{"history":[],"article":{"id":"20eb1570-daad-4230-8acc-f418cb4112dc","title":"SIGMET","slug":"sigmet","content":":::summary\n:::\n\n# \n**SIGMET**, or **Significant Meteorological Information** (AIM 7-1-6), is a severe [weather](https://bliptext.com/articles/weather) advisory that contains [meteorological](https://bliptext.com/articles/meteorological) information concerning the safety of all [aircraft](https://bliptext.com/articles/aircraft).\nCompared to [AIRMETs](https://bliptext.com/articles/airmet), SIGMETs cover more severe weather.\nToday, according to the advancement of technology in civil aviation, the SIGMET is sent as [IWXXM](https://bliptext.com/articles/iwxxm) model.\n\n# Types\nThere are three main types of internationally recognized SIGMETs per ICAO:\nThis information is usually broadcast on the [ATIS](https://bliptext.com/articles/automatic-terminal-information-service) at [ATC](https://bliptext.com/articles/air-traffic-control) facilities, as well as over [VOLMET](https://bliptext.com/articles/volmet) stations.\nThey are assigned an [alphabetic](https://bliptext.com/articles/nato-phonetic-alphabet) designator from N through Y (excluding S and T).\nSIGMETs are issued as needed, and are valid up to four hours.\nSIGMETS for hurricanes and volcanic ash outside the [CONUS](https://bliptext.com/articles/contiguous-united-states) are valid up to six hours.\n\n## Convective SIGMETs\nFor airmen in the U.S., there is an additional category of SIGMET known as a **convective SIGMET**.\nThese are issued for [convection](https://bliptext.com/articles/atmospheric-convection) over the coterminous U.S..\nThere are three types of convective SIGMETs:\nThere are also a few special issuance convective SIGMETs to cover extreme weather more common in the U.S., including\n\n# Structure\nSIGMETs are internationally used by ICAO and WMOs using standardized abbreviations\nand are split into three lines:\nIn sum, a standardized SIGMET will have the following structure:\n**TTAAii CCCC YYGGgg [BBB]**\n**CCCC SIGMET [n][n]n VALID YYGGgg/YYGGgg CCCC-**\n**CCCC FIR OBS/FCST [AT GGggZ] [MOV XXX xx KT/KMH] [INTSF/WKN/NC] =**\n\n## Header\nThe header line consists of the following characters\n**TTAAii CCCC YYGGgg [CCx]**\n\n## Summary\nThe first line of the broadcast is a summary line consisting of the following characters\n**CCCC SIGMET [n][n]n VALID YYGGgg/YYGGgg CCCC-**\n[a] – if it a convective SIGMET, then this will read **SIG[E/C/W] CONVECTIVE SIGMET ##[E/C/W]**.\nWhere **E/C/W** indicates whether it's over the Eastern, Central, or Western United States, and **##** indicates the number of the convective SIGMET issued for that region.\n\n## Body\nThe main body of a SIGMET can be much more variable, and consists of\n**CCCC [FIR/CTA list] OBS/FCST [AT GGggZ] [MOV XXX xx KT/KMH] [INTSF/WKN/NC] [FCST AT Z ]=**\n**CCCC [FIR/CTA list]** is again the 4-character ICAO location, followed by the affected flight or control regions.\n**** is a code describing the meteorological phenomena as follows:\nIf it is a convective SIGMET, the following codes may appear\n****OBS**/**FCST** [AT GGggZ]** indicates whether the phenomenon is observed (**OBS**) or forecasted (**FCST**), and the Zulu hour and minute that it was observed or will be forecasted.\n**** is a general description of location of the meteorological phenomenon, typically utilizing latitude and longitudinal coordinates.\n**** helps denote the altitude that the phenomenon will be occurred, and can be expressed as\n**[MOV XXX xx KT/KMH]** if it is a moving front, the direction and rate of movement given as a compass direction (XXX, e.g. \"N\" or \"WNW\"), and the rate is given in KT (or KMH).