Arizona Scientists Keep An Eye On Latest La Niña



Graphic from the National Oceanic and Atmospheric Administration

Along with lower-than-average precipitation, higher-than-average temperatures are predicted to accompany La Niña into the spring, increasing the risk of wildfires in the Southwest.

An unwanted visitor has made her way to Arizona, and it’s not your irate aunt here to put a damper on the holidays.

Continuing this winter and into the spring, a moderate-to-strong La Niña is predicted to reign across most of the United States. This natural cycle, brought about by cooler temperatures in the equatorial Pacific Ocean, has historically meant lower-than-average precipitation for the Southwest.

“The Pacific jet stream is weaker and it’s pushed a little north, so the winter storms that form in the Pacific Ocean get pulled north of us and we are drier,” said Zack Guido, associate staff scientist with Climate Assessment for the Southwest (CLIMAS), a program housed at the University of Arizona Institute for the Environment.

La Niña could mean bad news for parts of Arizona and northern Mexico, where most of the last 10 years have been dry, leaving water levels dangerously low.

In an effort to “improve the region’s ability to respond sufficiently and appropriately to climatic events and climate changes,” CLIMAS will debut the La Niña Drought Tracker the first week of December.

The monthly online publication will provide information on current and future drought conditions to ranchers, water managers, wildlife managers and others who could be affected by La Niña’s outcome.

“The major impact of the La Niña will likely be the expansion of drought,” Guido said.

According to the National Oceanic and Atmospheric Administration, the exacerbation of drought conditions will also put Southwest states at risk of having above-normal wildfire conditions in the coming months.

But just like any climate prediction, its occurrence and severity are a toss-up.

“It’s a gamble because these are statistics, and it doesn’t always hold,” Guido said. “But by and large it holds, and it is less of a gamble in La Niña years than El Niño years.”

El Niño, sometimes called La Niña’s sibling rival, is characterized by warmer ocean temperatures in the tropical Pacific Ocean and generally brings more rain to the Southwest region. Data from the National Weather Service, a division of the NOAA, shows that the last time El Niño made its mark was from May 2009 through March 2010.

The National Weather Service has already reported that La Niña conditions across the tropical Pacific Ocean stayed strong during October and early November and are expected to hold through the end of the year.

The La Niña Drought Tracker will incorporate these climate signals as a way of informing people about future conditions.

Dino DeSimone of the U.S. Department of Agriculture Natural Resources Conservancy Center in Phoenix will also put the publication to use.

As Arizona’s water supply specialist, DeSimone focuses on streamflow forecasting. By monitoring stations and focal points around the state, using both manual snow surveys and automated snow telemetry, DeSimone helps water managers prepare for what La Niña might have in store.

“Some years the storm track can be way north and then the upper Colorado River Basin will also lose out,” said Gregg Garfin, a UA climatologist. “Other years it will fly north of Arizona and hit Utah and Wyoming and Colorado and everything will be just fine. It is a little dicey to try to predict what will happen, but all of the water managers are kind of on the edge of their seats.


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