Freaking out over snow around here next week? It's a bit early...
All right, we get it.
You're all looking at your weather apps and seeing a snowflake in Portland for Monday and Tuesday and already your blood pressure is rising, either in fear or eager anticipation. Word is already spreading like wildfire online and in social media.
Let me be the wet blanket-- for now.
It's WAY TOO EARLY to try to be solidly predicting lowland snow in the Willamette Valley with any great confidence. Getting snow in Portland is a difficult achievement as so many things have to go right (wrong) for it to happen, and it's even more challenging to ask a 7-8 day forecast model to accurately predict it. I'd be still nervous at 7-8 hours ahead.
So how did the snowflake get there? The weather apps go off pure automation. Computer forecast model puts a cold spot of air with moisture in the general vicinity? Sure, that's worthy of a raw snowflake (although it'd be nice if some of these apps had more icons in their arsenal -- like maybe a rain/snow mix? Some do, but others are just going with a simple snowflake: Dusting? 2"? 8"? Blizzard? After all, it's still showing high temps in the 40s). And I get the computers behind the apps are tasked with a 7 day forecast and have to put something there, so they go with what their current calculations show. But it certainly needs some nuance around here. Most spots in the nation might brush off a snowflake on their app as "winter" but the folks at Weather Apps R Us don't put in a Northwest caveat where "winter" and "autumn" are kinda the same.
Before social media and phone apps, when the human meteorologists solely disseminated the forecast it was easier to nuance it and not make a big deal of it until the confidence was far greater. But we understand this is 2016 and weather information is available from dozens to hundreds of sources. With that it's imperative to understand where some of that information comes from.
But since the cat is clawing its way out of the bag on this event (or, might possibly, already be out of the bag, out the front door, and halfway to Sacramento...)
Yes, some long range models are hinting at a large scale pattern change starting after a front moves through on Sunday, dragging some cooler air in its wake from the Gulf of Alaska Monday into Tuesday. If I had to go at raw value of the forecast models today, I could see some snow showers down to 500-1,000 feet in this pattern. It's not a classic widespread snow event at this point, and it wouldn't be a lot of snow if it pans out as currently projected.
But again, we're a week out -- far too early for me at least to have any solid confidence in that forecast. Heck, many of you were chastising meteorologists over the Oct. 15 "windstorm" forecast that was made a 2-4 days ahead on a way more reliably forecasted event for going overboard. We have considerably less confidence in this scenario at this time.
Now, that's not to say it can't happen. We're certainly entering the time of year when lowland snow can and has occurred in Portland. If on Thursday and Friday the forecast model pattern is still looking like it does today, then sure, confidence would be higher and we'll be banging the fringey snow drum with zest. But many times you'll see a snow event look good on Day 7-8 out, only to see a few days later that the promised cold air is now over Alberta instead and we're back to rain.
I'll close with it is perfectly plausible for snow fans to cross your fingers. But just don't get TOO excited yet!