January 28, 2021

The Blob is Weakening

 There are a lot of Blob enthusiasts in the Northwest and I wanted to provide an update on their favorite ocean/atmosphere feature.

The Blob, as many of you know, is an area of persistent above-normal temperatures in the northeast Pacific.    The Blob has substantial impact on western Washington weather, tending to increase daily minimum temperatures, sometimes by as much as 2-8 F.   The Blob also has implications for local marine life, including the northward movement of subtropical marine species.

If we take a look at sea surface temperature anomaly (difference from normal conditions or climatology) for last October, one can view a "healthy"  Blob off our coast, with portions 3-4 °C (6-8F) above normal,

But by mid-December, the Blob had weakened considerably (no more red colors), 

And by yesterday, it was quite anemic.  In fact, if you look closely, you will notice some blue colors (below-normal temperatures) along the West Coast and in the Gulf of Alaska.

Why is the Blob weakening?

 Blob's tend to develop when there is persistent high pressure...also known as ridging....over the northeast Pacific.   Such high pressure is associated with light winds, which minimizes vertical mixing in the upper ocean.  Mixing that brings colder water to the surface.   Thus, high pressure and light winds tend to produce warmer than normal temperatures......a Blob situation.

If we look back to mid-October through mid-November, there was, in fact, persistent high pressure over the northeast Pacific (see sea level pressure anomaly--difference from normal-- below).  Red colors indicate higher than normal pressure.

But during the last few months the situation has changed radically, with stormier than normal conditions over the same region (see pressure anomaly for last month below). Purple indicates lower than normal pressures, which suggests stormier than normal conditions.

No wonder the Blob is not doing well!

Consistent with a weakened BLOB, minimum temperatures at Sea Tac Airport have frequently dropped to normal minima, something that rarely happened in October (see blow below).  


  1. Sorry Cliff,
    after actually reading the blog post. “Political Violence is Always Destructive” instead of just skimming for something to disagree with, I realized your comments about the Seattle riots were spot on. My replies were inappropriate and off the mark. Wish I could take them back.

    Thanks for the Blob update :)

  2. I read NOAA latest update today..said models are picking up potential cooler air for the end of next week...and yes I know it's a week out...BUT with a weakening blob and high pressure setting up west of us...does THIS open the door for some lowland snow...I mean if we are gonna get some would like it in February not March...like Jim Carey said...so you say there is a chance...give yo Gus straight Cliff..I can take it...well kinda

    1. Not according to the phone weather apps who show mid 40's by next weekend. Subject to change of course.

  3. Is this better news for more wet weather along the west coast us and wetter winters

  4. Looks like the Blob has moved to the South Pacific for the winter. Do Blobs migrate?

  5. Let me guess, the blob recurring every 2ish years has nothing to do with climate change.

    1. Geez. Climate change CAN'T be natural causes. Hmmmmmmm. Either it's all manmade or not real! (face palm).

      The models are broken because of this trap of thinking.

  6. I really noticed the colder than normal waters off the South America coast looking very prominent. Does that indicate a strong LaNina, or have there been LaNina's that were stronger than this one?

  7. Every time something like this pops up you refer to it as an anomaly. Now I understand that the language is tied to scientifically measured data, but from a layman's perspective, when every year is anomalous for 6 years it starts to feel like it's no longer an anomaly. This winter seemed really warm, and I don't feel like you ever give any real explanation about when weather extremes cease to be a matter of chance. I don't go so far as to call you a denier, and I am also aware that you are more educated in the subject than I could ever dream of being. But when there are increasing high temp record year after yearas well as above average temperatures I really start to question when you will address this as being potentially more than just a one-off. This damn blob thing had been a summer fixture it seems for the last 5 years and high temps exceeding the average have been normal. It starts to feel like more than just a random event to me.


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

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