Whether everyone knows exactly what it means or not, the 'El Nino' cycle has become a household word in farm country. Most people knows it has a great deal to do with weather, and weather patterns affect both the planting and harvest season, but also the growing season and the potential effect upon markets. Since the El Nino cycle is worldwide, it can affect crop production in Brazil and other South American countries, just as much as it can impact weather conditions here in the U.S.
Most people know the three parts of the cycle- the El Nino, or warm phase, the neutral phase and the La Nina, or cool phase. What these terms refer to is the temperature of sea surface water of the tropical Pacific coast, well out in the Pacific Ocean. A typical cycle extends over several years. Differences in intensity in how much the sea surface temperature varies, how big an area it covers, and exactly where it occurs can play a big role in the effect of these events. It's how it affects atmospheric pressures and air circulation patterns aloft, not the actual temperatures in the Ocean themselves, that are the key.
Jim Newman, a former Purdue University agronomist, now retired, was a key player in interpreting how El Nino cycles worked through the 1960s through the 1990s. He helped introduce these terms to farm folk through print articles and extension talks beginning in the early 1980's. The PIK year, 1983, was a classic example of an El Nino cycle, and made it the teachable moment for many farmers.
This past few months we're coming out of an EL Nino cycle. Although first thought to be the event that would bring hot, dry weather, most climatologists now realize while the El Nino exists, conditions are favorable to perhaps too wet. It's the cool phase, or La Nina cycle, that is now associated with drier periods and or/droughts. Timing of these cycles during the year can make a tremendous difference in how things play out as far as affecting crop growth.
Popular talk right now is that the El Nino cycle has ended, which is apparently true. The same popular story goes that a La Nina will follow, meaning we could be in for a dry summer, as we approach mid-summer.
What those who play out this scenario forget is that there is lag time in these events. In other words, sea surface temperatures don't change and affect atmospheric pressure overnight. Newman discovered that the lag time can last from several weeks to several months. That's why there is often a neutral phase in between.
The upshot is that even if a La Nina will soon follow the end of the El Nino warm phase, the lag time before its effects in the U.S. are felt could be well after this crop completes its critical period, at least for corn. If anything might be in jeopardy at all, it might be the latter half of the reproduction cycle for soybeans.
These comments are not based on comments by a climatologist. Consult the NOAA weather service site for updates. They're simply meant to reinforce an important part of the cycle Newman emphasized during his career- these developments can happen over time. A lag phase is nearly always part of the equation. Some feeding their hype into the popular press to warn of an impending drought seem to have forgotten this principle.