Large wildland fires are com­plex, dynamic phenomena that can encounter a wide range of fuels, terrain, and weather during a single event. They can produce intense firewhirls that snap mature trees and generate blowups. They can send 300-foot (100-m) bursts of flame shooting ahead of the fire-line at speeds up to 100 miles per hour (160 km/h). They can spawn firewinds 10 times stronger than ambient winds, deep pyrocumulus clouds, and firestorms in which the fire-generated winds overwhelm ambient winds. Counterrotating firewhirls brought to the fire’s head can combine at the tip and roll over, forming turbulent balls of flame that burst ahead of the fire-line.