Storm surges will also be a risk, with forecasts of 2 to 5 feet in parts of Texas and Louisiana. A storm surge warning is in effect from Port Aransas to Sabine Pass, Texas, and for Galveston Bay, Aransas Bay, San Antonio Bay, and Matagorda Bay; it indicates danger within 36 hours of a fatal flood due to rising water moving inland.
Nicholas had sustained winds of a 60 mph storm and was 45 miles northeast of the mouth of the Rio Grande, the hurricane center said in an 11 a.m. ET update. The tropical storm was still trying to develop as it slowly moved north toward the Texas coast.
The Nicholas center will spend Monday morning near the coasts of northeastern Mexico and southern Texas and move to the coast late Monday afternoon or evening along the southern or central Texas coast. , the hurricane center said.
Nearly 10 million under lightning surveillance
Nicholas flash flood risk is increasing, with a level 4 in 4 risk of excessive precipitation along the coast today between Galveston Bay and Matagorda Bay.
There is “an extremely humid tropical air mass in place” in these regions, resulting in forecasts of high precipitation totals, the Weather Prediction Center said. Nearly 10 million people are under flash flood surveillance.
Some places will receive a lot more rain than others.
“Rainfall amounts exceeding 10 to 15 inches with higher isolated totals are expected through the end of Tuesday in some locations,” the National Weather Service office in Houston said.
“Rather than falling into an even distribution, heavy precipitation will result in large totals over relatively short periods of time, increasing the threat of flash flooding.”
Some spots could reach up to 20 inches, CNN meteorologist Dave Hennen said.
Heavy rains will be the main threat, with a widespread 5-10 inch wave expected for southwest Louisiana. On the middle and upper coasts of Texas, the storm is expected to produce 8 to 16 inches, the hurricane center said.
“This storm has the potential for widespread flash flooding. Houston can easily have problems with 4 to 5 inches of rain,” CNN meteorologist Tom Sater said. “More than that will create bigger problems.”
There is also a considerable flood threat through Wednesday in areas ranging from Corpus Christi, Texas, to the greater Houston area and parts of western Louisiana, including Lake Charles.
Louisiana governor declares state of emergency
Louisiana Governor John Bel Edwards declared a state of emergency on Sunday ahead of Nicholas, he said in a press release.
“The most serious threat to Louisiana is in the southwestern part of the state, where recovery from Hurricane Laura and the May flooding is underway. In this region, heavy rains and flash floods However, it is also likely that all of southern Louisiana will experience heavy rain this week, including areas recently affected by Hurricane Ida, ”Edwards said.
Houston gears up by lowering Lake Houston
Houston is bracing for moderate to heavy rain overnight Nicholas, Mayor Sylvester Turner said Monday morning.
“It’s a storm again with some unpredictability, but we know it’s going to be mostly a rainy event,” he said.
Everyone should finish what they’re doing before sunset so they can get home safely when the storm passes, he said.
The city is preparing for the rain by lowering Lake Houston one foot and deploying high-water equipment throughout the city, as authorities cannot determine which places will receive more rain, the mayor said.
Schools in the Houston Independent School District will be canceled Tuesday due to bad weather, according to the school district’s website. All Monday extracurricular activities are also canceled. The district is the largest in Texas, with more than 275 schools.
CNN’s Ralph Ellis, Carma Hassan, Brandon Miller, Haley Brink, Michael Guy and Gregory Lemos contributed to this report.