Skip Navigation 
NOAA logo - Select to go to the NOAA homepage National Weather Service

 Headquarters Office NWS logo
NWS Office of the Chief Information Officer/Telecommunication Operations Center
Text Forecast is the U.S. government's official web portal to all federal, state and local government web resources and services.

ISCS Data Stream Descriptions

Meteorological products and observational data will be transmitted from the Washington WAFC / Washington RTH to the contractor facility using the WMO X.25 protocol specifications. Each class of data is separate in a Permanent Virtual Circuit (PVC). The generic types of data content of each PVC is described below.

A complete list of data by WMO heading is also available for review. The WMO heading list is updated monthly.

All PVCs are available as output from the VSAT equipment at the receiving site on a single X.25 port from the Memotec PAD at 38.4 Kbps for the workstation.

  1. The first three numbered PVCs will be used to carry the WAFS data broadcasts [Descriptions ].
  2. The second three PVCs will be used to carry the RMTN-IV data broadcasts [ Descriptions ] (includes the old ANMET & CEMET).

The term OPMET will be used for all data in the alphabet 5 (ASCII code form) provided for the WAFS broadcast; and the term RMTN-IV will be used for PVC 4, PVC 5, and PVC 6, which includes data in alphabet 5 (ASCII code form), binary model products, and facsimile/image products for the WMO Broadcast.

ICAO Broadcast

PVC-1 WAFS GRIB Products [ 33,925,456 octets in 7,908 bulletins ]

PVC-2 WAFS Alphanumeric Data Bulletins (OPMET Broadcast) [ 6,739,777 octets in 18,001 bulletins ]

PVC-3 WAFS T4 Graphics Products [ 46,358,720 octets in 3339 chart segments ]

The WAFC Washington compiles the METAR & TAF collectives for broadcast over the WAFS alphanumeric channel, to reduce the transmission of redundent reports, and to standardize & reduce the number WMO headings required for dessimination.

GTS Broadcast

PVC-4 RMTN-IV GRIB Products [ 3,572,124 octets in 786 bulletins ]

PVC-5 GTS Alphanumeric Data Bulletins (WMO Broadcast) [ 1,751,654 octets in 2,785 bulletins ]

PVC-6 RMTN-IV T4 Graphics Products [ 5,970,471 octets in 911 chart segments ]

The directory list of WMO Headings switched to these channels are provided for your information. The list will be updated periodically through the year.


    US Dept of Commerce
    National Oceanic and Atmospheric Administration
    National Weather Service
    Office of Operational Systems (OPS)
    1325 East West Highway
    Silver Spring, MD 20910
    Page Author: NWS Internet Services Team
Information Quality
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities
     Page last Modified: 4 November, 2013 11:13 AM