A-12
Revision 6 Feb/2009
RPRTD (reported) BY ACFT (aircraft) IN VCNTY (vicinity)
RPRTD BY SVRL (several) ACFT
8
.
Issuers initials.
If conditions end more than one half hour prior to the indicated expiration
time, and the report does not state that conditions will continue, a cancel-
lation will be issued with CNCL SIGMET as the report designator. If con-
ditions are expected to continue, a new SIGMET will be issued. If condi-
tions end within one half hour of the indicated expiration time, the
SIGMET will be allowed to expire without cancellation. Once the report
is cancelled or expires, the FIS system no longer broadcasts the report.
UNDERSTANDING CONVECTIVE SIGMETS
The following is an example of a typical Convective SIGMET with an
explanation of the elements.
1.
Station Identifier:
MKCC
MKC
is the station identifier of the Aviation Weather Center (AWC)
in Kansas City.
The
C
denotes the report is for the Central portion of the continental
United States. The choices are as follows:
C
Central
E
East
W
West
Convective SIGMETs are issued for:
Severe weather including: (a)Surface winds
≥
50 knots,
(b) Surface hail
≥
3/4 inch in diameter or (c) Tornadoes
Embedded thunderstorms (obscured by haze or other phenomena)
Line of thunderstorms
Thunderstorms
≥
VIP level 4 affecting
≥
40% of an area
≥
3000 sq.
mi.
KMD 550/850 FIS Addendum
Appendix A
Understanding Weather Reports
MKCC WST 221855
CONVECTIVE SIGMET 20C
VALID UNTIL 2055Z
ND SD
FROM 60W MOT-GFK-ABR-90W MOT
INTSFYG AREA SVR TSTMS MOVG FROM 2445. TOPS ABV FL450.
WIND GUSTS TO 60KT RPRTD. TORNADOES…HAIL TO 2 IN…WIND
GUSTS TO 65KT PSBL ND PTN.
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