Hurricane Harvey remains a serious threat as it continues a slow march over Texas, even as the National Hurricane Center downgraded it to a Category 1 storm with gusts up to 80 mph by early Saturday.

While the wind was weakening Saturday, the rain proved to be relentless.

“We could see isolated areas with rainfall amounts as much as 40 inches and that’s going to cause life threatening flooding over the next several days,” said Mike Brennan, senior hurricane specialist at the National Hurricane Center. “We’re really looking at a multi-day rainfall disaster unfolding.”

When Harvey hit land about 30 miles northeast of Corpus Christi around 10 p.m., CDT, Friday, it was a massive Category 4 storm bringing winds of 130 mph, says The Associated Press.

It was the strongest hurricane to hit Texas since 1961, reports The Houston Chronicle.

By 7 a.m., CDT, Saturday, Harvey was centered less than 50 miles from the middle Texas coast near the city of Victoria, Brennan said, and moving north-northwest around 6 mph.

“The center of Harvey is going to meander here over the middle Texas coast basically through the weekend and into the early and middle portions of next week and that is going to result in catastrophic flooding — life threatening flooding,” Brennan said.

In the small coastal city of Rockport, Texas, 10 people were being treated for storm-related injuries, City Manager Kevin Carruth told media outlets. Among the injured were people at a senior housing complex where the roof had collapsed. A local jail was serving as a makeshift hospital, Carruth said.

Corpus Christi is in the process of assessing the damage.

The city’s police department tweeted Saturday, “Much road debris and downed power lines. Most traffic lights are out. Please be patient.”

The city urged “extreme caution,” to those venturing outside due to “many active power lines down or compromised citywide.”

Corpus Christi has also issued a “precautionary” boil water notification, “to ensure destruction of all harmful bacteria and other microbes.” Residents are being urged to limit toilet and faucet use because power was knocked out at the city’s wastewater treatment plants.

By Saturday morning nearly 300,000 Texas residents were without power, according to the Electric Reliability Council of Texas.

“As the winds gradually come down, we’re still looking at hurricane force winds near the eye wall and in rain bands near the coast,” said Brennan of the National Hurricane Center. But he cautioned that water levels will remain elevated through Saturday. “We’re seeing tide levels, storm surge inundation reports, of still four to five feet above ground level among portions of the middle Texas coast.”

NPR’s Russell Lewis spent a rough night in Corpus Christi at a hotel overlooking the bay.

“All night long you could feel the windows rattling,” Lewis says. “You could feel the building swaying and there was just debris hitting the hotel all night long.”

On Friday, Lewis reported that he could see shingles blowing off the hotel. He said there were hundreds of Corpus Christi residents who opted to hunker down at the hotel rather than leave town.

Texas Gov. Greg Abbott had urged residents between Corpus Christie and Houston “to strongly consider evacuating.” But Houston Mayor Sylvester Turner tweeted Friday, “Please think twice before trying to leave Houston en masse. No evacuation orders have been issued for the city.”

Houston, the nation’s fourth biggest city, is notoriously prone to flooding, reports the AP. By Saturday morning, high water areas were already reported in the city, according to The Houston Chronicle.

A complicating factor on Saturday was a tornado threat for the middle and upper Texas coast, which remains in effect throughout the day, Brennan said.

Houston was under a Tornado Watch on Saturday, meaning tornadoes could form at any time. The city reported tornadoes “have already formed and caused damage in neighboring communities this morning.”

Also Saturday, EPA Administrator Scott Pruitt waived “certain fuel requirements,” to address shortages caused by Harvey.

An EPA statement said Pruitt determined “extreme and unusual fuel supply circumstances exist in portions of Texas as a result of the hurricane, and has granted a temporary waiver to help ensure an adequate supply of gasoline is available in the affected areas until normal supply to the region can be restored.”

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