Tropical Storm Nicholas Monday morning had maximum sustained winds of 60 mph and was located over the Gulf of Mexico.
The storm was northeast of Brownsville, Texas, and was moving due north at 12 mph. Hurricane watches and storm surge watches were on the rise for parts of the southeastern Texas coast, including Galveston Bay and Corpus Christi Bay.
Heavy rains associated with the outer bands were already falling on the coasts of Texas and Louisiana, including in the metropolitan area of Houston. Tropical storm force wind gusts were already occurring along the central Texas coast.
After competing with dry air and strong winds overnight, Nicholas was organizing himself on the warm waters of the Gulf. The reorganization process led to erratic movement in the center, leading to some uncertainty as to the ultimate trajectory and intensity before landing.
Landing was expected Monday evening or very early Tuesday between Corpus Christi and Galveston as a high-end tropical storm or low-end Category 1 hurricane.
Regardless of the force on arrival, however, the expected impacts will not change, the most important of all being significant flash floods.
Precipitation rates could be 3 to 4 inches per hour under the heaviest rain bands. Infrastructure is struggling to cope with such intense rainfall rates, likely leading to significant flash floods, especially in urban areas.
To make matters worse, the heaviest rainfall for Houston and surrounding areas appears to occur after dark, compounding the danger. Meteorologists urge not to drive on water-covered roads, as the majority of flood-related deaths occur in vehicles.
The flood threat then moves to Louisiana on Tuesday and Wednesday, including areas still being cleaned up after Hurricane Ida made landfall on August 29.
Total storm precipitation through midweek could be extreme in some cases. For the middle and upper coast of Texas, 8 to 16 inches, with isolated maximum amounts of 20 inches are possible. Across the rest of the Texas coast to southwest Louisiana, totals could be 5-10 inches with locally higher amounts.
A potentially fatal storm surge will also be possible for parts of the immediate Texas coast, with a maximum of 3 to 5 feet possible.
When Nicholas was named Sunday, it became the 14th named storm of the 2021 season, corresponding to the climatological average number of named storms per season.
Only four more years in the era of satellites (back to 1966) had 14 storms as of September 12 and these are 2005, 2011, 2012 and 2020.
Nicholas will be the eighth storm to make landfall in the United States since the start of the year.