

With this, forecasters overall confidence has increased. So while it is too soon to nail down some of the specifics of what we could see, it is safe to say that we are about to enter a much cooler pattern of below average temperatures. By now you’re probably sick of the background information and just want the specifics of if school and work will be cancelled or if you need to start clearing out the grocery stores like snowmageddon last year.

The Timeline:

Tonight – Saturday:

Cold air is currently filtering into the Puget Sound lowlands in the wake of yesterday’s storm system. This combined with some leftover moisture means that we are getting some very typical fringe snowfall in the favorable areas north of Seattle and in areas above 500ft. Quite a few reports of falling snow started showing up around Granite Falls and Lake Stevens late this afternoon. Generally we could see a wet inch or two of snow in the snow favored areas into Thursday morning. This might have some minor impacts but most should escape with just some wet roadways. Showers taper during the day on Thursday into Thursday evening.

A much stronger storm moves in early on Friday bringing gusty winds and heavy precipitation. We will still have some cold air entrenched in the lowlands so we could again see another quick dusting of snow in the favored locations early Friday before the cold air is scoured out and snow switches to rain. Rain continues into the day on Saturday as another area of low pressure begins to slide down the coast.

Mountain pass travel will be VERY messy from Friday morning through the rest of the weekend. A Winter Storm Watch is in effect for the Cascades on Friday for 12-24″ of snow. Powder will be great this weekend but with considerable avalanche danger currently, I would be shocked if the passes don’t close repeatedly throughout the weekend.

Sunday – Monday:

Now this is where things begin to get more interesting. By mid Sunday morning models have an area of low pressure sliding down Vancouver Island into Northern Washington. Once that low starts moving east it opens up the doors for colder air to filter in from the north, and if models are correct then there is some really cold air ready to make its way south. By the time cold air really starts to push into the region, our moisture will be starting to diminish. Overall models are less enthusiastic about snow going into the cold spell as they once were, but this setup does remind me of a more typical arctic front which can drop a few inches of snow in a short amount of time.

Regardless, it will be COLD by the time Monday morning rolls around. The most recent run of the WRF-GFS Model shows 850mb temperatures dropping down to -16 to -20 degrees Celsius in the central sound around Seattle. While I am still skeptical of extreme cold, I feel pretty confident in saying that temperatures will drop below average for this time of year. Monday afternoon another low slides into southern Oregon allowing even more cold air to be pulled southward out of interior British Columbia. Depending on how close this low gets to Western Washington we could see some snow out of this event.

Both the GFS and ECMWF models show a couple of possible snow events mid next week towards the following weekend, but those are too far out to nail down any sort of specifics.

At this point the question is if it will be cold and snowy or just mainly cold. Low placements will make all the difference and even slight variation can have significant impacts (as we saw in February 2019). Typically, the colder we are, the drier we are, and all of the ingredients have to come together just right for the combination of cold and precipitation in order to have snow. Right now I think it would be worthwhile to prepare and take steps to winterize your home and to make sure that you have proper supplies and warm clothes in all of your vehicles.

Check out this post by Mark for information on the weather in Eastern Washington over the next few days!