Shadows Of 1983 Lurking For 2016 U.S. Summer Weather
By Drew Lerner
Kansas City, December 22 (World Weather Inc.) – El Nino continues to be in a steady state of great strength and will remain at this plateau for a few more weeks before weakening accelerates in the heart of the Northern Hemisphere winter season. Only then, in the dead of winter, will a clearer signal over the fate of El Nino and the prospects for La Nina begin to emerge. But, long before the prospects of La Nina were circulating around in the media this autumn there was some evidence of a drier summer in the lower U.S. Midwest, Delta, southeastern states and southern Plains for 2016. The drier and warmer potential associated with La Nina (if it occurs) will not show itself for quite a while, especially if La Nina does not evolve until late in 2016. If La Nina is slow in evolving, as World Weather, Inc. believes, the odds will be high of a cool and wet spring in key U.S. crop areas. The drier and warmer tendencies will likely come along a little later in the year in a manner similar to 1980 and especially 1983. The combination of late winter and spring wetness and summer dryness may become reminiscent of 1983 and might just drive commodity trade to higher levels of volatility for a while in 2016 because of the similarities to 1983 and the potential impact that a cool, wet, spring and dry summer might have on agriculture.
Late autumn and early winter weather conditions are evolving in a mostly typical El Nino manner this year. Drought is prevailing in South Africa while southern Brazil deals with torrential rain and northern Brazil experiences – what seems like – very unusual erratic rainfall. Drought in Southeast Asia has recently broken – at least temporarily and the U.S. is in the midst of a very active jet stream bringing frequent storms to portions of the nation. All of this is not unusual for typical El Nino years, but it does raise a question as to where we are going from here?
The 2015 El Nino has been closely paralleling that of 1997-98 and if the trend prevails through winter and into spring some exceptionally wet weather will impact the U.S. Delta, southeastern Plains and lower Midwest. There will also be excessive moisture at times in parts of California and the southeastern United States while the north-central Plains and a part of the northern Midwest are unusually warm and somewhat drier biased.
The most striking characteristic of the 1997-98 El Nino was the constant barrage of strong storms moving from the southwestern United States into the heart of the Midwest, Delta and Tennessee River Basin, just like the weather of recent weeks. The stormy weather continued until the 1998 El Nino started transitioning aggressively into La Nina and then patterns changed greatly.
There has been quite a bit of debate in recent weeks among meteorologists over the prospects of La Nina in 2016. The majority of moderately strong to strong El Nino events in the past were followed by La Nina. Speeds in which the transition from El Nino to La Nina takes place had been theorized to have some influence on the significance of dryness that evolves in U.S. crop areas during the spring and summer seasons following El Nino’s peak intensity. However, more recent in-depth studies by World Weather, Inc. reveal that the summer weather following El Nino is dictated more by prevailing weather patterns playing out in the background behind the El Nino phenomenon than is influenced by transitioning into La Nina.
Not every El Nino was followed by La Nina – at least not in the same growing season and the impact of La Nina versus neutral ENSO conditions in the summer is extremely interesting and when adding those possible influences on the 18-year cycle presents summer 2016 with some interesting parallel to 1983 and 1980.
Computer forecast models – programmed by some of the sharpest meteorologists and climatologists that ever lived – are not very good at predicting El Nino and La Nina events very far in advance. The main reason for that is that most scientists do not yet understand what makes the ocean temperatures change in El Nino and La Nina events. Once we understand that part of the mechanics in our ocean temperature trends, long range forecasting will take a giant leap forward. For now, some of the best ocean temperature modeling programs do a good job predicting sea surface temperature changes out about four months, but four months from now will be March and that does not help us much with the long range forecast for summer 2016. Scientists will know much more in March about the fate of ocean temperature trends and the prospects for La Nina because computer forecasts will be projecting their expectations for ocean temperatures out into mid-summer at that time.
There are only three potentials scenarios. The first scenario might be that El Nino prevails through the summer of 2016, but this is highly unlikely. The second scenario would be the evolution of La Nina conditions and the third would be the potential that El Nino dissipates and neutral ENSO conditions prevail this summer. Each of these solutions would have a different impact on 2016 weather and crop development potential.
World Weather, Inc. looked at all of the significant El Nino events of the past and split the years into two groups. The first requirement was that El Nino had to be of strong intensity in the first quarter of the calendar year. Then we separated the years into two groupings. The first group included years in which a transition from El Nino to La Nina occurred between January and August and the second grouping was for years in which El Nino dissipated in the January through August period, but only neutral ENSO conditions were present in this second grouping. We did not care whether La Nina evolved in the fourth calendar quarter or in the following year. We then looked at temperatures and precipitation anomalies in that summer. The discoveries were very interesting.
- El Nino to La Nina years had very warm growing seasons with temperatures in the May through August period averaging notably above normal
- In contrast, those years in which neutral ENSO conditions followed the strong El Nino, spring and summer temperatures tended to be cooler with the April, May and June periods most notably cooler biased
- El Nino to La Nina years tended to be a little drier than usual in the southern Plains, Delta, lower Midwest and southeastern states during the May through August period
- However, El Nino to Neutral ENSO years were also drier biased in some important crop areas; including the central and southern Plains and western and central Corn Belt while parts of the southeastern states were wetter biased instead of drier biased in the El Nino to La Nina years
The study was of great interest because of a few factors. First it did not seem to matter whether there was a La Nina event or not because there was a drier tendency in parts of the southern Plains and lower Midwest in both scenarios. The biggest difference in those drier years was dictated by temperatures with the La Nina years having a warmer bias to accompany the below average precipitation resulting in a greater struggle for crop moisture at times.
