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AVIATION WEATHER PRODUCTS

SIGMET

SIGMET

A SIGMET is a warning issued to provide urgent advice to aircrat o the actual or expected

occurrence, in areas over which meteorological watch is being maintained, o weather

phenomena that are potentially hazardous. A SIGMET will contain inormation on one o the

ollowing phenomena:

Code Description

OBSC TS Obscured thunderstorms

EMBD TS Embedded thunderstorms

FRQ TS Frequent thunderstorms

SQL TS Squall line thunderstorms

OBSC TSGR Obscured thunderstorms with hail

EMBD TSGR Embedded thunderstorms with hail

FRQ TSGR Frequent thunderstorms with hail

SQL TSGR Squall line thunderstorms with hail

TC Tropical cyclone

SEV TURB Severe turbulence

SEV ICE Severe icing

SEV ICE FZRA Severe icing due to freezing rain

SEV MTW Severe mountain wave

HVY DS Heavy duststorm

HVY SS Heavy sandstorm

VA Volcanic ash

RDOACT CLD Radioactive cloud

A SIGMET will provide inormation on the location, extent, intensity and expected evolution

o the specifed phenomenon.

SIGMETs or thunderstorms are only issued when they are:

obscured(OBSC)byhazeorsmoke

embedded(EMBD)withincloudlayers

frequent(FRQ),i.e.withlittleornoseparationbetweencloudsandcoveringmorethan

75% o the area aected

squallline(SQL)thunderstormsalongalineofabout100nauticalmilesormoreinlength,

with little or no separation between clouds

SIGMETforthunderstormsdonotincludereferencetocumulonimbuscloud(CB)or

associated icing and turbulence as these are implied as occurring.

Pilots in command o

aircrat encountering

any phenomenon in

this table not notifed

by SIGMET must

report details o the

phenomenon in anAIREP SPECIAL

FURTHER INFORMATIONAviation Weather Services

Visit us at www.bom.gov.au

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SIGMET or tropical cyclones include cumulonimbus but not associated icing and turbulence

as these are implied as occurring.

Responsibility for the issuance of SIGMET within

the Australian Flight Information Regions

SIGMETsforvolcanicasharetheresponsibilityoftheVolcanicAshAdvisoryCentre,Darwin.

SIGMETsfortropicalcyclonesaretheresponsibilityoftheTropicalCycloneWarningCentres

inPerth,DarwinandBrisbane.

SIGMETsforturbulenceandicingaboveFL185aretheresponsibilityoftheAviationWeather

Centre,Melbourne.

SIGMETforallotherphenomenaaretheresponsibilityoftheMeteorologicalWatchOfces

locatedinPerth,Darwin,Adelaide,Hobart,Melbourne,SydneyandBrisbane.

SIGMET Structure

Bulletin Identifcation

WCAU01forSIGMETfortropicalcyclones

WVAU01forSIGMETforvolcanicashcloud

WSAU21forSIGMETforotherphenomena

Originating Ofce (WMO Location Indicator)

TheWorldMeteorologicalOrganisation(WMO)locationindicatorsforAustralian

MeteorologicalWatchOfcesare:

APRM Adelaide

APRF Perth

ABRF Brisbane

ASRF Sydney

ADRM Darwin

AMRF Melbourne

AMHF Hobart

AMMC AviationWeatherCentreMelbourne

Note:ThesedifferfromtheICAOindicators

(beginningwithY)usedelsewhereinthemessage.

WSAU21AMMC180357

YMMMSIGMETMM01VALID180439/180839YMMC-

YMMMMELBOURNEFIRSEV

TURBFCSTWIS3200E12800-

S3200E13000-S4700E13600

-S4700E13400FL260/400

MOVE25KTNC

STS:NEW

WVAU01ADRM200100

YBBBSIGMETBT04VALID

200100/200700YPDM-

YBBBBRISBANEFIRVA

ERUPTIONLOCS0416E15212

VACLDOBSAT200100Z

A100/180APRX120NMBY

40NMS1130E14530-S1330

E14900-S1030E15030

-S0830E14700-S1130

E14430MOVSW20KTFCST0700ZVACLDAPRXS110

E144530-S1230E14930

-S1050E15130-S0800

E14700-S1130E14400

STS:REVSIGMETBT03

191900/200100

WCAU01APRF180217

YMMMSIGMETPH01VALID

180215/180815YPRF-

YMMMMELBOURNEFIRTC

ILSAOBSAT0000ZS1330

E11324CBTOPFL500WI

120NMOF

CENTREMOVWSW17KT

INTSFFCST0815ZTCCENTRE

S1418E11036

STS:NEW

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Issue Date/Time

Issuedate/timeisgiveninUTCintheformDDHHMM,whereDDisdayofmonth,and

HHMMistimeinhoursandminutes.

