Ag Weather Forum

Forecast maps on Friday, October 6, continue to present a difficult scenario for harvest in the Western Corn Belt through mid-October, and keep in place the wettest harvest season in almost ten years, dating back to 2009. The pattern features upper-level low pressure troughing in the northern Rockies, focused on southern Idaho, while over the eastern half of the continental U.S., a broad, flat upper-level high pressure ridge is indicated. The eastern edge of the trough and the western edge of the ridge meet/collide in the Northern Plains/western Midwest, depending on the day and on the relative intensities of these two features at a particular time.

This is not a promising outlook for harvest weather, especially in the Western Corn Belt, where heavy rainfall has already put the clamps on harvest. On Twitter this past week, I posed the question of how long the harvest delays would be in the Western Corn Belt. Responses from central Nebraska to eastern Iowa were unanimous on a two-week to three-week delay in harvest. I take these producers' opinions seriously, as I've known many of them for a long time.

An additional detail on the pattern that's concerning when it comes to continued rain potential is that the upper-level low in the northern Rockies shows characteristics of being a cutoff low -- split off of the prevailing jet stream flow. In that case, the trough can twirl around in a given region for quite a while. And, that circulation can help drag in moisture to generate precipitation. Also, it doesn't take much extra water vapor in this cooler season to saturate the air and lead to showers.

Will there be a few days of drier weather in the next week? Yes -- however, any drier trend does not mean that harvest has a wide-open scenario from here on. Precipitation forecasts over the next three to six weeks, ending in mid-November, on average have two to three inches liquid equivalent for the majority of the central U.S. And, in this period, the maximum amount of precipitation is in the range of four to six inches. The takeaway message with this forecast is that harvest 2017 still looks like a slower season for the Western Corn Belt.

Bryce Anderson can be reached at bryce.anderson@dtn.com

Follow him on Twitter @BAndersonDTN

(CZ)

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