A tropical storm warning is in effect for the Gulf coast of Mexico from Boca de Catan north to the mouth of the Rio Grande river as a system over it has a 70% chance of developing into a cyclone in the next 48 hours, the U.S. National Hurricane Center (NHC) said on Saturday.

The system, currently labeled a disturbance, is expected to reach the coast of northeastern Mexico late afternoon and then move across the Rio Grande valley on Saturday and Sunday, the NHC said.

Heavy rains could cause flash floods across portions of south Texas and northeastern Mexico through Sunday morning, it added.

The disturbance could still strengthen slightly and become a tropical storm later on Saturday before reaching the coast of northeastern Mexico, according to the NHC.

The Hurricane Center said an Air Force Hurricane Hunter aircraft was en route to investigate the disturbance.

(Reporting by Akanksha Khushi in Bengaluru, Editing by Mark Potter)