Recognizing the Potential for Dangerous Nocturnal Fire
Growth and its Implications on Fire Weather Products and Services (58)
Steven Pfaff, National
Weather Service, Wilmington, NC
Joshua Weiss, National
Weather Service
Richard Neuherz, National
Weather Service
Terrence Lebo, National
Weather Service
Abstract:
Numerical weather prediction
tools currently available to forecasters are incapable of initializing
relatively small-scale features, such as large fires, that can adversely modify
the local environment to support rapid fire growth. As a result, fire weather
forecasters must use caution when producing and relying on Spot Forecasts from
the gridded output that does not recognize contributions from large fires, especially
during the nighttime operational periods. This is especially true when the
tendency of the models is to stabilize the boundary layer with the loss of
diurnal heating and the absence of boundary layer warm air advection. In
reality, large fires located where models depict stable conditions can
significantly transform the local environment and lead to extreme fire behavior
(EFB) at night. One example was the Highway 31 Fire in Horry County, SC on
22-23 April 2009 where significant atmospheric modification occurred and
resulted in life-threatening, extreme nocturnal fire growth. Thus it is
imperative that forecasters demonstrate the ability to diagnose the potential
for nocturnal EFB through analysis of antecedent conditions, ventilation rate,
visual observations, National Weather Service (NWS) Weather Surveillance Radar
(WSR-88D) imagery, and atmospheric stability. This paper will provide fire
weather forecasters with information about the factors that led to a period of
dangerous nocturnal fire growth during the Highway 31 Horry County, SC fire,
how to identify the potential for nocturnal EFB that may occur through the use
of a decision tree, and resulting decision support implications for the 22-23
June 2011 Juniper Road fire in Pender County, NC.