Mexico Braces for more Ernesto Flooding Rain

By , Expert Senior Meteorologist
August 10, 2012; 4:56 AM ET
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Ernesto made landfall Thursday, and tremendous rain is falling across Mexico.

According to Tropical Weather Expert Dan Kottlowski, "Ernesto is forecast to take a west-southwest path, aiming south of Mexico City."

Ernesto made Landfall Thursday south of Veracruz City and north of Coatzacoalcos, Mexico. The storm is currently a tropical depression. See latest satellite loop of Ernesto churning over the southwestern Gulf of Mexico in the Bay of Campeche.

Because of its large size, Ernesto brings a rather widespread flooding potential. Bands of heavy showers and thunderstorms extend well away from the center of the storm, which is a trait likely to continue even though the storm has made landfall.

"While rainfall will become more spotty as Ernesto moves well inland and diminishes, people should not just focus on the center of the storm, nor its intensity in terms of flooding," Kottlowski said.

After heavy rain, gusty winds and rough surf blast the area around Veracruz, locally heavy rain is forecast to reach inland Thursday night into Saturday.

Veracruz was being hit with drenching downpours Thursday. Minatitlan, Mexico, just south of Coatzacoalcos was experiencing true tropical storm conditions with windswept heavy rain and gusts to near 60 mph.

The rugged mountains that make up mainland Mexico will tear up Ernesto's circulation. While the towering mountains will make quick work diminishing the wind, it will come at a price, in the form of torrential rainfall and dramatic runoff in some areas.

The heaviest rain is likely to fall on the windward facing slopes of the Sierra Madre Oriental mountains, which line the eastern side of the Mexico mainland.

The heaviest rain is likely to fall between Veracruz and the Sierra Madre Oriental front, which represents roughly a 10,000-foot rise in elevation.

Rainfall rates on the order of 1 to 2 inches per hour with local totals of a foot or more are possible on these mountainsides, raising the risk of not only flash flooding, but mudslides Thursday into the weekend.

Significant rises on the rivers, which drain the region in the path of the storm, are likely.

Although Mexico City, at an elevation of about 7,300 feet, is protected by mountains to the southwest, south and east, communities on the mountainsides in the region are at risk for flash flooding and slides.

According to International Weather and Geography Expert Jim Andrews, "Mexico City lies in an old lake bed. Storm water and sewage must be pumped out rather than drain on its own."

AccuWeather.com meteorologists are expecting an average of 1 to 2 inches of rain to fall on the extensive Mexico City metropolitan area with the potential for greater amounts on hillsides with northern and northeastern exposure. In general, the heaviest rain will fall south and east of the city.

"If the city were to receive heavier rain than now anticipated, there could be flooding problems within the Mexico capital," Andrews added.

Other cities between Coatzacoalcos and Mexico City lie in the path of the drenching rain including Orizaba, Puebla and Matamoros.

People are urged to avoid crossing flooded roadways and to move to higher ground ahead of Ernesto.

Travel along mountainside roads and streams could be especially dangerous during the storm and for a time thereafter until the runoff completes its journey.

There is a remote chance that the upper-level portion of Ernesto's remains will emerge along Mexico's west coast. If so, it could regenerate into an entirely new tropical system in the Pacific Basin.

Expert Videos on Ernesto

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