wet

10pm Sunday…

Well, that’s been an exciting 5 days since the election started eh? Since I love numbers and politics I’ve watched everything closely. Now that things are settling down I figure we should talk about weather. And what a change we’ve seen!

For the first time this season we’ve seen sticking snow down below 3,000′. I took a run today, midday, with a temp in the upper 30s. It felt like December under a gray sky (east side of metro). Portland saw it’s coldest day of the fall, just 47 degrees

You know winter is close when at 8pm we’ve already got parts of the metro area below freezing.

Expect widespread mid-upper 20s tonight for another hard freeze. Whatever survived frosts a couple weeks ago probably won’t make it through tonight. We’ve seen a few inches of snow at Government Camp, maybe 4-5″ higher up at the ski resorts. Here’s the 8:45pm view from the top of Upper Bowl at SkiBowl

The rainy season has arrived; that’s the screaming message on maps/models this evening. In fact if you’re looking for a 3 day period of dry weather? Extremely unlikely…

Summary of What’s Ahead

  1. Expect steady rain or showers just about every day for at least the next week to 10 days west of the Cascades. IF we somehow squeeze in a mostly dry day, consider that a bonus! Somewhere between 2-4″ rain could fall in the next 10 days…
  2. Temperatures will remain between 40-50 degrees most of the next week too. A mild Pacific airmass will be in control of our weather most of that time.
  3. I don’t see a setup for low elevation snow OR ice/snow in the Gorge for at least a week, probably much longer. There’s no sign of cold Canadian air surging south in the next 7-10 days either
  4. Snowpack will be building in the Cascades over the next week. IF we don’t get a set of warmer systems NEXT week, I could see ski areas trying to open up at least a few runs!

Details

As expected we’ve seen a surge of cool/dry air drop south into the Pacific Northwest, thus the cold temps tonight. But starting tomorrow afternoon our weather will be dominated by a succession of cool-ish weather systems coming in off the Pacific. For at least the next week, none of these are forecast to be “warm” or related to atmospheric rivers. For example check out the ECMWF 850mb ensemble chart. Each thin line represents one of the 51 ensemble members. That’s for the next two weeks. It’s temperature (C) at around 4,000′. So the “zero” line means freezing around Government Camp.

Notice there is general agreement that there won’t be any extra-warm ridging or cold spells. In fact there’s only one or two of those members showing anything really “cold”, at the end of the run. Otherwise it’s generally just a little below average (green line) for this time of year; excellent for mountain snowpack.

Then check out precipitation from the GFS ensembles. Tomorrow through a couple of days before Thanksgiving (2 weeks out). Wet!

It shows six hourly rain totals for each of the 31 ensemble members. Each horizontal line (upper part of chart) is one member. You don’t see many gaps do you? This says it’ll be hard to find much dry weather the next two weeks. Other models are similar. The reason? A typical November Pacific jet stream aimed at the West Coast. Six days out, this coming Saturday

Models are telling us somewhere between 2-4″ rain could fall in the next 10 days west of the Cascades. Very wet, but…it IS November. And precipitation in Cascades maybe around 8-12″. Get ready for an overdue soaking, it’s time.

Snow levels linger between 3-5,000′ over the next week.

Snow at 4,000′ will come and go, but it’ll be ALL snow up above 5,000′. The ECMWF model shown here would imply 2-3 feet may fall at the top of Skibowl, and the upper parts of Mt. Hood Meadows and Timberline ski areas too. Ignore the Gorge, that’s a contouring issue with the terrain.

This COULD be enough to jump-start the ski season a bit early! What we don’t want to see this early is a warm/wet storm following next week to melt the snow. That’s not unusual in November. Last year there was some very basic skiing for Thanksgiving, but then things lagged until we got to mid-January. But this upcoming pattern looks great!

Again, there’s absolutely no sign of lower elevation snow. This is a mild westerly-flow setup, just a bit cooler than normal. Take a look at the stable temperature regime from the ECMWF, actually that’s weirdly stable.

Maybe this will be a 2007-2008 type La Nina winter? That’s when it hardly snowed in Portland, but multiple systems came down in WNW flow pummeling the Cascades AND the foothills with feet of snow. We will see. It’s still very early…kind of like looking at those first few hours of election results and making an assumption of how things were going to play out.

So remember, you’ve got a mainly dry day tomorrow to get outdoor projects done (I have a few), and then it’s on to wet, wet, wet…

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