NEW ORLEANS – Tropical Storm Barry, building strength as it churned through the heated waters of the Gulf of Mexico, was on track to hit the Louisiana coast early Saturday as a Category 1 hurricane, threatening to pack its biggest punch not with high winds but heavy rain and a dangerous storm surge.

Across Louisiana, National Guard troops and rescue crews manned boats and high-water vehicles while utility repair crews with bucket trucks moved into position. Homeowners sandbagged their property or packed up and left.

"The real damage has never been about wind; it has always been about rain," Gov. John Bel Edwards said Friday after a meeting with his command center team.

Edwards said there are forecasts for 10 to 20 inches of rain over widespread areas and up to 25 inches in isolated areas.

As of 10 p.m. CDT, Barry was 75 miles south of Morgan City, Louisiana, and was crawling through the Gulf of Mexico at 3 mph. The storm is expected to shift northwest overnight, approaching the Louisiana coast Friday night. Landfall is expected over the south-central Louisiana coast on Saturday, followed by the storm turning toward the north, the National Hurricane Center says.

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Barry was packing sustained winds near 65 mph, only 9 mph shy of the hurricane designation of 74 mph. Forecasters said it was still possible Barry would remain a tropical storm when it went ashore.

The governor noted to USA TODAY Network earlier that the National Hurricane Center's forecast of life-threatening flooding "ought to get everybody's attention."

NHC Director Ken Graham warned that the "preparedness window" is shrinking: “It’s powerful. It’s strengthening. And water is going to be a big issue.”

Authorities said the speed and timing of Barry's arrival is critical. "The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the weather service said.

If it hits at the time of high tide, the weather service said, water could swell 3 to 6 feet above ground from the Atchafalaya River to Shell Beach, 3 to 5 feet from Shell Beach to Biloxi, Mississippi and 3 to 5 feet at Lake Pontchartrain.

Heavy rain packs the biggest danger over the region through the weekend. Forecasters said up to 20 inches is expected over southeast Louisiana, including New Orleans, Baton Rouge and Alexandria, and in southwest Mississippi, with as much as 25 inches in some isolated areas.

In all, some 14 trillion gallons of rainwater is forecast to fall on Louisiana, Mississippi and Arkansas during Barry, according to an estimate from BAM Weather meteorologist Ryan Maue.

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The weather service said the rains "are expected to lead to dangerous, life-threatening flooding over portions of the central Gulf Coast into the Lower Mississippi Valley."

Around New Orleans, the heavy rain and a storm surge could mean up to 3 feet of water in an already swollen Mississippi River.

Late Friday, National Weather Service forecasters predicted that the river would crest at about 17 feet above sea level in New Orleans over the weekend. Earlier they had predicted 19 feet, close to the levee system's 20-foot limit in some places.

A spokesman for the Army Corps of Engineers, however, expressed confidence that the levee system could handle the rapid rise, even if water should spill over in some spots.

“We’re confident with the integrity – the levees are extremely robust and designed to handle a lot of pressure,” Corps spokesman Ricky Boyett said.

Tornadoes were also a threat in southeastern Louisiana, according to AccuWeather meteorologist Dan Kottlowski.

Some areas in south Louisiana have issued curfews restricting roadway travel for motorists who are not emergency personnel. The city of Abbeville and St. Martin Parish have both issued evening curfews that will extend into the weekend.

For residents of New Orleans, the message from authorities was to hunker down. Mayor Latoya Cantrell noted that the city only orders evacuations for a Category 3 hurricane or stronger. "Therefore, sheltering in place is our strategy," the mayor said.

In New Orleans, an early line of thunderstorms dumped as much as 7 inches of rain within a three-hour period Wednesday morning, leaving up to 4 feet of water in some streets.

City officials said the pumping system that drains streets was at full capacity. The immense amount of rain in three hours would overwhelm any system, said Sewerage and Water Board Director Ghassan Korban.

Many residents in the Big Easy used the lull before the storm to stock up on supplies Thursday.

At the Tchoupitoulas Walmart, which sits across the street from the Mississippi River and a concrete flood wall, residents emptied shelves of bottled water, ramen noodles and produce.

Ruby Sterling said she lives in more elevated part of the city but admitted she was feeling "a bit panicky."

"I don't know if the city can hold up," Sterling said. "But I'm hopeful."

A few aisles up, Asia Daniels and her husband pulled case after case of bottled water into their cart. Ordinarily, floodwater only rises to the first step of their house in uptown New Orleans. Wednesday's storms brought the water to the second.

Doug Stangin and Doyle Rice reported from McLean,Va. Leigh Guidry reports for the Lafayette Daily Advertiser.

Contributing: Greg Hilburn in Baton Rouge, Brett J. Blackledge in Lafayette; The Associated Press

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