CHAPTER 3
SURFACE OBSERVATION CODES
INTRODUCTION
The World Meteorological Organization (WMO) is
an international organization located in Geneva,
Switzerland. Operating as part of the United Nations, its
purpose is to provide international exchange of
meteorological, oceanographic, and geophysical data
and to conduct research in these areas. Most members of
the United Nations are also members of the WMO, and
have agreed to an international exchange of data in code
forms specified by the WMO. These codes are used
throughout the world and are known as the WMO
International Codes. International codes have been
established for reporting surface weather conditions,
aviation weather conditions, upper atmospheric
conditions, climatic conditions, oceanographic
conditions, earthquakes, and volcanic activity. In this
chapter, we will discuss weather logs for recording
observations, the applicable reference sources, and the
four surface observation codes. Now let’s take a closer
look at the WMO regions and code forms.
WMO REGIONS AND CODE FORMS
LEARNING OBJECTIVES: Recognize the
seven WMO regions. Distinguish between the
various regional and national codes. Identify
the four different code forms used by weather
observers. Identify the primary references for
weather observations used by Navy and Marine
Corps personnel.
The WMO has divided the world into the following
seven regions:
Region I - Africa
Region II - Asia
Region III - South America
Region IV - North and Central America
Region V - South-west Pacific
Region VI - Europe
Region VII - Antarctic
Within each region, certain codes are used that are
not used in any other region. These codes are called
"Regional codes." When information is included in
these codes that does not conform to international code
formats, the format difference is called a "Regional
coding practice."
Many countries are contained in each WMO region.
When a particular country elects to report additional
information in an International code that does not
conform to either the Regional coding practice or to the
International code format, it is known as a "National
coding practice." Similarly, when a particular country
chooses not to use an International code but reports
conditions by using their own code, the code is known
as a "National code form."
The WMO International codes are explained in
detail in WMO Publication 306, Manual on Codes,
Volume I, International Codes. This publication has
been republished by Commander, Naval Meteorology
and Oceanography Command (CNMOC) as NAVAIR
50-lP-11. (See appendix IV, WMO Code Tables.) A
more complete listing of regional and national coding
practices is contained in WMO Publication 306,
Manual on Codes, Volume II, Regional Codes and
National Coding Practices. Both publications have
been distributed to all Navy and Marine Corps
observation sites.
Weather observers throughout the world record and
report surface weather observations in four different
international code forms. The four code forms are
METAR Code;
SPECI Code;
Land Synoptic Code; and
Ship Synoptic Code.
A modified version of the METAR and SPECI code
is used by federal agencies in the United States. Surface
Weather Observations and Reports, Federal
Meteorological Handbook No. 1 (FMH-1) is a
publication developed by the National Oceanic and
Atmospheric Administration (NOAA) for use by the
National Weather Service. It contains detailed
instructions for the METAR and SPECI codes as used in
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