Long & rare November dry spell plus gusty east wind

10pm Monday…

You have to admit, the bright sunshine was spectacular today! As I was driving into work, the parkway was line with bright yellow/orange maple trees, finally donning their fall outfits 2-3 weeks later than normal. We should see 5 more days like today…that’s Tuesday through Saturday. Then the normal November rain returns

November started with a soaker, but now we’ve gone 7 days without rain, and 5 more are likely. That means we’ll end up with at least 12 consecutive dry days, the November record is just 13. So this long dry spell in November is quite rare. It’s interesting that happened in the 3rd year of a La Nina…November 2000.

The reason for the unusually dry weather is the return of that pesky upper-level ridge along the West Coast. Here’s tomorrow’s forecast of 500 millibar heights, about 18,000′ overhead. The flow is going well around us, north into Alaska and Yukon, then heading south into the Midwest…brrr!

By Friday, the pattern isn’t much different

But a well-advertised change occurs Sunday through Tuesday. Wet westerly flow punches through the ridge…the view on Tuesday

I think it’s safe to say the first half of Thanksgiving Week will be wet, but it’s too early to know if that will continue through the holiday weekend. The ECMWF ensemble 24hr rainfall chart shows the change very well. Each horizontal line is one of the 51 ensemble members…but they are all wet aren’t they?

So we’re headed into mild/wet weather NEXT week, but this week we’ve got the sunshine, plus a gusty east wind.

November through February IS the “east wind season” in our area. What does that mean and why? In the cool season the sun angle is very low and we don’t get much energy from that sun. So when weather systems with clouds/rain are blocked from moving overhead, long nights lead to cold air pooling in the lowest elevations. There happens to be a bit of a “bowl” in Eastern Washington and north-central Oregon. This is the Columbia Basin. That “bowl” tends to fill with cold air and then the weak sun is not able to warm it up due to short days. That cool airmass can grow quite deep, often up around 3,000-4,000′ deep. The dense/heavy air means an area of high pressure develops. This is a pretty good depiction of that cool/heavy airmass.

Of course it’s trapped by the Cascades, like a dam holding back water (except that it’s heavy air). BUT there is just one gap below 3,000′ through the Cascades between Canada and California. That’s the Columbia River Gorge. So that heavy air surges west through that narrow gap and then spills out into the flatlands west of the Gorge. There’s an additional item, remember the cold airmass in the central Gorge is typically 3-4,000′ thick, but it’s usually less than 2,000′ once it reaches the east metro area. So it’s a bit of a “waterfall of air” too. Wind accelerates and peaks just inside the west entrance to the Gorge. Peak gusts reach 50-70 mph many times in this area during the cool season and can peak up around 100 mph during very cold easterly flow when a low pressure area approaches from the southwest. The strongest wind I have ever seen in that area was the day before the big February 1996 flooding rains arrived. Temperatures around 10-15 degrees were accompanied by a 101 mph gust in Corbett on a high-quality wind sensor. Strongest wind is always a combination of large pressure gradients plus a strong inversion and unusually warm temperatures overhead. The 2nd highest wind event I’ve seen was in January 2009. Peak gusts reached 50-60 mph even into Gresham.

As you can see, the eastern metro area gets the brunt of the cool season easterly wind. Strongest gusts are concentrated east of I-205 near an south of the Columbia river in a typical setup. The wind goes away in spring when the stronger sunshine starts heating land effectively east of the Cascades; that’s in mid-late March.

Tonight the satellite picture shows the “cold pool” has developed nicely east of the Cascades (clouds in white). The X marks Portland.

That’s another feature of the cold season…low clouds and fog (depends on your elevation) stuck in the cold air eastside. Places like Hood River, The Dalles, Maupin, and Madras can sit under gray low clouds for a week at a time. Yet Timberline and Mt. Hood Meadows will be in warm sunshine. During these inversion events you want to head UP to find warmer temperatures.

By the way, there’s no sign of a cold spell or lowland snow in the next two weeks. I think we are clear for Thanksgiving Weekend. Notice almost no ECMWF (Euro) model members produce any snow in Portland through the end of the month.

That’s it for now…enjoy the sunshine and try to stay out of the wind!

