Published April 05, 2013
The storm system responsible for tremendous rainfall and deadly flooding in Buenos Aires and La Plata, Argentina, has moved offshore.
The weather pattern over the next week should aid in rescue and recovery operations, as well as cleanup as the waters have or continue to recede in local areas of the South America nation.
A slow-moving storm system fueled a cloudburst over the region spanning April 1 and 2, 2013, and targeted an urban area.
The thundery rains deposited between 5 and 10 inches of water in 24 hours at major airports in the region. However, there have been unofficial reports of double that amount in some localities.
Much of that rain fell in several hours during Monday night into early Tuesday around Buenos Aires and Tuesday night into early Wednesday around La Plata, which is located farther east.
The rain simply had no place to go and led to tremendous flash flooding. Waters containing fuel, sewage and debris overwhelmed drainage systems.
Men carry water past a car that flipped on its side during flooding in La Plata, in Argentina's Buenos Aires province, Thursday, April 4, 2013. Buenos Aires Gov. Daniel Scioli says 49 people died in this flooded capital of Argentina's largest province as torrential rains swamped entire neighborhoods, washing away cars and flooding some houses to their rooftops. The overall death toll is now 55, and more than 20 people are missing. (AP Photo/Natacha Pisarenko)
According to the Associated Press, dozens of people have been killed and more than 250,000 were without power in the two Argentine cities. There are shortages of safe drinking water.
Many people are in temporary shelters and there are concerns of disease, multiple sources said.
Comparisons to New Orleans after Katrina have been made, referring to the flooding of low-lying neighborhoods and failed drainage systems.
However, it was not a tropical storm or hurricane that caused the flooding.
According to South America Weather Expert Rob Miller, "The deluge was caused by a slow-moving pocket of cold air aloft."
The pocket of chilly air moved into a zone of warm, humid air at the surface, allowing that air to rise and form towering clouds and slow-moving thunderstorms.
Dry air to the west was moving in, but very slowly and only advanced about 40 miles farther east from one evening to the next. During the day the air is more mixed, but at night light winds at the surface allow the air to rise and cool forming the towering clouds.
"Most fronts, disturbances and their thunderstorms move along swiftly," Miller said, "However, once in a while, the is not moving along at a rapid pace and can lead to excessive rainfall."
This appears to be a case where rising air caused the thunderstorms to pulse one night over Buenos Aires, then a second night farther east in La Plata.
Much of the time over the next week or so will be free of rainfall as a large high pressure system builds in slowly.
A weak disturbance may bring a couple of brief showers or thundershowers during Saturday, but nothing like the event the region just experienced, since less humid, less moist air has moved in.