The mountains and foothills southwest of Pueblo, combine with the Arkansas River valley and the Raton Mesa to make for some very interesting weather across the region.

During the summer months, the river valley helps act as a channel for low-level moisture from the Gulf of Mexico. This moisture pushes up the slopes of the Sangre de Cristo range, the Wet mountains and the Raton Mesa to help develop thunderstorms.

Mountain-Plains Circulation
The elevation difference between the mountains and the plains in this region helps to create a typical daily wind pattern. Winds at lower elevations blow from the plains toward the mountains during daytime and from the mountains toward the plains at night. The mountain-plains wind system is most apparent on individual days when skies are clear and the general prevailing winds are weak, but it is also seen in climatological averages.

Downslope Wind Storms
The orientation of the Sangre de Cristo and Wet Mountain ranges are favorable for the creation of mountain waves during the cooler months of the year when the atmosphere tends to have more stable layers in it. These mountain waves are created when stable air moves up and over the mountains.

The creation of mountain waves are quite complex, but there are two types of mountain wave downslope windstorms. The warm (Chinook) , pre cold front type tends to be more localized for the strongest gusts as the crest of the mountain wave reaches the ground whereas the cold (Bora) type occurs behind a cold front and tends to impact a wider area.

Interesting temperature variations can occur across this area during when extremely cold airmasses from the Canadian plains or the arctic back into eastern plains of Colorado. This very cold and dense air will find the lowest possible spots as gravity acts on it, very much like water in a bowl. As you can see in the topographic map above, the Arkansas River valley is the low spot from west to east across this area. It isn’t uncommon for mountain areas to be warmer than the lower valleys or the plains during the winter months. These inversions can be quite stark, sometimes a 40 degree difference or more!