Hurricane Laura · Lake Charles, Louisiana · August 2020

The marsh edge and the next street

At the upwind edge of a subdivision facing open marsh, Laura stripped roofs to the decking. One street downwind, roofs were largely intact. A 1 km catastrophe model gives both streets the same wind.

NOAA aerial photograph after Hurricane Laura, north up: open marsh on the right, a drainage canal, a row of homes with roofs stripped and blue tarps, and across the curving street, homes with intact dark roofs. — NOAA aerial, August 2020, north up. Hover or tap the numbers.

Why the two streets fared differently

Wind near the ground is set by what it has just crossed. Over the marsh it stays fast close to the surface. Behind the first row of roofs it is slower and more turbulent, and the second row stands in that air.

Under building codes, design pressure on the same house is about 50% higher in open terrain than in a suburban setting.¹

A susceptibility modifier for this street

A 1 km model gives one value for this street. A susceptibility modifier would give thirteen, above 1 along the marsh edge and below 1 in the second row.

The values shown are illustrative, and are not model output or a claim about these homes.

Where the modifier sits in a workflow →

“When I look at post-event imagery, like this residential block after Hurricane Laura, I see evidence that these effects really matter: houses fronting an open expanse see their roofs ravaged while those deeper in the development appear sheltered.”

Ted Amdur, announcing Downstream, September 2026.

← All case studies Next: Ian, a whole landfall →

Sources

ASCE 7‑22, Table 26.10-1.

Pen sketch of a shore neighborhood at sunrise, hip-roofed houses and palms above a beach.

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