We watched with dread last night as Category 4 Hurricane Laura made landfall on the southwestern Louisiana coast. In South Florida, we know what it’s like to face one of Mother Nature’s fiercest storms.
Laura’s winds were not as strong as those in Hurricane Andrew, but the storm was bigger across. The effect of the larger diameter is like pushing the water in the bathtub with your forearm versus your hand. The larger-circulation storm moves more water, so the storm surge is higher and pushes farther inland.
The difference in the wind speed between Laura and Andrew is made up for by the power of the storm being spread over a larger area.
Hurricane Andrew was stunningly strong, but relatively small in diameter. The eye was only 10 or 12 miles across. Hurricane Laura’s eye was about 30 miles across when it made landfall.
The fear yesterday was that right-side onshore winds would push a monstrous storm surge up the Calcasieu river and lake system 30 miles or more. A version of that likely happened, but early reports from river gauges show the surge was perhaps half of the worst-possible forecast.
On the satellite shot at the time of landfall, you can see why that might have happened. Notice the lake visible in the clear eye. That’s Calcasieu Lake. Since Laura’s strongest onshore push of water was just east of there, the maximum surge apparently missed the opening to the Calcasieu river and lake system, which would have allowed the giant surge to be pushed as far north as Lake Charles and beyond.
Much of the area to the east of Calcasieu Lake is lightly populated, and we certainly hope everybody got out. That’s where the surge of 15 to 20 feet likely occurred. Still, life-threatening surge pushed north through the lake, and over much of the Louisiana coast, so there is a long process to come to search that large area for anyone who stayed behind.
The Gulf coast in general, and southern Louisiana in particular, is extremely vulnerable to storm surge. The gradual slope of the offshore sea bottom raises to water to stunning heights – nearly 30 feet in the case of Hurricane Katrina – when a hurricane’s extreme winds power the surge over the coast. The forecast surge from Laura was 15 to 20 feet, based on the wind speed of the storm and the particular characteristics of the coastline in that area.
A village at the south end of Calcasieu Lake named Cameron is the site of past hurricane disasters. In 1957, Hurricane Audrey surprised people by arriving sooner than forecast. More than 400 died. In 2005, Hurricane Rita wiped out a good part of the town. The same area took a hard hit from Laura.
Farther north, Laura's fierce winds have left a swath of devastation across Louisiana.
Recovery from this is going to take a long time and be a process fraught with challenges – the COVID problem just to start.
Elsewhere in the tropics, no development is expected through the weekend. The National Hurricane Center is noting a disturbance that just moved off Africa. It might develop next week near the Caribbean islands, although the long-range computer forecast models are not showing it organizing at this time. And there are more in the pipeline. All of them will travel through the part of the Atlantic that we have to watch closely this time of year.