Now Delta is trying to tarnish the northern Gulf Coast in its dangerous second act later this week with the coast of central and western Louisiana in its crosshairs.
“Delta is expected to grow in size as it approaches the northern Gulf Coast, where there is an increasing likelihood of life-threatening storm surges and dangerous hurricane-force winds starting Friday, particularly for parts of the Louisiana coast,” the National Hurricane Center wrote Wednesday.
Delta could have a serious impact on some of the distressed parts of southwest Louisiana, which were badly hit by Category 4 Laura in late August.
On Wednesday morning, the Hurricane Center released a Hurricane Watch for the zone between High Island, Texas and Grand Isle, Louisiana, including the zone where Laura landed.
The storm could come ashore not far from Lake Charles, where Laura wreaked weeks of serious damage in some areas and cut power. Although Delta̵
However, the effects of the storm will extend well beyond the coast.
A storm surge watch stretches from High Island to the Alabama-Florida border and includes Pontchartrain Lake and Mobile Bay. The rise could cause up to 11 feet of flooding along the central Louisiana coast.
The storm’s region of influence is expected to grow as the storm’s wind field expands prior to landing. New Orleans can escape with only minor tropical storm winds, but any shift eastward could exacerbate the storm effects there.
“NOW is the time to make sure you have a plan if you live anywhere on the northern Gulf Coast,” wrote the New Orleans National Weather Service.
Winds with tropical storm strength could hit the coast of Louisiana as early as late Thursday evening or Friday morning.
Although disruptive mid-level winds weakened the delta to a Category 2 level prior to landing in Mexico, re-intensification is likely as it moves across the warmer waters of the southwestern Gulf of Mexico. The small storm has a tight, compact circulation, making it more prone to rapid fluctuations in intensity.
Delta was over the Yucatán Peninsula, about 65 miles west of Cancun, at 11 a.m. on Wednesday, moving northwest at 27 km / h to surface over the Gulf of Mexico. The storm had weakened further as it crossed the Yucatán, with maximum winds announced at 105 miles per hour. His central air pressure had increased significantly, a sign that he was no longer lifting and evacuating the air in the upper levels as efficiently as before.
Microwave satellite images indicated that Delta’s former holey eye was ragged and disheveled, and a much larger eye was beginning to form. This is one of the reasons why the winds contained in the eye wall had decreased. Much like a whirling ice skater stretching out his arms, a radial expansion means a decrease in rotational speed or wind speed.
Winds of 84 mph occurred in Cancun, along with a gust of 106 mph. Puerto Morelos reported sustained winds of 54 miles per hour and a gust of 75 miles per hour behind the center. Cozumel recorded a gust of 64 miles per hour.
Re-intensification over the Gulf of Mexico
When Delta emerges over the Gulf of Mexico on Wednesday afternoon, the Delta is expected to strengthen again as it is exposed to water temperatures between 81 and 85 degrees. The Hurricane Center plans for Delta to regain Category 3 strength on Thursday, with peak winds reaching 120 mph.
The type of rapid intensification that occurred while the Delta was over the Caribbean is less likely in the Gulf because the ocean’s heat content – a measure of how much energy a hurricane can extract from the ocean’s surface waters – is lower. About a fifth to a quarter as much “fuel” is available, just enough for Delta to maintain and steadily strengthen itself.
Delta is likely to weaken a bit towards the coast as it meets slightly cooler waters over the continental shelf. At the same time, the wind shear or a change in wind speed and / or direction increases with altitude. That could continue to work against Delta.
Even so, Delta is still expected to land in Louisiana as a Category 2 or Lower Category 3 dangerous hurricane.
Effects on the USA
Delta will create multiple storm hazards along the northern Gulf Coast, including storm surges, noxious winds, flash floods, and tornadoes.
The Hurricane Center predicts a “life-threatening” surge or storm-induced surge in water over normally dry coastal land over a large area from the Texas and Louisiana border to the Alabama and Florida border. The rise is maximized just east of where the center crosses the coast.
The most likely location for landing is anywhere along the western or central Louisiana coast between the Calcasieu and Atchafalaya Rivers, or southwest of Lafayette.
The Hurricane Center projects the largest rise between Pecan Island and Port Fourchon, La., Where the water can rise 7 to 11 feet above dry land when the maximum rise coincides with the high tide. But areas as far east as Mobile Bay in Alabama have seen increases of 2 to 4 feet. The storm could also raise water levels one to three above normal west to Galveston Bay, Texas.
In the area destroyed by a wave of up to 17 feet during Hurricane Laura near and east of Cameron, La., The Hurricane Center projects a wave of 4 to 7 feet.
Destructive winds are also a problem.
Residents between the Rockefeller Wildlife Refuge and Morgan City, including those bordering Vermillion Bay, should prepare for gusts of 100 to 115 miles per hour near the immediate shore. Further inland, gusts of 85 to 95 miles per hour are likely in the Lake Arthur to Lafayette corridor.
The strongest winds are found in the eye wall or in the ring of strong thunderstorms that surround the eye of a hurricane.
Unless Delta’s track shifts east, New Orleans will likely only see gusts in the 40 to 45 mph range, which are safely east of the core circulation.
Widespread rainfall of 4 to 8 inches with localized 12 inch amounts is also likely within the swath covered by Delta Core that currently appears to be moving north through central Acadiana, Louisiana. Some flash floods are likely.
The rains from Delta will migrate north into the Mississippi Valley on Saturday and into the Tennessee Valley and the Central Atlantic by Sunday.
As Delta comes ashore, some tornadoes cannot be ruled out, particularly east of center in southern Mississippi and on the far west coast of Alabama.
Delta in a historical context
Delta will be the tenth named storm to hit US soil during the 2020 hurricane season. That year the storms were so numerous that the National Hurricane Center’s conventional list of names was exhausted for only the second time on record. Forecasters have forced the use of Greek letters for names; Delta became the strongest Greek storm observed on Tuesday.
Between Monday morning and Tuesday afternoon, Delta’s peak winds catapulted 110 mph from a tropical depression of 35 mph to 145 mph Category 4.Delta’s 70 mph intensity jump in the 24 hours between Monday morning and Tuesday morning is the second-fastest hurricane since October in the Atlantic, just behind Wilma in 2005. This type of rapid intensification is likely to become more common and severe in a warming world. With six Atlantic storms in 2020, there was a rapid intensification.
When Delta expanded into a hurricane on Monday, it formed the ninth in the Atlantic in 2020. “Only three more years in the satellite era (since 1966) through October 5, 1995, 2004 and 2009 produced nine or more Atlantic hurricanes in 2005,” tweeted Phil Klotzbach, a hurricane researcher at Colorado State University.