In this August file photo, lightning strikes around the Santa Rita Mountains as traffic flows on Houghton Road. The β€œnon-soon” summer followed by a La NiΓ±a winter could spell trouble for water resources in Arizona.

 Kelly Presnell / Arizona Daily Star

On the heels of the driest monsoon ever recorded in the Arizona, state and federal weather officials are predicting a warmer and drier than normal winter here.

The β€œnon-soon” summer followed by a La NiΓ±a winter could spell trouble for water resources and wildfire conditions in a state already gripped by drought, the officials said.

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β€œGoing into a dry winter after this dry summer is going to be making the drought worse, for sure,” said Nancy Selover, a state climatologist at Arizona State University.

Usually occurring once every two to seven years during the winter, the La NiΓ±a weather pattern stems from a cold phase of the Pacific Ocean that shifts the jet stream, leading to colder weather in the north and warm and dry weather in the Southwest.

If the La NiΓ±a weather system β€œdoes what it normally does – sub-normal precipitation and above-normal temperatures in the winter time – that’s exactly what Arizona and the Southwest does not need this winter,” said David Miskus, a meteorologist at the Climate Prediction Center at the National Weather Service. The long-term outlook is calling for just that.

The entire state is currently undergoing drought, with 84% to 76% of Arizona under an β€œextreme” or β€œexceptional drought” classification, according to the United States drought monitor. Extreme drought results in insufficient water for livestock and other harms to ranching, and it can stress plants and trees, making them likely to act as tinder for wildfires.

β€œWe already have a fire issue because we had a dry summer, so everything is already very dry,” Selover said.

During a dry winter, trees tend to dry severely, which can lead to sap depletion. That, in turn, gives room for beetles to infest dried-out trees that die and become fuel to spread any wildfire that starts.

β€œIf we continue this dryness through the winter, we can potentially just extend our wildfire season into the winter,” Selover said.

All those factors β€” a drought, a dry monsoon season and the expected La NiΓ±a winter β€” mean levels of β€œlarge reservoirs are going down and down,” Miskus said. That can be a particular problem for ranchers and Native American reservations in parts of semi-arid Northern Arizona that rely on summer rainfall and winter snowfall, he said.

β€œWhen you get a lack of precipitation in a semi-arid area, it really hurts,” Miskus said. During times of little to no precipitation, ranchers and tribes must β€œget water sent to them or pump” it.

Selover added that since La NiΓ±a is a β€œwinter phenomenon,” if Arizona winters keep getting warmer and drier, it could lead to decreased snowfall, which can cause severe water shortages down the road.

β€œWe depend on the snow to store water,” she said. β€œBut if there’s more rain than snow in the winter, it (water) immediately soaks into the ground.”

Ongoing wildfires, extreme drought and the driest monsoon in Arizona β€” Miskus called it a perfect storm in the summer, and now (because of La NiΓ±a) not a very good winter outlook either.”

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