Monsoon pattern brings heavy rain, flash flooding to Arizona and Utah

In our last blog post, we discussed the start of the monsoon season across the Southwest U.S.  Over the past week, this pattern has brought a significant increase in moisture to the canyon regions of Arizona and Utah, and as a result significant rainfall to many areas.  Much of the drought-stricken region has experienced above-average rainfall over the past 7 days, as evidenced in the map below.  Farther north into the Wasatch of Utah, and farther east into Colorado, rainfall has been less impressive.



While moisture in general is welcome news to the Southwest right now, as is often the case with monsoon season rainfall, too much rain in a short amount of time also causes problems.  Flash flooding has become a common occurrence with thunderstorms in recent days, and on Thursday July 12, a major flash flood occurred at a popular backcountry destination – Havasupai Falls in Grand Canyon National Park.  Backpackers who had hiked down to the popular falls noticed the turquoise waters began to turn muddy, and shortly thereafter, water levels quickly rose.  The many hikers in the vicinity were forced to quickly scramble up the hillsides to escape the rising torrent.  A total of 200 people ended up being rescued by helicopter from this area, but fortunately no injuries or fatalities occurred.

In Utah, a recent burn scar from the Black Mountain Fire that occurred earlier this summer received heavy rainfall and significant runoff and flooding late this past week.  Burn scars are highly susceptible to flash flooding and mudslides since the recently burnt soil can’t absorb much water.  Portions of Zion National Park and surrounding areas also received heavy rainfall and flooding that forced road and trail closures and home evacuations.  The heavy rains extended farther west into Nevada as well, with portions of the Las Vegas metro area receiving heavy rain and flash flooding.

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