Update: Residents of Fargo are breathing a collective sigh of relief, at least for now. The Red River has crested at just over a record 40 feet. That's below the 43-foot level forecasters said was possible a few days ago.
Still, forecasters say the water level could rise again. Residents are taking no chances.
They're continuing to reinforce the 43-foot high walls of sandbags they've built around the river in hopes of protecting their nearby homes.
Officials say the water is pressing hard against the dikes and levees holding it back.
As the people living along the Red River in North Dakota and Minnesota intensified their efforts Saturday to fend off floodwaters, a revised National Weather Service estimate offered some hope — especially for the people of Fargo, N.D.
Forecasters put out an alert Saturday that said the river is expected to remain below 41 feet and to slowly decrease over the coming days. That is significantly lower than the 43-foot crest earlier predicted.
Still, under mandatory evacuations, thousands of people have fled from their homes in Fargo and across the river in Moorhead, Minn.
Mike Hudson at the National Weather Service said Saturday the Red River may have crested around midnight at 40.82 feet. As of 8 a.m. it had dropped to around 40.69 feet.
"The best news we can take from this is the river has crested," Fargo Mayor Dennis Walaker said. "But diligence is going to have to be required for at least eight more days and hopefully things will continue to drop. The only thing that would change all that optimism would be to have a significant storm that could change that. I'm optimistic."
The improved situation is a result of the frigid weather: Cold temperatures froze the water that would have flowed into the river, halting its rise, said Hudson. By the time that water thaws, the biggest flooding threat should have passed, he said.
Forecasters acknowledged that the situation could still take at turn for the worse, with a storm predicted to strike early next week with more snow and strong wind.
On Saturday, authorities deployed high-tech Predator drone aircraft, called up more National Guard troops and asked residents to be on the lookout for any breaches in levees.
Residents and National Guard troops have been working around the clock, stacking up millions of sandbags, hoping that will be enough to hold back the rising waters.
Officials in Fargo and Moorhead say they've built makeshift dikes as high as they can, 43 to 44 feet in most places.
Walaker said everyone is now just keeping watch to see how high the water goes, while National Guard troops patrol the dikes to watch for leaks.
Meanwhile, as forecasters try to get a fix on what will happen in coming days, Mother Nature's variables create various good news/bad news scenarios.
Bone-chilling overnight temperatures gave Fargo a much-welcome reprieve from the worst possible flooding. But warmer temperatures were expected Saturday, meaning more melting snow could flow into the river.
And while the temperatures that plunged to near zero overnight kept snow from melting into the river, they make sandbags less effective.
"Well, they freeze," Walaker says. "I mean, basically they turn into rocks. As far as making a good sandbag dikes, frozen sandbags don't do a good job."
The city of Fargo has some 300,000 sandbags reserved indoors for when they're needed to shore up leaking dikes.
No major levee breaches or other issues were reported overnight.
Officials said they were increasing the number of guard troops from 1,700 to 1,850 and bringing in 300 large bags that hold a ton of sand and could be dropped by helicopter into breaks in the levees.
Predator drones from the Grand Forks Air Force Base began flying overhead Saturday morning, providing officials bird's-eye views of the situation and allowing them to react quickly if flooding worsens.
"They will be up there for 10 hours today providing video of the flood situation," North Dakota Gov. John Hoeven said in an interview Saturday with The Associated Press.
President Barack Obama assured the nation Saturday he was keeping close watch on the Midwest floods and putting the government's full weight behind efforts to prevent disaster.
"Even as we face an economic crisis which demands our constant focus, forces of nature can also intervene in ways that create other crises to which we must respond — and respond urgently," the president said in his weekly radio and Internet address.
"I will continue to monitor the situation carefully," he pledged. "We will do what must be done to help."
While the situation in Fargo was getting the most attention, officials across the river in Moorhead, Minn., were also dealing with the threat of heavy flooding. Thousands of people had evacuated the city of 30,000, although others have stayed behind.
"Right now we're confident, but if the dikes break we'll have people standing on their roofs," said Clay County, Minn., Sheriff Bill Bergquist.
Temperatures were in the single digits in Morehead during the night, preventing snow from melting and feeding the rising river. The Red rose less than a foot Friday, compared to 2.5 feet on Thursday.
Officials of the city of 92,000 people said Saturday they didn't immediately need any more volunteers.
"Now it's time to stand and defend," said Tim Mahoney, a Fargo city commissioner.
Hundreds more Guard troops poured in from around North Dakota and neighboring South Dakota, along with scores of American Red Cross workers from as far away as Modesto, Calif. Homeowners, students and small armies of other volunteers filled sandbags. Missouri Gov. Jay Nixon said Saturday his state's National Guard was sending two C-130 aircraft with at least 34 troops to help.
"It's to the point now where I think we've done everything we can," said Fargo resident Dave Davis, whose neighborhood was filled with backhoes and tractors building an earthen levee. "The only thing now is divine intervention."
Federal officials we prepared to shelter and feed 30,000 people for a week, said Homeland Security Secretary Janet Napolitano. More people than that may be evacuated, but she said officials expect most people would seek help through friends and family first. She said the Coast Guard had participated in 82 rescues by Friday.
In a flooded small community north of Fargo and across the river, fire destroyed a house surrounded by so much water that firefighters couldn't get within 200 feet. More than 100 residents of Oakport Township, Minn., had to be rescued by boat.
Fargo escaped devastation from flooding in 1997, when Grand Forks was ravaged by a historic flood 70 miles to the north. This year, the river has been swollen by heavier-than-average winter snow, combined with an early freeze last fall that locked a lot of moisture into the soil. The threat has been made worse by spring rain.
"I think the river is mad that she lost the last time," said engineer Mike Buerkley, managing a smile through his dark stubble as he tossed sandbags onto his pickup truck after working 29 straight hours.
National Guard member Shawna Cale, 25, worked through the night on a dike, handing up sandbags that were 30 to 40 pounds and frozen solid.
"It's like throwing a frozen turkey," said sister-in-law Tawny Cale, who came with her husband to help with the sandbags and then to help Shawna move her valuables as she evacuated.
This story draws on reports from NPR, Minnesota Public Radio and The Associated Press.