August 11, 2021

The Summer's Second Heatwave Comes Into Focus (And Slightly Cooler Than Initially Predicted)

As we get closer to the heatwave event, our more potent tools (like high-resolution ensembles of many forecasts) become available.  

And the latest information suggests that this week's heatwave will be a bit less intense than initially predicted.  And FAR less threatening than the June event.  

In the June event, everything came together to produce a "black swan" severe event.  Record ridge of high pressure, approaching trough of low pressure, strong offshore flow, and the occurrence when the sun was near maximum.  None of these ingredients will be present this week.

The National Weather Service has an excessive heat warning for a significant portion of the region (red colors below).

Bottom line:  a typical heatwave for the region.  I suspect there won't be any attribution reports for it.

The Forecast

The most powerful tool available to local meteorologists is the UW high-resolution multi-forecast (ensemble) system, which only goes out 72 hours.

Below is its forecast for SeaTac.  Today will get to around 86F.  But tonight will drop into the mid-60s, so with a fan you can cool down your apartment or house.  Tomorrow (Thursday) will see lower 90s, with a few degree uncertainty. Thursday night/Friday morning will cool to the 60s. Friday will be a touch warmer, reaching about 95F.  Although not shown, Saturday will be cooler and Sunday MUCH cooler

Portland is bit warmer (see below), getting near 99 F today and low hundreds tomorrow..but note the uncertainty of several degrees.  Slightly cooler on Friday.  Minimum temperatures are warmer the low 70s Friday morning.  The Willamette Valley lacks the cool water enjoyed by western WA.

Eastern Washington (Pasco) will be around 105 F each day, perhaps a few degrees warmer on Friday.   Agricultural workers should be protected during the heat of the day.

Some locations in the Northwest may break daily records, but nothing more serious than that.

Next, let me show you the high-resolution forecast maps for 5 PM each day, near the time of highest temperatures.  

Today, temperatures will be moderate on the coast and Northwest Washington, mid-80s over Puget Sound country, upper 90s  in the Willamette Valley, and a bit over 104F in the lower Columbia Basin. 

Slightly warmer on Thursday, particularly over southwest Washington and in the Fraser River Valley.  I never appreciated how warm the exit (western) region of the Fraser River can be.

Friday will be modestly warmer in the lower Columbia Basin, but similar west of the Cascade crest.

And as mentioned above, a step down on Saturday and far cooler on Sunday.  

A typical Northwest summer heatwave.  I hate to think what some local newspapers will be saying about it.....😊😊


  1. Would love to hear your analysis of the newly released IPCC report. Not sure where they get some or their numbers,seems they use numbers not available to us civilians. I'm guessing the papers will point this heat wave out as proof Again.

    1. What sort of numbers do you feel you are missing? The Working Group 1 report alone (the other groups are still working on their update) is almost 4,000 pages, plus there are dozens of additional documents containing supporting information. Embedded within the report are countless citations of other research that supported the analysis.

      Are you saying you've reviewed all of that already and can't trace the data?

      As far as some general commentary on the new report - the 6th Assessment Report is an update to the 5th Assessment report to incorporate the last 8 years of additional data, as well as refinements to their models, such as higher resolution of the models. I think they also took a closer look at some of the topics. For example, from a brief look yesterday, the section on sea level rise seemed to have more discussion about polar ice sheet stability than I recall in AR5.

    2. The IPCC was debunked years ago, when independent researchers asked them to release their data in order to ascertain the validity of their conclusions. They stumbled around for weeks until admitting that they amazingly, somehow "lost" their initial data. And if you believe that, I've got a bridge to sell you in the Mojave Desert.

    3. Eric, can you provide more info about this? I tried to look up any instances of missing data and the closest I found was the IPCC report omit some country specific data (presumably to appease China and other Asian nations with heavy carbon footprints). However, these data were published separately in a Science article. Is this the instance you had in mind?

    4. And if you look into their definitions of terms used in likelihood of occurrence it's nonsense verbiage.

    5. Eric, your post makes no sense. The IPCC reviews the tens of thousands of studies and synthesizes that work every so often in the Assessment reports which, by the way, cites those tens of thousands of studies (i.e., the "data" to which you refer). In other words, The IPPC does not collect their own data, the review the existing literature and cite that literature. Also, there actually are bridges in the Mojave Desert.

    6. Cliff, I would also love to hear your comments on the IPCC report. I asked you a few years ago to do so and don’t recall that you responded. As someone who has been reading your blog for years and has been trying to give you the benefit of the doubt when other sources have maligned you, I’d really appreciate you at least acknowledging the release of this report. It strikes me as a bit odd that you haven’t done so.

    7. Kimya...I will be doing a blog about this new report. I have mentioned the IPCC reports MANY times in my blogs. If you don't believe this, do a search for IPCC in my blog...cliff

    8. I believe you. I guess I missed it. Thanks and looking forward to your post.

    9. SYoung -here is where scientists started seriously questioning the IPCC:

      Additionally, this might be the article in Science you referenced:

      So here we scientists admitting on the record that they've been scaremongering for years now. But trust us, we're not doing that anymore!

    10. Unknown -

      "Also, there actually are bridges in the Mojave Desert."

      Metaphors - how do they work?

    11. Eric...the metaphor is a bridge in Brooklyn to sell you.

    12. It's a not seeing the forest through the trees analogy. Arguing about each weather extreme and denying the role of warming due to human activity misses the changes that have occurred over the past 50 years. They have paralleled the rise in CO2 as predicted and undoubtedly will continue to progress. Yes you can argue that any individual event is weather as usual but you can't argue the global changes over time are not real.

  2. I think today Thursday is gonna be hotter than predicted. It's already mid 70s in some places as of 9am.

  3. Thank you professor! Following your guidance closely during all these enervating anomalous..

    > "Bottom line: a typical heatwave for the region."

    ...typical-alities [wink]

  4. What's the smoke forecast looking like? I am reading different reports for the air quality this weekend. Would be nice to have it be clear for the Perseids!

  5. 91 here on the canal today, running the usual 3 degrees above most of the forecasts. Bodes poorly for the next few days.

  6. I think you have to call this a little more than "a typical heat wave" here on the east side of the Cascades. The 105 at the Wenatchee Tree Fruit Research Center today was a record for the date. The all time August high of 108 could be equaled or possibly broken in the the next couple of days and the daily highs through Saturday will likely be broken.

  7. smoke may keep it a bit cooler, although not necessarily more comfortable! If the temps drop at night, we can cope.

  8. Western Fraser Valley here, forecast says 37°C (99°F).

  9. Bellingham has now tied the all-time record set in June, 3 degrees hotter than the previous all-time record from 2009.

  10. Bellingham airport tied the record temp of 99 F that was set in the June heat wave.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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