After a very dry spring, there is hope that the clouds on the southern horizon will be bringing some needed moisture for the Southwest. The arrival of the monsoon to our area is welcome news, but like all weather events, it’s a bit of a mystery as to when and why this annual event occurs.
Doing a bit of research on our “monsoon,” I find an interesting bit of information about its nature. The definition of a monsoon from the American Heritage Dictionary: “A wind system that influences large climatic regions and reverses direction seasonally.”
In the case of our monsoon, the driving forces are the hot deserts of Mexico and Arizona and the cooler Pacific Ocean. When the desert air becomes hot enough compared to the cooler Pacific Ocean, it causes the upper-level winds to shift from their normal flow out of the southwest to an easterly flow that then draws warm, moist air in off the Gulf of Mexico. This easterly flow brings in large quantities of warm, moist toward Tucson and southern Arizona.
During their summer monsoons, the Tucson area receives about 6 inches of moisture on average. Additional warm, moist air moving north from the Gulf of California causes this large mass of moisture to turn toward the north, eventually reaching as far as the Four Corners and Southwest Colorado.
If you watch satellite images of the weather, you can see this large swirl of moisture as it arrives around the Tucson area and then rotates up into our area.
Our spectacular mountains add the final ingredient to this weather event and causes us to have our cooling afternoon showers. After this mass of warm, moist air crosses the low desert and begins to gain elevation, it begins to cool. With the quick upward push the San Juan Mountains cause, the air will finally cool enough to form our afternoon thunderstorms that give us the refreshing rains.
While the monsoons are wonderful events that cool our area and help extinguish our wildfires, they are like all weather events: unpredictable. To learn more about this fascinating weather event you can look at the NOAA website www.wrh.noaa.gov/twc/monsoon/monsoon_tracker.php. Additional sources of information can be found by searching for “southwest monsoon” with your favorite browser.
So as I walk through my drought-parched pastures, I will watch the skies for the building clouds that will hopefully keep the fires at bay and my grass alive until fall.
Doug Ramsey has farmed in La Plata County for more than 30 years. He can be reached at 385-4375.