What's Going on Inside the Fearsome Thunderstorms of Cordoba Province?

[Zorro]

Scientists are studying the extreme weather in northern Argentina to see how it works — and what it can tell us about the monster storms in our future.

When he thought back to the late-December morning when Berrotarán was entombed in hail, it was the memory of fog that brought Matias Lenardon the greatest dread. He remembered that it had drifted into the scattered farming settlement in north-central Argentina sometime after dawn. Soon it had grown thicker than almost any fog the young farmer had seen before. It cloaked the corn and soybean fields ringing the town and obscured the restaurants and carnicerias that line the main thoroughfare. He remembered that the fog bore with it the cool mountain air of the nearby Sierras de Córdoba, a mountain range whose tallest peaks rise abruptly from the plains just to the town’s northwest. Like any lone feature in flat country, the sierras had long served as lodestar to the local agricultural community, who kept a close watch on them for signs of approaching weather. But if Lenardon or anyone else in Berrotarán thought much of the fog that morning in 2015, it was only that it obscured their usual view of the peaks.

At the time, Lenardon was at the local radio station, where he moonlighted as the town’s weather forecaster. It was a role the 22-year-old had inherited, in some sense, from his grandfather Eduardo Malpassi, who began recording daily weather observations in a family almanac almost 50 years before. Like many farmers in Córdoba Province, Lenardon had learned from older generations how to read the day’s advancing weather according to a complex taxonomy of winds and clouds that migrated across the pampas — the vast pale grasslands that blanket much of the country’s interior. If the winds turned cool as the day wore on, Lenardon knew it meant rain, brought north from Patagonia. More troubling were the winds that blew in wet and hot from the northwest — off the sierras.

As forecaster, Lenardon’s chief concern was identifying weather patterns that might breed a thunderstorm, which on the pampas are notoriously swift and violent. Few official records are kept in Córdoba and the surrounding regions, but over the previous two years alone, newspapers reported that hail, flooding and tornadoes had damaged or razed thousands of acres of cropland, displaced more than five thousand people and killed about a dozen. Locals described barbed hailstones, shaped like medieval flails, destroying buildings and burying cars up to the hoods. Lenardon’s own family had lost their entire harvest to flooding three of the last five years, forcing them at one point onto state assistance. People in Berrotarán spent much of their summer bracing for the atmosphere to explode; the fire department had recently taken to standing at the ready with rescue equipment and heavy machinery, in hopes of getting a jump on digging people out of debris. Even so, Lenardon didn’t think much of the fog when he first saw it. The cool, moist air didn’t indicate anything, as far as he knew, except a welcome relief from the heat.

As Lenardon prepared to leave the station, he pulled up the feed from the region’s lone radar dish in the nearby city of Córdoba, more out of habit than anything else. When the radar completed its 15-minute sweep, a massive red splotch flashed on the screen — a powerful storm appeared to be bearing down on them. Convinced it was a glitch, Lenardon raced outside to check the sky — forgetting in his panic that it was shrouded by fog. While the fog had little meteorological effect on the storm, it had nonetheless ensured that it would be maximally destructive. “No one could feel the wind,” he said. “No one could see the sierras.” Though he rushed to go live on the radio, it was already 9 a.m. by the time he issued a severe storm warning for 9:15.

The storm descended quickly. It engulfed the western side of Berrotarán, where winds began gusting at over 80 m.p.h. Soon, hail poured down, caving in the roof of a machine shop and shattering windshields. In 20 minutes, so much ice had begun to accumulate that it stood in the street in mounds, like snowdrifts. As the hail and rain continued to intensify, they gradually mixed into a thick white slurry, encasing cars, icing over fields and freezing the town’s main canal. With the drainage ditches filled in and frozen, parts of the town flooded, transforming the dirt roads into surging muddy rivers. Residents watched as their homes filled with icy water.

https://www.nytimes.com/interactive/2020/07/22/magazine/worst-storms-argentina.html

A long and excellent article about what we may expect in future decades due to the effects of a warming atmosphere.