IRFP-01
Metro Review
5. Responsibility for Issuance - The National Aviation Weather
Advisory Unit (NAWAU) in Kansas City, Missouri, has the
responsibility for issuing WAs, WSTs, and WSs for the
conterminous United States
a. Designated forecaster(s) maintain watch on weather
developments using weather radar, surface observations,
PIREPs, and satellite image information
b. Additional information used consists of information from the
National Meteorological Center (NMC), products from the NMC
National Severe Storms Forecast Center, Hurricane advisories,
and forecasts from Weather Service Field Offices (WSFO)
6. Standardizations - The following standardizations shall apply to all
In-Flight Advisories
a. All heights or altitudes shall be stated with reference to mean
sea level (MSL), except in the case of low ceilings which shall
be referenced to “above ground level” and indicated by “CIGS,”
e.g., CIGS BLO 10
b. Domestic In-Flight Advisories shall describe designated
weather conditions up to and including 45,000 ft (150 millibars)
c.
Any abbreviations or contractions used in the advisories shall
conform with FAA Contractions Handbook 7340.1
d. Weather and obstructions to visibility shall be indicated by
using the weather abbreviations used for METAR (see FLIP
GP Chapter 8)
7. CONVECTIVE SIGMETs (WST) at 55 minutes past the hour
Fig 31: Convective
(H+55) 21.1.1.11.2
SIGMET (WST)
a. Issued hourly
(1) As thunderstorms are likely to be accompanied by severe
or greater turbulence, severe icing, and low-level wind
shear, these conditions shall not be specified in the
advisory
(2) “NONE” shall be used as the text if appropriate
(3) Valid for up to 2 hours or until superseded by the next
hourly issuance
(4) Special WSTs as required
(8-97) Original
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