Figure 1. July 8 Drought Monitor map for Nebraska shows slight decrease in drought area.

There is no doubt that June was exceptionally wet across the eastern three-fourths of the state.  National Weather Service cooperative observer reports indicate 9-15 inches of moisture fell across northeast Nebraska, with the central third of the state receiving 6-10 inches. East central, southeast, southwest, and west central Nebraska reported 3-7 inches of moisture.  The Panhandle region was the driest area with 2-5 inches of moisture reported.

Considering that June normally brings about 4 inches of moisture to eastern Nebraska and about 3 inches to western Nebraska, precipitation across the eastern three-fourths of the state averaged 200%- 400% of normal.  In fact, the greatest monthly June precipitation total was 16.76 inches, recorded by a NeRAIN observer in the Hubbard area.  To place this value in context, 60% of normal annual precipitation fell during  June at Hubbard.

All of the consternation about the lack of moisture during the winter and early spring has now become a distant memory. There has been a substantial shrinkage of the drought signature across Nebraska during the past 45 days. On the current U.S. Drought Monitor, drought across eastern and central Nebraska and all traces of extreme (D3) and exceptional (D4) drought across the state have been eliminated.

Unfortunately, most of the June moisture was accompanied by severe wind and hail that brought widespread crop and infrastructure damage.  Areas of the state that have escaped wind and hail damage are beginning to enter the critical corn reproductive phase.  As of July 6, 8% of the Nebraska corn crop had tasseled, which should easily reach 75% by July 17.

Short-term models indicate cooler than normal temperatures are likely through June 18, with highs consistently in the 70s and 80s.  High temperatures July 19-25 are projected to return to the upper 80s to mid 90s. Growing degree day units are running 60-180 units behind normal across the western half of Nebraska for the past 60 days, while GDD units are within plus or minus 60 units from normal in the eastern half.

It is too early to complete a risk analysis in regards to freeze susceptibility, but the current thought is that the Dakotas, Minnesota, Wisconsin, and Michigan currently have the highest hard freeze (< 28°F) risk. If temperatures average more than 2°F below normal for the next 45 days, extreme northern Iowa and Nebraska would likely see their hard freeze risk rise above 50%.  A detailed freeze risk analysis will be performed (if needed) during the second half of August and the results will be presented in the late August edition of CropWatch.

Extreme heat during pollination appears unlikely for at least three-fourths of the corn acreage in Nebraska.  However, if the 90s stick around through early August and precipitation during this period remains below normal, replanted corn acreage could be impacted by pollination issues.  The greatest yield threat for most corn producers during the next two weeks will be from thunderstorms.

Models are having difficulty resolving the timing of individual precipitation events and how much moisture they will provide.  Precipitation is expected this weekend, with drier conditions developing much of next week.  The summer monsoon season in the southwestern U.S. is projected to increase over the next two weeks and could translate into active weather for western Nebraska July 19-30.

Al Dutcher
UNL State Climatologist