10 September 2015

Questions About El Nino Answered

Posted by Dan Satterfield

The El Nino in the Pacific is now very strong. It is now passing the intensity of the record event of 1997.

The El Nino in the Pacific is now very strong. It is now passing the intensity of the record event of 1997.

The 2015 El Nino event will go down in history as one of the strongest ever, and likely as THE Strongest. While it is impossible to give an exact idea of what this will mean for your area, we can give you some likely scenarios for the upcoming winter, with more confidence in some areas than in others. There are also some misconceptions out there that I hopefully will dispel in this post!

First the general idea of what kind of weather a strong El Nino brings to the U.S.(see the graphics below).


These images ctsy, NOAA Climate.gov.

These images ctsy, NOAA Climate.gov.

Now, that you’ve seen the graphics, a few points to remember.

1.First of all, remember these are averages for a 3 month period. This does not mean that a major flood event could not happen in the dry areas or a long dry spell is possible in the areas that tend to be wet. It also does not mean that there will be extreme cold in the south, it just means that the average will likely be cooler than normal. People tend to remember the winter weather based on cold snaps or big snow events, not the averages!

2. Notice that Northern California and the Pacific NW will get normal or below normal rainfall in a strong El Nino event. This means that the odds that the severe drought in these areas will lessen much. Also, to break the California drought, you need heavy SNOW in the northern Sierra’s. Rain down south will just cause mud slides, but will do little to help the farmers in the Central Valley.

3. This is a super El Nino and we have a sample size of ONE. Surprises are likely.

4. A moderate El Nino in 2010 combined with a strongly negative NAO (pressure pattern in the Atlantic) to produce extreme cold and snow along the Eastern Seaboard from DC,Delmarva and into the New England states. If this happens during a super ENSO event then what will be the result? We do not really know, but I suspect it could be much the same.

5. There’s been much discussion about the blob of warm water off the coast of California and the role it could play in this ENSO event. Several studies have been recently published that this will not be a significant player, and while I was at first skeptical, I’m fairly convinced now that this is true. (See the links for much more on this, and note that in science it’s OK to change your mind when presented with valid evidence. Some politicians who deny climate change, and the age of the Earth could take a lesson from that)

If you want to dive deep into El Nino then I highly suggest that you read the excellent El Nino blog at NOAA’s climate.gov website.