May 11, 2007

Flooded field in southeast Nebraska; precipitation levels of 5 or more inches were typical from a series of storms that moved through the area May 5-7. (IANR Photo by Brett Hampton)

Pivots May Get a Break This Year

Intense thunderstorm activity erupted once again across the central Plains May 4-6, leading to widespread flooding. Extensive flooding has been reported in Texas, Oklahoma, Kansas, Nebraska, Iowa and South Dakota. Storm event precipitation totals in excess of 5 inches were common, with numerous areas reporting over 7 inches.

Almost every tributary from northeast through southeast Nebraska reported record daily streamflow rates May 5-7. The worst hit basins appear to be the Nemaha, Blue, Platte and Salt, along with the confluence region of the Missouri and Platte. It may take a minimum of a week for river bottom areas to dry out sufficiently to conduct damage assessments.

With the abundance of rain, corn planting delays continue to be problematic. As of May 6, only 40% of the crop was planted, compared to 63% last year and the five-year average of 58%. Expectations are that 60-65% of the crop will have been planted by the May 14 release by the Nebraska Agricultural Statistics Service. Most of the planting activity is expected to be concentrated across the western half of the state where rainfall totals were less than 1.5 inches.

Precipitation in inches in Nebraska May 3-9 (Source: High Plains Regional Climate Center)

What is really needed now is a sustained period of dryness to alleviate future flood potential, as well as firm up soils for farm machinery. During the next 10 days, weather models indicate that the best opportunity for rainfall will occur May 13-14. Depending on how quickly the system moves through, heavy rain may be possible across the southern third of the state, west of Grand Island. Otherwise, dry conditions should prevail and temperatures will be in the 70s to low 80s.

If the weather models are correct, a sustained period of inclement weather could materialize by May 20 and last for several days. This storm could include severe thunderstorms, with the potential of additional flooding, particularly across the southern half of the state. By the time May is over, much of the Plains Region from Texas to North Dakota are projected to have received above normal moisture, with large areas approaching twice their monthly normal.

In addition, a sharp revision has been made to the June-August forecast. Most of the western third of the United States previously had been projected to receive above normal temperatures this summer in previous monthly releases. The most current release indicates that only the desert Southwest should have a good chance of above normal temperatures. In addition, only a small area of central Colorado through Wyoming is placed in the below normal precipitation category for the summer months.

The driving force for our summer weather pattern may well rest with the strengthening drought across the southeastern United States. If the drought persists into the summer, high pressure aloft should continue to pump moisture from the Gulf of Mexico into the central Plains. In addition, this pattern would favor an upper air trough across the Pacific Northwest which should be able to interact with the Gulf moisture and lead to favorable moisture conditions for much of Nebraska during at least the first half of the summer.

Al Dutcher
State Climatologist