Nebraska Fall May See More Precipitation, Threat of Freeze Nonissue

Sept. 18, 2013

LINCOLN, Neb. — It could be a wet fall, the University of Nebraska-Lincoln climatologist says.

The state is seeing an uptick in precipitation just as harvest will be getting underway across Nebraska, said Al Dutcher, state climatologist in the university's Institute of Agriculture and Natural Resources.

"We have a strong monsoonal flow still holding on" in the desert southwest, he said. "We've seen heavy precipitation through the southern and central Rockies with mass flooding. As upper air troughs push into the Central Plains, they are bumping up against this tropical moisture and therefore we get stationary thunderstorm development, which are high precipitation events. Secondarily these are falling on areas that have been burnt by forest fires the past couple years so a lot the precipitation is running off and compounding the flood threat."

The monsoonal flow has expanded to the western high plains of Kansas and parts of Texas. Western Nebraska also sits on the northern perimeter of this, he said.

"We do have some potential of seeing improvements in soil moisture levels based on this monsoon flow," he said.

The brief battle with extreme heat is over, Dutcher said. There could still be a day or two this fall that will hit the 90 degree mark, particularly in Western Nebraska, but for the most part models are showing typical fall temperature swings from warm to cool, warm to cool, etc.

"And when we get these swings in temperatures, we have the ability to generate precipitation," Dutcher said. The 90 day forecast for the eastern half of the state is for above-normal precipitation. The rest of the state has equal chances of above, normal or below precipitation.

"Unfortunately, in order to get soil moisture built up this fall, it is going to come at a price, and we would expect to see some harvest delays if the model projections are correct."

Hurricane Ingrid dumped over a foot of rain in northern Mexico with lesser amounts as far north as the Big Bend, Texas, region. Another storm is projected to follow a similar path over the next seven to 10 day period. These tropical systems will likely enhance an already strong monsoonal flow into the southern Rockies.

"In addition, we have entered the favorable period when tropical systems generally move up the Baja Peninsula and enhance desert precipitation," Dutcher said. "While it might not eliminate the drought, it will moisten up those lower levels of the atmosphere and that will aid in suppression of the semi-permanent ridging pattern."

It also will allow troughs to deepen into the central and southern Rockies and will likely enhance precipitation patterns across the central and southern Rockies and adjacent High Plains regions.

This could help increase soil moisture levels and be a positive for winter wheat planting. There is nothing to indicate this would continue through winter and spring, but if this pattern does continue, the state could experience an "interesting winter," Dutcher said.

In addition, future precipitation events will fall on areas that currently have saturated soils. This should enhance snowmelt next spring as a greater portion of the water in that snow goes to runoff instead of soil infiltration.

"From the standpoint of crops, it's moisture and the longer we can keep it around the better," Dutcher said.

As far as the state's first freeze, it may be slightly early in the eastern half of the state, but Dutcher doesn't think it will be a problem as far as growing conditions are concerned.

The Panhandle and north central part of the state typically see the first freeze around Oct. 7-10. In the southeast part of Nebraska, the freeze date typically is around Oct. 17-24.

For more information about weather and crops, visit CropWatch, UNL Extension's crop production newsletter, at cropwatch.unl.edu.