The weekly Crop Progress report is mostly the work of Extension and FSA employees, at the least the data collection part. They report local crop conditions to state USDA offices, mostly on Monday morning, who in-turn tally those numbers and pass them along to Washington, D.C. for compilation and release on Monday afternoon. Work at the University of Illinois shows a strong relationship between the end-of-season crop condition ratings and crop yield, however, agricultural economist Scott Irwin says that doesn't hold so well for the rest of the season

The first corn rating of the season, released just after Memorial Day, wasn't good. The crop had been cold and wet. It showed up, or in this case didn't show up, in the good and excellent categories USDA NASS uses. Those are the two grades the U of I economist say correlate. The math works like this; the first corn condition rating was 65% good or excellent, minus 8 points for the average drop to the end of the season rating, which brings you to 57 percent

If you do, in about mid-July you can use the math in the farmdocDaily article to forward calculate the national average yield for corn; mid-August for soybean.