Hurricane Watch or Warning: what the words actually mean
The watch gives you forty-eight hours. The warning gives you thirty-six. Almost everyone has that backwards.
No tropical watches or warnings for Columbus, OH right now. This page turns into a live briefing when that changes — it reads the same National Weather Service alerts your forecast page does, and explains whichever of them is in force.
Storms the National Hurricane Center is tracking
| Storm | Strength | Sustained wind | Position | |
|---|---|---|---|---|
| Fay | Tropical Storm | 40 mph 35 kt |
29.8, -40 | Advisory |
| Odalys | Hurricane Category 1 |
86 mph 75 kt |
15.6, -126.7 | Advisory |
| Polo | Hurricane Category 5 — major |
161 mph 140 kt |
16, -102.4 | Advisory |
Live from the National Hurricane Center. A storm being tracked does not mean it is coming for you — most spend their whole lives over open water. Track and intensity on the weather map.
The terms
Watch vs Warning
A watch means conditions are possible, and is issued 48 hours ahead. A warning means they are expected, and is issued 36 hours ahead. The watch gives you more time, not less — which is the opposite of what most people assume, and the reason preparations belong in the watch rather than the warning.
Tropical depression
A tropical cyclone with maximum sustained winds of 38 mph (33 knots) or less. No name yet, but it can still flood you.
Tropical storm
Sustained winds of 39 to 73 mph (34 to 63 knots). This is where the storm gets a name, and where outdoor preparation stops being safe.
Hurricane
Sustained winds of 74 mph (64 knots) or more. Called a typhoon in the northwest Pacific and a cyclone in the Indian Ocean and South Pacific — same storm, different ocean.
Major hurricane
Category 3 or above: 111 mph and up. The jump from Category 2 to 3 is where damage stops being expensive and starts being structural.
Storm surge
The abnormal rise in sea level caused by the storm — the difference between the observed water level and the level there would have been without the cyclone. It can exceed 20 feet and span hundreds of miles of coast. Surge, not wind, is what kills most people in hurricanes.
Storm tide
The actual water level: the ordinary astronomical tide plus the storm surge on top of it. A modest surge arriving at high tide can do more damage than a large one at low tide.
Eye and eyewall
The calm centre, and the ring of the strongest winds around it. The lull is not the end — the far eyewall arrives next, with the wind reversed in direction.
Cone of uncertainty
The NHC forecast cone shows where the centre of the storm may track, and historically contains it about two thirds of the time. It says nothing about how wide the storm is: damaging weather routinely extends far outside the cone.
The Saffir-Simpson scale
| Category | Sustained wind | What that does |
|---|---|---|
| 1 | 74-95 mph | Very dangerous winds will produce some damage. Roof, shingle and gutter damage; snapped branches; days of power loss. |
| 2 | 96-110 mph | Extremely dangerous winds will cause extensive damage. Major roof and siding damage; shallow-rooted trees uprooted; near-total power loss for days to weeks. |
| 3 major |
111-129 mph | Devastating damage. Major structural damage to homes; most trees snapped or uprooted; water and electricity unavailable for days to weeks. |
| 4 major |
130-156 mph | Catastrophic damage. Severe structural failure; most of the area uninhabitable for weeks or months. |
| 5 major |
157+ mph | Catastrophic damage. A high percentage of homes destroyed; the area uninhabitable for weeks or months. |
The scale measures wind and nothing else. It says nothing about storm surge, rainfall or flooding, which is why a Category 1 can still be the deadliest storm of a season — water kills far more people than wind does.
Definitions from the National Hurricane Center; live alerts from the National Weather Service for US locations. Informational only — when officials tell you to go, go, whatever this page says. More: Survival Kit · Survival Guide · Global Hazard Watch