Wet field conditions in the United States are a huge concern for many producers and analysts. An active lunar cycle has been generating frequent precipitation events across the contiguous United States since last autumn, and most of the breaks in this pattern have been short in duration. As long as the pattern prevails, rainfall across key U.S. crop areas likely will increase rather than decrease because as seasonal warming evolves the atmosphere can retain greater amounts of moisture that can be rained out in a short period of time through strong to severe thunderstorms.
A part of this lunar cycle (often referred to as the 18-year cycle) is a tendency for cool air to be pooled in Canada and the northern U.S. Plains at the same time warm air builds up across the southern and eastern parts of the nation. The temperature contrast alone will help fuel strong to severe thunderstorms, but moisture streaming northward from the Gulf of Mexico and excessive moisture on and in the ground that will be evaporated periodically into the atmosphere will collide with the cooler air to the north creating very intense thunderstorms and bouts of torrential rainfall. The setup may not be much different from that of 1993 except for the area to be impacted is likely different.
There is also a semblance to 1983, when the United States had an incredibly wet spring in the lower Midwest, southern Plains, Delta and southeastern states that suddenly was followed by chronic dryness and a serious dry finish to the growing season. Many comparisons are being made to these two years, but every year is a little different, and this situation promises to present a new challenge for producers in getting crops planted before it is too late.
Today’s farm technology is so far advanced that given a few days of dry and warm weather there is a good chance that many farmers will get much of their fieldwork completed. There are tractor implements that will plant up to 54 rows of corn in a single pass, and some producers may have more than one planter and can extend that planting rate by running two tractors side by side. Not all producers can afford such equipment, and many do not have the ability to accomplish quite so much in a short period of time, but they are willing to work 24 hours per day and seven days per week if they need to get this crop in the ground as prevent plant dates approach. Prevent plant dates are still off in the distance and there is much of May left ahead that weather can turn around on.
The latest weather pattern is rather threatening. Similar to late January, a pool of relentless cool air appears to be present over parts of Canada. This pattern will send wave after wave of cool air into the central United States this month. That cool air will feed into the heart of the moisture stream and warm air that is present in the central and eastern United States, resulting in frequent storm system development. Rain should fall frequently during the month, and any short-term break in the pattern must be interpreted as an opportunity for farmers to get into their fields to plant despite the lack of optimum conditions to do so.
Two changes will occur this month. First, a weak, but persistent, high-pressure ridge will develop over the southeastern United States that promises to shut off rainfall in that part of the nation and induce much warmer temperatures. The situation in the southeastern states is expected to prevail into June, and possibly July, eventually creating drought-like conditions in that part of the nation.
The strong lunar cycle prevailing across the remainder of the nation will bring frequent weather systems from southwest to northeast across the Great Plains to the western and northern Corn Belt. Those storm systems will have potential to produce impressive rainfall at times, as waves of colder air pool up in Canada and come racing southward into the Great Plains. Starting mid- to late May, some ridge building will begin aloft over the central United States. This ridge of high pressure is not unusual and occurs in most spring seasons. The ridge of high pressure in the central United States will not be strong enough to cut out the dynamics of the lunar cycle, the ridge of high pressure in the southeastern states and the Gulf of Mexico moisture streaming northward, but it will lift the jet stream to the north. Lifting the jet stream northward during the second half of May will help relocate the greatest rainfall from the Delta and parts of the lower Midwest to the Upper Midwest.
A period of welcome drying will impact the Delta and lower Midwest during the second half of this month, while the southeastern states are more significantly dry. Too much moisture in and on the ground in the southeastern Plains, Delta and Tennessee River Basin will feed back into the atmosphere during the warmer days in late May and June, resulting in more showers and thunderstorms. The rain that occurs in the lower Midwest and Delta in late May and June will not be the kind that soaks the region and induces floods. Instead, the situation will favor less frequent and less significant rainfall, and as seasonal warming evolves eventually evaporation rates will outpace the rainfall and the region will start to see much improved planting conditions, albeit the change comes rather late in the season.
In the meantime, the northward shift in the jet stream resulting from weak ridge building in the central United States will force the greatest and most frequent rainfall that had been occurring in the Delta and lower Midwest in late April and early May to the Upper Midwest. This northward shift in significant precipitation could prove to be tragic for producers in the eastern Dakotas, Minnesota, Wisconsin and parts of Iowa, since too much moisture was already present in the early-to-middle part of this spring and some flooding is still lingering from that period. Shifting the jet stream to the northern Plains and Upper Midwest will result in a significant increase in precipitation that will result in more widespread saturated soil and new flooding.
If any area in the United States is going to suffer from too much rain for too long a period of time this spring it likely will be the Upper Midwest, and production may end up cut in that region because of reduced plantings, flood conditions and cooler-than-usual May temperatures.
This period of weather will be an opportunity to challenge farmers with the newest farm equipment. Larger planters, GPS controlled tractors and precision farming will go up against nature to see how much fieldwork can be accomplished in a short period of time and in poor weather conditions. Less corn and more soybean acres planted may result if weather conditions fail to change soon and/or some producers will opt to not plant at all through the prevent plant program.
World Weather, Inc. believes much of this year’s crops will get planted, but production potentials may be lowered because of late seeding and some prevent plant. June and July weather looks to be mostly favorable, but there is some concern for a late summer dry finish. If that happens, soybean production might also be lowered. In the meantime, the southeastern U.S. is still poised for dryness this summer, and that could set the stage for some northwestward shifting dryness late in the summer and on into 2020.