Associated Press

HOUSTON — Tropical Storm Nicholas gathered strength Monday and threatened to blow ashore in Texas as a hurricane that could bring up to 20 inches of rain to parts of the Gulf Coast, including the same area hit by Hurricane Harvey in 2017 and storm-battered Louisiana.

Although the system was expected to generate only a fraction as much rain as Harvey, nearly all of the state’s coastline was under a tropical storm warning that included potential flash floods and urban flooding. Texas Gov. Greg Abbott said authorities placed rescue teams and resources in the Houston area and along the coast.

Forecasters at the National Hurricane Center in Miami said the system’s top sustained winds were 70 mph, nearly hurricane strength and an increase of 10 mph from earlier in the day. If the winds hit 74 mph, the storm would become a Category 1 hurricane. It was moving north-northeast at 12 mph and was predicted to make landfall late Monday night along the central Texas coast.

An automated station in Matagorda Bay registered a sustained wind of 55 mph with a gust of 71 mph, the hurricane center reported.

In flood-prone Houston, officials worried that heavy rain expected to arrive late Monday and early Tuesday could inundate streets and flood homes. Authorities deployed high-water rescue vehicles throughout the city and erected barricades at more than 40 locations that tend to flood, Mayor Sylvester Turner said.

“This city is very resilient. We know what we need to do. We know about preparing,” said Turner, referencing four major flood events that have hit the Houston area in recent years, including devastating damage from Harvey, which flooded more than 150,000 homes in the Houston area.

Turner and Harris County Judge Lina Hidalgo asked residents to stay off the roads Monday evening to avoid risking their lives or the lives of first responders who might be called to rescue them from flooded roadways.

“What I need each resident to do is get where you need to be by 6 p.m. and stay there,” said Hidalgo, the top elected official in Harris County, which includes Houston.

The Houston school district, the state’s largest, announced that classes would be canceled Tuesday because of the incoming storm. The weather threat also closed multiple 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 evening in Houston.