{"id":16364,"date":"2025-08-01T06:30:34","date_gmt":"2025-08-01T11:30:34","guid":{"rendered":"http:\/\/www.universalweather.com\/blog\/?p=16364"},"modified":"2025-08-07T07:47:06","modified_gmt":"2025-08-07T12:47:06","slug":"aviation-weather-intro-to-sigwx-charts","status":"publish","type":"post","link":"https:\/\/www.universalweather.com\/blog\/aviation-weather-intro-to-sigwx-charts\/","title":{"rendered":"Business Aviation Weather: Intro to SIGWX Charts"},"content":{"rendered":"

Significant Weather (SIGWX) charts provide invaluable meteorological information to business aircraft operators and flight crew. Particularly for longer flights, or when weather issues may be a factor, SIGWX charts can be a vital flight planning tool.<\/p>\n

Here is an overview of what you need to know:<\/p>\n

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Know what SIGWX stands for<\/h2>\n

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Significant Weather \u2013 or SIGWX \u2013 is a high-level chart indicating forecast position of jet streams, tropopause heights, thunderstorms\/Cumulonimbus (CBS), turbulence, and fronts.<\/p>\n

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HIGH SIGWX charts are issued and updated throughout the day<\/h2>\n

SIGWX charts are issued four times a day: at 00, 06, 12, and 18Z. Two International Civil Aviation Organization (ICAO)-sponsored World Aviation Forecast Centers (WAFCs) \u2013 one in the US and the other in the UK \u2013 are responsible for issuing worldwide SIGWX charts. These are referred to as the Washington WAFC and London WAFC, respectively.<\/p>\n

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Know what HIGH SIGWX charts are available<\/h2>\n

High-level SIGWX charts provide world coverage between FL250 and 630.
\nMid-level charts cover FL100-450 for the North Atlantic region. Additionally, the National Weather Service (NWS) issues surface Prognostics (PROGS) for the continental U.S. and Hawaii. NWS Alaska issues surface PROGS for Alaska.<\/p>\n

Nav Canada provides PROGS for Canada.<\/p>\n

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Know how SIGWX information is gathered<\/h2>\n

Forecasters use model data and pilot reports, as well as satellite imagery, to produce SIGWX charts. Tropical cyclone information is gathered from Tropical Cyclone Advisory Centers (TCACs). Meanwhile, volcanic information is derived from Volcanic Ash Advisory Centers (VAACS) on the location of volcanic eruptions producing ash clouds of significance to aircraft operations.<\/p>\n

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Assorted information is provided on SIGWX charts<\/h2>\n

SIGWX charts provide surface frontal positions\/jet streams (direction, depth, and max speed); upper and surface high and low tropopause heights; thunderstorm\/CBS coverage and tops; turbulence (moderate or severe) in cloud or clear air (with base and tops); moderate or severe icing (base and top); and indications of widespread sandstorms, dust storms, volcanic ash, or radioactive materials.<\/p>\n

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Know how flight levels are indicated on charts<\/h2>\n

SIGWX charts indicate weather activity in increments of thousands of feet. FL340, for example, indicates 34,000 feet. Low-level charts should be used by aircraft flying from the surface to FL240. High-level SIGWX charts are used by aircraft flying FL250 and above.<\/p>\n

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Know the symbol indications for different weather<\/h2>\n

Symbols used on SIGWX charts are generally the same and are standard for aviation. The following link provides documentation on symbols used on SIGWX charts:<\/p>\n