1959 US Army Vietnam War Terrain Intelligence ... - Survival Books

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b. Format. Weather forecasts may be presented in coded (numerical),
graphical (pictorial), or written (plain language) format.
Normally, weather forecasts for use by Army units will be issued in
plain language form. Because forecasts are subject to sudden change,
they are usually transmitted by electrical means. Abbreviations are
used extensively. The abbreviations used in weather messages are
contained in JANAP 169 and in the Civil Aeronautics Administration
publication, Contractions.
c. Sources. Weather forecasts and special studies are provided by
agencies of the Air Weather Service under the direction of the
theater Air Force commander. Usually a weather central is established
at theater headquarters, a weather center at field army or army
group headquarters, and a tactical weather station at corps headquarters.
Division and lower units receive weather forecasts through
intelligence channels (app. V).
d. Types of Forecasts.
(1) Shortf-peiod forecasts cover a period up to 48 hours in advance
of issue, giving detailed values of the weather elements
expected to occur during the period and the time of anticipated
weather changes. They are sufficiently reliable for
use in detailed short-range planning.
(2) Mediumn-period forecasts cover a period of 3 to 5 days, and
exteided-period forecasts cover periods in excess of 5 days.
They are less detailed and specific than short-period forecasts.
Usually the weather information is expressed in
terms of departure from normal conditions and is suitable
only for preliminary planning purposes.
(3) Severe qweather forecasts provide warnings of weather conditions
that will create unusual difficulties. Examples of
severe weather include tropical cyclones, thunderstorms,
strong and gusty surface winds, heavy precipitation, and extremes
of temperature. The Air Weather Service furnishes
such warnings when requested by commanders, based upon
the needs of their particular unit or installation. The
weather conditions. that will be critical vary with the
type of unit or installation. For example, one unit may
require warnings of winds in excess of 15 to 20 knots, while
another may not be adversely affected by wind until the speed
reaches 35 to 40 knots or more.
(4) Radiological defense forecasts are special forecasts of winds
and temperatures aloft used to determine the area that would
bIe covered by a nuclear fallout. The information is presented
in a numerical code form.
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