Effective 15 July 2008, AWC has enhanced its page for International SIGMETs. We changed the name from "International"
to "Oceanic" in order to better convey which products can be expected on this page. The Oceanic
SIGMET page will show active SIGMETS for the Oceanic FIRs which AWC has SIGMET issuing
responsibility. These FIRs are: New York Oceanic, San Juan, Miami Oceanic, Houston Gulf,
and a large portion of Oakland Oceanic. These areas are colored a light blue.
On occasion, users may see other SIGMETs displayed in the darker blue areas. These SIGMETs
are issued by other offices, but we can not guarantee that all other SIGMETs will be
displayed. At the present time, SIGMETs for Mexico, Central and South America, Asia,
Alaska, Greenland, are not shown on this web page. We advise users to please contact your
flight briefing service to obtain SIGMETs for any oceanic or international flight.
An AWC Oceanic SIGMET (SIGnificant METeorlogical Information) advises of weather
potentially hazardous to all aircraft. The purpose of this information is to advise
pilots of the occurrence or expected occurrence of en-route weather phenomena which may
affect the safety of aircraft operations. Criteria for Domestic and AWC Oceanic
SIGMETs are similiar, however the format, contractions, and wording used are different.
AWC Oceanic SIGMETs are issued for oceanic areas Pacific and
Atlantic adjacent to the United States by a
Meteorological Watch Office (MWO). The National Weather Service has MWOs at Anchorage,
AK, Honolulu, HI, and the Aviation Weather Center in
Kansas City, MO.
AWC Oceanic SIGMET criteria:
- Thunderstorms
- Tornadoes
- Lines of thunderstorms
- Embedded thunderstorms
- Large areas of thunderstorms
- Large hail
- Tropical cyclone
- Severe icing
- Severe or extreme turbulence
- Duststorms and sandstorms lowering visibilities to less that three (3) miles
- Volcanic Ash
These SIGMET items are considered to be widespread because they must be
affecting or be forecast to affect an area of at least 3000 square miles at any one
time.
AWC Oceanic SIGMETs are issued for 12 hour periods for volcanic ash events, 6 hours
for hurricanes and tropical storms and 4 hours for all other criteria. If conditions
persist beyond the forecast period, the SIGMET is updated and reissued.
|