Ag Weather Forum

The latest drought assessments for the Southern Plains and the Upper Missouri River Basin point to dry times ahead this fall.

In the Southern Plains, the Aug. 8 Drought Update from the National Integrated Drought Information System (NIDIS), a division of the National Oceanic and Atmospheric Administration (NOAA), minces no words, with the update titled "Southern Plains Drought to Persist and Expand into Autumn."

The Southern Plains outlook key points include intensified drought conditions in parts of the region due to hot temperatures that were much above average in late July and early August; moderate to severe drought expansion over central Kansas and Oklahoma during the last few weeks; rainfall from Hurricane Beryl bypassing the driest areas of Texas in July; and only short-term benefit from mid-August rain in Kansas and Oklahoma.

A similar situation is in place for the Northern Plains, highlighted by the U.S. Army Corps of Engineers forecast for river flows in the Upper Missouri Basin north of Sioux City, Iowa. The USACE July report notes the Upper Missouri basin runoff in July was 2.8 million acre-feet, which was 15% below average. The USACE Missouri River Basin Water Management Division chief, John Remus, said in the report, "July brought warmer and drier weather to the Missouri River Basin. While every state experienced storms that produced small pockets of above average rainfall, overall precipitation was below normal for the basin." The Corps of Engineers is forecasting the annual runoff above Sioux City at 23.9 million acre-feet, 7% below average. River flow releases this winter from Gavins Point, South Dakota, are predicted to be near the minimum level of 12,000 cubic feet per second.

Conditions this week will bring more drought stress into the Southern Plains with daily maximum heat index values topping 100 Fahrenheit in Oklahoma and Texas. The Northern Plains region has shower and thunderstorm activity in store to offer at least short-term dryness relief. However, for the entire month of August, much of the Northern Plains region is expected to have drought either developing or intensifying according to the Drought Mitigation Center; and in the Southern Plains, large portions of Kansas and Oklahoma have drought either expected to form or get worse. Seasonal outlooks for the two regions through the fall season continue this drought development and/or worsening combination across both regions.

The anticipated onset of La Nina this fall looms as a key feature in the dry forecasts for the two regions. La Nina, the cool-water phase of the equatorial Pacific Ocean, is correlated with below-average precipitation in the Great Plains, especially the Southern Plains, during the fall months. How strong La Nina becomes and how long it lasts will be key for winter wheat planting and early growth, groundwater supply, and winter pasture and hay prospects.

Bryce Anderson can be reached at Bryce.Anderson@dtn.com

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