\nSometimes STNR (Stationary) may be used instead if no significant movement is expected.\n**[INTSF/WKN/NC]** denotes the change in strength over time.\n**[FCST AT Z ]** helps note where the front is expected to be at the end of the SIGMET's validity period.\n\n## SIGMET Renewal and Cancellation\nIf when the validity period is due to expire but the phenomenon is expected to persist, a new sequence number is added to the SIGMET to renew it.\nIf during the validity period of a SIGMET, the SIGMET is to be cancelled, the following replaces the SIGMET message\n**CNL SIGMET [n][n]n YYGGgg/YYGGgg**\n\n# Examples\nWSUS32 KKCI 071655\nAn en-route weather phenomenon in the U.S., issued by the Aviation Weather Center in Kansas City, MO on the 7th of August, at 16:55 UTC\nSIGC\nCONVECTIVE SIGMET 83C\nThis is a convective weather pattern in the central region of the contiguous U.S. with sequence number 83C\nVALID UNTIL 1855Z\nThat is valid until 18:55 UTC\nMI IN WI IL IA LM That covers Minnesota, Indiana, Wisconsin, Illinois, Iowa, and Lower Michigan flight regions\nFROM 30E GRR-30S GIJ-30SSW BDF-10ENE IOW-50ENE DBQ-30E GRR\n**A** description of the area of the storm, where GRR (Grand Rapids, MI airport), GIJ (Niles, MI VOR**T****A****C**), BDF (Bradford, IL VOR**T****A****C**), IOW (Iowa **C**ity, I**A** airport), and DBQ (Dubuque, I**A** airport) are **C**on**T**rol **A**reas (**C****T****A**s).\nAREA TS MOV FROM 25025KT.\nTOPS TO FL450.\nThunderstorms moving from 250 degrees (roughly WSW) at 25 knots, covering an altitude from the cloud cover to 45,000 ft.","current_revision":null,"created_by":"kACnuQmH5k9Nr5VNVEpVeg7XpvUmMctD","created_at":"2025-01-26T07:00:36.327Z","updated_at":"2025-01-26T07:00:36.327Z","search_vector":"'sigmet':1","search_content":" \n \n\n# \n**SIGMET**, or **Significant Meteorological Information** (AIM 7-1-6), is a severe [weather](https://bliptext.com/articles/weather) advisory that contains [meteorological](https://bliptext.com/articles/meteorological) information concerning the safety of all [aircraft](https://bliptext.com/articles/aircraft).\nCompared to [AIRMETs](https://bliptext.com/articles/airmet), SIGMETs cover more severe weather.\nToday, according to the advancement of technology in civil aviation, the SIGMET is sent as [IWXXM](https://bliptext.com/articles/iwxxm) model.\n\n# Types\nThere are three main types of internationally recognized SIGMETs per ICAO:\nThis information is usually broadcast on the [ATIS](https://bliptext.com/articles/automatic-terminal-information-service) at [ATC](https://bliptext.com/articles/air-traffic-control) facilities, as well as over [VOLMET](https://bliptext.com/articles/volmet) stations.\nThey are assigned an [alphabetic](https://bliptext.com/articles/nato-phonetic-alphabet) designator from N through Y (excluding S and T).\nSIGMETs are issued as needed, and are valid up to four hours.\nSIGMETS for hurricanes and volcanic ash outside the [CONUS](https://bliptext.com/articles/contiguous-united-states) are valid up to six hours.\n\n## Convective SIGMETs\nFor airmen in the U.S., there is an additional category of SIGMET known as a **convective SIGMET**.\nThese are issued for [convection](https://bliptext.com/articles/atmospheric-convection) over the coterminous U.S..