Editor's note: February PCT included the feature "El Nino Packs a Wallop," a look at how this winter's weather phenomenon might impact pest management. The following "online extra" is explanation of El Nino.
El Niño is a warming of the central and eastern Pacific Ocean near the equator that happens every two to seven years and lasts six to 18 months. It is measured by noting departures from average sea surface temperatures (SSTs). The El Niño we are experiencing now began in May 2015 and intensified through year-end. In January, NOAA announced that SSTs for the fourth quarter of 2015 had been 2.3°C (36.1°F) warmer than average, tying the temperatures of the strongest El Niño in recorded history (1997-98). It is expected to neutralize by early summer.
El Niño can affect weather conditions around the world, with results ranging from heavy rain to extreme drought, persistent warmth to stubborn cold, and inactive to hyperactive tropical cyclone seasons. In the United States, El Niño typically brings below-average temperatures and above-median precipitation in the South, and above-average temperatures and below-median precipitation in the North.