2016 U.S. Heat, Dryness Greatest In Late July, August

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By Drew Lerner

Kansas City, April 21 (World Weather Inc.) – Convincing oceanic and atmospheric data from the equatorial Pacific Ocean and in many other areas around the world are certainly trending quickly away from El Nino and toward La Nina. The demise of El Nino will come quickly in the next few weeks with some eastern equatorial Pacific Ocean surface temperatures to already be near normal in the next couple of weeks. Despite market fears and rather vociferous comments from a few alarmists, the coming summer may not be the disaster chatted about in cyberspace. Oh, it will have some trials and tribulations, but when we get to late August and look back we just might have to say conditions were better than feared.

Everyone has an opinion and that is what makes the world go around. This meteorologist certainly sees La Nina coming on rather quickly during the summer. However, the speed in which the transition evolves from El Nino to La Nina is liable to create some atmospheric confusion and for a few weeks weather will become rather erratic, volatile and difficult to follow, but that will get cleared up just as soon as La Nina conditions get fully established. That complete establishment may come relatively late in the summer and because of that and the fact that planting will likely advance relatively well this spring the impact of developing La Nina may not be as serious as some have suggested.

            Already deviations from past El Nino to La Nina years have been noted with the lack of unusually cool weather so far this spring and a general decrease in surplus rainfall events in the past few weeks. In past episodes of significance the spring seasons were cooler biased and wetter in the heart of the Midwest, in additional to that of the Delta and southeastern states.

Of course, spring is not over and there is still time for change. World Weather, Inc. believes strongly that we have not done all of our homework on the tendencies of La Nina and El Nino. Some scientists have made sweeping generalizations about the behavior of ENSO events which is why in this past year predictions of drought in Australia and New Zealand busted and the behavior of the summer monsoon in India was not quite what it was predicted to be. We need to anticipate similar deviations of what we believe is typical La Nina over the next 18 months. That does not mean that weather this summer will not have a negative        impact on crop production, but it does leave room for a less punishing environment and feared. Only time will tell how this El Nino will differ from those in the past. It is, however, extremely important to realize that there have only been three other well documented strong El Nino to La Nina events since 1950 and that is hardly a good sampling of data. Two of those years, 1972-73 and 1997-98 translated from strong El Nino to strong La Nina over a few short months.

The summer of 1998 was wetter biased from June through August from the northern Plains to the heart of the eastern Midwest with dryness mostly confined to the southern Plains and a part of the southeastern states.

The summer of 1973 was drier than usual in the northern Plains and western Corn Belt, but wetter biased in the lower eastern Midwest. June 1973 was drier biased in the Plains and western Corn Belt with July wetter in many summer crop areas and then August was much drier. In the case of 1998, June was wettest in most summer crop areas and July was wettest in the central Plains and lower Midwest and August was wettest in the northern Midwest and northern Plains with a drier tendency in the lower Midwest and central Plains. These two years may not have looked the same from an El Nino to La Nina translation, but the impact was not tremendously different with both years having no serious deviations from trend yield.

Temperatures in the two summers were also starkly different with the southern Plains, Delta and southeastern states warner than usual in 1998 while cooler than usual in 1973. Temperatures in the northern Plains and upper Midwest were seasonable in 1998 and warm in 1973. So where is the excessive heat that has been chatted about? Mostly wrapped up in years like 1983 and 1988, but those years are not necessarily good matches for 2016.

The third year of strong El Nino to strong La Nina occurred in 1982-84. However, in this case the transition to La Nina did not happen in the same year the El Nino peaked. La Nina actually evolved in the following year, 1984. Huge production cuts did occur in the summer of 1983, but was it really a part of the transition from El Nino to La Nina or was it some other pattern? World Weather, Inc. believes it had to do with another weather pattern that was playing out in the background when El Nino evolved in 1982 and continued in the spring of 1983.  The same kind of anomalous scenario may have played out in 1988 to help induce that drought.

We are totally convinced that anomalous weather is not created by ENSO events alone, but is the interaction of several weather patterns that occur simultaneously that create the big bad drought years. Just because La Nina evolves does not dictate disaster. The best way to look at La Nina is to remember that La Nina takes moisture out of the atmosphere and interjects warmer temperatures. The best forecast of La Nina years is to pay attention to the prevailing weather patterns and take some moisture out of the pattern and warm the atmosphere somewhat and see how that impacts the pattern.

