SIGMET and AIRMET areas display in the Enroute Charts view when the Weather toolbar button is enabled and the Time Slider is set to a time when AIRMET or SIGMET data is available.
View the text information for an AIRMET or SIGMET by right-clicking its boundary and selecting Properties.
NOTE | AIRMET/SIGMET
rendering errors on the enroute chart may occur due to inconsistencies
in data from the various reporting agencies.
Please refer to the textual information in the tooltip if an error is suspected. |
SIGMETs (Significant Meteorological Information) are issued for severe icing and turbulence, volcanic ash, tropical cyclones and severe dust storms affecting an area of at least 3000 square miles for the U.S., Oceanic Areas, and International FIR regions. SIGMETs are issued by the Aviation Weather Center in the U.S. and by state meteorological agencies internationally.
Volcanic ash SIGMETs are shown in black.
SIGMETs are issued as conditions warrant and valid for a 4-hour period for turbulence and icing, and for a 6-hour period for tropical cyclones and volcanic ash and dust.
Convective SIGMETs are issued for severe thunderstorms, lines of thunderstorms at least 50 miles long where 40% of the length is affected by thunderstorms, and for active areas of thunderstorms at least 3000 square miles where 40% of the area is being affected by thunderstorms. The Storm Prediction Center in Norman, OK, is responsible for issuing Convective SIGMETs in the U.S. and adjacent oceanic areas. Convective SIGMETs are issued for the Eastern, Central, and Western U.S.
Convective SIGMETs are issued every hour as needed and are valid for a 2-hour period.
Convective Outlooks are forecasts of potential convective activity issued for a 4-hour period. Text for outlooks is contained in the tooltips for the related SIGMET.
AIRMETs (Airmen's Meteorological Information) are issued for moderate icing (Zulu), moderate turbulence (Tango), IFR and Mountain Obscurations (Sierra), surface winds in excess of 30 knots, and non-convective low-level wind shear (LLWS) below 2000 feet AGL. AIRMETs are issued by the Aviation Weather Center (AWC) for the U.S. in six geographic regions, as well as for regions in Alaska and Hawaii.
AIRMETs are issued at 0300, 0900, 1500 and 2100 UTC and are valid for a 6-hour period.