The third straight La Niña winter in the U.S. is likely to cause drought to expand and deepen from California to the Plains, branching out across the Southeast, NOAA said Thursday.
How it works: Currently, water levels along certain stretches of the Mississippi River are so low that centuries-old shipwrecks are being revealed, and modern-day barge traffic is imperiled.
- Farmers in multiple states are facing the prospect of a challenging winter wheat season.
- After a dry winter, if spring rains falter in Texas, there would be a growing possibility of summer water supply constraints, experts warn.
The big picture: The new seasonal drought outlook through January depicts a weather pattern that is heavily influenced by a rare, three-winter "triple dip" La Niña in the tropical Pacific Ocean.
- La Niña conditions feature cooler-than-average ocean temperatures in the equatorial tropical Pacific. They can influence weather patterns worldwide.
- About 82% of the country was facing at least abnormally dry conditions as of Tuesday, the largest drought footprint in the Lower 48 states since the Drought Monitor was unveiled in 2000.
- Texas is entering the cool season with about 68% of its reservoir storage capacity, which compares to an average of 80% at this time of year, Texas state climatologist John Nielsen-Gammon told Axios via email.
Yes, but: Some areas got good news Thursday, with wetter conditions likely throughout winter in the Pacific Northwest.
What they're saying: “If we don't get replenishment this winter, and especially this spring after La Niña wanes away, water supply issues could become much worse than they were last summer in Texas,” Nielsen-Gammon said.
Between the lines: Climate change exacerbates weather whiplash, as regions oscillate between drought and flood.
- During dry periods like Texas is seeing, higher temperatures tend to make the droughts more severe than they otherwise would have been.
- Rainfall is coming in shorter torrents, which boosts surface water runoff without replenishing soil moisture, Nielsen-Gammon said.
Texas illustrates the La Niña and climate change-related swings between drought and deluges.
Driving the news: For example, the Dallas metro area saw most of its summer rainfall come in just three weeks between Aug. 10 and Sept. 5, said Victor Murphy, a meteorologist at the National Weather Service.
- During this period, Dallas experienced a 1,000-year rainstorm with about 15 inches of rain falling across the metro area on August 21-22.
- Some 3.01 inches of rain fell at Dallas Fort Worth International Airport in just one hour, setting an all-time record.
Context: Such extreme precipitation events are consistent with climate studies showing these are becoming more common and severe as temperatures increase.
- Since that three-week stretch ended, Murphy said, it has “turned bone dry.”
- This is the first calendar year with two separate 40-plus day stretches without measurable rainfall at DFW, Murphy said.
Threat level: Going into the cool season, Murphy said, Texas’ water resources are only about 13% better than they were at this point during the extreme drought in 2011 when supply worries reared their head during a La Niña summer.
- More people have moved to Texas, increasing water demand since then, Murphy noted.
- “I shudder to think where we would be right now without that three-week deluge,” he said.
