August 26, 2020

Hurricane Laura Could Reach Major Hurricane Strength By Landfall On Wednesday Night


Hurricane Laura will rapidly intensify over the next 24 hours as it heads toward Texas and Louisiana. It's likely that the storm will make landfall as a major hurricane near the state line on Wednesday night. The intense winds, deep and widespread storm surge, flooding rains, and tornadoes will make this a life-threatening situation for communities in the path of this hurricane. The potential for flash flooding and widespread power outages will extend far inland from the point of landfall. 

Tuesday night's update from the National Hurricane Center found a healthy hurricane that's strengthening in favorable environmental conditions and a hot Gulf of Mexico. Laura's pressure steadily dropped on Tuesday evening and its winds rose in kind; Hurricane Hunters found its maximum winds up to 90 MPH at the 10:00 PM CDT advisory.


Forecasters expect Laura to make landfall as a major hurricane. The only things that can slow or impede Laura's strengthening between now and landfall are 1) dry air wrapping into the system and disrupting its core, or 2) the hurricane struggling with its internal structure. The longer we go without either of those disruptions, the stronger the storm can get. 

Laura is sitting beneath a ridge of high pressure over the southeastern United States right now, which is why the environment is so favorable for strengthening. Calm upper-level winds and ample ventilation allow the storm to breathe and develop its inner-core. The storm will continue moving northwest through Wednesday afternoon, at which point a trough over the Mid-South will begin weakening ridge and allow the hurricane to curve north toward the coast.

The timing of this northward turn will determine where the hurricane makes landfall. Forecasters believe the northward curve will bring the storm ashore near the Texas/Louisiana border, pushing the most intense winds and storm surge into southwestern Louisiana. The cities of Port Arthur, Beaumont, and Lake Charles are at risk of suffering a direct hit from the core of this hurricane on Wednesday night.

However, any westward wobble could bring dangerous winds, heavy rains, and storm surge closer to densely populated communities in southeastern Texas. Anyone in or around Houston and Galveston needs to prepare for the potential for power outages, wind damage, and flash flooding.

If you live somewhere expected to be on the outer fringes of this hurricane, you've still got time to make sure you're ready for any strong winds or heavy rain. Bring in or tie down any loose items on your porch, balcony, deck, or in your yard. Make sure you've got enough supplies to get through a power outage. Know alternate routes to get around flooded roadways, and have a plan to leave if you live in a flood-prone area. You've got a little while on Wednesday morning to get ready—or to get out if you're told to do so by authorities.

Here's what communities in the direct path of the hurricane can expect as it comes ashore.

Storm Surge

Source: National Hurricane Center
Laura is heading for a landfall along a stretch of coastline that's exceptionally vulnerable to storm surge. A powerful hurricane like Laura can shove a storm surge deep into this swampy terrain, potentially inundating communities that are dozens of miles from the coast.

The NHC warns that Hurricane Laura's storm surge "could penetrate up to 30 miles inland from the coastline in southwestern Louisiana and far southeastern Texas." Really! Here's a look at the agency's latest inundation forecast, mapped out to include all those inland communities:


Winds are awful in their own right, but storm surge—and the waves on top of the surge—can wash away what the wind can't dislodge. There are almost certainly going to be people who ignore evacuation orders and find themselves in precarious situations, risking the lives of the rescuers who have to go out in the floodwaters to help them after the storm lets up.

Lots of factors can affect local storm surge depths. The shape and makeup of the coastline, the storm's precise track, the intensity of the winds at landfall, the angle the storm comes ashore, and the timing of the surge in relation to high and low tide are all factors in a location's exact surge depths.

Wind

The winds of a major hurricane will leave behind extensive damage in the hardest-hit areas. Sustained winds in excess of 100 MPH can easily destroy mobile homes and prefabricated homes that aren't well reinforced. Even well-built homes could experience major damage as a result of the hurricane's intense winds, likely including roof and wall failures and blown-out windows and doors.

Widespread power outages are likely along the storm's path inland into Arkansas, including in communities far to the west and east of the point of landfall. Extensive power line and tree damage could leave some communities in the dark for a week or longer. The power outages will probably come as a surprise to people far inland who weren't prepared.

Homes that are built to withstand strong winds may still be susceptible to flying debris and falling trees. A tall tree or sturdy limb can easily penetrate a roof or a wall, posing a serious threat to the safety of people and pets.

Flash Flooding


Rainfall totals could reach or exceed five inches along the path of the core of the storm as it makes its way inland. The heaviest rainfall totals are possible in Arkansas as the storm (or its remnants) get caught up in the jet stream, slowing down and turning east over the state. More than seven inches of rain could fall across a large swath of Arkansas, potentially leading to widespread flash flooding if persistent bands of heavy rain keep training over the same communities.

Some communities that experience a storm surge during landfall could experience river flooding in a couple of days as all the rainwater runoff drains back toward the Gulf of Mexico.

Tornadoes


Tornadoes can be a significant hazard during landfalling tropical cyclones. There's enough low-level spin in a tropical cyclone that thunderstorms in the rainbands can spawn quick tornadoes. These tornadoes can be tricky to get ahead of; tornado warning lead time can be as little as just a few minutes. These tornadoes can occur far away from the point of landfall.

The greatest threat for tornadoes during Hurricane Laura will exist along and to the east of the center of circulation. This covers almost all of Louisiana beginning on Wednesday afternoon and it'll last for the duration of the storm. The tornado threat will move north into Arkansas on Thursday.

[Satellite: NOAA]


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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I ran Gawker's The Vane for two years and I've contributed to Mental Floss, Forbes, Popular Science, and the Washington Post's Capital Weather Gang. I also teamed up with Outdoor Life to write a book called The Extreme Weather Survival Manual, which came out in October 2015.

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