Will a La Nina Winter Return?

La Nina La Nina, oh where art thou La Nina. While many people would have hoped La Nina was in our rear view mirror, after experiencing a dismal winter and an even worse Spring, it looks like we won't be able to drive fast enough away from her. The Climate Prediction Center is the major government body in the US that predicts our ENSO cycle (El Nino Southern Oscillation) and they have just recently posted a La Nina watch for this upcoming winter. So if you didn't enjoy this past winter or Spring, you may consider taking a nice long trip to Mexico for a break or two.

For those of you who would like to know a little more about La Nina, read on

La Nina is declared when the Sea Surface Temperature in the Central and Eastern Pacific averages .5 degrees Celcius below normal for 3 consecutive 3 month intervals. Here is a graphic that I hope explains this more.

This graphic shows the last La Nina we went through this Winter and Spring. The declaration of a La Nina occurs with temperatures taken from the 3.4 region shown in the 2nd box above. I'm not sure why it has to be this region but I know it is.

These are the regions here with the 1+2 box nearest the South American Continent.

You can see in June and into July we we starting to just average positive sea temperatures and now in August we have retreated back to negative anomalies. Model projections that are run by the Climate Prediction Center as well as many other agencies around the world are beginning to show the return of La Nina this winter or we enter into a Neutral phase, between El Nino and La Nina.

The average of these model runs is shows to hover near neutral conditions and not "double-dip" to La Nina. But if current conditions continue, I wouldn't be surprised to see the average of these models continue to inch closer to La Nina conditions. The CPC's own model is also run numerous times.

Their's clearly shows a double-dip La Nina scenario predicted.

While this last winter wasn't the Snowmaggedon projected by many media outlets, La Nina winters do typically give Washington cooler and wetter weather patterns. I will be anxious to see what the next outlook says.

(How La Nina forms: Trade winds in the tropics move from the east to the west, contrary to here in the mid latitude areas where the winds move from West to East. During a La Nina episode these trade winds are strong and move warm ocean waters on the surface of the Pacific to the West. This brings upwelling to the eastern Pacific (cool, deep ocean water moves up) and this is why we register colder sea surface temperatures. The atmosphere and it's circulations are affected by this surface temperature movement in a variety of different ways and current research is still being done today on how these changes affect weather in Washington and all along the West Coast. It is a challenging research area since the period of oscillations are so large and we have only approximately 60 years of La Nina/El Nino records)