Figure 1 shows the differences between the two methodologies using data from our automated weather station mesonet, a statewide network of environmental monitors. The most significant difference are across western Nebraska where maximum temperatures in July were much warmer that in eastern Nebraska. With dry conditions and some moderate drought across the northern Panhandle, maximum temperatures for more than half of July were in the 95-105°F range.

Most of the accumulated differences across eastern and southern Nebraska occurred in June when temperatures exceeded the 90°F mark for 10 to 20 days, with the highest totals reported across southeastern Nebraska. Unless you know the history of GDD accumulations during from June through August, the numerical values in Figure 1 may not contain enough information to make an informed decision.

If you convert the differences in Figure 1 to percent accumulation difference between the old GDD calculation and one with an unlimited upper base, a more interesting picture occurs. Figure 2 indicates that using the unlimited upper base equation generated 5%-10% greater GDD accumulations during the past 2.5 months across western Nebraska. The range of differences across eastern Nebraska varies from 3% to 7%, with the smaller values occurring across northeastern Nebraska.

In short, the differences between the eastern and western regions of the state in regards to temperature impacts occurred during two distinct time frames.  For eastern Nebraska, much of the blazing heat occurred during the vegetative phase for corn, while western regions experienced their worst heat just prior to pollination through the first half of grain fill.

Outlook for Remainder of August

It does appear that weather models are backing off of excessive heat for the remainder of August, with short-term trends pointing toward below normal temperatures through the end of August. Although a day or two of maximum temperatures in the 90s may impact the western half of the state, most locations will remain in the 80s or lower as the jet stream begins to pull Canadian air masses into the region. This should also increase our opportunities for above normal rainfall, if the models are correct.

The early release of the 30- and 90-day outlooks (Figures 3-6) from the Climate Prediction Center fail to show any moisture trend for the central Plains.  Some above-normal moisture is indicated for the Dakotas, but in the remainder of the Corn Belt there are equal chances for above normal, normal, or below normal precipitation. Temperature forecasts only show a moderate tendency for above normal temperatures during the September-November period for the entire continental United States.