In
the field forecasting is an important skill for the backcountry hiker. Learning the basics is an important first
step.
Let me begin by stating that forecasting begins at
home. Monitor the local news and the cable
weather channels to get a broad, general idea of the weather conditions before hitting
the trail. Further refine that
information by checking inter net sources such as www.wunderground.com and the National
Weather Service’s site www.noaa.gov.
My
“go to” reference is Northwest Mountain
Weather by Jeff Renner (published by the Mountaineers.) Renner is a professional meteorologist and
broadcaster, an outdoorsman
The balance of this post will focus on what to consider
about hiking during periods of thunderstorm activity.
The dark clouds of a
thunderstorm provide a strong sense of mass and energy. They can be seen a long way off. Avoid them when possible.
As a storm develops you will notice that the clouds may
change shape, grow taller and darker.In many cases an anvil
shaped cloud growing tall and developing a distinct leading edge maybe
observed. This is a sign that a storm is
on the way.
Lightning is the predominant killer associated with a
thunderstorm. Roughly 40 people are
killed each year and approximately 240 are injured. Visit the National Weather Service’s site for
more information about lightning safety; http://www.lightningsafety.noaa.gov/medical.htm
The ideal action to avoid the danger of a significant
storm is to get out of the weather.
Leave the field for the safety of a building or a car. Caves can provide shelter but must be deep
and dry. A shallow cave offers almost no
protection.
Renner’s guide lines and actions include:
“Do
watch for cumulus showing strong upward development.
Do
choose a campsite uphill from valley floor.
Do get
away from exposed areas, pinnacles, peaks.
Do get
away from water.
Do seek
low ground in open valleys and meadows.
Do move
at once if hair or scalp feels tingly.
Do not
stand under trees.”[1]
Wilderness Survival trainer Peter Kummerfeldt amplifies
Renner’s comment by adding the following:
“Be
proactive – don’t wait until you are getting wet to suspend outdoor activities.
Don’t be connected to the
tallest object in the area. If caught
outside, move into low trees of even height and stand away from tree trunks. Stay away from isolated trees.
Water is a great conductor
of electricity – get out of the water at the first sign of a storm developing.”[2] (For more information visit Kummerfeldt’s web
site, www.outdoorsafe.com.)
Thunderstorms have the potential to deliver large
quantities of water. Look for higher ground and stay out of stream beds that may flood significantly
and without warning.
I monitor my GPS receiver’s barometer. I change my elevation plot to a pressure plot
and leave the receiver on. Even though a
GPS receiver may not be the most accurate it is the plot’s trend over time that
I am concerned about. Should I see the
pressure drop noticeably I’ll take shelter or return to my vehicle.
The key is to stay alert and make a plan of action when a
storm approaches.
I previously posted a short article about using your GPS
to monitor barometric pressure while in the backcountry; go here
to read the post. I thought it might be
worthwhile to cover a few other topics about in the field observations. This post is about thunderstorms.
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