United States summer crop weather was nearly ideal in June. A huge crop of corn and soybeans could be reaped from the US Midwest this year if conditions were to remain unchanged. However, corn and soybeans are quickly approaching a turning point in which weather will have a huge influence on yields.
Long-term weather trends in the atmosphere have been evolving away from the excessive moisture environment of the past two years and turning toward a drier bias. How dry the US Midwest becomes this year largely will be determined by the tropics. The drier tendency slated for the Corn and Soybean Belt is not a death sentence for crops, despite growing commodity trade hype that the United States is facing some production issues in 2020. The reality is that many summers have had regional dryness and warm temperature biases and yet yields have come out looking very good.
Recent history suggests that it takes a rather extreme year like 2012 to bring along enough crop moisture stress to seriously cut into production potentials. Below-average precipitation during the summer does not mean what it used to mean. Crops that are faced with warmer-than-usual temperatures and below-average precipitation are not destined for failure or even significantly lower yields as long as subsoil moisture is maintained at favorable levels and some periodic showers occur. Much does depend on nighttime temperatures, and the warmer those readings stay in an environment that is a little short on moisture the more likely yields will slip lower.
In the past two growing seasons there were numerous periods of nighttime temperatures near or above 75 degrees F and yet crops performed well, but that was because of the abundance of soil moisture. This year may be different with warmer-than-usual temperatures and below-average precipitation expected to lead to low soil moisture and some crop stress. That stress could be exacerbated by warm nighttime temperatures and a close watch on the scenario is warranted.
July was expected to be dominated by a high-pressure ridge during the early part of the month. The ridge was forecast to generate warmer-than-usual temperatures and restricted rainfall, the combination of which will lead to lower soil moisture as time moves along. The abundance of soil moisture initially during the month will keep relative humidity high at night, and that is why nighttime temperatures may stay above 75 at times, limiting crop stress relief at night, which has proven to be important for protecting crop yields.
Most of the atmospheric trend modeling for July suggested a westward shift in the high-pressure ridge during the second half of the month. This change is important for crop yields in corn and soybean areas because shifting the ridge to the High Plains region and Rocky Mountains introduces a northwesterly flow of air aloft across the Midwest, and that brings in brief bouts of cooler air and a chance for showers. If the high-pressure ridge fails to relocate to the west, dryness and heat stress will quickly become a problem and production potentials will be at risk in late July and August for late corn and soybeans. If the ridge successfully shifts to the west, there “may” be enough rain and cooler air to reduce crop moisture stress and could provide just enough moisture and nighttime cooling to perpetuate a good production year.
Confidence is relatively high that the ridge will shift west for a while, mostly because the mean position of summer high-pressure ridges tends to be in the Great Plains and the western High Plains, which are already hot and dry. Actually, most of the western United States is dry-biased and warm. These conditions are always more supportive of high-pressure ridges and that will be one of the greatest reasons why the ridge will be comfortable to the west outside of the Midwest.
The tropics also will have a huge influence on this year’s corn and soybean production. An active tropical cyclone season is expected with a high number of tropical cyclones expected in August and September with a few possible in late July. These storms should favor the southeastern US coastal waters and most of them will either follow along the coast or move inland. Florida, the Carolinas and Virginia may end up with a high frequency of rain from these tropical weather systems. A couple of tropical cyclones also may reach into the eastern Gulf of Mexico. In most cases, the greatest rainfall associated with the tropical cyclones will be in the southeastern United States. As each of the tropical systems approaches and/or possibly influences the southeastern states, a mini high-pressure ridge is expected to evolve over the Midwest or the main ridge over the Plains and eastern Rocky Mountain region may relocate a little farther to the east. The more frequently tropical systems impact the southeastern US, the higher the potential for the Midwest to trend drier biased, and this will occur mostly in August and September.
If tropical cyclones impact the southeastern US often enough, the more eastward relocation of the high-pressure ridge surely will lead to hotter and drier conditions in the Midwest. Those conditions could significantly stress corn and soybeans, especially if July already has depleted soil moisture by its warm and drier bias.
Producers likely are hoping that the tropical cyclones this late summer will at least occasionally come into the Gulf of Mexico and bring moisture inland through the central Gulf Coast states and ultimately into the Midwest. That would provide timely relief to dryness and reinforce favorable production potentials.
If the tropics are not much of an influence on summer weather, most of the Midwest will experience below-average rainfall and warmer-biased temperatures, but there could be enough periodic rain to support crops well enough to minimize any cut in production. But since the tropics are a huge wildcard and difficult to predict, summer weather in the United States this year may be largely determined by the tropical cyclone pattern. A drier bias is expected, and that will present at least a little more concern about production, but no major drought is expected.
In the meantime, we are closely watching France and some neighboring countries due to expanding dryness and rising temperatures. France already is trending a little too dry. Another region trending too dry is the area from eastern Ukraine into Russia’s southern region. Enough dryness already is occurring in this latter region, raising crop stress for corn, soybeans and sunseed, among other crops. Winter cereal harvesting should go well, however.
China, India and Brazil coarse grain and oilseed production are expected to advance relatively well with little change expected.
Drew Lerner is senior agricultural meteorologist with World Weather, Inc. He may be reached at firstname.lastname@example.org. 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.