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'''SIGMET''',<ref>http://www.faraim.org/aim/aim-4-03-14-437.html</ref> or '''Significant Meteorological Information''',<ref name=faa/> is a [[weather]] advisory that contains [[meteorological]] information concerning the safety of all [[aircraft]]. There are two types of SIGMETs - convective and non-convective. The criteria for a non-convective SIGMET to be issued are severe or greater [[turbulence]] over a {{convert|3000|sqmi|km2|sing=on}} area, severe or greater [[Atmospheric icing|icing]] over a {{convert|3000|sqmi|km2|sing=on}} area or [[Instrument meteorological conditions|IMC]] over a {{convert|3000|sqmi|km2|sing=on}} area due to [[dust]], [[sand]], or [[volcanic ash]].
'''SIGMET''',<ref>http://www.faraim.org/aim/aim-4-03-14-437.html</ref> or '''Significant Meteorological Information''',<ref name=faa/> is a [[weather]] advisory that contains [[meteorological]] information concerning the safety of all [[aircraft]]. There are two types of SIGMETs - convective and non-convective. The criteria for a non-convective SIGMET to be issued are severe or greater [[turbulence]] over a {{convert|3000|sqmi|km2|sing=on}} area, severe or greater [[Atmospheric icing|icing]] over a {{convert|3000|sqmi|km2|sing=on}} area or [[Instrument meteorological conditions|IMC]] over a {{convert|3000|sqmi|km2|sing=on}} area due to [[dust]], [[sand]], or [[volcanic ash]].


This information is usually broadcast on the [[Automatic Terminal Information Service|ATIS]] at [[Air traffic control|ATC]] facilities, as well as over [[VOLMET]] stations. They are assigned an [[NATO phonetic alphabet|alphabetic]] designator from N through Y (excluding S and T).<ref name=faa>{{cite web|title=Pilot's Handbook of Aeronautical Knowledge|url=http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/phak%20-%20chapter%2012.pdf|website=|publisher=Federal Aviation Administration|accessdate=17 September 2015}}</ref> SIGMETs are issued as needed, and are valid up to four hours. SIGMETS for hurricanes and volcanic ash outside the CONUS are valid up to six hours.<ref>http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC-0045G_chg1_fullDocument.pdf</ref>
This information is usually broadcast on the [[Automatic Terminal Information Service|ATIS]] at [[Air traffic control|ATC]] facilities, as well as over [[VOLMET]] stations. They are assigned an [[NATO phonetic alphabet|alphabetic]] designator from N through Y (excluding S and T).<ref name=faa>{{cite web|title=Pilot's Handbook of Aeronautical Knowledge|url=http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/phak%20-%20chapter%2012.pdf|website=|publisher=Federal Aviation Administration|accessdate=17 September 2015}}</ref> SIGMETs are issued as needed, and are valid up to four hours. SIGMETS for hurricanes and volcanic ash outside the [[Contiguous United States|CONUS]] are valid up to six hours.<ref>http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC-0045G_chg1_fullDocument.pdf</ref>


A '''Convective SIGMET''' is issued for convection over the Continental U.S. Convective SIGMETs are issued for an area of embedded thunderstorms, a line of thunderstorms, thunderstorms greater than or equal to VIP level 4 affecting 40% or more of an area at least 3000 square miles, and severe surface weather including surface winds greater than or equal to 50 knots, hail at the surface greater than or equal to 3/4 inches in diameter, and tornadoes.<ref>{{Cite web|url = http://www.aviationweather.gov/sigmet/help|title = AWC - Aviation Weather Center|last = Homepage|first = NOAA's National Weather Service - Aviation Weather Center|website = www.aviationweather.gov|language = en-us|access-date = 2016-04-13}}</ref> Severe thunderstorms are characterized by [[tornado]](s), [[hail]] 3/4 inches or greater, or wind gusts 50 knots or greater.<ref>see 3</ref> A Convective SIGMET is valid for 2 hours and they are issued every hour + 55 min.<ref>see 4</ref>
A '''Convective SIGMET''' is issued for convection over the Continental U.S. Convective SIGMETs are issued for an area of embedded thunderstorms, a line of thunderstorms, thunderstorms greater than or equal to VIP level 4 affecting 40% or more of an area at least 3000 square miles, and severe surface weather including surface winds greater than or equal to 50 knots, hail at the surface greater than or equal to 3/4 inches in diameter, and tornadoes.<ref>{{Cite web|url = http://www.aviationweather.gov/sigmet/help|title = AWC - Aviation Weather Center|last = Homepage|first = NOAA's National Weather Service - Aviation Weather Center|website = www.aviationweather.gov|language = en-us|access-date = 2016-04-13}}</ref> Severe thunderstorms are characterized by [[tornado]](s), [[hail]] 3/4 inches or greater, or wind gusts 50 knots or greater.<ref>see 3</ref> A Convective SIGMET is valid for 2 hours and they are issued every hour + 55 min.<ref>see 4</ref>

Revision as of 08:19, 11 December 2016

SIGMET,[1] or Significant Meteorological Information,[2] is a weather advisory that contains meteorological information concerning the safety of all aircraft. There are two types of SIGMETs - convective and non-convective. The criteria for a non-convective SIGMET to be issued are severe or greater turbulence over a 3,000-square-mile (7,800 km2) area, severe or greater icing over a 3,000-square-mile (7,800 km2) area or IMC over a 3,000-square-mile (7,800 km2) area due to dust, sand, or volcanic ash.

This information is usually broadcast on the ATIS at ATC facilities, as well as over VOLMET stations. They are assigned an alphabetic designator from N through Y (excluding S and T).[2] SIGMETs are issued as needed, and are valid up to four hours. SIGMETS for hurricanes and volcanic ash outside the CONUS are valid up to six hours.[3]

A Convective SIGMET is issued for convection over the Continental U.S. Convective SIGMETs are issued for an area of embedded thunderstorms, a line of thunderstorms, thunderstorms greater than or equal to VIP level 4 affecting 40% or more of an area at least 3000 square miles, and severe surface weather including surface winds greater than or equal to 50 knots, hail at the surface greater than or equal to 3/4 inches in diameter, and tornadoes.[4] Severe thunderstorms are characterized by tornado(s), hail 3/4 inches or greater, or wind gusts 50 knots or greater.[5] A Convective SIGMET is valid for 2 hours and they are issued every hour + 55 min.[6]

See also

References

  1. ^ http://www.faraim.org/aim/aim-4-03-14-437.html
  2. ^ a b "Pilot's Handbook of Aeronautical Knowledge" (PDF). Federal Aviation Administration. Retrieved 17 September 2015.
  3. ^ http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC-0045G_chg1_fullDocument.pdf
  4. ^ Homepage, NOAA's National Weather Service - Aviation Weather Center. "AWC - Aviation Weather Center". www.aviationweather.gov. Retrieved 2016-04-13.
  5. ^ see 3
  6. ^ see 4
  • IWXXM 1.0 Official WMO/ICAO representation of SIGMET information in XML


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