Tropical Storm Marco fell apart Monday as it approached the southeast coast of Louisiana, turning attention to Tropical Storm Laura, which poses a serious threat to the coasts of Louisiana and Texas.
Computer models suggest that Laura could tap the exceptionally warm waters of the Gulf of Mexico and intensify into a large and dangerous hurricane as it moves toward the Gulf Coast.
The storm is forecast to make landfall late Wednesday or early Thursday with winds over 100 mph in the zone from near Galveston, Tex. to just west of Morgan City, La, where hurricane watches have been posted. Houston is under a tropical storm watch.
The National Hurricane Center is forecasting a âlife-threateningâ storm surge which could reach up to 7 to 11 feet above normally dry land at the coast and has issued storm surge watches from just southwest of Houston to coastal Mississippi. In addition, the storm is forecast to unload 4 to 8 inches of rain when it comes ashore and up to a foot in some areas, causing flash flooding.
Meanwhile, Marco was falling apart Monday afternoon due to shear, a change in wind direction and speed with altitude â and was barely a tropical storm.
The National Hurricane Center issued its first hurricane and storm surge watches for the U.S. coast associated with Tropical Storm Laura. The storm, currently located about 40 miles to the east of the Isle of Youth, just south of mainland Cuba, is moving toward the open waters of the Gulf of Mexico and is expected to intensify into a strong Category 2 or 3 storm before making landfall on Wednesday night or Thursday morning.
Computer model guidance has come into better agreement on the likely landfall zone, but it is still a broad area.
The latest group of computer model simulations suggest that Houston and Galveston, Tex., are plausible landfall locations for Laura and that residents should be preparing for a hurricane.
The map above shows track simulations from the European modeling system, in red, and the American modeling system, in blue. The bold red and blue lines represent the average of each group of simulations.
The European model track simulations are clustered near Houston, while the American model simulations are clustered somewhat to the northeast, near Port Arthur, Tex.
These forecasts suggest that the zone from just north of Corpus Christi, Tex., to just west of Morgan City, La., is most likely to see hurricane impacts based on the latest available data. Houston and Port Arthur are smack in the middle of this zone, while New Orleans has become less likely to endure a direct hit.
As the storm is still more than 48 hours from landfall, this plausible landfall zone could still shift. And it will also probably shrink as the amount of variation among the simulations decreases and the various track forecasts become more tightly packed together, indicating more confidence in the forecast.
Several jurisdictions have begun to issue requests for voluntary and mandatory evacuations in Louisiana and Texas as the threat from Tropical Storm Laura grows.
The storm, predicted to be a Category 2 or possibly stronger hurricane at landfall late Wednesday into Thursday, poses âan increasing risk of dangerous storm surge, wind, and rainfall impactsâ according to the National Hurricane Center.
The National Hurricane Center has dropped all tropical storm and storm surge warnings for coastal Louisiana as Tropical Storm Marco is torn apart by relentless wind shear in the northern Gulf of Mexico.
On satellite imagery, the center of Marco is a swirl of low-level clouds, while its strongest winds and heaviest rains are displaced well to the northeast, over the Florida Panhandle. This is because of strong upper-level winds that have disrupted the storm, and the Hurricane Center doesnât see any opportunity for Marco to regain intensity now that itâs so close to shore. This is good news for residents of coastal Louisiana and Mississippi who were preparing for damaging winds and storm surge flooding as recently as Monday morning.
âBased on how quickly the vortex has been spinning down and the anticipated decrease of convection, it is reasonable to assume that sustained tropical storm force winds will no longer reach the northern Gulf Coast,â the Hurricane Center, which is part of the National Oceanic and Atmospheric Administration, said in an online discussion.
Tropical Storm Laura is holding its own despite being so close to land, moving just 15 miles south of Cayo Largo, Cuba, as of 2 p.m. Eastern. The storm is moving west-northwest at a rapid clip of 20 miles per hour, and once it clears the western tip of Cuba, the only impediments to its intensification will be found in the atmosphere. For example, wind shear, or winds blowing with different speeds or direction with height, can inhibit a tropical storm or hurricane from strengthening or even tear it apart.
