SIGWX

SIGWX is a Significant Weather Chart defined by ICAO.
Weather charts being issued by World Area Forecast Centres, presenting the most important meteorological phenomena relevant especially for air traffic transport. WAFC publishes them in two formats

BUFR code
PNG images

Charts are typically being issued every six hours. The SIGWX charts only show the forecast for the specific hour, however it is common place for parameters such as the JetStream, CAT & CB to be interpreted +/- 3 hours of the chart validity time. . Prognoses are typically prepared for two ranges of heights:

SWH - High Level SIGWX
SWM - Medium Level SIGWX

Weather phenomena:

Cloud - including information about cloud type, height of base and top, turbulence and icing risk
Clear Air Turbulence - including base and top height, strength of turbulence
Jet Stream - including base and top height, wind speed
Tropopause Height
Tropical Cyclone, Sandstorm
Volcanoes
Frontal system

IMPORTANT NOTE: Amendment 74 to ICAO Annex 3 eliminated the requirement for depiction of surface fronts and well-defined convergence zones on WAFS SIGWX forecasts. WAFC still publishes frontal bulletins, but they contain no data.