17 Responses to Long & rare November dry spell plus gusty east wind

  1. Ken in Wood Village says:

    I’m a little shocked what I saw on the Crown Point observation website. Just before 5pm, it recorded two wind gusts of 94 mph 😳

  2. WEATHERDAN says:

    Looks like to me a return to more normal late November weather. Average temps and precip. Then drier and cooler after Thanksgiving. Still no sign of an Arctic blast but maybe some snow for the mountains. And no atmospheric river. In the meantime I want to wish all of you on this blog a fantastic Thanksgiving. And go Ducks. Peace.

    • Anonymous says:

      Go ducks! Hopefully we get so much rain it causes flooding, and so much snow in the mountains the ski resorts have to temporarily close.

  3. Doinko - Bethany says:


    Tomorrow looks very windy. The WRF-GFS is forecasting gusts 40-45mph here in Bethany. And the WRF is weaker with the Columbia Basin High than current obs show. Could this nearly warrant a wind advisory?

    • runrain says:

      They should issue an advisory as officially they predict 46 mph gusts. Also, looking forward to some warmer moisture-laden nights next week (hopefully), ones you can leave the window open and not freeze out the house!

      • Jake says:

        It is going to be intense if the drive through the gorge this morning was any indication of what’s to come.

    • Ken in Wood Village says:

      The NWS issued one

      URGENT – WEATHER MESSAGE
      National Weather Service Portland OR
      247 PM PST Wed Nov 16 2022

      ORZ006-WAZ039-171200-
      /O.NEW.KPQR.WI.Y.0005.221116T2247Z-221118T1500Z/
      Greater Portland Metro Area-Greater Vancouver Area-
      Including the cities of Hillsboro, Portland, Wilsonville,
      Oregon City, Gresham, Troutdale, Vancouver, Battle Ground,
      Ridgefield, Washougal, Yacolt, and Amboy
      247 PM PST Wed Nov 16 2022

      …WIND ADVISORY IN EFFECT UNTIL 7 AM PST FRIDAY…

      WHAT…Northeast winds 15 to 25 mph with gusts up to 50 mph.
      Expect strongest wind gusts east of I-205.
      WHERE…In Oregon, Greater Portland Metro Area. In Washington,
      Greater Vancouver Area.
      WHEN…Until 7 AM PST Friday.
      IMPACTS…Gusty winds could blow around unsecured objects.
      Tree limbs could be blown down and a few power outages may
      result.

      PRECAUTIONARY/PREPAREDNESS ACTIONS…

      Use extra caution when driving, especially if operating a high
      profile vehicle. Secure outdoor objects.

      • ViRGE says:

        Meanwhile the rest of the valley gets an Air Stagnation advisory for a lack of wind.

        There’s just no winning this week. Either it’s too much weather or not enough.

  4. Roland Derksen says:

    Thick fog here this morning- the first real significant fog I’ve seen this autumn. However, it doesn’t appear to be lasting longer than today. We’ll get some outflow winds tomorrow.

  5. Roland Derksen says:

    Long stretches (i.e more than 7 days) of dry weather in November aren’t quite as rare as we sometimes think, but for the record my longest without measurable rainfall was in November 2000 with 14 days. I doubt I’ll beat that this time.

    • Andrew says:

      I’ve grown quite used to winter ridging and long dry stretches. Seems fairly commonplace now. Maybe a little more odd in November than Jan or Feb however.

      • Roland Derksen says:

        Hi Andrew- received your response to my earlier comment- thanks! Just wondering if you’re a long time weather observer in the PNW as I am. I live north of Portland across the Canadian border, but I’ve been reading the KPTV blog for some years now, as it’s always intresting to compare the weather conditions. Sometimes very similar, sometimes not.

  6. jack says:

    Hey Mark – any chance the new “blog” site can have an RSS feed so it can be added to a feed reader? This blog has an RSS feed but the new site doesn’t.

  7. OC550 says:

    Thanks Mark. Hoping for a good La Nina ski season. The mention about a similar dry stretch in November 2000 is a little concerning. If I recall correctly, the winter of 2001 was relatively dry with a low snow pack. I may be wrong about that.

  8. Virginia Mayo says:

    Thank You Mark!

    Sent from my iPhone

    >

  9. tim says:

    The first half of November is running about five degrees below normal for highs in Seattle, at some point we have to make up for it rather it be this winter or next summer with extreme heat either way we are due for a warm spell.

  10. tim says:

    There’s no sign of cold and snow because that happened during the first week of November which means it’s unlikely will see that again any time soon perhaps for the rest of the winter.

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