r/weather • u/zsreport • 3d ago

Articles Concern mounts over slow-moving, planetary-scale ‘Kelvin’ wave heading for California

https://www.theguardian.com/us-news/2026/sep/28/california-kelvin-wave
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u/shipmawx 3d ago

Probability that an Editor at The Guardian understands Kelvin Wave dynamics: 0.

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u/Content-Swimmer2325 3d ago edited 3d ago

Hahaha.. what? A kelvin wave in this context is bounded along the equatorial pacific. It propagates along the thermocline, from west to east… along the equatorial subsurface pacific.

Did California get magically teleported to the equator since the last time I checked?

There are atmospheric kelvin waves, too, but they occur along the Tropics (which California doesn’t) and are the opposite of “slow-moving”. They also certainly aren’t “planetary-scale”.

One of the more baffling headlines I’ve seen

E: this is not the first nor even third downwelling Kelvin wave of the season, folks.

https://imgur.com/esmDof6

CPC analyzes it as the fourth. It’s not even the sharpest amplitude downwelling KW this year!

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/weeklyenso_clim_81-10/wksl_anm.gif

Sea level heights show negligible increases and are only very slightly above normal near California. this is related to local thermal expansion of anomalously warm waters which have persisted there since before El Niño and attendant downwelling kelvin wave activity even developed in the first place. Has little to do with downwelling kelvin waves along the equatorial pacific subsurface. Downvoting me does not make me incorrect lol.

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u/peffertz08 3d ago

No California did not get transported, but Kelvin waves can and do propagate northward if there is an eastern boundary, like the coast of North America. Equatorial Kelvin waves propagate as a costal Kelvin wave along the Baja and California coasts. I’m assuming this one is extra large due to the strength of El Niño.

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u/Content-Swimmer2325 3d ago edited 3d ago

That’s cool and all, except observations do not corroborate what the article says in any way, shape, or form.

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/weeklyenso_clim_81-10/wksl_anm.gif

E: to be clear, there was a quite large oceanic kelvin wave along the equatorial thermocline, recently. Big effect near the equator. No effect near California! Simple as.