The study used a computer program to compare weather patterns simulated by a climate model to real weather data for western North America. The model accurately reproduced different types of weather patterns, but there were some differences in how often these patterns occurred in different seasons. These differences suggest that the model has small errors in predicting weather on a large scale. This means the model may not be reliable for studying how climate change will affect this region. The comparison method used in the study can help us understand how global climate change might impact regional weather patterns.