May 04, 2024

Sea Surface Temperatures: West Versus East Coast.

Perhaps, this blog spends too much time talking about the atmosphere, so to make amends today, let's see what is happening to the temperature of the ocean surface.  And see whether anything unusual is going on.

 Let's start with yesterday's sea surface temperatures around North America (below).  Sorry, it is all in °C.   Keep in mind that 10°C is roughly 50F,  20°C is around 68F, and 30°C is approximately 86F.

The eastern Pacific near the West Coast is cold (about 50F), with central California's waters a bit cooler than ours. You must head to the southern tip of the Baja Peninsula to find the water warm enough for comfortable swimming.

The East Coast is a study in contrasts.  The water off of New England is crazy cold (dropping below 7C), while the uber-warm Gulf Stream is found along the west coast of Florida, moves past the Carolinas, and then heads northeastward into the Atlantic.    

There is a HUGE temperate contrast between the Gulf Stream current and the cold water of the Northeast.    A blow-up of the sea surface temperatures off the Northwest really shows the amazing horizontal temperature changes north of the Gulf Stream

Look closely and you will waves in the interface between warm and cold water in the Atlantic and a fascinating loop in the warm water over the Gulf of Mexico (first image above).    Very warm water over the Caribbean and west of Central America

Your next question is probably:  is the current pattern of sea surface temperature unusual?  

To evaluate this, the next map shows the difference between yesterday's sea surface temperature and normal conditions (also called the SST anomaly).

Pretty close to normal off the Northwest coast.  A few degrees colder than normal for California's coastal waters. And near normal on Mexico's west coast.   Most of the Gulf and Atlantic coast is slightly above normal. Temperature is cooler than normal north of the Gulf Stream, which suggests that the Gulf Stream is south of its normal position by a hundred miles or so.

The biggest sea surface temperature story is what is happening in the tropical Pacific.  Last year, a strong El Nino brought MUCH warmer than normal sea surface temperatures from South America, westward into the central Pacific.  

But something major has happened.  The tropical Pacific surface waters are rapidly cooling, resulting in cooler than normal waters in many locations (see map, with arrows showing you some of the coolest spots).

El Nino is dead.  Long live La Nina, its frigid cousin!


  1. " Long live La Nina, its frigid cousin!" Why, should we in the PNW hope for La Nina, Prof. Mass?

  2. If you like snowpack, water supply, and decent skiing, hope for La Nina. If drought and wildfire smoke are your thing, hope for El Nino.

    1. Actually "La Nada" is my preference. According to Cliff, it brings the most exciting storms, but it has been getting short shrift lately.

  3. Would the El Nino to La Nina transition be a good time to talk about the ocean-atmosphere interaction and solar interaction? I've heard one meteorologist say the La Nina is the solar recharge phase for the equatorial pacific and El Nino is the release phase.

  4. Alas, yes. Washington State has a lot to offer but, if I had to name its single biggest drawback, it would be that the sea is too cold for swimming all year, which is something I like to do. Only in some lakes is the water (sometimes) warm enough. Contrast the East coast where the water south of Cape Cod is warm enough to swim in for at least 2-3 months.

  5. This is a very instructive post, very informative. I'm not certain how long (or how precisely) ocean temperatures have been recorded, and I don't know when (or how) theories about the cycles were developed. What does seem true is there's significant variability in ocean temperatures - both Pacific and Atlantic - and I suspect that there's considerable "chicken or the egg?" uncertainty as to how atmospheric conditions drive ocean temps and vice-versa. Some currents (both oceans) do seem to have long cycles like the AMOC (Atlantic meridional overturning circulation) that are probably tied-in to solar cycles. "What we know" is probably as ever-changing as the phenomena themselves. Again - all very interesting, and it may be that there have never been (and perhaps can never be) firm "set-points" beyond range(s). I have no idea how much ocean temperatures are effected by geological activity (the 'Ring of Fire') in any given year or decade, but I understand that the Pacific is more geologically active than the Atlantic. There are a lot of factors to grapple with; it's an incredibly complex but intertwined thing, our planet's condition.

  6. The PNW is in store for some more government restrictions given this report by WA EPA


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