Drought is the sleeper weather story you’ll hear more about in 2021

Drought is an insidious climate threat – by the time it has a hold of a region, it already has harmed ecosystems and strained water supplies. It may not grab extreme weather headlines like the disrupted polar vortex or record hurricane season, but drought during 2020 and heading into 2021 is a looming story that will probably grow in importance.

Nowhere is this more true than in the Southwest. Population growth and years of drought conditions are putting the region on a collision course with drastic water management decisions. On Wall Street, traders can now bet on California water futures on commodity markets, enabling them to hedge against future scarcity, much as they trade gold, oil and agricultural products.

The forecast persistence of La Niña, a periodic cooling of the waters in the eastern tropical Pacific along the equator, through the winter favors a worsening of drought conditions along the southern tier of the United States.

In Southern California, the wildfire season finally came to an end in late December, but rains have been sporadic and light into the start of the new year. The state’s first snow survey of the year shows that the statewide snowpack was just 52% of average on Jan. 1. Storms are likely to increase that percentage during the next few weeks, but the dry fall has put the Golden State at a deficit that could be difficult to make up given the favored storm track.

Unlike El Niño years, which feature above-average water temperatures in the tropical Pacific and can direct a relentless fire hose of moisture at the West throughout the winter, La Niña winters tend to favor stormy conditions in the Pacific Northwest instead.

A total of 49% of the Lower 48 states were in moderate to exceptional drought conditions as of Dec. 29, with dry conditions extending north into Alberta.

While droughts come and go, there is increasing evidence that parts of the United States, namely the Southwest, are enduring long-term “megadrought” conditions seen in historical tree ring records. This is partly related to climate change, which worsens droughts by increasing

temperatures, thereby turbocharging the loss of moisture from plants and soils. Climate change is also shifting weather patterns in ways that favor drier conditions in the Southwest United States.

Data about the percent of total land area in the Lower 48 states that are in drought conditions shows a huge spike between 2010 and 2015, which coincided with a costly drought in Texas and California’s most intense and long-lasting drought in more than a millennium, and the recent climb that has not yet leveled off.

The seasonal precipitation forecast from the Climate Prediction Center at National Oceanic and Atmospheric Administration shows the likelihood of a La Niña-tinged winter weather pattern, with a drier-than-average southern tier. This would be bad news for states such as California, New Mexico and Arizona, but also southern Texas and Florida, too.