Our forecast for the late spring and summer is based on these tendencies.  We have stated since last August that summer 2016 would be dominated by a warmer and drier weather pattern from Nebraska and Iowa southward to Texas and in a secondary event in the middle and lower Atlantic Coast states. Adding our La Nina principal to the situation we get a worsening bout of dryness in the southwestern and west-central Corn Belt and expanding warmer and drier biased conditions northward to the eastern Dakotas, Minnesota and Wisconsin and east into Illinois. The heart of the driest and warmest conditions should remain in the central and southern Plains and southwestern Corn Belt when La Nina is applied to the pattern

The summer outlook will also be influenced by Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO).  PDO has been strongly positive during the past 18 months of El Nino and that has helped to reinforce a ridge of high pressure on the west coast of North America. PDO will remain positive through the balance of spring and into early summer, but it will lose its intensity. A positive PDO will try to keep some ridge presence over the western parts of North America – especially during the balance of spring and early summer. However, another repeating pattern in the atmosphere will try to bring a ridge into the middle of the country. The conflict in these two patterns is liable to maintain some split jet stream conditions during the next few months. The split pattern will allow the south-central U.S. to become quite warm to hot during the late spring and summer while Canada, the northern U.S. Plains and upper Midwest are impacted by periodic shots of cool air moving into the region from the northwest. The conflict in air masses is likely to translate into a frontal boundary that may lie across the northern Plains and parts of the Midwest in May and especially June inducing more rain. The pattern could be similar to that of 1998.

Over time, PDO will weaken further and will either become neutral or will move into its negative phase. A negative phase of PDO during mid-summer would reinforce a high pressure ridge in the middle of the nation and would closely match the prevailing upper air wind flow pattern that is expected to prevail in the heart of the summer. If PDO turns negative the heat and dryness in the southern Plains will likely expand northward and broaden out to include a larger part of the Midwest and Great Plains. If PDO becomes neutral this summer its influence on weather will become more neutralized and the weak central U.S. ridge of high pressure expected this summer will remain in place allowing some timely rain to fall across the production region in May, June and early July.

The arrival of La Nina this summer will take moisture away from the prevailing pattern and allow extra heat to evolve. World Weather, Inc. believes the only way to get a disastrous drought this summer is if La Nina evolves quickly and PDO becomes strongly negative.             That does not mean summer will be perfectly fine. The dominating summer weather pattern with a weak ridge in the middle of the nation will see to it that the central and southern Plains and west-central and southwestern Corn Belt have enough heat and dryness to stress some crops. La Nina will allow this to expand to the north.

World Weather, Inc. expects May to be warmer than usual in much of the Midwest and Plains while cool conditions impact the far northeastern states and in the Great Basin. The contrast in air masses across the central and western U.S. will promote frequent showers and thunderstorms from the Great Basin into the interior northern Plains and upper Midwest. Dryness will be present in the eastern Midwest and middle and lower Atlantic Coast States and in much of the southern Plains.

June weather will allow a little more cool air into the Great Lakes region and northeastern U.S. while the central and southern Plains, Delta and southeastern states are drier and warmer biased. The contrast in air masses will generate periodic rain in the Midwest, northern Plains and Great Basin. Sufficient rainfall will likely keep Iowa, Illinois and Indiana favorably moist along with the Dakotas and Minnesota. Dry weather in the southern Plains, Delta and southeastern states will be persisting in June resulting in growing moisture deficits and crop stress.

The summer outlook has not changed greatly over that of earlier this year, although we have given the pattern a little more heat and dryness in the upper Midwest and Illinois whereas previous temperatures and rainfall were a little more favorable. The change in the forecast is not great enough to induce a 2012 style drought, but yields will be reduced in the western Corn Belt and in the middle and Southern Atlantic Coast States.

The western U.S. will have a summer of periodic rainfall from both a sufficient monsoon flow and from weather systems moving inland to the Pacific Northwest and northern Rocky Mountains. Places like Idaho, Utah, Nevada, Montana and southern Canada’s Prairies will be included in the wetter and milder temperature regime.

La Nina has also increased the number of tropical cyclones for the summer and that brings a couple of systems into the Gulf of Mexico offering some relief from persistent dryness.

Overall, spring and summer this year will stress crops in the western Corn Belt and Great Plains. Yields will be below trend in many areas from Nebraska and western Iowa to Texas and parts of the Delta. However, favorable production is expected from the eastern Midwest and that should help to keep this summer less threatening to crop production than 2012, but a little more stressful than either that of 1973 or 1998.

World Weather, Inc. forecasts and comments pertaining to present, past and future weather conditions included in this report constitute the corporation’s judgment as of the date of this report and are subject to change without notice. Comments regarding damage or the impact of weather on agricultural and energy as well as comments made regarding the impact of weather on the commodity and financial markets are the explicit opinions of World Weather, Inc. World Weather, Inc. cannot be held responsible for decisions made by users of the Corporation’s information in any business, trade or investment decision.

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