Agri View: El Niño Fading

Dan Agri View, Weather

El Niño
Everett Griner talks about what is next after El Niño fades in today’s Agri View.

El Niño Fading


March 2016 El Niño update: Spring Forward

Author: Emily Becker

The strong El Niño of 2015/16 is on the decline, and the CPC/IRI forecast says it’s likely that conditions will transition to neutral by early summer, with about a 50% chance of La Niña by the fall. In this post, we’ll take a look back at this past winter and forward to what may happen next.

Current events

El Niño has begun to weaken, with sea surface temperature anomalies across most of the equatorial Pacific decreasing over the past month. The large amount of warmer-than-average waters below the surface of the tropical Pacific (the “heat content”) also decreased sharply, despite getting a small boost in January. The heat content is the lowest it’s been in over a year, and since the subsurface heat feeds El Niño’s warm surface waters, this is another sign that the event is tapering off.

That said, there’s still a lot of extra heat in the tropical Pacific, and we expect El Niño’s impacts to continue around the world through the next few months. So far this winter, global rain and snow patterns have mostly been consistent with the expected patterns of El Niño, with some exceptions.

The winter that was

December 2015 – February 2016 rain and snow patterns, shown as the difference from the long-term mean. figure from CPC data. Large image.

December 2015 – February 2016 rain and snow patterns, shown as the difference from the long-term mean. figure from CPC data. Click for Large image.

In South America, southern Uruguay, Paraguay, and southern Brazil have received much more rain than their long-term December–February average, and the northern portion of the continent has been dry, as usually occurs this time of year during El Niño. Also consistent (so far) with El Niño’s typical impacts have been Africa’s rainfall patterns (wet in portions of Kenya and Tanzania and dry in southeastern Africa and southern Madagascar), the dryness through Indonesia and northern Australia, and the rains in southeastern China.

As Michelle discussed, the precipitation impacts in North America haven’t been quite as consistent with expectations so far, although the southeast and particularly Florida have received a lot more rain than average. Over the December–February season, the western coast of North America showed a pattern of drier north/wetter south, but the line between the two is shifted somewhat north of where it was during earlier El Niño events.

It’s a warm, warm world

El Niño’s effect on regional temperature is a little less distinct than its effect on precipitation patterns. Since El Niño changes the circulation of the atmosphere all around the world, it essentially changes where we expect rain to fall by steering storms to different locations. Temperature operates differently, especially since global warming is changing the averages. Michelle broke down some of the factors going into the super warm November and December in eastern North America – a good example of how attribution of seasonal temperature patterns is a complicated matter.

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Images courtesy of Climate,gov.