There's a 50 percent chance that El Niño conditions will develop during the second half of 2012, the National Weather Service announced today (June 7).
When El Niño conditions are in place, water temperatures in the tropical Pacific are warmer than normal, which has far-reaching consequences for climate and weather patterns around the globe.
The prediction follows the end of a La Niña cycle — the "opposite" of El Niño, with cooler-than-average surface waters — which has prevailed for much of the last two years. This La Niña cycle had a substantial impact on the extreme winter weather of 2010-2011, as well as last spring's terrible tornado season. La Niña conditions may have helped bring about some of the massive snows that blanketed much of the northern United States last winter, but its waning may actually have been the culprit in ramping up the tornado season.
ENSO-neutral conditions have been in place since May (ENSO refers to the El Niño-La Niña climate cycle), which the National Oceanic and Atmospheric Administration expects to last throughout the summer. After September, the models scientists use to make predictions diverge, with roughly half predicting continued neutral conditions and half favoring continued warming associated with El Niño.
The low-level trade winds and convection over the central equatorial Pacific were near average during May, measures that indicate neutral conditions.
If El Niño conditions develop, the northern United States could be in for a warmer and drier winter than average, while the Southwest and Southeast could find itself with more rain than usual.
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