Of saddles and chimneys and
safety in general
A saddle is the low area between two high points or
hilltops in a ridge line. In a wildfire saddles become channels for high
winds as the heat from the fire flows uphill. The wind tends to speed up as
it squeezes between the hilltops and then blows over the ridge with greater
force. Saddles are not good places to site homes, nor are they good places
to seek refuge if caught in the open by a wildfire.
A chimney is a narrow side canyon usually tilted up toward a ridge line. The
steeper and narrower the side canyon, the more it will act like a chimney
drawing hot air from a fire into it and speeding it uphill. Chimneys can
become infernos in a wildfire.
Chimney and saddles are especially important for their effects on roads
running across a slope. Heat normally flows uphill anyway, but a road
passing through a chimney can represent a major danger to a vehicle trying
to use the road, whether a fire engine or someone seeking to escape the
fire. The same is true for vehicles following a road passing through a
saddle. Fire conditions can worsen almost in an instant.
Chimneys can be recognized by the fact that when a road turns into the
hillside it may be passing into a chimney. When the road seems to pointing
away from the hillside it is leaving a chimney and heading toward the
'nose.' The nose, or most forward part of the curve, is probably the safest
place to be if caught in the open. This is because the wind and heat tend to
flow to either side of the nose. If caught in this position, lie in as bare
a spot as you can find on the uphill side of the road in as low a spot as
you can-in a ditch if possible. This maximizes the chance that the wind will
carry the heat of the fire over you.
Heat is a major risk factor and potential killer.
Dehydration is the least of it, though is not to be ignored. In the
wind-driven fire typical of wildfires in our area, the hot wind can cause
serious burns if bare skin is left exposed too long. Wind gusts can carry
bursts of super-heated air that can cause serious burns almost instantly.
Strong winds can drive a literal blizzard of sparks, burning branches, hot
dust and sand, all of which lodge in clothing or even wrinkles in skin.
The psychological effects of the stress of remaining near a wildfire in full
cry may cause one to become less sensitive to pain. The result can be that
you may not become aware of a burn until after it has become potentially
serious. The following diagram suggests the extent of the danger. The
suggested margins are not forbidden zones, rather they suggest the
precautions one needs to take and the danger one needs to be aware of within
200-400 feet of a wildfire.