National Weather Service United States Department of Commerce

Cold Front Slowly Moves East On Sunday

A slow moving cold front is cutting through the Central U.S today. Behind the cold front, unseasonably cold weather and high elevation snow is occurring. Ahead of the front, temperatures are more typical of mid-summer running 15 to 20 degrees above normal with some daily records expected. The front separating these extremes will be the focal point for locally heavy rain. Read More >


The WMO Communication Header

Telecommunications Abbreviated Heading
Symbolic Structure Explained

The structure and meaning of the alpha and numeric characters of the WMO abbreviated heading ( "COMMS" header, as it is called) is outlined here for a better understanding of how the abbreviated heading is built and what the character designators that make up the heading represent. The WMO abbreviated heading is a component of the WMO Meteorological message agreed by WMO members for use in exchanging data and products on the Global Telecommunication System between National Meteorological Centers of the world. (see the documentation on the GTS on this web site.)

PURPOSE of the Abbreviated Heading;

  • The heading is to provide a means by which communication data managers recognize a bulletin for telecommunication "switching" purposes.
  • The heading permits a uniqueness for a bulletin, which is sufficient enough to control the data for selective transmission required to meet the needs of the receiving end.
  • The heading is for accountability in the transmission delivery process by the switching system for data management purposes.
  • The heading is not intended for the data processing systems, as the first few lines of the text (bulletin content) further defines it for processing. (ref. WMO Codes Manual 306)

The structure of the heading is briefly outlined to provide for a better understanding of the meaning implied in the communications abbreviated heading. The heading does define data content through character deginators contained in the WMO & U.S. National Practice "tables" that are used to construct the heading. This is a limited definition of content for transmission management only. Those pages from the WMO Manual on the Global Telecommunication System, No. 386; and the U.S. national practice tables are provided on this web site to help in understanding the structure of the heading. The published WMO Manual No. 386 contains the complete technical description of the WMO meteorological message. (refer to our WMO web page for how to obtain WMO manuals)


The symbolic form of the abbreviated heading for the WMO Message containg the bulletin is:


T1 T2 A1 A2 ii   CCCC   YYGGgg   (BBB)

Where character;

T1   is taken from WMO Manual 386 table A. It is an alpha character that designates the general code form of the contents of the bulletin (Coded or plain text).

T2   is taken from WMO Manual 386 tables B1 through B6 depending on the designator T1 in table A. It is an alpha characher that designates the data type.

A1  is taken from WMO Manual 386 tables C1 through C6 depending on designator T1 in table A ( U.S. National practice through C9 ). It is an alpha character that designates the geographical area the content of the bulletin covers.

A2   is taken from WMO Manual 386 tables C1 through C5 depending on designator T1 in table A ( U.S. National practice through C9 ). It is an alpha character that designates the geographical area, or may define the forecast period.

ii   is taken from the WMO Manual 386 paragraph defintion, or from table D1 or D2 depending on designator T1 in table A ( U.S. National practice table D3 replaces D2 ). It is a numeric set of two characters. Go to the WMO message structure for more details on this group.

CCCC   is the identification of the processing center that generated the bulletin. Commonly centers use alpha character identification designators from ICAO's "Location Indicators Doc 7910/80", but this is not consistant throughout the centers.

YYGGgg   is the day, hour, and minute the bulletin was prepared or the reporting time of the contained reports in it.

(BBB)   is an optional group of alpha characters, reference BBB Group explaination.

NWS Gateway Communications Header Policy Documentation

The NWS has a national practice variation on the standard WMO Abbreviated Heading design. This is detailed to some extent in the descriptive documentation on the AWIPS Identifier. The joining of the WMO Abbreviated Header as the first line of the product communications identifier and the further definition of the content of the bulletin as a second line of information was established for the operational implementation within the AWIPS communications environment. The WMO abbreviated heading uses standard WMO definitions for the TTAA and the ii fields. The CCCC field as an originating center designation is used to define the forecast office or product originating site such as a NEXRAD. This was done to facilitiate handling of the bulletins in the data delivery environment of the AWIPS data satellite broadcast and data exchanges within the AWIPS wide-area network. The broadcast is called the NOAAport broadcast or "SBN" for Satellite Broadcast Network which supports the transmission of data and products to the NWS forecast offices and the for the Family of Services (FOS) broadcast to the general meteorological community.

NCEP CCCC Definitions

There is a further definition to the CCCC field within the first line of the communication identifier. This is an NCEP's National Centers heading practices that defines the model which produced the forecast field or tells the user from which NCEP center the product was produced. This practice of unique NCEP originating center definitions does not define geographical location of the content. The list of definitions for the CCCC field of the standard WMO abbreviated heading is found as part of the NWS Communications Header Policy Document under The NCEP and other NWS Centers CCCC Defintions.

International CCCC Assignments

To find the source for a known bulletin by WMO Internationally assigned CCCC you can go to the WMO Server in Geneva and request a look up. The location of this new experimental service is on the WMO Server. It is called the "Publication No.9 Volume C1 Interactive Search" service. You will be provided the ability to find the bulletin description and content for each bulletin exchanged on the GTS, which includes the source of the bulletin by CCCC.