Event (29) Non-diurnal overnight escalation of fire behaviour, not linked to wind.

Field Observer

The graph above compares a stylised diurnal cycle for FFDI with a typical noctural FFDI escalation event. This is typically related to a fall in DP between midnight and sunrise, arising from events such as subsidence inversions or low-level jets. These events tend to affect sites over 1500m elevation, and may be spatially discontinuous. Careful observation is thus essential. Note the rapid onset after midnight.
Detection of such events relies on access to AWS data or to data from hand-held instruments.

Implications

Phenomenon	Urgency	Indicated Red Flag Warning
Nocturnal Dew Point Depression event	3	7) Dew Point Depression Event
Thermal Belt	3

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This material arises from work carried out by the HighFire Risk Project.

Material prepared by R. McRae September 2009.