Map, Compass & GPS

Map, Compass & GPS
Wild flowers along Fall Creek on the way to the Green Lakes - Oregon

Thursday, July 31, 2014

Dangerous Weather in the Backcountry.

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 internet 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 and flight instructor.  Northwest Mountain Weather provides a superb overview on how “the weather works” in the Pacific Northwest.  Uniquely focused to this region, this book provides an overview on climate and weather, local weather patterns, snow and avalanche conditions, and provides many charts and data sources.  My favorite part of the book is Chapter Seven’s “Field Forecasting Guidelines.” This chapter identifies what to watch for and monitor while in the backcountry.  

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. 



[1] Jeff Renner, Northwest Mountain Weather, (The Mountaineers, 1992), p 100
[2] Peter Kummerfeldt, Surviving a Wilderness Emergency, (OutdoorSafe Press, 2006), p56-57

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