Haiyan: the strongest landfall on record

Haiyan formed in the western Pacific near Micronesia and crossed the warm western Pacific at speed, intensifying into one of the strongest tropical cyclones ever observed. It made landfall at Guiuan, on the southern tip of Samar, then crossed Leyte Gulf and Leyte itself before moving into the South China Sea.

The wind alone was devastating, but the sea did most of the killing. Leyte Gulf narrows towards Tacloban, and the surge rose there to 5–6 metres, higher in places, flattening the waterfront districts.S1N1

ERA5 places the storm well. Twenty hours before landfall a closed low sits east of the islands; by the evening of 7 November it reaches Samar and Leyte, with the strongest winds wrapped round its centre.

ERA5's grid is 0.25°, about 28 km, and the model behind it cannot build a core as tight and deep as Haiyan's. The reanalysis spreads the storm out: the pressure falls far less, and at Tacloban the wind on 8 November peaks near 18 m s⁻¹ rather than the 70 m s⁻¹ and more that hit Samar. The track and timing are right; the intensity is not.

This is true of every intense tropical cyclone in a global reanalysis, and worth remembering when reading the other storms in these pages: the Lab shows where and when, and the rain and wind around a storm, far better than its peak.

Haiyan moved fast, about 30 km h⁻¹, so its rain was heavy but brief at any one place: ERA5 puts 72 mm at Tacloban on 8 November. The daily map shows the rain band crossing the Visayas from east to west.