Like just about every possible snowstorm in the Pacific Northwest, it’s been pretty tricky to nail down details of who will see snow, and how much. At this time we have a pretty good idea that certain areas will receive snow. However, there are many areas that may end up right on the fringe of heavy snow, including a major metro area with a population of about 2.4 million.

Portland weather fanatics have been sitting on the edge of their seat the past few days watching models initially show a northward trend, then reverse and show a very dramatic (and uncommon) southerly trend. While they were initially cheering for this trend, they may have cheered too much, sending the low a little too far south on some of the models. So lets dive into what this mornings models are showing and go through a couple of possible outcomes.

If you want snow in Portland and maybe even Seattle, the European model is your friend. The 12z run brought the low slightly further south than its 06z run, but keeps precipitation totals about the same with anywhere from 2-5″ in Portland, 6-8″ around Salem, and maybe a foot or more down in Eugene. Up in Seattle we may only see flakes in the sky to a light dusting of snow, if that.

The strength of this low pressure system may also shift its track from what is currently modeled. The Euro initialized the low that is providing this snow at 1012mb, when it is actually currently at 1008mb according to the NWS’s surface analysis. Stronger low pressure systems in our region tend to curve further north than their weaker counterparts, so we will have to keep a close eye on that to see if this low continues to be stronger than modeled as is could change where that precipitation develops.

The GFS on the other hand keeps most of the snowfall south of even Portland. With this run Portland only receives 1-2″ of snow, Salem 2-3″ and Eugene 3-6″. If this GFS run pans out Seattle may stay completely dry through the event.

Overall models went through a dramatic change over the last 48 hours which makes this storm very difficult to predict as consistency in the models is our best friend. It is going to be important to keep an eye on that low strength but also keep in mind that models sometimes tend to underestimate the northern extent of precipitation shields in events like this.

So what should you expect:

Seattle: I think, as of right now, that we will stay mainly dry. I wouldnt rule out some snow showers tomorrow evening, but as of right now I don’t expect any significant accumulations beyond a dusting.

Portland: You are right on the edge of what could be a significant snow storm. The further south and east you are the more snow you will receive. I would expect Portland to see 1-4″ from the north side of the metro to the south east side of the metro, with isolated 5-6″ totals the closer you are to Salem. Snowfall will begin early tomorrow morning in time for the morning commute and will last into the evening. Totals are still iffy but knowing that it doesn’t take much snow to cripple our hilly, mild, Northwest cities, there is a good chance that this will have significant effects on the work day Monday.

Salem: Timing is a few hours earlier than Portland and will still have a big impact on the commutes. Totals right now look to be around 3-6″. Right now Salem has about the best chance to have a significant snow day in the Willamette Valley. If the low goes further north, it will bring in warmer pacific air south of the low. Salem is just north enough where even if it goes further north it should still have cold enough air to remain snow throughout the event.

Eugene: You either have the chance to score big or risk being to warm if the low goes much further north than modeled. Right now I feel comfortable with forecasting a wide range at the moment of 3-8″ depending on this low track.

This could be a significant storm and while we are still trying to iron out the details on this storm, its a good idea to be prepared and stay home tomorrow if possible as this storm will be impacting both the morning and evening commute. Stay tuned for some nowcasting as the low gets closer to the coast!