The El Nino to Neutral ENSO years rarely had serious dryness issues because of the cooler bias in spring temperatures that helped conserve soil moisture for use later in the growing season when dryness was still prevailing. The impacts of summer weather patterns that are a little drier biased on crop production is directly tied to the temperature anomalies which is why the Neutral ENSO years usually yielded better than the El Nino to La Nina years.
So what are the prospects of having a cool spring and seeing the El Nino to Neutral ENSO scenario play out? World Weather, Inc. believes the prospects are relatively good this year for two reasons. First, there seems to be a general lack of cooler than usual water around in the oceans right now. The lack of cool water in the Pacific Ocean Basin should make it more difficult for La Nina to evolve because it will take a huge amount of cold water to neutralize this El Nino and still leave time and energy to continue the cooling trend for La Nina before the Northern Hemisphere summer season is over. World Weather, Inc. believes La Nina will evolve, but probably not in the time period required to have a big impact on summer crop development.
The second reason why a cooler biased spring is possible this year may lie in the Arctic Oscillation. El Nino events generate quite a bit of warmth in North America during the late autumn and winter months. This is mostly true for Canada and the northern U.S. However, this year’s exceptional warmth is also being controlled by a strongly positive Arctic Oscillation (AO). Strong AO events usually result in well above average temperatures in the heart of North America with below average precipitation in the northern Plains and upper Midwest. This particular bout of strongly positive AO began around November 1 making this a two-month event so far.
AO events of significance usually do no last for a quick couple of months and then abate. Normally, the strongly positive AO will last around four months. There have been longer and shorter periods of strongly positive Arctic Oscillation, but for the sake of argument we are going to use the average of four months. That implies strongly positive AO conditions will prevail through February before there is much chance for change. Remember that positive AO and El Nino both promote warmer than usual temperatures in North America and many other areas in the Northern Hemisphere and the longer these conditions last the deeper we will get into winter without a serious change in temperature anomalies.
AO is an oscillator and it will move from its positive phase to its negative phase and back again over a several month period. The odds are very strong that the strongly positive AO may become weaker in late winter or early spring. The oscillation may change phases eventually and a negative AO usually translates into colder than usual weather in central North America from Canada into the heart of the U.S.
A negative AO in the spring would help to further support the potential for cooler than usual conditions in North America during spring 2016 and that is a similar signal to that of the El Nino to Neutral ENSO years which resulted in the April, May and June periods being colder than usual in key U.S. crop areas. In other words, the trend in AO right now lends support for a change toward cooler biased conditions in the spring when El Nino should be transitioning to neutral ENSO.
In addition to the El Nino to Neutral ENSO years producing a cooler than usual bias and the same for negatively phased AO events, there is also the 18-year cycle which does promote a cooler bias in the southern United States while a warm bias continues in the northern states. All three of these weather events seem to be pointing to the cooler spring.
In the meantime, the parallel with the 1997-98 El Nino event and this year’s autumn weather has been significant enough that we must perpetuate the wet bias into spring even though northern portions of the Midwest will likely not be as wet as they have been in recent weeks and months.
So far in our discussion, we have illustrated similarities in this year’s weather pattern that have led to a wet and cool spring in the past. El Nino has already generated some impressive precipitation events and much of the central Midwest and Delta are saturated with moisture. World Weather, Inc believes El Nino will remain strong enough for long enough into the spring to maintain very wet field conditions. Wet weather in March will delay southern U.S. spring plantings and that is certainly not hard to imagine if temperatures are cool and rainfall abundant. April would likely create similar delays in fieldwork across the lower Midwest.
Drying out the weather pattern will be largely determined by the strength of El Nino. The stronger the phenomenon remains in the spring the longer it will take for the wet weather pattern to break down and greater delays in spring planting might evolve.
The wet spring, if it occurs, will culminate several months of wet-biased weather in a part of the southeastern Plains, lower Midwest and Delta. Prolonged periods of wet weather like that are often followed by notable periods of drier weather and if that evolves in 2016 it might just take place during the summer. The flip flop in weather trends over the growing season may be reminiscent of the 1983 drought.
The 1983 drought was not La Nina driven since La Nina did not evolve until 1984. However, as we stated above it does not seem to matter 
whether there is a La Nina or not, since both the El Nino to La Nina years and the El Nino to neutral ENSO years both produced some drier biased conditions. As noted above, there may be more dryness on the charts above for the neutral ENSO year than in the La Nina episodes. However, temperatures trend to be cooler bias in the neutral ENSO years making it less likely for a serious dryness issue from evolving during the spring or early summer.
With that said one of the repeating cycle years for 2016 will be 1980. In that year there was quite a summer heat wave and dryness problem in the southern Plains, lower Midwest and Delta – not much different from that of 1983. That raises the potential for a cool wet spring to translate into a drier summer like that of 1983. 1983 was one of the stronger drought years that impacted U.S. production and if there is any parallel to that year in 2016 U.S. producers should be watching for volatility in the market trade and additional worry over the prospects for dryness in 2016.
One last comment needs to be made and that is that ridge building will be present in the central United States during the summer 2016 and La Nina – if one occurs – would have the potential to intensify the ridge bringing greater concern over heat and dryness.
The bottom line to this discussion is that there are a couple of interesting scenarios that the weather may take this year. Resolving the mystery over sea surface temperatures will dictate the presence of La Nina or not. If there is a La Nina the level of concern over 2016 crop production will rise greatly because of the potential for not only being drier biased in parts of the key crop region, but warm too. For now, World Weather, Inc. is looking for neutral ENSO conditions during the summer 2016, but the situation will be closely monitored with a more educated guess for summer weather coming in March after a better determination of La Nina prospects is made. The official World Weather, Inc. outlook does not change much from that of our August forecast for 2016 in which we suggested a wet spring and drier summer in 2016. The significance of these anomalies will not be fully known until we get into the growing season.
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