Hurricanes, typhoons and floods, right now

What you are looking at

A spiral marks each tropical cyclone: hurricane, typhoon or cyclone, the same storm under three names depending on the ocean. The solid line is the path it has taken, the dotted line and the pale cone are where forecasters expect it to go, and the coloured area is where the wind is strong now. Drops are floods and triangles are erupting volcanoes. The colour is GDACS's alert level — green, orange or red — an estimate of how much harm the event may do, from its strength and from how many people live in its way.

How to read it

• Green means little harm is expected, orange a moderate impact, red a severe one that may need international help.
• The cone is not the size of the storm: it is where its centre may be in the coming days, and it widens because forecasts grow less certain.
• Tap a mark for the storm's category, its winds, the countries in its way and GDACS's full report.

Questions

What is the difference between a hurricane, a typhoon and a cyclone?

Only the place. The same kind of storm is a hurricane in the Atlantic and the eastern Pacific, a typhoon in the north-western Pacific and a cyclone in the Indian Ocean and the South Pacific. All are tropical cyclones, and all are classed by their sustained winds.

How many tropical cyclones are there at once?

Usually between none and five, most of them from August to October in the northern hemisphere and from January to March in the southern. Around eighty to ninety form in a year, and about half reach hurricane strength.

What do the alert colours mean?

GDACS scores each event by its physical strength and by the people and buildings exposed to it. Green expects little humanitarian impact, orange a moderate one, red a severe one. A very strong storm over empty ocean can be green; a weaker one over a crowded coast can be red.