Officially, the Hurricane Center is forecasting Laura to make landfall somewhere along the Texas or Louisiana coastline on Wednesday night as a Category 2 hurricane. However, forecasters there are cautioning it could grow more intense, and computer models are showing how that could play out. Hurricane and storm surge watches are expected to be issued for the Gulf Coast by Monday evening in anticipation of the stormâs arrival.
Tropical storms Marco and Laura are both tracking toward the Gulf Coast. Here are their 2 p.m. coordinates:
The Weather Channelâs Greg Diamond has pointed out that Tropical Storm Laura is on a similar path to the Sept. 8, 1900, Galveston Hurricane, the deadliest natural disaster in U.S. history.
That storm, a Category 4, was blamed for 8,000 fatalities, although exact estimates vary. Most of the deaths occurred from the storm surge, the rise in water above normally dry land at the coast, which resulted in over 15 feet of inundation. The area was not evacuated ahead of the storm, and as waters rapidly rose, it was too late for many to escape, and there was little high ground to flee toward.
The story of Isaac Cline, the U.S. Weather Bureau meteorologist who attempted to warn Galveston residents about the forthcoming danger the day the storm approached, is chronicled in the popular book âIsaacâs Storm,â by Erik Larson.
Although Laura has followed a track similar to the Galveston storm so far, there remain a wide range of possibilities for its ultimate landfall location, somewhere between Corpus Christi and New Orleans in the Wednesday night through early Thursday time frame. The current National Hurricane Center forecast suggests that the most likely landfall location is near the Texas-Louisiana border.
Itâs also not clear whether Laura will be anywhere near as intense as the 1900 hurricane. The current Hurricane Center forecast projects it to make landfall as a Category 2 storm with 105-mph winds, although some computer models suggest it could be stronger. The 1900 hurricane had peak sustained winds estimated between 130 and 140 mph.
Galveston now has a sea wall to protect it to some extent from storm-surge inundation. The judge for Galveston County reportedly declared a state of disaster on Monday afternoon ahead of the storm.
As Laura plowed through the Dominican Republic and Haiti over the weekend, it unloaded torrential rainfall that led to deadly flash flooding.
The Associated Press reported at least 11 deaths from the tropical storm, which caused wind damage in addition to flooding.
âHaitian civil protection officials said they had received reports that a 10-year-old girl was killed when a tree fell on a home in the southern coastal town of Anse-a-Pitres, on the border with the Dominican Republic. Haitiâs prime minister said at least eight other people died as Laura passed by and two were missing,â the AP wrote. âIn the Dominican Republic, relatives told reporters a mother and her young son died after a wall collapsed on them.â
The National Hurricane Center had forecast 4 to 8 inches of rain in the two countries, with isolated amounts to one foot that would cause âlife-threatening flash and urban flooding, and the potential for mudslides.â
Social media video showed examples of significant inundation from heavy rainfall in both Haiti and the Dominican Republic.
Tropical Storm Laura is continuing to batter Cuba with strong winds and heavy rain, and the National Hurricane Center is warning of the possibility that the storm will not only intensify, but will do so rapidly as it traverses the unusually warm waters of the Gulf of Mexico between Cuba and the Gulf Coast, starting Tuesday.
In an online forecast discussion, NHC forecasters wrote: âGiven the very conducive upper-level wind pattern depicted by the global models, a period of rapid strengthening is possible once Laura reorganizes an inner core after its passage over western Cuba.â
What this means is that the storm could jump a few categories on the Saffir-Simpson hurricane intensity scale in a 24-hour time frame, which would instigate more hurried preparedness measures, along the Gulf Coasts of Texas and Louisiana in particular. Multiple computer models used to aid forecasters in plotting out the stormâs future path and intensity show the storm eventually getting to major hurricane status of Category 3 or greater. However, predicting intensity fluctuations is notoriously difficult, and itâs possible that it will remain a Category 1 or 2 storm before making landfall.
The latest update from the National Hurricane Center shows that the center of Tropical Storm Marco, located about 55 miles southeast of the mouth of the Mississippi River, is expected to come ashore this evening as the storm weakens to a tropical depression. Due to strong winds in the upper levels of the atmosphere, most of the heavy rain and strong winds were occurring 50 miles or more to the northeast of the storm center, including over the Florida Panhandle. This trend is expected to continue throughout the day on Monday.
