Monday, August 18, 2014

Modoki El Nino Gaining Control; Winter Outlook Grows Colder

It appears that a Central-Based, or Modoki El Nino is now gaining control, resulting in the outlook for this winter growing colder.

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The image above, provided by the JAMSTEC agency, shows typical sea surface temperature anomalies during a Modoki El Nino. The presence of this Modoki Nino is clearly shown by the positive anomalies in the central portion of the Pacific, hence the interchangeability between Modoki and Central-Based El Nino. During the Modoki Nino, cooler than normal SST anomalies tend to appear offshore Ecuador, something we'll discuss a little later in this post. Looking towards the north Pacific, predominantly warm SST anomalies are observed, from the Sea of Japan, to the Bering Sea, to the Gulf of Alaska. Warm water anomalies are also recorded near Baja California.
Out in the Atlantic, warmer than normal waters surround Greenland and are placed into western Europe, with cool water providing a separation between that mass of warmth, and the second body of warm water juxtaposed near the Canadian Maritimes. The Indian Ocean also exhibits a slightly negative Indian Ocean Dipole signal (identified by cold water near Somalia and warm water near India) during Modoki El Ninos.

Let's now compare this typical  Modoki set-up with today's SST anomalies.

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Taking a look around the globe, we can identify several points of interest and discussion when comparing the Modoki composite image, and the daily SST anomalies from August 17th. Beginning in the Pacific, we see warm water anomalies off the coast of Ecuador, and cool anomalies in the central Pacific, basically opposite of a Modoki set-up. We'll dive deeper into that a little later in this post. Moving up to the North Pacific, we observe a swath of warmer than normal water temperatures in the Northeast Pacific/Gulf of Alaska, nearly identical to the anomalies seen during a Modoki Nino. The comparison is once again similar when we confirm warmer than normal waters stationed off Baja California, as also seen in the composite image. The Sea of Japan was well above normal earlier this week, as it is during typical Modoki El Nino events, but has since cooled due to the passage of Typhoon Halong over that area.
Transitioning to the Atlantic, additional similarities are found. We can see the warmer than normal waters near Greenland, pushing east into western Europe, as was also found in the Modoki composite image. There isn't much of a cold pool of water just south of Greenland, but warmth is observed near the Canadian Maritimes. The Indian Ocean is also displaying the same negative IOD pattern observed in a typical Modoki El Nino event.

Now, all of these similarities are impressive, but what about the El Nino itself in the Pacific? It looks nonexistent- actually opposite, of what the Modoki composite image shows us.

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The animation above shows us water temperature anomalies, the same variable examined earlier in this post, but now analyzed on a depth chart. The legend on the left displays depth in meters along the Equator, while the bottom legend indicates longitude lines. Looking over the animation, we can see that opposite pattern of cool waters in the central Pacific (top-middle of animation) and warm waters in the eastern Pacific (top-right of animation), but what is stirring below is even more interesting. We find a body of cold water pushing to the surface in the eastern Pacific, as well as a swath of positive water temperature anomalies manifesting itself below the surface in the central Pacific. Put two and two together, and the Modoki signal in the Central Pacific is definitely present, just not at the surface yet.

Now that we have shown how the Modoki El Nino is nearly completely present in water temperature anomalies around the globe, let's talk about the effects it may have on the upcoming winter.

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The graphic above displays worldwide temperature anomalies during a Modoki El Nino. As we can see, cold weather is typically observed in much of the Central US during a Modoki El Nino, while warmth prevails in the Western US. Slightly warmer than normal anomalies are also visible along the Eastern Seaboard.
What this tells us is that, at least for now, the risk of another cold winter in the Central US is rising, while a warm winter along the West and into Alaska is also becoming a real possibility. Those in the East may need to watch for a slightly warmer than normal winter.