January 15, 2022

The Tonga Volcano Affects the Weather and Water of the Pacific Northwest

Yesterday, around 0400 UTC 15 January (8 PM PST 14 January), there was a massive, explosive eruption near Tonga, in the southern tropical Pacific, about 5642 miles from Seattle (see map).

The volcano was clearly evident in satellite imagery from the massive ash cloud (see below, about 1-h after the eruption)


The explosive eruption created shock waves in the atmosphere (pressure waves) that rapidly propagated away.  These waves are evident in some infrared (water vapor channel) imagery as concentric rings (shown below).


The oceanic eruption also pushed away a massive amount of water, which created a tsunami on nearby islands (such as Tonga) and deep water waves that moved away at the speed of a jet plane, reaching the West Coast this morning.  This is why some local tsunami warnings went out this AM.

The Pressure Wave Reaches the Northwest

Local barometers indicated a well-defined pressure wave passing over our region around 4:30 AM this morning.  Here in Seattle, the University of Washington barometer showed the feature, with an amplitude of roughly 2 hPa (2 mb).  The arrow indicates the feature. Very impressive.


So it took about eight hours and 30 minutes to go about 5643 miles--thus a speed around 664 miles per hour.  

The water wave moves slower, around 400 mph (and occasionally approaching 500 mph)....so a later arrival was expected.   Thus, at Neah Bay, at the entrance to the Strait of Juan de Fuca,  the water wave arrived around 9 AM (17:00 UTC as shown on the chart), as indicated by the waviness in the water level after that time.  The amplitude of the variation is around 2 feet.




If you really want to be impressed, check out the same figure at Monterey, California.  Just wow.  The amplitude was up to 3-4 feet.
An amazing event and one that shows how interconnected our planet is--both in the air and in the water.


28 comments:

  1. How does this affect the weather in the pnw?

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  2. Here on the west side of Port Angeles, our home has a beautiful view of the strait. I looked out around the time the wave was supposed to hit, and the strait was socked in with thick white fog that was rolling towards us. I walked away and walked back a few moments later and the rolling fog that was still coming our way had turned brown. It was a solid, mucky brown. Usually our fog is pure white. The brown blob rolled over us and sat with us for awhile until I looked up again and it was all white. We are still socked in by some crazy thick white fog, but at least its white again. Did the disturbance throw some sand up in the air? Wild times. Sending love to the people of Tonga.

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    1. Why would your fog turn brown?

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    2. We wouldn't have ash out here, but I am thinking if the surf was rough enough it kicked some dirt up in the air. That's just my guess -

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  3. Gotta love data and those charts! Thanks Cliff!

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  4. This morning our smartphones came to life with tsunami advisories for our area, so we timed our walk to be in position to observe whatever the eruption had sent our way.

    There was a break in the thick fog at the estimated tsunami 9:30 am time of arrival, so we stopped to watch from the north end of S McDonald Street.

    It was subtle but observable.

    First a set of small waves wrapped around Point Angeles to the west on an otherwise absolutely waveless lake-like day. They peeled all the way down the beach eastward. Their backwash was more evident than that of swells pushed in by waves or distant storms.

    Then a series of very long straight swells popped up and moved shoreward from the Strait of Juan de Fuca.

    That enormous volume of additional water then disturbed the surface and you could see widespread but random current patterns stretching to the east of Ediz Hook sandspit.

    It was a special kind of magic to see the changes caused by an event that occurred so far away.

    Suddenly thick fog moved in to obscure everything like a white curtain. It was quite a performance.

    I wish I could have been watching the pilings at the marina as well. The rise in water there would probably not have been turbulent, but measurable over a short time span.

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    1. Thank you for capturing the moment so well with what you wrote! What a thing to observe.

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  5. This is what I love to read about! Nature is awesome! Thanks Cliff Mass

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  6. I have been following Geology Hub on youtube. He reported on this particular volcano last month. His thought is that this eruption probably started as a landslide into the old Caldera exposing the magma to seawater.

