Tutorial
SIGMET
SIGMETs (WSs) are broadcasted for hazardous weather that is considered of extreme importance to all aircraft.
SIGMETs (acronym for "SIGnificant METeorological information") warn of the following weather hazards:
severe icing, severe and extreme turbulence, duststorms, sandstorms, or volcanic ash lowering visibility to less
than 3 miles. A Convective SIGMET (WST) is issued for hazardous convective weather (such as tornadoes, thunderstorms,
hail) and covers severe or great turbulence, severe icing, and low-level wind shear.
A SIGMET (WS) example is shown below.
DFWA UWS 051710 SIGMET ALFA 1 VALID UNTIL 052110 AR LA MS FROM MEM TO JAN OCNL SVR ICING ABV FRZLVL EXPCD. FRZLVL 080 E TO 120 W. CONDS CONTIG BYD 2100Z.
Line 1
This is an urgent weather SIGMET (UWS) for the Dallas Fort Worth area issued on the 5th day of the month at 1900.
Line 2
This is the first issuance of this SIGMET (ALFA 1 and is valid until the 5th day of the month at 2110 (Note: The
first report of a different weather hazard is noted by ALFA 1, with its second notice given the notation ALFA 2.
The first report of a weather hazard different from the first one would have been labeled BRAVO with its second
notice given the notation BRAVO 2.; The first report of a weather hazard different from the first two would have
been labeled CHARLEY with its second notice given the notation CHARLEY 2.; that is alphabetical order beginning
with A-B-C;
Line 3
This weather report is good for the Arkansas, Louisiana and Mississippi area.
Line 4
From Memphis, Tennesee to Jackson, Mississippi
Line 5
Occasional (OCNL) severe (SVR) icing above (ABV) freezing level (FRZLVL) expected (EXPCD)
Line 6
Conditions (COND) continuing (CONTG) beyond (BYD) 2100 Zulu time