Ag Weather Forum

By now you have probably memorized USDA's corn production figures from last week's Ag Outlook Forum. "Record Corn Production Projected on Extremely Higher Yields" was the headline in Katie Micik's article. To reiterate--USDA projects corn planted acreage of 99 million acres, yield of 163.6 bushels per acre, and production of 14.5 Billion bushels. There were not one but two detailed power points spotlighting how important summer weather is to yields, discounting the dry soils that dominated much of the central US until recently, and bolstering this lofty projection.

In one presentation, USDA meteorologist Brad Rippey detailed the impact of the Drought of 2012 on crops. He also showed a comparison slide of Iowa corn production that compared Drought Monitor values in mid-February in Iowa during from 2000-2013 with yields in those years. His point was to show that in years with mid-February drought in Iowa, the overall effect on final corn yield is negligible. The years used in this conclusion were: 2000 (144 bushels/acre), 2003 (157 bushels/acre), and 2006 (166 bushels/acre).

Another even more detailed rundown featured research by USDA ag economist Paul Westcott, who is with the Global Agricultural Markets Branch, Market and Trade Economics Division. This discussion also featured the idea that late-spring and summer weather -- especially July temperature and precipitation -- is the real driver behind final corn yield, not antecedent conditions (like mid to late winter drought).

However, there was one feature missing in both these presentations--and that was the actual forecast for this year. As I viewed the power points from the Ag Outlook Forum website, it seemed that Brad Rippey's presentation was geared to support the research that Paul Westcott presented as opposed to really looking forward to the weather trends that we might see this year. That was different that Mr. Rippey's presentation a year ago--when he cited forecast features that might come into play and affect crop yields.

And, that's where the glitch comes in when I view these presentations. Because I don't know if the forecast truly supports the 163 bushels per acre yield that USDA is presenting. Here's why:

Forecast weather models, as I have been showing in presentations this winter (and I presume other weather presentations have as well), are consistently calling for a neutral Pacific equator trend this coming spring and summer (La Nada, for those of you who were in Missouri Valley or Spencer Iowa, or in Baldwin or Cumberland Wisconsin last week.) That doesn't sound like a bad thing, with no threat from either an extreme warm trend in the Pacific (El Nino) or a cool trend (La Nina). However, my colleague Jeff Johnson took a look at the spring and summer temperature and precipitation trends when the Pacific is in neutral following a La Nina episode (like we have had the last 2-3 years). And, the result of Jeff's study from these comparison years is that temperatures are generally mild--running normal to about 1 degree Fahrenheit below normal--throughout the spring and summer in the Corn Belt. However, precipitation is near to below normal during the spring, and generally below normal in the summer (June/July/August).

That's where the issue comes in regarding precipitation. Because if you apply the USDA stance that summertime weather trends are the true drivers behind yield (and I think we all agree on that), then how does a summer with below-normal precipitation support the call for the second-largest yield on record?

That's my question.

Bryce

Twitter @BAndersonDTN

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