Hurricane Nicholas made landfall along the Texas coast, posing a threat of precipitation of up to 50cm over parts of the Gulf Coast that have already been hit by storms this year.
Nicholas is the 14th named storm of the 2021 Atlantic hurricane season.
Almost all of the Texas coastline is subject to a tropical storm warning, which includes potential flash floods, power outages, and storm surges.
Forecasters are more concerned about how much precipitation Nicholas could produce, especially in flood-prone Houston.
City officials have deployed deep sea rescue vehicles throughout the city and erected barricades at more than 40 locations that tend to be flooded, Mayor Sylvester Turner said.
“This city is very resilient. We know what we need to do. We know how to prepare,” said Turner, referring to four major floods that have hit the Houston area in recent years, including devastating damage to Hurricane Harvey in 2017.
Harvey has been blamed for at least 68 deaths, including 36 in the Houston area.
The Houston School District, the state’s largest, along with others, said classes would be canceled on Tuesday and Texas Gov. Greg Abbott said rescue teams had been deployed in case they would be necessary.
The weather threat has also closed several COVID-19 testing and vaccination sites in the Houston and Corpus Christi areas, and forced the cancellation of a Harry Styles concert scheduled for Monday night in Houston.
Six to 12 inches (15 to 30 cm) of rain was expected along the middle and upper Texas coast, with isolated maximum amounts of 18 inches (46 cm) possible.
Other parts of southeast Texas and south-central Louisiana and southern Mississippi could see 10 to 20 cm over the next few days.
President Joe Biden has declared an emergency for Louisiana and ordered federal assistance to complement local response efforts due to conditions resulting from Nicholas, the White House said.
One or two tornadoes could be possible Tuesday along the upper Texas coast and southwestern Louisiana, according to the National Hurricane Center in Miami.
The concern with Nicholas will be how slowly he moves. Storms have moved more slowly in recent decades and Nicholas could find himself stuck between two other weather systems, said hurricane researcher Jim Kossin of the Climate Service.
Louisiana Gov. John Bel Edwards declared a state of emergency Sunday night, before the storm arrived in a state still recovering from hurricane Ida, Hurricane Laura from last year, and historic flooding.