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High Level SigWx Chart Help

Description of High Level Chart

NWS Product Description Document (PDF)

NWS Directive (PDF)

Package Issue Time
24 hour forecast package valid at 00Z 08Z
24 hour forecast package valid at 06Z 14Z
24 hour forecast package valid at 12Z 20Z
24 hour forecast package valid at 18Z 02Z

High level SIGWX charts are valid at specific fixed times: 0000, 0600, 1200, and 1800 UTC. They show significant en-route weather phenomena over a range of flight levels from 250 to 630, and associated surface weather features. The significant weather elements are defined by WMO and ICAO, and include:

  • thunderstorms and cumulonimbus clouds

  • tropical cyclones    Cyclone

  • moderate or severe turbulence

  • tropopause heights High tropopause height Flat tropopause height Low tropopause height
  • jetstreams (80kt and above depicted)
    Jet stream, 100 knots

  • volcanic eruptions Volcanic eruption

  • Jet Depth *

    Jet Depth

  • Hash Marks (each pair indicates successive 20kt wind speed changes referenced to Jet Max)
    Convergence Zones

  • Release of Radioactive Materials   Cyclone

NOTE: Jet Depth: The vertical depths to the 80 knot wind field above and below the jet steam using flight levels. Jet stream vertical depth forecasts are included when the maximum speed is 120 knots or more.

WAFS Significant Weather (SIGWX) Data in BUFR


This document has been prepared by the World Area Forecast Centres (WAFCs) for the purpose of providing guidance to software developers who have the task of constructing WAFS SIGWX BUFR visualisation software. The document is designed to assist developers in the construction of compliant visualisation software that receives its data input from text files obtained from BUFR decoding software.