A hurricane is a heat engine: warm ocean water evaporates, rises, condenses, releases heat, and drives more rising air, with the earth's rotation organizing the whole system into a spiral around a calm low-pressure core. It needs water around 80°F, moisture, and low wind shear, shear tears the structure apart.
The category scale measures one thing
That's it, sustained wind speed, nothing else. The Saffir-Simpson scale says nothing about storm size, forward speed, rainfall, surge, or tornado potential. A sprawling slow Category 1 can do far more total damage than a compact fast Category 3, which is exactly what has happened repeatedly.
Pressure tells you more than you'd think
Central pressure is the other headline number, and it's a good proxy for a storm's overall energy. Ordinary weather sits near 29.92 inches. A strong hurricane core drops below 28.00. Watching a barometer fall through a landfall is watching the engine's throat open, which is why measured pressure from stations in the path is such powerful real-time information.
Storm surge, ocean water pushed ashore by wind and low pressure, causes about half of all US tropical cyclone deaths. It is driven by storm size, angle of approach, forward speed, and the shape of the coastline, none of which appear in the category number. Shallow gently sloping coastlines like Florida's Gulf coast amplify surge dramatically.
How to read the cone
The forecast cone shows where the center of the storm is likely to travel, and only about two-thirds of the time at that. It is not a damage map. Effects routinely extend hundreds of miles beyond the cone's edge, and the most dangerous quadrant is usually the right front relative to motion, where forward speed adds to rotational wind.
Three habits fix most cone misreadings: don't focus on the center line, don't assume being outside the cone means safety, and expect the forecast to shift. That's what the widening shape is telling you.
What to watch during the event
When a storm is close, forecasts matter less than measurements, and nobody should be shopping for an app subscription while taping their windows. Actual wind, actual pressure, actual rainfall from stations along the path tell you what is genuinely happening, and unlike a model, they can't be a few hours off.