Spotting

Written by

in

Tecnobosque Wildfire Knowledge Graph · Fire Behaviour

Reference Concept · v1.0

Definition → relationship → calculation → evidence context

Technical definition

Spotting is fire behaviour in which sparks or embers are carried by wind and/or convection and start new fires beyond the zone of direct ignition by the main fire.

ProcessTransport + new ignition
CarrierFirebrands / embers
Can crossRoads · breaks · treated areas
Growth effectDiscontinuous spread

What is spotting?

Spotting breaks the assumption that wildfire growth always occurs by continuous flame-front propagation. New ignitions can appear ahead of the mapped perimeter and later merge with the main fire.

Short-range and long-range spotting depend on firebrand generation, lofting, wind and atmospheric structure as well as receptive fuels at the landing point.

Why it matters

Spotting can accelerate incident growth, cross barriers and make a simple continuous-front rate of spread inadequate for describing what happens.

In plain language

The main fire does not have to spread continuously across every metre of ground. A transported firebrand can land ahead and create a separate spot fire.

What controls or changes this quantity?

Fire intensity

More energetic burning can loft larger numbers of firebrands.

Wind profile

Strong winds aloft can extend transport and create directional spotting corridors.

Source fuels

Bark and other materials differ in their ability to generate persistent burning particles.

Receiving fuels

A transported ember matters only if the landing environment can ignite and sustain combustion.

Engineering context

Main front

Continuous spread of the primary fire edge.

Firebrand transport

Particles leave the source and travel through the atmosphere.

Spot ignition

A new ignition occurs beyond the direct-flame zone.

Coalescence

Spot fires can grow and merge with each other or the main perimeter, producing rapid apparent growth.

How to interpret it correctly

  1. Do not represent spotting as ordinary linear ROS unless the measurement specifically describes the spot-fire front.
  2. Preserve timestamps for first detection and confirmed ignition separately.
  3. Consider barriers and roads as penetrable when ember transport is plausible.
  4. Distinguish observed spot fires from modelled spotting potential.
Interactive engineering tool
Use the calculator as a transparent technical aid and keep its assumptions explicit.
Explore Fire Growth Calculator →

Why it matters in wildfire analysis

In wind-driven incidents, spot fires can change evacuation and containment problems faster than a simple head-fire speed suggests.

Wildfire Black Box can preserve spot-fire detections as time-stamped evidence rather than retroactively treating the final merged perimeter as continuous spread.

Limitations and boundaries

  • Spotting distance is highly variable and stochastic.
  • Remote sensing may detect a spot fire only after it has already grown.
  • Simple growth calculators do not simulate ember lofting, atmospheric transport or ignition probability.

Spotting FAQ

What is spotting in wildfire behaviour?

It is the process by which sparks or embers are transported and ignite new fires beyond the main fire’s direct ignition zone.

What is a spot fire?

A spot fire is a separate new fire started by spotting.

Can spotting cross a firebreak?

Yes. Firebrands can be transported across roads, control lines and fuel breaks if conditions support lofting and ignition.

Is spotting included in rate of spread?

Not automatically. Linear ROS describes movement of a defined front, while spotting creates discontinuous new ignitions ahead of that front.