March 30, 2007

Climate events since last August have led to a large disparity between the have’s and have-not’s across Nebraska in terms of drought conditions, soil moisture recharge and planting prospects. An active weather pattern forecasted to continue for the next few weeks will only add to the uncertainty.

The eastern two-thirds of the state has received beneficial moisture, almost to the point of excess, since the monsoon kicked in last August. In August, record to near record rainfall occurred across the central Platte River valley only to be followed by above normal moisture during September. Dry conditions in October and November allowed producers to harvest crops.

Fears of short-term dryness were quickly squelched in December when every weather recording site in the eastern two-thirds of the state recorded the wettest to third wettest December dating back to the 1890s. Near normal moisture fell in January, only to be followed by robust precipitation in February. March moisture has been close to normal, but will likely end with a bang as heavy precipitation is projected for the final days.

Unfortunately, the western third of the state missed out on the ample August and December precipitation, with moisture during the last three months coming in slightly below normal. Soil moisture monitoring sites indicate a continued decrease in stored moisture in the top four feet of the profile. Most locations have 1-2 inches of available moisture in the profile.

Soil moisture conditions across the eastern two-thirds of the state have benefited from the generous moisture contributions since last August. Every soil moisture monitoring site has 5-7 inches of available moisture in the top 4 feet of the soil profile. These are some of the most favorable widespread conditions since the spring of 1999.

The primary concern for eastern Nebraska is too much of a good thing. There is little room for additional moisture, so lowland flooding may become an issue with moderate to heavy precipitation. In addition, field activities may be limited due to moist soils and planting may be delayed if the forecasts hold true.

Western Nebraska producers will need the active weather to continue in order to replenish soil profiles prior to planting, as well as aid pasture growth and relieve stress on wheat acreage. The moisture will need to continue through the growing season as the Wyoming snowpack is even less than last year. The snowpack peaked around mid March -- a full month ahead of normal — and is less than 80% of last year.

Platte River System. There is little hope for significant recovery in reservoir levels within the Platte River system. Lake McConaughy is nearly 5 feet lower this year as compared to the same period last year. Peak level of McConaughy will likely occur by April 15. The current situation is eerily similar to spring 2005 and will require similar climatic conditions through the growing season. Well above normal moisture fell across the western third of the state between April and August 2005, significantly alleviating the need for supplemental irrigation and limiting expected reservoir declines in McConaughy.

Republican River System. Conditions with the Republican River basin have improved over last year due to good moisture the last eight months, including the monster snowstorms that hit the eastern Colorado Plains of Colorado last December. Although streamflow rates have shown improvement, they haven’t responded as much as anticipated. It is suspected that much of the moisture went into soil infiltration in the head water region of eastern Colorado.

With good surface moisture conditions in eastern Colorado, additional moisture events within the upper reaches of the Republican River basin should begin to improve streamflow rates. It is unlikely that rates will return to normal in the near future, but normal moisture during the upcoming growing season should maintain flows at considerably higher levels than the past few summers. If weather conditions revert to warm and dry, streamflow rates will likely deteriorate rapidly.

Al Dutcher
Extension State Climatologist