As a derecho rolled through the northern Plains Tuesday, the sky turned green. A derecho is a powerful wind storm, but this cluster of storms brought more than just the intense, destructive wind. The ominous green color in the sky is caused by the water and ice inside the storm clouds and is an indicator that the storm is producing large hail. 

Both the heat and humidity will climb Sunday which creates more storm energy in our area. The timing and intensity of those storms will be tough to forecast, so let's discuss why it's so complicated and what you can expect.