A hurricane watch means hurricane conditions — sustained winds of at least 74 mph — are possible within 48 hours of the watch being issued.
The risk for flash flooding from Nicholas is increasing, with a level 3 of 4 risk for excessive rainfall issued for coastal sections of Texas from Monday through at least Tuesday night, according to the Weather Prediction Center.
“This brings 48 hour totals for some areas to 9 to 12 inches which could lead to significant flooding concerns, especially for urban areas like the Houston metro,” said the Weather Prediction Center.
While it is still unclear where the heaviest rain will fall, there will be locations that receive a storm total of at least 15 inches by the end of this week.
Torrential rains are forecast for the Texas coast, and there is a considerable flood threat through Wednesday in areas from Corpus Christie, Texas, through the Houston metro area and portions of western Louisiana, including Lake Charles.
Nicholas, the Atlantic hurricane season’s 14th named storm, formed in the Gulf of Mexico Sunday. A 14th named storm in the Atlantic basin, the total number of storms in an average season, typically doesn’t form until November 18.
Threats of torrential downpours and up to 5 feet of storm surge
The center of the storm should move through or near southern Texas on Monday and Tuesday for upper portions of the coast.
Heavy rain will be the main threat, with a widespread 5 to 10 inches expected for southwest Louisiana. Across middle and upper coastal Texas, the storm is expected to produce 8 to 16 inches, the NHC said.
“This storm has the potential for widespread flash flooding. Houston can easily have problems with 4 to 5 inches of rain,” said CNN Meteorologist Tom Sater. “More than that will create bigger problems.”
Storm surge will also be a risk, with 2 to 4 feet forecast through parts of Texas and Louisiana.
The stretch of Texas Gulf Coast from Port O’Connor to San Luis Pass could see a surge of up to five feet and a storm surge warning is in place.
CNN’s Michael Guy contributed to this report.