The first outlooks for the early Fall 2020 season have been released. Drought continues to be an issue across more than two thirds of the state. The outlook for August calls for continuation of that pattern with an increased chance of drier-than-normal conditions across the southern third of the state, and neutral conditions for the remainder. The combination of warmer and drier conditions would be favorable for fall harvest, but less favorable for establishment of fall-seeded crops such as winter wheat. Degree-day accumulation with the warmer temperatures would also be favorable, as late-planted crops are still lagging in maturity as long as minimum temperatures remain seasonal.
Figure 1. August outlooks and averages for precipitation and temperature (Kansas Weather Data Library, top; and CPC, bottom).
As the outlook is extended to the fall season, the temperature outlook continues with warmer-than-normal temperatures across the state. However, this doesn’t indicate the magnitude of those temperatures compared to normal. Another consideration is that average temperatures are on the downward slide as we move closer to winter – decreasing each day through August, September, and October. With below-normal precipitation, surface moisture is limited in all but the central regions of the state. With this increased rainfall, central Kansas will see increased evaporation at the surface. As a result, additional moisture is evaporated into the atmosphere increasing humidity and heat index. It won’t take as much “heat” to make conditions feel unbearably warm and heat indices will be quite high even with cooler-than-normal temperatures. Keep in mind - normal high temperatures for August typically reach low-to-mid 90s for much of the state.
Chances of precipitation fall into the below normal distribution for much of the state. Still, this does not indicate the degree of departure, nor how the precipitation will be distributed. Even a slightly drier than normal fall, with well-distributed rains could be beneficial. This scenario would provide a window for harvest and planting operations but sufficient moisture for establishment of fall-seeded crops. Crops running late could benefit from a dry pattern allowing for a rapid harvest. The areas of the state still facing drought would benefit more from average or above average precipitation.
Looking at an influential pattern impacting our weather - a La Niña watch has been issued. Unfortunately for Kansas, this has typically meant warmer and drier than normal conditions in the fall. Still other factors, such as antecedent conditions, the Madden-Julian oscillation, and blocking/stagnant patterns can significantly influence conditions.
Figure 2. Fall outlooks versus normal for the August, September, October period (Kansas Weather Data Library, top; and CPC, bottom).
Mary Knapp, Weather Data Library/Mesonet
Chip Redmond, Weather Data Library/Mesonet
Tags: weather Climate fall outlook