The Monsoon Causes Deadly Arizona Flash Flood

Good morning bloggers,

The monsoon over the southwestern United States has become deadly.  At least nine people were killed in a horrific and very deadly flash flood yesterday in Arizona. Around an inch of rain fell in less than 30 minutes near this popular spot in Arizona.  A group of people from Phoenix and Flagstaff, Arizona had met for a day trip along a popular swimming hole near Payson, around 100 miles northeast of Phoenix.  They set up lounge chairs not knowing that a thunderstorm capable of producing the conditions for a flash flood had developed not that far away.  The rain from the thunderstorm was falling over an area that had a big wildfire recently and the lack of vegetation likely played into this disaster.   Around a 6-foot-high wall of water organized and collected dark ash from the ground influenced by the fire. The thunderstorm was likely visible and not that far away. And, the worse case scenario happened with the torrent of water crying nine people to their deaths.

Take a look at the developing pattern and the conditions for more monsoon thunderstorms this week:


The Southwest Monsoon:

The southwestern United States monsoon, sometimes called the North American monsoon, or the New Mexican monsoon, or the Arizona monsoon is caused by a seasonal shift in the wind patterns aloft caused by the anticyclone, what I have called the “heat wave creating machine”.  During the summer months, usually by the end of June, the heights rise aloft and this anticyclone forms. The flow around this system causes thunderstorms to form over the mountains of Mexico. These drift northwest towards Arizona, New Mexico, and Southern California.  Low level moisture from the Gulf of Mexico and the Gulf of California gets drawn in and the humidity actually rises at times over the deserts of the southwestern United States.  Thunderstorms are the result that are fueled by daytime heating and mountain lift (orographic lifting).  Disturbances often move west and then rotate around the anticyclone.  Eventually the jet stream will shift south by late August or September and the seasonal monsoon will come to an end as fall approaches.

Screen Shot 2017-07-17 at 7.03.26 AM


The tropics are also active off of the Mexico coast over the eastern Pacific Ocean.  Hurricane Fernanda has formed and there are two other systems that may form into tropical storms as well.

Farther north there is a monsoon disturbance moving out of eastern Colorado and into the plains. Take a look:


This disturbance will at least bring a slight chance of showers and thunderstorms out over Kansas into western Missouri later Tuesday.  And, then that anticyclone will be building and we will make a run at 100 degrees by Friday.  Remember it has been almost 4 years since Kansas City at KCI Airport officially reached 100 degrees. This happened on September 8, 2013.  We will likely test this streak out later in the week.

Have a great day!!!! And, thank you for participating and sharing in this weather experience. We have been having some great conversations over on the Weather2020 blog, so go over there and join in, or you can leave a comment here as well.


Share and Enjoy:
  • Print
  • Digg
  • StumbleUpon
  • del.icio.us
  • Facebook
  • Yahoo! Buzz
  • Twitter
  • Google Bookmarks

1 comment to The Monsoon Causes Deadly Arizona Flash Flood

  • Richard

    Tragic about those in the flash flood. Tragic

    Not looking forward to this week of heat. Do you see it breaking back to the 80’s next week ? What is August looking like