Hurricane Harvey will turn into a "beast" of a storm, meteorologists say, one that's forecast to bring catastrophic, life-threatening flooding to much of Texas.

Even after the storm makes landfall late Friday or early Saturday near Corpus Christi as a likely Category 3 hurricane — potentially the USA's strongest hurricane in 12 years — Harvey will stall and spin for the next three to five days, dumping up to 2 feet of rain across the region.

"The forecast for Harvey continues to grow more dire," warned the National Weather Service in Corpus Christi.

Though a 4-6 foot storm surge and howling, 100+ mph winds will be a deadly threat, the storm's biggest concern may eventually turn out to be flooding from days of torrential rain.

Harvey "may be nothing short of a flooding disaster," for Texas, according to AccuWeather meteorologist Alex Sosnowski, who said that some communities could be underwater for days.

The storm will cause much worse damage from flooding and wind than would normally occur from a fast-moving storm of similar size, he said.

Once it moves ashore, even if it weakens to a tropical storm, Harvey will essentially be "trapped" between two sprawling areas of high pressure, the National Weather Service said. One high-pressure area will be over the Desert Southwest and the other central Gulf of Mexico, Weather Channel meteorologist Jon Erdman said.

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This will leave Harvey as a potent but rudderless rainstorm with nothing to steer it or push it around.

While it sits and spins, phenomenal amounts of rain will be wrung out of Harvey; some projections say as much as 60 inches. It's possible Harvey's heavy rain may not entirely exit the areas of Texas it soaks until next Wednesday.

"This could become a prolonged and very dangerous rain event," the weather service in Houston said.

In all, the storm could dump at least 15 trillion gallons of water on Texas, WeatherBell meteorologist Ryan Maue said.

In addition to the Corpus Christi area, near where the storm should make landfall, Harvey "has the potential to cause very serious flooding in such highly populated, flood-prone regions as the Austin-San Antonio corridor and the Houston metro area," Weather Underground meteorologist Jeff Masters said.

Harvey may be the strongest landfall in this area known as the Texas Coastal Bend since infamous Category 3 Hurricane Celia hammered the Corpus Christi area in August 1970 with wind gusts up to 161 mph, the Weather Channel said.

Celia damaged almost 90% of the city's businesses and 70% of its residences.