SIGMET

SIGMETs provide information on observed or forecast hazardous weather conditions, particularly thunderstorms, severe turbulence, volcanic ash, tropical cyclones, severe icing, and severe mountain waves.

They are issued for an FIR region, are valid for four hours (or six hours for volcanic ash and tropical cyclones), and are reviewed after three hours or when further information is available, especially from PIREPSs and AIREPs . They are sequentially numbered so it's easy to work out whether you have the most current SIGMET or not.

The height of the SIGMET phenomena included in SIGMETs is given in feet above mean sea level up to 10,000 feet and then in flight levels above this.

Invercargill

Above mean sea level

TCu

Towering Cumulus

agl

above ground level

Cb

Cumulonimbus

Flight Information Service communications

ATS

Air Traffic Service

Royal New Zealand Air Force

in vicinity of aerodrome Thunderstorm

ATC

Air Traffic Control

VC

in vicinity of aerodrome

Probabilityxx%

TIL

Until

FM

From

Becoming

Temporarily

Routine air report from aircraft in flight

FIR

Flight Information Region

Internet Flight Information Service

VFR

Visual flight rules

Automatic Terminal Information Service

BWR

Basic weather report

New Zealand Flight Information Region

Aerodrome special routine meteorological report

Automatic aerodrome routine meteorological report

Aerodrome routine meteorological report

TAF

Aerodrome forecast

Area forecast

Significant meteorological information