Ag Weather Forum

Outside of some specific areas in the U.S. Corn Belt, the weather this summer has been awfully good. It's been enough to forecast record yields for corn and soybeans from the USDA and close to records from some private forecasts. As we turn the calendar over to September this Sunday, many are turning their attention to harvest preparations and the weather forecast may play into those preparations as well.

The good weather that we have seen throughout most of the Corn Belt can be attributed to a variable upper-air pattern throughout the summer season. We never really saw a locked-in pattern for very long, and usually the opposite would occur after a brief period; meaning some areas saw some hot and dry conditions for a while, then found some cooler weather and some rain, or vice versa.

Some in the West and Texas may argue, correctly, that they've been on the receiving end of some hot and dry conditions this summer, and during the last few weeks, that has certainly been the case.

And for the Upper Midwest, the weather pattern has been the opposite, a little cool and a lot wet. Issues have been noted in both areas. But for the vast majority of the country, variable weather has been good for crop production.

Part of the reason for this variable pattern has been the lack of a driving force in the Pacific Ocean. The La Nina, that was forecast to develop this summer, didn't occur. The cool phase of the El Nino Southern Oscillation has been absent this summer, with the index in what is considered a neutral state. With a lack of a front-seat driver, the other pattern drivers in the proverbial backseat have been taking their turn, which has led to the changing of conditions rather frequently.

But as DTN's Bryce Anderson notes here, https://www.dtnpf.com/…, La Nina looks like it is starting to take shape. It has been close most of the summer, but just did not have the kicker it needed to push it over the edge. But that push is making its way to bring about those cooler conditions in the central Pacific Ocean during the next few weeks.

That sets up this fall with a bigger driver for the weather pattern. What we have seen during developing La Ninas in the fall has been overall drier conditions with above-normal temperatures throughout much of the U.S., but especially the West and Plains. Some more variable conditions are likely to the east, and the month of October may be a big exception to the warm forecast.

In years like 2012 and 2020, two years that DTN is following as part of our package of analogs, note that a burst of cold air came through both years. Models are suggesting this may be the case again this year as well. For those across the north that had slower development, or for others that had late planting or replanting be part of their season, the potential cold shot could quickly end their season.

Precipitation is expected to be below normal for most areas of the country, but specifically the South. That is good news for most areas for harvest, but not for those that have late-developing crops, like those in the Upper Midwest that planted late or needed to replant. It's also not a good sign for those in the southwestern Plains that need rain for winter wheat planting, or those that need to see some soil moisture gains prior to them freezing this winter.

The two caveats would be if La Nina does not become a dominant player in driving global weather, and the other would be the tropics. Models are unsure if La Nina will be weak or strong, though recent runs have suggested a more moderately strong episode this fall and early winter.

Hurricanes become more common during developing La Ninas than other years, mostly due to an increase in disturbances coming off the coast of Africa and reduced upper-level shear, or the change in wind speed and direction and height. A more favorable atmosphere for developing tropical systems atop ocean waters that are already very favorable for development could lead to an increase in tropical potential during the next few months. If they hit the U.S., which is nearly impossible to predict, that could throw some water on the drier forecast a bit.

To find more weather conditions and your local forecast from DTN, head over to https://www.dtnpf.com/…

John Baranick can be reached at john.baranick@dtn.com

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