Septemer 20, 2013

The latest long lead outlooks from the Climate Prediction Center back down earlier predictions for above normal moisture this fall in the central and eastern Corn Belt and much of eastern Nebraska.

Figure 1. US Climate Prediction Center temperature outlook for October 2013. Above normal temperatures are indicated for much of the western two-thirds and the upper northeast of the US, with probabilities ranging from 33% to 50%.  EC indicates areas with equal chances of above or below normal temperatures.

Figure 2. US Climate Prediction Center precipitation outlook for October 2013. Nebraska sits in an area with 33-40% probability of having below normal precipitation in October. A indicates areas expected to have above normal precipitation. EC indicates areas with equal chances of above or below normal temperatures.

The CPC is now indicating that Nebraska lies at the center of an area of below normal precipitation that includes eastern Colorado, southeastern Wyoming, Kansas, southern South Dakota, and western Iowa. October temperatures are projected to be above normal for all but the eastern third of the U.S. and the Pacific Northwest.

The October-December forecast indicates that Nebraska has equal chances of receiving above normal, normal, or below normal precipitation and temperatures. The only region with a tendency for above normal moisture lies across the northern Rockies and includes northern Wyoming, northeastern Oregon, western Washington, northern Idaho, and all of Montana.

We need to remember that these two-week lead forecasts are highly dependent on trends depicted in the 8-14 day forecast. I would not be shocked to see a change to the 30-day forecast issued at the end of September for October. There has been a trend toward changes in the CPC monthly intervals at two to three week intervals for most of the growing season as upper air patterns shift from a trough to a ridge.

Even though short-term model forecasts are hinting at the reestablishment of an upper air ridge over the western U.S. in early October, recent upper air patterns have been more progressive recently and I expect that trend to continue during the next 30 days. If this does occur, harvest weather will be more challenging than recent years when an absence of moisture during October led to a rapid conclusion of combine activity.

Al Dutcher
Extension State Climatologist