March 08, 2024

El Nino's Collapse Has Begun

The entire character of this winter has been characterized by a strong El Nino.  

El Nino impacts have included low snowpack over Washington State, huge snowpack and heavy precipitation over California, and warm temperatures over the Upper Plains states.

However, El Nino's days are numbered and its decline is proceeding rapidly right now. 

First, consider the critical measure of El Nino:  the sea surface temperatures in the central tropical Pacific (the Nino 3.4 area).  The warmth of this El Nino peaked in late November (about 2.1°C above normal) and is now declining fairly rapidly (currently at roughly 1.3°C above normal).


But the cooling is really more dramatic than that:  a LOT of cooling has been happening beneath the surface!

To demonstrate this, take a look at subsurface temperatures (the difference from normal) for the lowest 300 m under the surface for a vertical cross-section across the Pacific (below).   

On 8 January, there was a substantial warm layer extending about 100 m beneath the surface.


But look at the same cross-section on 27 February.  

Wow--what a difference!  The warm water has dramatically cooled, with only a thin veneer of warmth evident for much of the Pacific.   Rapidly cooling has occurred beneath the surface and this cool water is about to spread to the surface.

If you really want to appreciate the profound cooling take a look at the amount of heat in the upper ocean for the western tropical Pacific (below, the difference from normal is being shown).

A very, very dramatic change has occurred.  The heat content of the upper ocean peaked in late November and then plummeted.   Declined so much that the water below the surface is now COOLER than normal.


El Nino fans will be further dismayed to learn that models are going for a continuous decline....so much so that they predict a La Nina next year!


So why should folks care about this major decline in El Nino here on the West Coast?

El Nino results in a trough of low pressure centered to our south and west, something evident in the upper-level maps (for 500 hPa, about 18,000 ft) for February hown below. The blue colors indicate lower-than-normal heights/pressures.


But with El Nino weakening, a major pattern change is possible, and the latest model  forecast is for a major change, with a huge ridge (red color) over our region for March 13-20th.  

FINALLY, we may experience some real springtime weather.  Like highs in the mid-60s!  I can't wait.  Tired of one frosty morning after another!










7 comments:

  1. " take a look at subsurface temperatures (the difference from normal) for the lowest 300 m under the surface for a vertical cross-section across the Pacific (below)."

    How is this data collected? Is there some method of making subsurface temperature measurements via satellite, are there vessels taking soundings, or simply a sizeable number of buoys out there?

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  2. A nice analysis. Forecast – we'll see. :)
    Early March > nasty; late March > nice.
    How long has "in like a lion" and so on been around.
    Consider the night sky: constellations Leo (a lion) and Aries (a ram, or lamb)
    … or "there is nothing new under the sun"

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  3. The warm weather forecasted by next weekend will certainly be nice, but I am concerned about the implications this will have on the low BC snow pack as we move into April-May. Things have improved here during late Feb - early March significantly but still only reading 66% average across the province.

    https://governmentofbc.maps.arcgis.com/apps/webappviewer/index.html?id=b57800e08e46468bab506f9b9f0cbad6

    https://www.castanet.net/content/2024/3/large/blue_bkgd_centre_copy_327_8_copy_11_p3770305.jpg

    You may be better off south of the border than us but an early drought and fire season is a concern if we have a long warm + dry period moving towards April... especially after what happened last year. Hopefully we have at least one more wet month before summer.



    ReplyDelete
    Replies
    1. Wet weather increases forest undergrowth. More fuel to burn. Careful what you wish for.

      Delete
  4. What did the groundhog say this year? I forget.

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  5. Hey Cliff - Just curious if there are any weather implications to such an abrupt cooling trend in the equatorial pacific. Specifically, would a potential La Nina next winter carry any unique qualities owing to its rapid formation? Thanks.

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