Rainfall amounts of 3 to 6 inches with isolated amounts of up to 10 inches are expected across southeastern Louisiana, parts of Mississippi and the Florida Panhandle as the loosely organized circulation of Tropical Storm Marco spins toward the coast.
Computer models in the last several hours have shifted the most likely track zone for Tropical Storm Laura slightly south and west, which potentially puts Texas at greatest risk.
Both the European and UKMet computer models, which rank as the most accurate, project a Texas landfall.
That said, models have been oscillating on the track forecast for several days, and landfall is still about 60 hours or so away. Additional shifts in the track are possible, and the entire zone from roughly New Orleans to Corpus Christi should pay close attention to the forecast.
The National Hurricane Center will update its forecast track for Laura at 11 a.m. Eastern time, and a westward shift is quite possible.
The one-two punch from Marco and Laura could bring extremely high rainfall totals and flooding to parts of the Gulf Coast, especially in any areas hit by both storms.
The National Weather Service has placed much of southern Louisiana in a slight- to moderate-risk zone for flash flooding through Thursday.
Already, Marco has begun to produce moderate to heavy rain in the Florida Panhandle and parts of coastal Alabama. Heavy downpours are predicted to spread over coastal Mississippi and Louisiana as Monday wears on, continuing into Tuesday. Some pockets of flooding could develop.
While Marco may unload 3 to 5 inches of rain in some areas along the north-central Gulf Coast, with isolated amounts up to 10 inches, Laura may dispense more widespread heavy rainfall as it comes ashore.
âFrom late Wednesday into Friday, Laura is expected to produce rainfall of 5 to 10 inches, with isolated maximum amounts of 15 inches across portions of the west-central U.S. Gulf Coast near the Texas and Louisiana border north into portions of the lower Mississippi Valley,â the National Hurricane Center wrote. âThis rainfall could cause widespread flash and urban flooding, small streams to overflow their banks, and the possibility of some minor river flooding across this region.â
In any areas where rainfall from the two storms overlaps, the flooding risk will be elevated. However, the exact landfall zone for Laura is still coming into focus.
Tropical Storm Laura may be centered to the south of Cuba, but its large circulation is producing gusty winds all the way to the Florida Keys. Tropical storm warnings have been issued for the Florida Keys from Craig Key to Key West, where sustained winds of 39 mph or greater, along with higher gusts, are expected on Monday.
The Keys also face an isolated tornado threat as squalls from Laura swing through the area on Monday.
The most significant impacts from Laura are occurring Monday in Cuba, Jamaica and the Cayman Islands, where wind gusts to hurricane force, heavy rain and storm surge flooding is ongoing. The stormâs center is skirting the southern coast of Cuba, possibly helping the storm avoid weakening despite its interaction with land.
The U.S. National Hurricane Center expects Laura to become a hurricane by Tuesday morning, and anticipates issuing hurricane watches for portions of the Gulf Coast by Monday evening. In Jamaica and Cuba, the storm is dropping a widespread 4 to 8 inches of rain, with maximum amounts of a foot. Such rains on steep terrain can cause mudslides and flash flooding, the Hurricane Center warns.
Tropical Storm Marco is bringing strong onshore winds to the vulnerable, low-lying coastline of southeastern Louisiana. This is an area especially susceptible to storm-surge flooding, and the stormâs slow forward speed will keep waters elevated across multiple high tides. However, the flooding is not expected to be severe or threaten the elaborate levee system that protects New Orleans.
A Storm Surge Warning is in effect for Morgan City, La., to Ocean Springs, Miss., including Lake Borgne. The storm is expected to cause 2 to 4 feet of surge in this entire region, which is down from the previously expected 4 to 6 feet of surge when Marco was a Category 1 hurricane.
âProtect against life-threatening surge having possible significant impacts across coastal portions of southeast Louisiana and coastal portions of Mississippi west of Ocean Springs,â the National Weather Service office in New Orleans stated Monday morning.
The surge is impacting areas of coastal Louisiana that have lost large amounts of land to the Gulf of Mexico from erosion, land subsidence and sea-level rise.
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