Eagle River Watershed Council: Banking on the monsoon
I made pretty good tips as a tour guide in Colorado during my summer breaks from college, mostly because I had a party trick. Each morning, a tourist would invariably ask if it was going to rain that day.
I would always say “yep, around 2 or 3 today,” and boom it would happen. I wasn’t a magician and had no interest in meteorology. I was just a kid who had been born and raised in the Colorado mountains and the summer’s afternoon rains were simply a part of everyday life.
At the time, I didn’t know that the predictable weather pattern of afternoon rains was a monsoon. To me, monsoons involved exotic creatures bubbling out of mud pits in India surrounded by a thriving green oasis that, just seconds before, was a dry and barren landscape with wildlife expiring in the dry heat — all with a David Attenborough voiceover.
But, in fact, the afternoon showers we are accustomed to in the summer are part of the North American monsoon — not nearly as dramatic as in India, Southeast Asia or Australia, but still absolutely critical to the environment, agriculture and economies of the American Southwest and up into Colorado. The associated flash floods, hail storms and wind storms can also be ruinous and deadly.
The word monsoon refers to a specific change in wind patterns that bring moisture, not the seasonal rainstorms themselves. The North American monsoon occurs as rising temperatures on the ground create a low-pressure system that forces wind patterns to reverse. Typically, the winds move from Arizona to the Pacific, but as they reverse, they bring moisture from the gulfs of Mexico and California with it. The monsoon first hits Mexico and works its way into New Mexico, Arizona, Nevada, Utah and Colorado. We can experience it in Colorado anytime from June through September.
Meteorologists note the arrival of the North American monsoon by tracking the humidity in Phoenix, Arizona. This year, the monsoon was detected on July 24, but has stalled and may not return. The monsoon typically appears around July 10, meaning it arrived two weeks behind schedule this year. In a drought year, such as this, ranchers and water managers bank on the monsoon to bring us out of the dry period, but it looks as though a monsoon will not be the saving grace we need in 2020.
Fast-forward a couple of decades from my lucrative tour-guiding gig and the monsoonal flows seem to be much less predictable. And that is a problem. Ten percent of our annual precipitation in Colorado (and about 50% in Arizona and New Mexico) comes during the monsoon and it is conveniently well-timed to take place during the hottest part of the year, providing relief for wildlife and agriculture.
A 2017 report and model from researchers at Princeton and the National Oceanic & Atmospheric Administration (NOAA) revealed that the previous assumption that climate change was only delaying the North American monsoon isn’t the full story. Climate change is also significantly reducing the overall rainfall from the monsoon — up to a 40% reduction in annual rainfall.
They predicted that the largest reduction will be felt along the northern edge of the monsoonal region, which happens to be Colorado. It seems we are already experiencing this reduction. If so, agriculture, wildlife, recreation, and our economy will undoubtedly suffer.
Clearly, this is yet another argument for swift climate action — by government, but also by individuals. We cannot make it rain but we can combat climate change with personal, local action. Refer to climateactioncollaborative.org to learn more about what you can do. Additionally, it sheds light on the importance of water resource management planning as well as local resiliency planning.
Looking at the near-term, it is important to appreciate the power of these storms when we are lucky enough to get them. Keep an eye on the sky while out recreating, hike early and watch for lightning. After the storm ends, go out and enjoy the fresh smell and be on the lookout for those rainbows.
Holly Loff is the executive director for Eagle River Watershed Council. The Watershed Council has a mission to advocate for the health and conservation of the Upper Colorado and Eagle River basins through research, education, and projects. Contact the Watershed Council at (970) 827-5406 or visit erwc.org.
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