Landfall vs. direct impact: What's the difference, and why does it matter

The hurricane center may stay offshore, but dangerous wind, flooding rain and storm surge can still reach land. Here’s what a hurricane’s direct impact means.

The forecast track stayed west of Kauaʻi. For someone glancing at the map, that could have looked like good news.

It wasn't.

Hurricane Lowell brought a 92-mph wind gust to Puʻu Lua on Kauaʻi and dumped 21.11 inches of rain at Kilohana. The storm's center never crossed the coast, but its wind and flooding rain still became dangerous.

That's the difference between landfall and direct impact.

A hurricane makes landfall when its center crosses the coastline. It is a precise meteorological event tied to a specific location. But the center is only one part of the storm. Wind, flooding rain, storm surge, rough surf and rip currents can extend far beyond the point of landfall.

The forecast track shows only the most likely path of the storm's center. It does not show the full reach of a storm's hazards, which can spread far from the center and, in some cases, hundreds of miles inland.

“We never want people to focus only on where the center makes landfall. While most of the time the worst weather is near where the center of a storm makes landfall, however, significant, life-threatening impacts can still extend hundreds of miles away from the center of a storm. And flooding impacts can extend well inland away from where a storm makes landfall,” AccuWeather Lead Hurricane Expert Alex DaSilva said.

A storm can miss the coast and still directly affect the people who live there. To better communicate that risk, AccuWeather recently enhanced its U.S. direct-impact definition and forecast, providing a clearer picture of where meaningful tropical impacts are expected, even when a storm's center stays away from the coast.

Why a direct impact can still be just as dangerous as landfall

Under AccuWeather's definition, a tropical storm or hurricane directly impacts the contiguous United States if it makes landfall or produces at least one of several measurable effects.

Those effects include wind gusts reaching at least 40 mph over a period of four hours or longer at three or more land-based stations at least 50 miles apart, at least 4 inches of rain at four or more observation stations at least 25 miles apart, five reported instances of flash flooding or at least 2 feet of storm surge along at least 50 miles of coastline.

The definition is different for islands and remote areas, where fewer weather stations are available to document a storm's impacts. There, a direct tropical impact includes landfall, wind gusts of at least 40 mph at one or more land-based stations for three hours or longer, at least 4 inches of rain at one or more observation stations, one reported instance of flash flooding or at least 2 feet of storm surge.

The enhanced forecast also incorporates the AccuWeather RealImpact™ Scale for Hurricanes, which, unlike the Saffir-Simpson Hurricane Wind Scale, focuses on the impacts a storm is expected to produce, including flooding rain, storm surge, wind damage and effects on populated areas.

The goal is to help people understand not only where a storm is going but also what it is likely to do.

“This is why it's important for residents and business to follow the AccuWeather forecast where we provide different maps illustrating not just where we expect the center of a storm to move but also where the impacts will be,” DaSilva said.

Lowell is a reminder of why that matters. A forecast track that stayed offshore still brought damaging winds and flooding rain to Kauaʻi.

Before a tropical system approaches, people should look beyond the forecast track and pay close attention to forecasts for wind, flooding rain, storm surge and surf, along with local watches and warnings. A forecast line that stays offshore can still be accompanied by dangerous impacts.

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