Section 8. Flight Advisories (SIGMET/WS-AIRMET/WA-Convective SIGMET/WST)

9-8-1. GENERAL

Flight Advisories are issued by the NAWAU in Kansas City, Missouri, for the conterminous U.S. and the appropriate WSFO in Alaska and Hawaii to provide notice of potentially hazardous weather conditions by amending or supplementing portions of the valid FA. The report type designator WS for SIGMETs, WST for Convective SIGMETs, and WA for AIRMETs is used to effect selective distribution. The text of the message identifies which advisory is being transmitted. WSs are identified with letters N (NOVEMBER) through Y (YANKEE) with the exception of S (SIERRA) and T (TANGO). WAs are identified with the letters S (SIERRA), T (TANGO) and Z (ZULU). The latest message for each system is kept in the computer's active storage file by the WMSC: WA for 360 minutes, WS for 240 minutes, and WST for 45 minutes.

NOTE-
Honolulu issues international SIGMETs available as WSPA1 PHNL and WSPA2 PHNL, which are retained by WMSC for 360 minutes.

9-8-2. DISTRIBUTION

SIGMETs, both WST/WS, are distributed unsched- uled to all Service A circuits. AIRMET data is distributed as a scheduled product at 0145Z and every 6 hours thereafter, and any updates or amendments issued between scheduled periods will be a complete replacement for the previously issued AIRMET.