FRIDAY, March 29, 2024
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Tropical storms Laura and Marco churn toward Gulf of Mexico, poised to threaten Louisiana and Texas next week

Tropical storms Laura and Marco churn toward Gulf of Mexico, poised to threaten Louisiana and Texas next week

Two tropical storms - Laura and Marco - are lumbering toward the United States, and are anticipated to make landfall between Monday and Wednesday along the Gulf Coast at hurricane strength.

The current National Hurricane Center track forecast presents an ominous scenario in which Marco strikes coastal Louisiana on Monday, followed by a second wallop from Laura on Wednesday. In other words, the forecast suggests that the New Orleans area could contend with hurricane conditions twice in three days.

The zones where the two storms could reasonably strike is large, spanning from coastal Mississippi and northeast Texas for Marco and between coastal Alabama and Louisiana for Laura. These may shift in future forecasts.

But the impact zone from the two storms may well overlap, with Louisiana in the crosshairs. The Hurricane Center warned of "a prolonged period of hazardous weather" for areas that contend with both storms. Such a rare meteorological confluence could prove a challenge to local residents and strain resources and government agencies during the ongoing pandemic.

The current Hurricane Center forecast calls for Marco and Laura to possess hurricane strength in the Gulf of Mexico simultaneously, which would represent a first in historical weather records.

Marco, predicted to come ashore Monday, is the most immediate threat. A hurricane watch has been posted from Intracoastal City, La., eastward to the Mississippi/Alabama border, and includes New Orleans. A storm surge watch covers the entire Louisiana, Mississippi and Alabama coastlines. Here, waters at the coast may rise several feet above normally dry land when Marco comes ashore, causing substantial flooding.

Laura would then follow quickly on Marco's heels, making landfall Wednesday. The storm, which developed near the Leeward Islands early Friday, has prompted tropical storm warnings for the northern Leeward Islands, the Virgin Islands, Puerto Rico, much of Haiti and the Dominican Republic and the southeast Bahamas. Tropical storm watches extend into the Florida Keys.

The pair of storms come during an already hectic hurricane season, Laura and Marco becoming the earliest L and M storms on record respectively. The season, which has been nearly twice as active as usual, has also featured the earliest recorded C, E, F, G, H, I, J and K storms.

The ongoing active stretch is likely to continue at least into early to mid-September.

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Tropical Storm Marco had sustained winds of 65 mph late Saturday afternoon, just 9 mph from hurricane strength. The system was 50 miles west of the western tip of Cuba.

Initially it looked as though Marco would pass almost directly over the Yucatán, which would bring the area heavy rainfall but weaken the system. Marco has remained farther east, however.

Remaining over extremely warm water, the storm rapidly gained strength Saturday and was forecast to become a hurricane by Sunday.

The storm is shooting the gap between the Yucatán and western Cuba, and the National Hurricane Center called for 1 to 4 inches of rain along the adjacent shores.

 

As Marco enters the Gulf of Mexico, wind shear - or a change in wind direction with altitude - may slow or stop the storm's intensification. On the other hand, the storm will also be passing over very warm water favorable for strengthening.

The Hurricane Center's forecast calls for Marco to reach the Louisiana coast as a Category 1 hurricane with 85 mph winds. However, the track forecast for this storm has been a moving target, and the coastal zone from northeast Texas to the Florida Panhandle should monitor the storm.

"[I]t's entirely possible that the volatile shifts seen in the models could continue," the Hurricane Center wrote late Saturday afternoon, while warning: "Hurricane conditions, life-threatening storm surge, and heavy rainfall are possible along portions of the Gulf Coast beginning on Monday." 

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Tropical Storm Laura was 100 miles west of Ponce, Puerto Rico, about 5 p.m. Saturday, with maximum sustained winds of around 50 mph. Doppler radar revealed torrential tropical downpours over the island territory, while several flash flood warnings were in effect. Forecasts called for a widespread 3 to 6 inches with locally up to 8 inches. Waves to 12 feet were forecast as possible just offshore.

On satellite, Laura appeared to be gaining organization, a core of very cold, tall cloud tops evident toward the storm's center.

Laura will drift west or west-northwestward over the coming day, acquiring a bit more of a northerly component Sunday. The system will pass near or directly over Hispaniola, bringing heavy rains locally totaling half a foot or more to Haiti and the Dominican Republic. That will also present a mudslide risk, especially in Haiti, where decades of rampant deforestation has contributed to unstable hillsides vulnerable to excessive rainfall.

Cuba could be in line sometime later Sunday into Monday.

Laura's predicted passage over the rugged terrain of Hispaniola and then Cuba is expected to halt any intensification until it emerges back over water late Monday into Tuesday.

After passing over Cuba, the system is forecast to begin intensifying again, but its exact position by early next week is highly uncertain.

Right now, the National Hurricane Center predicts that Laura will attain Category 1 status with winds up to 85 mph over the Gulf of Mexico on Tuesday into Wednesday.

"The details of the long-range track and intensity forecasts remain uncertain," the Hurricane Center wrote. "However, Laura is forecast to strengthen over the Gulf of Mexico and could bring storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of next week."

A Category 1 hurricane may not be the ceiling for Laura's intensity. Winds in the upper atmosphere will be calm and supportive of further maturation, while extremely warm water temperatures near 90 degrees in spots may make a ripe breeding ground for rapid intensification.

It is not out of the question that Laura becomes a more serious hurricane.

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If, and presumably when, Laura and Marco both cram into the Gulf of Mexico next week, the two could influence one another. That is looking unlikely at this point.

"At this time the influence of small tropical cyclone Marco, which should move over the northwestern Gulf about a day or two before Laura, is not expected to be significant," wrote the National Hurricane Center. "This could change in the coming days however." 

In the remote chance an interaction known as the Fujiwhara Effect occurs, both cyclones could perform an elegant dance and slip around each other. They would orbit a common center, with Laura most likely propelled west-northwest while Marco's northward progress could be slowed.

If Laura and Marco churn through the Gulf of Mexico simultaneously, it will mark just the third time on record that two storms coexisted there. The other two times were in September 1933 and June 1959, according to Colorado State University hurricane researcher Phil Klotzbach. If both storms manage to become hurricanes in the Gulf of Mexico at the same time, it would be a first.

Five named tropical systems have made landfall along U.S. shores in 2020. If Laura and Marco follow suit, as forecast, 2020 will break the record for most continental U.S. landfalls in a single year.

 

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