March 16, 2013
Weather Investigation: The Monsoons Of America
The red highlighted area in the map below represents the region of the United States that is impacted the most by today’s investigation.
When most people talk about the word monsoon, the first thing that comes to mind is India. Well, let me be the first to tell you we have our own monsoon in the United States; it’s over the region highlighted in red above. People in Arizona, New Mexico, southern Utah and Colorado can affirm to this event. It’s when mother-nature turns on the faucet and dumps rain for days on end. That is the summer version of the story; however, there is also a winter version to the story. Let’s look at both in more depth.
We will start with the Southwest monsoon, which occurs during the summer time frame over this region. What happens is as the dessert starts to heat up, it releases all of this warm air up into the atmosphere creating a surface low pressure system over the region. Now this sets the stage for more warm air to rise northward out of Mexico and the Baja region, along with parts of the Pacific Ocean. All of this brings warm and moist air northward to the southwest United States. When this warm and moist air gets here, it rises up into the atmosphere vertically until it gets too heavy. Once this occurs it falls back to the surface as precipitation, mostly very heavy rainfall. This rainfall and process is very crucial to the region; without this rainfall every year, the region becomes prone to drought, wild fires and even worse impacts to society. So, as you may recall last year, this region (especially in the Colorado region) suffered massive wild fires because of the lack of the monsoonal rains. These past few years scientists have been studying the tree rings in this region, to see the normality of not having the heavy rains during the season; they want to see if this is more often or if its climate changing induced.
Now, on to the next monsoon, and that is the winter monsoon or dry monsoon. This monsoon is controlled by the higher elevation of the Rockies. What happens is that a high pressure builds up over the Rockies during the winter and causes the region to see northeasterly winds for a long period of time. Once again, this monsoon has been weaker than normal, which is leading to longer drier periods during the winter months in this region, this is hurting the mountains from snow pack during the winter time period.
Both of these monsoons are very important to the life and daily operations of our Southwest Untied States. So, with more study and more time, we can see if this is a permanent climate change or if this is just a period of time being impacted and thing will begin to improve. However, as we get ready to head into spring and summer this year, if the monsoon does not setup this year we could be looking at a rapid and highly dangerous fire season in the west again.
Featured Image Credit: pics4sale / Shutterstock