Is El Nino Coming?
Over the past week there have been news reports that in the coming year El Nino (warmer than normal temperatures in the sub tropical Pacific) is expected to develop.
These news reports heralded this possible development as great news for drought stricken California and the news reports even promised a much more mild winter season next year for most of the northern U.S.
Like any long range weather prognostication I strongly encourage you to take these news reports with a grain of salt. I don’t believe it was the intent of NOAA weather forecasters to give people such high expectations for next year (California rain and a mild winter next year), however, the media decided to highlight what can be expected to develop in a very strong El Nino weather pattern.
It is not just a matter of whether or not there is an El Nino or not. Much of the weather we can expect from a warmer Pacific has to do with the intensity and duration of El Nino. If it is going to be a weak El Nino, most, if not all the media promises will not come to fruition.
There are reasons to be skeptical. The last time an El Nino was predicted to develop was in 2012. While temperatures in the Pacific did rise in late 2011 they unexpectedly fell in early 2012 and El Nino never developed. Also, we are approximately 17 years into an overall colder phase in the Pacific (cold Pacific Decadal Oscillation or PDO) that may trump any significant or long lasting warming in the sub tropical Pacific.
While there are many indications that do suggest we will be in an El Nino later this year into 2015, it is likely going to be of the weak variety (short lived and not intense). The intensity of the El Nino will play a large role in the weather across North America late this spring into next winter.
Below is a graph showing the possible development (in computer modeling) of warmer water temperatures in the sub-tropical. This graph shows that many of the computer models predict a warmer Pacific (an El Nino is anything that is at or above the +0.5C line).
Please note that these are the same models over predicted the development of the very short lived El Nino of 2011/2012. The bias to predict water temperatures to be warmer than they actually end up.
The development of an El Nino (even weak) is good news for California as the next rainy season should provide some relief from the drought and it may help make the winter of 2014/2015 less severe, however, for many of the claims made by the media in recent weeks to come true this new El Nino has to overcome an overall colder Pacific environment and it would have to buck the recent trend of the models that have over forecasted the strength of El Ninos in the past.