Mountain Terrain, Weather, and Hazards

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A high pressure moving in will cause altimeters to indicate lower elevation.
A low pressure moving in will cause altimeters to indicate higher elevation.

OBSERVED WEATHER
1-108. Note changes or trends in observed weather conditions.

Deteriorating Trends
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Marked wind direction shifts. A high pressure system wind flows clockwise. A low pressure
system wind flows counterclockwise. The closer the isometric lines are, the greater the
differential of pressure (greater wind speeds).
Marked wind speed increases.
Changes in obstructions to visibility.
Increasing cloud coverage.
Increase in precipitation. A steady drizzle is usually a long-lasting rain.
Lowering cloud ceilings.
Marked cooler temperature changes, which could indicate that a cold front is passing through.
Marked increase in humidity.
Decreasing barometric pressure, which indicates a lower pressure system is moving through
the area.

Improving Trends
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Steady wind direction, which indicates no change in weather systems in the area.
Decreasing wind speeds.
Clearing of obstructions to visibility.
Decreasing or ending precipitation.
Decreasing cloud coverage.
Increasing height of cloud ceilings.
Temperature changes slowly warmer.
Humidity decreases.
Increasing barometric pressure, which indicates that a higher pressure system is moving through
the area.

UPDATE
1-109. Continue to evaluate observed conditions and update the forecast.

SECTION III. MOUNTAIN HAZARDS
1-110. Hazards can be termed natural (caused by natural occurrence), man-made (caused by an individual,
such as lack of preparation, carelessness, improper diet, equipment misuse), or as a combination (human
trigger). There are two kinds of hazards while in the mountains―subjective and objective. Combinations of
objective and subjective hazards are referred to as cumulative hazards.

SUBJECTIVE HAZARDS
1-111. Subjective hazards are created by humans; for example, choice of route, companions, overexertion,
dehydration, climbing above one’s ability, and poor judgment.

FALLING
1-112. Falling can be caused by carelessness, over-fatigue, heavy equipment, bad weather, overestimating
ability, a hold breaking away, or other reasons.

26 July 2012

TC 3-97.61

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