Figure 1. Departure from normal precipitation in inches for May 1 - May 31. (Maps link to larger versions.)	Figure 2. Departure from normal precipitation in inches for January 1 - June 2. (Source: High Plains Regional Climate Center.)

June 5, 2009

May precipitation across much of eastern Nebraska was below normal, continuing a trend that has been well established since early 2009. In contrast, generous moisture across most of western Nebraska has resulted in above normal levels for 2009 (Figures 1 and 2).

A broad area from south central through northeast Nebraska has received 4.5 to 7.5 inches less precipitation than normal since January 1. The most significant deficits appear to be in Lancaster, Saline, Saunders, and Seward counties. Conversely, areas of western Cherry County south to the Kansas border have had above normal rainfall of 1.5 to 6.0 inches since January 1.

Soil Moisture Declines

Figure 3. This week the National Drought Monitor expanded the area of Abnormally Dry conditions depicted in east central and eastern Nebraska and an area of the Nebraska Panhandle.

Moisture in the upper 2 feet of the soil profile has declined significantly in the past three weeks across eastern Nebraska due to limited precipitation and crop water demands, according to soil moisture monitoring by the High Plains Regional Climate Center. Declines stabilized in the last week in response to recent precipitation.

This week the U.S. Drought Monitor expanded the area of the Corn Belt labeled as abnormally dry (Figure 3), affecting eastern Nebraska, western Iowa, southern Minnesota, South Dakota, and a sliver of the central Nebraska Panhandle. Most of this area led the nation in planting progress for both corn and soybean. (See the June 5, 2009 CropWatch story, USDA: Nebraska Crop Emergence and Condition.)

It is critically important that these areas receive above normal precipitation in the next two weeks to offset increased crop water use. Model projections indicate that average daily water use from the growing corn crop is rapidly approaching normal daily rainfall. Daily crop water use will soon exceed what normally falls and soil moisture reserves will begin to decline under normal conditions.

An active weather pattern predicted for the central Plains during the first half of June could resolve this for the short-term. Current weather models indicate that from June 5 to June 19, only four days (June 9, 13, 16, and 17) will be dry as the northern and southern jets merge over the central U.S. and energize low pressure systems crossing the central Rockies.

Climate Prediction Center 30-day forecasts indicate that the northern plains, including the northern two-thirds of Nebraska, may have below normal temperatures. No precipitation tendencies were shown for Nebraska indicating that there are equal chances for above normal, normal, or below normal precipitation.

The 90-day forecast for June to August indicates a tendency for above normal temperatures in the western half of the Nebraska Panhandle. Elsewhere, equal chances for above normal, normal, or below normal temperatures are forecasted. The entire state is projected to have equal chances for above normal, normal, or below normal precipitation.

Al Dutcher
State Climatologist