Officials in Texas and Louisiana are sounding the alarm ahead of the latest tropical threat to take aim at the Gulf Coast region. Tropical Storm Nicholas was closing in on the coast of Texas on Monday, and AccuWeather forecasters said the storm could produce a significant flooding threat around the greater Houston area. Nicholas has been rated a 1 on the AccuWeather RealImpact™ Scale.
As of 1 p.m. CDT Monday, Nicholas was moving erratically about 105 miles south of Port O'Connor, Texas. The storm had maximum sustained winds of 60 mph and was moving t
o the north at a speed of 12 mph. Nicholas is an expansive storm, with tropical storm-force winds extending outward up to 115 miles from its center.
A hurricane watch covered areas from Port Aransas to San Luis Pass, Texas, while a tropical storm warning was in effect for the coast of Texas from the mouth of the Rio Grande to Sabine Pass, Texas, the National Hurricane Center (NHC) said. Storm surge warnings were in place for parts of the Texas coast.
A state of emergency was declared in Louisiana by Gov. John Bel Edwards Sunday while Texas Gov. Greg Abbott raised the state's emergency alert level and readied incident management teams which included swift water rescue boat squads.
The center of Nicholas formed and re-formed several times Sunday night into Monday as the National Hurricane Center described its behavior as erratic, with the latest center appearing farther east and offshore of the Texas coast Monday morning, according to AccuWeather Hurricane Expert Dan Kottlowski.
Despite the erratic behavior of Nicholas early Monday, AccuWeather forecasters expect the general northward movement of Nicholas to continue with landfall along the middle part of the Texas coast, just southwest of Port O'Connor, likely Monday night, although additional shifts in the storm's center and changes in exact timing and landfall are possible.
While wind shear and proximity to the Texas coast are factors that will tend to limit the overall strength of Nicholas, waters in the the western Gulf of Mexico are well into the 80s F and more than warm enough to allow a tropical system to strengthen.
"As long as the center of Nicholas remains off the coast, there is the risk for strengthening and the possibility for it to reach Category 1 hurricane intensity prior to landfall," AccuWeather Senior Meteorologist Adam Douty said.
Whether Nicholas makes landfall as a tropical storm or hurricane, the greatest risk to lives and property will be from flooding rainfall. With the forecast track of Nicholas, the heaviest rain will end up over a broad area to the north and northeast of the center of the storm and that includes a large portion of southeastern Texas and part of Louisiana.
Abbott noted that the state of Texas deployed resources ahead of Nicholas, which was already bringing heavy rain to coastal areas Sunday night into Monday. "We will continue to closely monitor this storm and take all necessary precautions to keep Texans safe," he said. "I encourage Texans to follow the guidance and warnings of their local officials and be mindful of potential heavy rain and flooding."
* Nicholas is expected to follow a curved path that will take the system northward to the central portion of the Texas coast Monday night and then northeastward across part of the upper Texas coast and into western Louisiana on Tuesday.
Even though steady movement is predicted from Nicholas Monday night and Tuesday, the storm will funnel a tremendous amount of moisture in from the Gulf of Mexico and produce torrential rainfall along and inland from the coast, including the zone from Corpus Christi to Beaumont, Texas, including the Houston metro area, as well as Lake Charles and Alexandria, Louisiana.
The intense rainfall occurring over the Gulf of Mexico Monday will pivot northwestward relative to the center of Nicholas during Monday night and Tuesday.
A general 8-12 inches of rain with an AccuWeather Local StormMax™ of 24 inches is forecast in the zone from near Corpus Christi to Houston and up through the Lake Charles area. This amount of rain will lead to widespread flash flooding, as well as significant flooding of rivers and bayous.
The stronger Nicholas becomes, the greater the risk of damaging winds near and northeast of the center of landfall. The strongest wind gusts of 60-80 mph with an AccuWeather Storm Max™ gust to 90 mph are forecast to occur along the middle portion of the Texas coast Monday night into early Tuesday. However, should the center continue to shift around, gusts near hurricane force could occur farther to the north along the Texas coast.
Storm surge flooding is also a concern near and north and northeast of where the center of Nicholas moves ashore. A storm surge of 3-6 feet with locally higher levels can occur from Corpus Christi Bay to Galveston Bay, Texas. A storm surge of 1-3 feet is anticipated farther south and north along the Texas coast and along the southwestern Louisiana coast.
During the middle and latter part of this week, rainfall and thunderstorms associated with Nicholas are forecast to move slowly from the Mississippi Delta region to the Tennessee Valley. Heavy rain and flooding can still occur in these areas and overlap in locations that were hit by Ida in late August.
Even though flooding equal in scope and magnitude to Harvey is not expected from Nicholas, 1-2 feet of rain in as many days will bring a great deal of water and runoff. That amount of rainfall is two to four times of what is typically picked up during the entire month of September in the region.
"Rapid water rises are expected and could strand motorists and isolate some neighborhoods in this situation," Douty said.
Due to the risks to lives and property, primarily from flooding, Nicholas will be a 1 on the AccuWeather RealImpact™ Scale, even if the storm hits as a tropical storm," Douty added.
Rounds of heavy rain and gusty thunderstorms will precede the arrival of Nicholas by many hours and were ongoing early Monday in much of southeastern Texas and southern Louisiana. Rainfall in these outer bands can be intense and lead to localized flash flooding. Meanwhile, gusty winds in some of outermost thunderstorms can be strong enough to knock down trees and power lines.
Isolated tornadoes and waterspouts may be spawned well in advance of Nicholas's arrival into Monday evening. This risk will continue well after landfall Monday night and into Tuesday along the upper Texas coast and in southern Louisiana.
Nicholas, the 14th named storm of the 2021 Atlantic hurricane season, was expected to bring heavy rain to areas of southwestern Louisiana still recovering from hurricanes Laura and Delta in 2020. Parts of the state that were struck by Hurricane Ida last month could also be impacted, Edwards said. “The most severe threat to Louisiana is in the Southwest portion of the state, where recovery from Hurricane Laura and the May flooding is ongoing. In this area heavy rain and flash flooding are possible," Edwards said.