JUL 23, 2017 01:28 PM PDT

American Southwest threatened by heavy-rain monsoons

A new study published recently in the Journal of Applied Meteorology and Climatology suggests that the North American Monsoon (NAM) is becoming more intense in the United States Southwest, particularly in Arizona. Their results show that while storms are not as frequent as they have been in the last 60 years, the rain episodes are heavier and include high winds, dust storms, and flooding, which often threaten residents and property. This pattern, the study concludes, is consistent with flux caused by climate change.

Monsoons often come on suddenly. Photo: The Arizona Experience

Because of specific Department of Defense installations in the Southwest, and because the existing models of the NAM do not represent patterns in the climate accurately, the team analyzed Arizona rainfall data from 1950-1970 and compared it with data from 1991-2010. Defining severe weather events as days when the highest atmospheric instability and moisture occur within a long-term regional climate simulation, the scientists found that while the mean precipitation for the region stayed the same during the different time epochs, the later time period had more heavy-rain storms.

"This is one of the first studies to look at long-term changes in monsoon precipitation," co-author Christopher Castro said. "We documented that the increases in extreme precipitation are geographically focused south and west of the Mogollon Rim -- and that includes Phoenix. What's going on in the changes to the extremes is very different from what goes on in the changes to the mean," Castro commented. "Big storms, heavy flooding -- we found out those types of extreme precipitation events are becoming more intense and are becoming more intense downwind of the mountain ranges."

The trick in the team’s strategy was to use a computer model that has a resolution of 1.5 miles (2.5 km). This high resolution simulates the physical structure of a monsoon and gave the scientists very accurate results of the rainfall data, lining up with the results that radar or satellite imagery would show. It’s because of this accuracy in rainfall data that the team is confident that the model can accurately predict wind speed data as well.

But stronger rains aren’t the only change that NAM is bringing to Arizona. Castro stated that monsoons, which used to occur in the late evening, are now passing by earlier in the day, which poses a bigger threat to people on the roads.

In an effort to better understand NAM, the team plans to continue research in Mexico.

Sources: Journal of Applied Meteorology and Climatology, Science Daily

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
DEC 24, 2018
Plants & Animals
DEC 24, 2018
Decoding the Secrets of Howler Monkey Evolution
There exist a bevy of ways that an animal species can be driven to evolve, but one of the more controversial methods of evolution involves a process known...
DEC 26, 2018
Earth & The Environment
DEC 26, 2018
Costa Rica just broke its own renewable energy record
This past month Costa Rica broke their own 2015 record of 299 days using only renewable energy for electricity: this year, they went 300 days. Known for de...
JAN 09, 2019
Videos
JAN 09, 2019
Researchers Create a Sustainable Plastic From Seaweed-eating Microbes
Plastic is a major pollutant that is contaminating our waterways and oceans. Researchers have now found a way to create bioplastic from microbes....
JAN 21, 2019
Plants & Animals
JAN 21, 2019
A Small Snake Eaten by a Larger Snake Turned Out to be a New Species
More than four decades ago, curious researchers carefully analyzed the stomach contents of a Central American coral snake that had been captured in Chiapas...
JAN 23, 2019
Earth & The Environment
JAN 23, 2019
Rethinking climate models
New research published in Science suggests that we had better rethink current climate models. The research comes from Hebrew University of Jerusalem Profes...
FEB 11, 2019
Plants & Animals
FEB 11, 2019
Researchers Are Cooling Down Sea Turtle Nests for Conservation Purposes
Climate change impacts all kinds of wild animals, including several varieties of sea turtles – many of which are now recognized by the International...
Loading Comments...