SIGMET

A SIGMET (significant meteorological) report. SIGMETs report the occurrence and/or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations, and of the development of those phenomena over time. The SIGMET report class represents the base SIGMET types that may be reported such as squall lines, thunderstorms, dust storms, turbulence, etc. Tropical cyclone and volcanic ash SIGMET reports are subclasses of SIGMET due to their ability to report additional information, including volcano/tropical cyclone identification and forecast position(s). SIGMETs may report either observed or forecast hazardous conditions. Additionally, a forecast position may be reported.

Semantic Correspondence

analysis

A SIGMET report may include a phenomenon covering more than one area within the FIR/UIR/CTA. This translates into observed and forecast conditions for each of these reported areas. All combinations of observations and forecasts of meteorological conditions, including changing conditions, are represented by their own SIGMETEvolvingCondition. Each analysis has a single SIGMETEvolvingConditionCollection as its result.

Semantic Correspondence

Notes

Report

cancelledReportSequenceNumber

The sequence number of a previous SIGMET that is cancelled by this SIGMET. Mandatory when this is a cancellation report, must be missing otherwise Examples: YUDD SIGMET 2 VALID ... YUDD SIGMET A3 VALID ...

Semantic Correspondence

cancelledReportValidPeriod

The valid period of a previous SIGMET that is cancelled by this SIGMET. Mandatory when this is a cancellation report, must be missing otherwise

Semantic Correspondence

forecastPositionAnalysis

A forecast of the phenomenon at the end of the valid period. This is modeled by SIGMETPosition for individual area of the phenomenon and aggregated into a single SIGMETPositionCollection as a result to forecastPositionAnalysis.

Semantic Correspondence

Notes

report

isCancelReport

Indicates whether the report is a 'CANCELLATION' report (true) which cancels a previously issued report or not (false or empty).

Semantic Correspondence

issueTime

The time at which this report was issued

Semantic Correspondence

issuingAirTrafficServicesRegion

The ATS region (FIR, UIR, CTA, or FIR/UIR)

Semantic Correspondence

issuingAirTrafficServicesUnit

The ATS unit serving the FIR or CTA to which the SIGMET refers ICAO Annex 3 / WMO No. 49-2: A6-1: Location indicator of FIR/CTA""

Semantic Correspondence

Notes

AIRM has no direct link between this and weather conditions

originatingMeteorologicalWatchOffice

MWO originating this report

Semantic Correspondence

phenomenon

The reported phenomenon, such as thunderstorm, tropical cyclone, icing, mountain wave, etc. The expected end of occurrence of volcanic ash (NO VA EXP") is indicated with a missing SIGMET phenomenon with a nil reason of nothingOfOperationalSignificance"

Semantic Correspondence

sequenceNumber

The sequence number of this message. For example: 5", "A3", or "2""

Semantic Correspondence

validPeriod

The valid period for the entire report covering all observations and forecast conditions. Each observation/forecast phenomenon includes its own temporal description for the described meteorological conditions, which is represented as phenomenonTime. For example, an issued tropical cyclone SIGMET may be valid from 1600 UTC to 2200 UTC with an observed position at 1600 UTC and a forecast position of the centre of the tropical cyclone at 2200 UTC. In this case the SIGMET validPeriod would be 1600 UTC to 2200 UTC, the analysis phenomenonTime would be 1600 UTC, and the forecastPositionAnalysis phenomenonTime would be 2200 UTC.

Semantic Correspondence