\nThere are three types of convective SIGMETs:\nThere are also a few special issuance convective SIGMETs to cover extreme weather more common in the U.S., including\n\n# Structure\nSIGMETs are internationally used by ICAO and WMOs using standardized abbreviations\nand are split into three lines:\nIn sum, a standardized SIGMET will have the following structure:\n**TTAAii CCCC YYGGgg [BBB]**\n**CCCC SIGMET [n][n]n VALID YYGGgg/YYGGgg CCCC-**\n**CCCC FIR OBS/FCST [AT GGggZ] [MOV XXX xx KT/KMH] [INTSF/WKN/NC] =**\n\n## Header\nThe header line consists of the following characters\n**TTAAii CCCC YYGGgg [CCx]**\n\n## Summary\nThe first line of the broadcast is a summary line consisting of the following characters\n**CCCC SIGMET [n][n]n VALID YYGGgg/YYGGgg CCCC-**\n[a] – if it a convective SIGMET, then this will read **SIG[E/C/W] CONVECTIVE SIGMET ##[E/C/W]**.\nWhere **E/C/W** indicates whether it's over the Eastern, Central, or Western United States, and **##** indicates the number of the convective SIGMET issued for that region.\n\n## Body\nThe main body of a SIGMET can be much more variable, and consists of\n**CCCC [FIR/CTA list] OBS/FCST [AT GGggZ] [MOV XXX xx KT/KMH] [INTSF/WKN/NC] [FCST AT Z ]=**\n**CCCC [FIR/CTA list]** is again the 4-character ICAO location, followed by the affected flight or control regions.\n** ** is a code describing the meteorological phenomena as follows:\nIf it is a convective SIGMET, the following codes may appear\n****OBS**/**FCST** [AT GGggZ]** indicates whether the phenomenon is observed (**OBS**) or forecasted (**FCST**), and the Zulu hour and minute that it was observed or will be forecasted.\n** ** is a general description of location of the meteorological phenomenon, typically utilizing latitude and longitudinal coordinates.\n** ** helps denote the altitude that the phenomenon will be occurred, and can be expressed as\n**[MOV XXX xx KT/KMH]** if it is a moving front, the direction and rate of movement given as a compass direction (XXX, e.g. \"N\" or \"WNW\"), and the rate is given in KT (or KMH).\nSometimes STNR (Stationary) may be used instead if no significant movement is expected.\n**[INTSF/WKN/NC]** denotes the change in strength over time.\n**[FCST AT Z ]** helps note where the front is expected to be at the end of the SIGMET's validity period.\n\n## SIGMET Renewal and Cancellation\nIf when the validity period is due to expire but the phenomenon is expected to persist, a new sequence number is added to the SIGMET to renew it.\nIf during the validity period of a SIGMET, the SIGMET is to be cancelled, the following replaces the SIGMET message\n**CNL SIGMET [n][n]n YYGGgg/YYGGgg**\n\n# Examples\nWSUS32 KKCI 071655\nAn en-route weather phenomenon in the U.S., issued by the Aviation Weather Center in Kansas City, MO on the 7th of August, at 16:55 UTC\nSIGC\nCONVECTIVE SIGMET 83C\nThis is a convective weather pattern in the central region of the contiguous U.S. with sequence number 83C\nVALID UNTIL 1855Z\nThat is valid until 18:55 UTC\nMI IN WI IL IA LM That covers Minnesota, Indiana, Wisconsin, Illinois, Iowa, and Lower Michigan flight regions\nFROM 30E GRR-30S GIJ-30SSW BDF-10ENE IOW-50ENE DBQ-30E GRR\n**A** description of the area of the storm, where GRR (Grand Rapids, MI airport), GIJ (Niles, MI VOR**T****A****C**), BDF (Bradford, IL VOR**T****A****C**), IOW (Iowa **C**ity, I**A** airport), and DBQ (Dubuque, I**A** airport) are **C**on**T**rol **A**reas (**C****T****A**s).\nAREA TS MOV FROM 25025KT.\nTOPS TO FL450.\nThunderstorms moving from 250 degrees (roughly WSW) at 25 knots, covering an altitude from the cloud cover to 45,000 ft.","revisionCount":0},"hasMore":false,"nextCursor":null}

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