AWH 3-20

Chapter 3, Overview of Aviation Weather Information 3-20 3.4.2.6 Products with Fog Information Table 3-9. Weather Element: Fog Type: text (T), graphic (G), image (I), voice (V) Fog Information Contained In: Type Summary Observations METAR and SPECI (ASOS, AWOS, ATIS) T, G, V Fog (including mist and haze) information is reported in METAR/SPECI from manual and ASOS stations and included in ASOS and ATIS broadcasts. Fog/mist/haze is not included in METARs/SPECIs from most AWOS, nor most AWOS broadcasts, depending on the type of AWOS. FG is reported when visibility is less than 5/8 SM. FZFG is reported when temperature is below 00 °C. BR or HZ is reported for visibilities from 5/8 SM to less than 7 SM, depending on the difference between the temperature and dewpoint. If the difference is 40 °F (~20 °C) or less, then FG is reported. Otherwise, HZ is reported. PIREP T, G, V Included if reported. Weather Camera I Fog may be seen on the camera. Analysis Surface Analysis Chart G Noted on the chart or in the station plots. Advisories AIRMET T, G Issued when weather phenomena such as fog/mist occurs or is expected to occur that could restrict visibility (less than 3 SM). Forecasts TAF T, G A visibility threshold must be met for fog to be included in the TAF (visibility of less than 5/8 SM). The fog code is “FG,” with the following additional terms: - Freezing fog (FZFG). - Shallow fog (MIFG). - Patchy Fog (BCFG). - Partial Fog (PRFG). - Fog in the vicinity (VCFG). Vicinity (VC) is defined as the area 5 to 10 SM from the center of the airport. - BR is included for visibilities from 5/8 to 6 SM. Aviation Surface Forecast G Derived from NOAA’s GFA and includes forecasts of areas of thunderstorms at specified valid times includes obscurations such as fog/mist. Alaska Area Forecast T Visibilities of 6 SM or less and obstruction(s) to visibility are included. Hawaii Area Forecast T Visibilities of 6 SM or less with obstruction(s) to visibility are included. Gulf of America and Caribbean Area Forecast T Visibilities of 6 SM or less and obstruction(s) to visibility are included. Alaska Surface Chart G Forecast of surface weather features including areas of fog/mist at specified valid times. AFD T Describes the weather conditions as they relate to a specific TAF or group of TAFs, including fog/mist.