August weather was a bit punishing to late corn and especially soybean production in the heart of the Midwest as a period of dryness was amplified by warmer temperatures. A steady decline in soybean conditions occurred in the second half of August. That, in combination with a growing need for soybeans in China, helped to stimulate an old-fashion weather market.
September is not expected to bring much relief to dryness in the central United States, which may have a diminishing impact on soybean production for this year. But with La Niña evolving it could leave central US moisture deficits in place for a prolonged period of time.
Early summer dryness that developed rather innocently and quietly in a small part of central Iowa grew into a drought during the summer. It became notably significant in late August when dry weather expanded across a larger part of the Midwest. The majority of crop areas from Indiana to southeastern South Dakota, much of Nebraska and northern and eastern Kansas ended the month with much less than half of normal precipitation for the month of August. Topsoil moisture became depleted over much of the region, and because of periods of warm and dry weather earlier in the summer some areas already had low subsoil moisture, as well.
Crop stress in late August then became rather significant for not only central Iowa, but many areas from Nebraska and eastern Kansas to central and northern Illinois. That is when crop ratings started to fall. Moisture deficits for summer have been most impressive in central and interior western Iowa where 6 inches to more than 8 inches of moisture were lost during the growing season. That moisture deficit must be replaced prior to next spring to reduce farmer anxiety over possible moisture shortages and crop stress again in 2021.
Moisture deficits were moderate over a larger part of the Midwest from southern Michigan and northwestern Ohio through northern Indiana to a part of eastern Iowa and also in portions of eastern Nebraska. Most of these areas were not nearly as dry as central and interior western Iowa, but moisture deficits of 2 inches to 6 inches did evolve.
Usually, the eastern Midwest does not have a difficult time getting moisture shortages relieved during the autumn and winter because the region is normally sufficiently moist and cool for the deficits to be eliminated. The same is expected for this autumn and winter. However, the situation in the western Corn Belt may be a little different.
Long-term weather trends are going to restrict rainfall in the western Corn Belt and a part of the northern and central Great Plains this autumn and winter. That would not be a big problem in most years since the cooler months do not usually instill much demand for substantial moisture and the summer crops are usually harvested in the autumn, of course. However, the problem this year is associated with La Niña.
A La Niña event is getting underway now and will prevail through the winter season. La Niña is a phenomenon that occurs infrequently, like El Niño, but occurs when eastern equatorial Pacific Ocean surface temperatures trend cooler than usual. The cooler weather leads to many changes in atmospheric conditions around the world, including a colder and drier winter across the Canada Prairies and the northwestern and north-central parts of the United States. There is also a tendency for late autumn precipitation in the US central and southern Plains and western Corn Belt to be lighter than usual. If La Niña prevails into early spring the same anomalous weather trend would occur into the start of the growing season.
If this La Niña event is like many of those in the past (and they are all somewhat different) there is a relatively good chance that the driest areas of the western Corn Belt, including Iowa, may not get a full replenishment of moisture prior to spring. If that ends up being true there will be some concern over possible returning dryness in 2021 that could harm corn and soybean production for a second year in a row. Obviously, there are many months of weather that lie ahead and it would be irresponsible to suggest that today’s 8-inch moisture deficit in parts of central Iowa would still be there next spring, but it does warrant a close monitoring since that dryness might lead to some increased potential for moisture shortages during times of drier and warmer biased weather in 2021.
Another area in the world that needs to be watched for the same reason is the Black Sea region. This area does not usually have a strong tie toward poor winter precipitation during La Niña events, but there is a definite tendency for western and central Russia to be bothered by less-than-usual rainfall during the growing season in a La Niña year. Today, moisture deficits in in the area from the lower Danube River Basin of southeastern Europe through southern and eastern Ukraine to Kazakhstan, including Russia’s Southern Region, are huge. Dryness in these areas has not just been from this year’s poor rainfall. For the past three years summer weather has generated much less-than-usual rainfall in this same region and all three years ended up quite dry like they are today.
Moisture deficits in the Black Sea region must be eliminated over the autumn and winter this year just in case La Niña decides to prevail through the summer of 2021. World Weather, Inc. believes that La Niña temporarily will break down in the spring and summer next year allowing for a little more “normal” rainfall to possibly evolve, but La Niña-like conditions likely will still be around.
A slight tendency toward La Niña can lead to another struggle for abundant moisture in 2021, and if the moisture deficits in this dry area of the world are not adequately dealt with this autumn and winter there may be yet another year of moisture stress and production issues.
In the meantime, La Niña should have a positive impact on eastern Australia summer crops like cotton, sorghum and sugarcane in 2020-21 when rainfall should be much more abundant. Weather conditions in eastern Australia have been anything but normal in the past several years, and if more rain falls there would be a tremendous rush to plant more aggressively in hopes of reaping better harvests. That hope for greater rainfall and better crop development was also present for winter wheat and barley in Queensland, Australia, for this current season, but in late August those crops were burned by frost and freezes and the region continues too dry to support a dryland crop that is usually reproducing in the first half of September. Queensland’s dryness will cut into winter wheat and barley production for the nation, but other areas are still poised to yield well — at least for now.