El Nino, La Nina, and.... La Nada????

Odds are you've heard of El Nino and La Nina (the abnormal warming and cooling of the eastern equatorial Pacific waters, respectively), especially if you've been reading my blog.  This past winter, the Pacific Ocean was in a very strong La Nina, which helped to produce the heavy snows and cold winter across the U.S., along with the severe drought conditions over the southern U.S. this year.

Late last winter, the strong La Nina that helped to ravage the nation early last winter finally came to an end and the Equatorial Pacific waters returned to their normal temperatures.  But this presents it's own issues.  Usually, when a La Nina period ends, an El Nino period begins, even if it's just a weak one, and vise versa.  So the waters off the coast of western South America never stay normal for very long.  But this year, we are seeing an unusually long period of near normal water temperatures.  In fact, one scientist, Bill Patzert, a climatologist and oceanographer at NASA's Jet Propulsion Laboratory has coined the term "La Nada" to describe this period of normalcy.

The latest satellite data of Pacific Ocean sea surface heights from the NASA/European Ocean Surface Topography Mission/Jason-2 satellite show near-normal conditions in the equatorial Pacific. The image is based on the average of 10 days of data centered on June 18, 2011. Higher (warmer) than normal sea surface heights are indicated by yellows and reds, while lower (cooler) than normal sea surface heights are depicted in blues and purples. Green indicates near-normal conditions. (Credit: NASA/JPL Ocean Surface Topography Team)

The problem lies in climate forecasting.  A "La Nada" period brings with it a large amount of uncertainty in the forecasts.  Many scientists believe that a "La Nada" period will bring about "normal" weather conditions, however, previous similar "La Nada" periods have delivered unruly jet streams and wild weather swings, going from one extreme to the next.  And we actually saw this!  As the La Nina ended and "La Nada" began, the jet stream was able to swing back and forth across the U.S. wildly and helped to bring the blizzards to the Midwest, South, and Northeast, along with the tornadic storms across the South and Tornado Alley. 

However, some climatologists are wondering if another warm El Nino pattern will soon emerge - which would be great timing for the United States!  If an El Nino pattern were to develop this summer, much needed rains would likely come to the drought and wildfire stricken southern U.S.  Plus, a late summer El Nino pattern also dampens the hurricane season in the Atlantic, which peaks in late August & September.  Thus, it would bring much needed rain to the South along with a mild hurricane season!

Climatologist and Oceanographers will continue to monitor the progress of the "La Nada" and watch for signs of an emerging El Nino or a returning La Nina.  Until then, try to enjoy your summer!