El Nino is Growing Stronger. What Does It Mean For Us?

El Nino
El Nino Jet Stream Pattern | Image by www.washingtonpost.com

There has been some talk lately about the phenomenon called El Nino. All indications point to it getting stronger and stronger (possibly the strongest ever) so as to control what our winter of 2015-2016 will look like. Let’s start with a good definition of El Nino. Wait a minute! I explained that in my column published September 16, 2013. It was titled “Whose Fault Is It? Could It Be El Nino, La Nina, Or Even La Nada”?

Sea Surface Temperatures As Of 8/18/15 | Image by NOAA
Sea Surface Temperatures As Of 8/18/15 | Image by NOAA

Here is the definition that I used in that column: El Nino is defined as a warm water current (shown in red/orange) that appears annually, around Christmastime, along the coasts of Ecuador and Peru. The name El Nino means the boy child and refers to the “Christ Child” who’s birthday is celebrated in December when the warm water pool extends itself closer to the South American coast. It was first discovered or noted by the fisherman who found warmer water where they usually would catch fish. The above chart shows the sea surface temperatures in degrees Celsius and you can easily see that the area in red is quite widespread. That indicates a very large area of ocean water that is getting even warmer and spreading out.

Jet Stream Position El Nino Or La Nina | Image by NOAA via slideplayer.com
Jet Stream Position El Nino Or La Nina | Image by NOAA via slideplayer.com

You might ask: How does El Nino actually control the winter weather pattern? The answer is quite simple. The warm water pool in the Pacific Ocean deflects the Jet Stream so as to keep us in the warm sector and in most cases the dry sector also.

The Climate Prediction Center, the National Centers for Environmental Prediction (NCEP),the National Oceanic and Atmospheric Administration (NOAA)- the National Weather Service (NWS) and the International Research Institute for Climate and Study collectively studied the various computer models and the latest available hard data and issued a formal “El Nino/Southern Oscillation (ENSO) Diagnostic Discussion.” The synopsis of their results is much easier to understand than the detailed version. They stated “There is a greater than 90% chance that El Nino will continue through Northern Hemisphere winter 2015-2016, and around an 85% chance it will last into early spring 2016.

90-Day Temperature Outlook | Image by NOAA
90-Day Temperature Outlook | Image by NOAA

Let’s take a look at the NOAA 90-day Extended forecasts. The Temperature outlook for October, November and December 2015 shows the temperatures for the Pacific Northwest from extreme Northern California through Oregon and Washington are expected to be above normal values.

90-Day Precipitation Outlook | Image by NOAA
90-Day Precipitation Outlook | Image by NOAA

The Precipitation outlook for the period October, November and December 2015 shows the precipitation, including rain and melted snow, will be below normal. So if we put the data from the two outlooks together it can be said that that 90-day period will be warmer and drier than normal. More to the point, it is a strong indication that the drought will continue due to warmer than normal temperatures which would mean another winter with below normal snowpack and not enough water in the spring for the reservoirs.

An article in the June 2015 issue of the Bulletin of the American Meteorological Society titled “Understanding ENSO Diversity” reveals that there are different types of of El Nino and that they have identified. ” To better understand ENSO diversity, several indices have been introduced to identify different event types, with emphasis on the warm (El Nino) ENSO phase. Indices have been constructed from (sea surface temperature) SST (indices a-d), subsurface ocean temperature (index e), sea surface salinity (index f), or outgoing longwave radiation anomaly information index (index g).” The best way to understand that is to know there are 7 indices which use various methods to determine the type of El Nino and what kind of weather pattern it will produce. The more we learn about how El Nino, La Nina and even La Nada work the better we can forecast them in advance and know what kind of weather to be prepared to experience.

Let me know what you would like me to talk about or explain. You can comment below or email me at: [email protected].

Tim Chuey is a Member of the American Meteorological Society and the National Weather Association and has been Awarded Seals of Approval for television weathercasting from both organizations.

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