    Here is the link https://youtu.be/B54HbfqDbK4

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  7. Even my rather simple wx station caught the pressure wave ~4:37am. I'm impressed.

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  8. This eruption produced an umbrella cloud 350-400 km in diameter in about an hour. Compare this with Pinatubo in 1991, the world's largest eruption since Katmai in 1912. It produced a 900-1,000-km-diameter umbrella cloud in 9 hours. This remarkable growth rate at Honga-Tonga suggests that its eruption rate was comparable to Pinatubo, event though the duration was shorter. Could entrained seawater have enhanced the umbrella growth rate? We don't know yet.

    Another remarkable feature is image quality. the 1-minute time resolution of the GOES-17 infrared images was better than any large volcanic umbrella cloud we've ever seen. Pinatubo was imaged by the Japanese GMS satellite with 1-hour time resolution. Kelut (Indonesia) in 2014 was imaged by MTSAT at 10-minute intervals. We can thank NOAA for these amazing, movie-quality images.

    Larry Mastin

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  9. Replies
    1. Why don't you get on weather.com and look at the 10 day forecast. Upper 40s with showers. No storms.

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  10. Looks like other side of wave hit here midnight last night (Sun morning). Here are 2 distinct spikes using a BMP180 sensor.
    https://www.labweather.com/media/tonga_full_ha.png

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    1. Thanks for posting this, Joel. I spotted the first shock on my wx station graph and then looked at over a dozen stations on wunderground.net ... it was interesting to see the times for each of the peaks and that they came earlier as I moved south. I see a second one near midnight just like you did. Unfortunately all the graphs on wunderground start at midnight and I was unable to see that it was actually a peak. Thanks for confirming what I saw. So what do we think this second spike is? Did the wave go all the way around the globe and hit us again?

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    2. Joel, I now realize what you meant by the 'other side' of the wave. Of course, this would be the side to the wave that took the long way around the planet. It makes sense now.

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  11. I have no idea why tsunami push notifications were sent to people in King/Snohomish counties. The Washington coast is exposed to Tonga along a direct line of sight, but was there *really* the slightest concern that a tsunami would enter at Cape Flattery, transit the Strait of Juan de Fuca, make a right around Admiralty Inlet, then make a left turn and crash over our beaches on the eastern shore of Puget Sound?

    I'm reminded of Jerry Seinfeld's parody of the JFK magic bullet theory in the Keith Hernandez episode.

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    1. I think media has covered pretty well what King County Emergency Management team's reasoning was. First, it was advisory. Second, it stated the waves and currents "may" reach Puget Sound but the effects are uncertain. No cry wolf, no alarmism, no drama. Be safe. I think one element of uncertainty is that this was caused by an underwater volcanic eruption and not an earthquake.
      I'm glad though that this reminds you of a Jerry Seinfeld episode. There's almost an episode to match every life circumstance.
      Your post reminds me of the obscure consequences in Seinfeld S6 E4.

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  12. Oh wow. I have two PWS units here. An Acurite 5 in 1 and an Ambient weather transmitting data to WU, CWOP, MADIS, and a few other weather services. Went back and looked at the data and sure enough you can see the barometer spike around 4:30 on both. Amazing!

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  13. This event definitely got me more interested in volcanology. However, it is worth noting that the West Coast received Tsunami Advisories, not Tsunami Warnings like you stated. Hate to be that guy, but it really is an important distinction.

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  14. My Garmin GPS watch picked up the pressure wave on its barometer!

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  15. So the Tsunami affected our weather, but global warming doesn't?

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  16. So… will this affect our weather here in the short term. Some people are wondering if it’ll affect the jet stream.

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  17. I'm not a climatologist or geologist. So, pushing all the earth's material up and displaying water, does that makes the sea levals rise as a natural event?

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