Flight Inormation Region

GivestheabbreviationfortheFIR(YMMMorYBBB)inwhichthephenomenonislocated.

Identifer

The message identifer is SIGMET.

Daily Sequence Number

Thefour-charactersequencenumberconsistsof:

atwo-letterdesignatortoindicatethegenerallocationoftheevent(asgiveninthetwo

mapsbelow),and

atwo-digitnumber,givingthesequencenumberofSIGMETsissuedbytherelevantofce,

withinthegivenFIR(BrisbaneorMelbourne)since0000UTC.

Thetwo-letterdesignators,andtheirassociatedgeographicalextent,forlow-level(below

FL185)SIGMETincludingtropicalcyclonesare:

Thetwo-letterdesignators,andtheirgeneralassociatedgeographicalextent,forvolcanic

ashandhigh-level(aboveFL185)icingandturbulenceSIGMETare:

A Altitude

ABV Above

APRX Approximately

BLW Below

CLD Cloud

CNL CancelDS Dust storm

E East or easternlongitude

EMBD Embedded

FCST Forecast

FIR Flight InformationRegion

FL Flight level

FRQ Frequent

FZRA Freezing rain

GR Hail

HVY Heavy

ICE Icing

INTSF Intensifying

KT Knots

LOC Location

MOV Moving

MT Mount

N North or northernlatitude

NC No Change (inintensity)

NM Nautical MilesOBS Observed

OBSC Obscured

RDOACTCLD

Radioactive cloud

REV Review

S South or southernlatitude

SEV Severe

SQL Squall line

SS Sand storm

STNR Stationary

STS Status

TC Tropical cyclone

TOP Cloud Top

TS Thunderstorm

TURB Turbulence

VA Volcanic ash

W West or westernlongitude

WI Within (area)

WKN Weakening(intensity)

Z Code for UTC(Universal TimeCoordinated)

SIGMET Abbreviations

MELBOURNE FIR

BRISBANE FIR

PH

BN

AD

ML

DN

SY

HB

160E

160E

150E

150E

140E

140E

130E

130E

120E

120E

110E

110E

100E

100E

90E

90E

80E

80E

0 0

10S 10S

20S 20S

30S 30S

40S 40S

50S 50S

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Originating Ofce (ICAO Location Indicator)

TheInternationalCivilAviationOrganization(ICAO)locationindicatorsforAustralian

MeteorologicalWatchOfcesare:

YPRM Adelaide

YPRM Perth

YBRF Brisbane

YSRF Sydney

YPDM Darwin

YMRF Melbourne

YMHF Hobart

YMMC AviationWeatherCentreMelbourne

Flight Inormation Region

ThisgivestheabbreviationandfullnamefortheFIRinwhichthephenomenonislocated.

Meteorological Inormation

This section includes:

typeofphenomenon

observedorforecast

location,bothhorizontalandverticalextent

movementorexpectedmovement

expectedchangeinintensity

forecastpositionattheendofthevalidityperiod(onlyinSIGMETforTCandVA)

The frst point o a polygon is not repeated when describing the horizontal extent o an event.

SIGMETfortropicalcyclonesdonotincludereferencetocumulonimbuscloud(CB)or

associated icing and turbulence as these are implied as occurring.

Cancel SIGMET

I during the validity period o a SIGMET, the phenomenon or which the SIGMET is no

longer occurring or is no longer expected, the SIGMET is cancelled by issuing a SIGMET with

theabbreviationCNLinlieuofmeteorologicalinformation.CNLisalsoincludedonthe

status line.

SIGMET Status

The status line indicates whether the SIGMET is:

NEW-theSIGMETisforanewphenomenon.

REV-theSIGMETreviewsanearlierSIGMETforthephenomenon.

CNL-theSIGMETcancelsacurrentSIGMET.

WSAU21AMMC180720

YMMMSIGMETMM02VALID

180720/180839YMMC-

YMMMMELBOURNE

FIRCNLSIGMETMM01

180439/180839

STS:CNLSIGMETMM01

180439/180839

Airservices Australia is the ocial distributor o aviation orecasts, warnings and observations issued

by the Bureau o Meteorology. Airservices fight brieng services are available at

www.airservicesaustralia.com. Telephone contact details or elaborative briengs are contained in

Airservices Aeronautical Inormation Publication Australia (AIP), which is available online through

their website.

Other brochures produced by the Bureau o Meteorologys aviation weather services program can be

ound at www.bom.gov.au/aviation/knowledge-centre.

CommonwealthofAustralia,17May2012