HOUSTON — Heavy rains and rising rivers continued to endanger much of Southeast Texas Friday.

Thousands of Texans were already displaced or under evacuation orders in places such as Polk, Montgomery and Harris counties. Others were without electricity. Schools and businesses were closed as roads and highways — especially in rural East Texas — were impassable. Emergency officials were comparing the amount of water inundating this region to levels seen during Hurricane Harvey, a Category 4 hurricane that made landfall in Texas in 2017.

No fatalities were reported as of Friday morning.

Numerous Southeast Texas counties remained under a Flood Watch — meaning flooding was possible — through Friday evening. At best, the rainfall would slow exiting floodwater, the weather service said. At worst, it would cause more flooding.

The Trinity River and the East and West Forks of the San Jacinto River were also dangerously on the rise and would be for at least a day more as the accumulating rainfall drained toward the Gulf.

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“We’re really dealing with both right now,” said Sean Luchs, a National Weather Service meteorologist in the Houston/Galveston office. “We’re getting both these events of heavy rain that in the short term cause flash flooding and are also contributing water in that runoff to cause rises in the rivers and we get that river flooding as well.”

Harris County Flood Control District Meteorologist Jeff Lindner expected ground-level homes along the East Fork of the San Jacinto River to be flooded to the rooftop. He also predicted flooding in areas along the West Fork of the river.

The Trinity River was meanwhile causing major problems in Polk and Liberty Counties.

“We’re looking at significant flooding on the rivers,” Lindner said. “This is significantly more serious than what we were dealing with earlier this week.”

Here’s how much rain has fallen in Southeast Texas counties in the last 72 hours

Forecasters expected to see more rainfall on Friday after at least a week of off-and-on rain. This afternoon, a storm is expected to reach Polk County, bringing additional rainfall that meteorologists expected would arrive tonight. The storm will move further west into Walker County, the national weather service said.

“Normally that rain wouldn’t cause floods,” a meteorologist told The Texas Tribune. “But because of the conditions in the last few days, plus the rivers, the rain will likely worsen the floods.”

In the last 72 hours, there have been up to 14 inches of rain in Polk County, with the surrounding areas receiving 8-10 inches, the National Weather Service said. Montgomery County has been awash with up to 12 inches of rain. In Harris County, that number ranges from 4-7 inches of rain.

— Carlos Nogueras Ramos

“That whole area is covered up in water”: Polk County continues under deluge

East Texas officials upheld mandatory evacuation orders for Polk County residents Friday morning, bracing for floods largely provoked by overflow from the multiple rivers in the region.

Meteorologists expect a lull in rainfall overnight but said flooding remains a concern because of the abundance of water flowing out of the rivers and creeks, worsening the flood conditions.

County officials said their focus was to monitor areas surrounding the Trinity River Basin, which they said are prone to exacerbated flooding because of their proximity to the continuing heavy discharges of water. In particular, officials are monitoring excess water flowing out of the Lake Livingston River Dam, which is adjacent to the city of Livingston.

“That whole area is covered up in water,” said Polk County Judge Sydney Sweeney. “And so some of that water is moving very, very quickly because of the amount of water that’s coming out of the dam. You have pine trees that are underwater.”

Meteorologists said they expect rainfall to slow by nightfall Friday in East Texas. Most showers are expected to buffet harshly in counties north of Houston, including Montgomery and Harris Counties. Montgomery is the most populous county in the state.

Flash flood warning for Montgomery County and an early warning for Galveston Bay

Montgomery County should expect more downpours that could bring up to an inch of more rain, the National Weather Service said Friday. A meteorologist with the weather service also said the agency is monitoring areas surrounding Gavelston Bay, south of Houston.

“We’re also dealing with ongoing river flooding in that area as well, and so the runoff from all this rain we’re getting is going to impact that,” the national weather service said.

The area received about 5-8 inches of rain within 24 hours. Some areas received up to 12 inches of rain, the Associated Press reported Friday morning.

County Judge Lina Hidalgo on Thursday issued a disaster declaration for Harris County, which includes Houston, for communities close to the East Fork of the San Jacinto River to Lake Houston. Hidalgo in the declaration said residents should “evacuate as soon as possible” if they are in a place to do so.

“Residents should either plan to stay where they are for the next two days or leave as soon as possible if they are not prepared to do that,” Hidalgo said in the disaster declaration. That’s in addition to the mandatory evacuations issued for residents near Houston.

Texas Department of Transportation officials said State Highway 30, north of Montgomery County, was closed due to severe weather conditions on Thursday.