As the World Warms, Extreme Rain Is Becoming Even More Extreme

New York Times

2 days ago

Colossal bursts of rain like the ones that caused the deadly flooding in Texas are becoming more frequent and intense around the globe as the burning of fossil fuels heats the planet.
Warm air holds more moisture than cool air, and as temperatures rise, storms can produce bigger downpours. When met on the ground with outdated infrastructure or inadequate warning systems, the results can be catastrophic.
These were the ingredients for tragedy in Texas, a state that is well acquainted with weather extremes of all kinds: high heat and deep cold, deluges and droughts, tornadoes and hail and snow. Indeed, the Hill Country, the part of the state where the Guadalupe River swelled on Friday, is sometimes called 'flash flood alley' for how at risk it is to seemingly out-of-nowhere surges of water.
Humid air blows into the area from two main sources, the Gulf of Mexico and the tropical Pacific Ocean. When this air collides with cool air drifting down across the Great Plains, severe storms can erupt. The hilly terrain and steep canyons quickly funnel the rain into river valleys, transforming lazy streams into roaring cascades.
In parts of Texas that were flooded on Friday, the quantities of rain that poured down in a six-hour stretch were so great that they had less than a tenth of 1 percent chance of falling there in any given year, according to data analyzed by Russ Schumacher, a professor of atmospheric science at Colorado State University.
The Guadalupe River rose from three feet to 34 feet in about 90 minutes, according to data from a river gauge near the town of Comfort, Texas. The volume of water exploded from 95 cubic feet per second to 166,000 cubic feet per second.
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