Examining Behavior of the 2017 Thomas Fire Using
Polarimetric Radar (181)
Sean Luchs, NWS
Houston/Galveston, Dickinson, TX
Rich Thompson, NWS
Los Angeles
Abstract:
Recognizing and anticipating
changes in fire behavior are critical to fighting wildland fire effectively and
safely. Information in service of this comes to wildland firefighters from many
sources: briefings, personal observations, communication with other
firefighters, and communication with aviation resources. Weather data is also
used, but is largely confined to direct weather impacts on the fire area. There
has been some work in using radar and satellite to describe a fire's
smoke/debris plume, but the descriptions have largely been limited to general
observations of the extent of smoke impacts with little effort in a tactical
evaluation of fire behavior. However, the Thomas Fire may have shown potential
for using radar data to gain insights on fire behavior.
By the time of its
containment in mid-January 2018, the Thomas fire was responsible for burning
over 280,000 acres, the largest on record in California. It was also intensely
destructive, consuming over 1,000 structures in the Wildland Urban Interface of
Los Angeles. This location also made it easily recorded and well sampled by the
National Weather Service's WSR-88D radars in the area. Video and radar data is
used to investigate reports on December 16, 2017, of a plume collapse. There
are indications that this collapse has a signature in differential reflectivity
data. A patch of lowered differential reflectivity present near the fire's
updraft diminishes with the plume collapse, and returns as a new plume returns.
This demonstrates the possibility of using radar data as a way to alert
firefighters to an impending threat to their safety and possible new erratic
fire growth. More study will be necessary to determine how much lead time is
possible, but speculate it may be similar to a tornado warning.