8pm Sunday...

We had our first taste of the cold season "fog inversion" this weekend. That means cool air remained in the valleys while the atmosphere overhead warmed. Yesterday Portland only made it up to 41 degrees...quite a taste of a typical winter day around here

High Temp Last 13 Days.png

Which brings up a good point...from a meteorological point of view we've pretty much entered "winter" west of the Cascades. I suppose it seems like a ridiculous thing to say with a week still left in November right? Nope, once we hit mid/late November, we've entered the busy three months of the year in our area. "Winter" tends to come early and melt away a bit quicker than in colder continental climates. No, I don't mean just snowfall. I'm referring to our usual weather events in wintertime.

Winter Months Explainer 2017.png

It's EXTREMELY rare to see a real arctic blast outside of this window. And if we're going to have an "all-day" snow event in the lowlands, the type where roads stay frozen, it happens during this time. Remember the past few years? When we've seen snow from mid-February onward the effects on lowland roadways are minimal mid-late day. That's because of increasing sun angle. If we get significant flooding this year, most likely it'll be within the next three months.

What's Ahead?

I took a few extra days off this past week; still have a few leftovers from our summer furlough days. When I came back in to the station today I noticed three specific items while perusing all the models/maps:

  1. I don't see a stormy weather pattern in the next 10 days
  2. After a wet Tuesday/Wednesday, we're headed into a drier weather pattern through at least the first few days of December
  3. There's no sign of lowland snow/ice or an arctic blast in the next two weeks. That means most likely we won't be seeing an early freeze this year (November or early December).

Basically the weather looks a bit on the slow side over the next 1-2 weeks. In the short term I see a couple weak systems moving inland tonight, then a stronger cold front and chilly airmass Tuesday/Wednesday. We should see another 1/2" rain early this week out of these systems.

Beyond Wednesday, upper-level ridging wants to be the dominant weather feature over the western USA for awhile. Take a look at 500mb height map from Canadian ensembles for this Friday

can500friday.png

and then 10 days from now...Wednesday the 2nd

canweddec2500.png

I think the ridging may be overdone on this model, other models show above average heights but not so extreme.

Weak (and wet) systems will probably still be coming through the ridge during this time, I don't think it'll be one of those "completely dry for 10 days" setups. But this eliminates the chance for any significant cold spell and/or snow in the lowlands for the next 10+ days.

Ski Area Weather

We've got a fantastic early season snowpack on the ground in the Cascades above about 3,500'. These numbers a bit deceiving since the average snowpack is very low this time of year; anything significant is way above the average. But you get the idea...

or_swepctnormal_update.png

Both Timberline and Mt. Hood Meadows have about a 3 foot (or more) snowpack on the ground now. Even Government Camp has somewhere between 4-10". In other years those first two ski areas would already be open, but of course COVID is throwing things off. Regardless, the slopes are just about ready! Timberline is opening this Wednesday the 25th and Meadows is opening for the season Monday the 30th! I don't see anything that would stop either from happening. Another foot or so should fall above Government Camp by Thanksgiving morning. At least according to the ECMWF model

ECMWF Snow Accumulation.png

The only possible rainy weather at the ski resorts would be Friday night or early Saturday as a weak system moves through the warm upper-ridge. So we should remain in good shape for an early start to the ski season through at least early next week. We'll see what happens beyond.

Enjoy the showers early this week; I'm focused on the dry weather later in the week. After Thanksgiving Day it's the Christmas season...good weather to hang some lights Friday-Sunday!

Christmas Tree Light Hang Forecast.png

Chief Meteorologist Mark Nelsen

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