Marco Downgraded to Tropical Storm, But Track Shifts Toward Houston; Laura Could Hit Coast as Cat 2 or Higher

At 7:00 a.m. CDT Monday, Tropical Storm Marco was moving north toward the mouth of the Mississippi at 10 mph. The National Hurricane Center predicts Marco will approach the Louisiana coast this afternoon, and then turn west toward Houston/Galveston, following the coast through Tuesday night.

NHC expects Marco to become a tropical depression late on Tuesday and dissipate on Wednesday over southeast Texas. Tropical-storm-force winds extend outward up to 105 miles (165 km), primarily northeast of the center.

Maximum sustained winds have already decreased to near 60 mph with higher gusts.

As One Storm Dissipates, Another Arrives

As Marco is breaking up, Laura could arrive as a Category 2 or higher hurricane.

The NHC still gives the Houston Area a 50-60% chance of experiencing tropical storm force winds, most likely from Laura (see below).

The most likely time for arrival of those winds is during the day on Wednesday.

Laura continues to move quickly WNW at near 21 mph.

“Details of when Laura will turn toward the NW and N and where the core of the system will cross the coast over the NW Gulf remain unclear,” says Jeff Lindner, Harris County Meteorologist.

The official NHC forecast brings Laura toward the TX/LA border, but landfall could be as far west as Galveston Bay and as far east as Vermillion Bay.

Models still show a wide spread of possible landfalls, but the largest cluster is on the TX/LA border.

Lindner says, “It is important to not focus solely on the exact landfall points as Laura will be a large hurricane with far reaching impacts.”

Laura Intensity

Laura is disorganized this morning. Likely little will change in Laura’s overall intensity today, due to interaction with the Cuban landmass. Once Laura reaches the SE Gulf of Mexico on Tuesday, intensification is likely.

“It is unclear how quickly the inner core of Laura will form. Broad systems such as Laura tend to take time to develop,” says Lindner.

Laura will likely reach hurricane status over the central Gulf and be near major hurricane status over the NW Gulf on Wednesday.

Jeff Lindner, Harris County Meteorologist

Impacts from Laura

As of 7 a.m., NHC advises, “From late Wednesday into Friday, Laura is expected to produce rainfall of 5 to 10 inches, with isolated maximum amounts of 15 inches near the Texas/Louisiana border. This 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.”

However, if the storm stays on its current course or shifts farther east, the amount of rainfall in the Houston Area will lessen. As of 4 a.m. this morning, Lindner predicted rainfall of:

  • 2-4 inches east of I-45 
  • 1-3 inches west of I-45

Squalls will begin to arrive along the upper TX coast Wednesday and increase into Wednesday night and Thursday.

Tides/Storm Surge: 

Laura will cause a large storm surge near and to the east of where the center crosses the coast. Significant swells will begin to arrive on Tuesday. This will likely drive water levels upward along the Gulf beaches and into Galveston Bay, especially at high tide. 

Note: water level rises will likely begin along the coast early Wednesday.


Sustained winds of 35-45mph will be possible east of I-45 with lower speeds west of I-45. Winds may gust higher in squalls especially over Chambers, Liberty, eastern Harris, and Galveston counties. Any shift west in the forecast track will bring stronger winds into the area.  

Sustained tropical storm force winds arrive along the upper TX coast by early evening on Wednesday.


Preparations for the landfall of a hurricane along the SE TX or SW LA coast should be underway.

Enact hurricane plans and follow all advice and recommendations from local elected officials and emergency management agencies.

Residents near the coast in evacuation areas, should review plans and react quickly should any evacuation recommendations be ordered.

Keep gas tanks full.

Posted by Bob Rehak on 8/24/2020

1091 Days after Hurricane Harvey