Monsoon 2015 in review

2015 Monsoon 4 City Rain Bars

Buoyed by another wet September, Monsoon 2015 ended with a bang for southern Arizona. Most cities saw above average rainfall, including Tucson. 6.63″ rain was registered between June 15th and September 30th, approximately 0.55″ above the normal mark of 6.08″. This makes for the wettest Monsoon in 5 years.

cbdrain093015

Casa de Beamish in Oro Valley picked up 7.77″ during Monsoon 2015. That’s the most I’ve ever recorded & helped keep 2015 on track for the wettest year in my backyard. Being at an elevation of nearly 3,000 feet certainly helps! Below is a map of Metro Tucson rain totals for Monsoon 2015. I feel for you, northwest siders.

Courtesy: Rainlog.org
Courtesy: Rainlog.org

THE TRENDS

Three things really stood out for me this Summer. This was my 8th Monsoon in Tucson. I can’t remember a Summer with more large hail events. The June 30th storms in particular stood out. An annoying theme of anvil shading occurred again this year. Also, we saw a late spike in lightning caused wildfires in the mountains.

Click here to read my blog post from late August for more details on these trends.

WHERE MY FORECAST WAS WRONG

Back in June, I predicted a near normal Monsoon with a final rainfall tally of 5.83″. What happened?

It all goes back to something I highlighted in my Monsoon 2015 forecast: the boom or bust scenario El Nino brings to the Monsoon. Warmer than normal Pacific waters can fuel an active hurricane season.

Such has been the case in 2015. 13 named storms developed in the eastern Pacific Ocean. 10 of those became hurricanes. The influx of moisture allowed for our Monsoon high and late season troughs to tap into this pool, enhancing rain chances.

WHERE MY FORECAST WAS RIGHT

Click to enlarge
Click to enlarge

10 of the last 17 Summer El Nino events have led to below average Monsoon rainfall in Tucson. Only 3 of those years registered above normal rainfall since 1951. Because El Nino can be a big wildcard, I opted to shy away from leaning on history.

FINAL THOUGHTS

In summary, my Monsoon 2015 forecast wasn’t great, but it wasn’t horrible either. It was a tough call to pinpoint whether the “boom” or “bust” scenario would win out. To the delight of many desert dwellers (yours truly included), we head into an El Nino Winter sans a yearly rainfall deficit.

How much rain fell in your backyard during Monsoon 2015? Post your total & location in the comment section below.

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