Chapter 3, Overview of Aviation Weather Information 3-17
3.4.2.3 Products with Wind Shear Information
Table 3-6. Weather Element: Wind Shear
Type: text (T), graphic (G), image (I), voice (V)
Wind Shear
Information
Contained In:
Type Summary
Observations
ATIS V LLWS and/or microburst is included in ATIS broadcast for 20 minutes
following last report.
PIREP/AIREP T, G,
V Wind shear is included in the RMK section when reported.
Analysis
Advisories
Convective
SIGMET T, G Possible LLWS is implied within the convective SIGMET area.
AIRMET T, G AIRMET Tango issued when non-convective LLWS potential below 2,000 ft
AGL is occurring or expected to occur.
LLWAS T A wind shear alert occurs when wind shear ±15 kt is detected.
Forecasts
TAF T, G Included in the non-convective LLWS group.
AFD T Describes the weather conditions as they relate to a specific TAF or group of
TAFs, including non-convective LLWS.
Tools
GFA Tool G Interactive website that includes overlay of AIRMET for non-convective LLWS.
Flight Service
Interactive Map G Interactive website that includes overlay of AIRMET for non-convective LLWS.
3.4.2.4 Products with Visibility Information
Table 3-7. Weather Element: Visibility
Type: text (T), graphic (G), image (I), voice (V)
Visibility
Information
Contained In:
Type Summary
Observations
METAR and SPECI
(ASOS, AWOS,
ATIS)
T, G,
Visibility is reported in the body section of the METAR/SPECI. The visibility is
reported in statute miles.
PIREP/AIREP T, G,
V Distance for visibility is reported by the pilot in statute miles.
Weather Camera I A rough estimate could be inferred when known distance features are seen on
the camera.
Analysis
Surface Analysis
Chart G Certain surface analysis charts may include the reported visibility in the station
plot model.
Chapter 3, Overview of Aviation Weather Information 3-18
Visibility
Information
Contained In:
Type Summary
Advisories
AIRMET T, G AIRMET Sierra depict areas of surface-based IFR (ceilings less than 1,000 ft
and/or visibilities less than 3 SM) that is occurring or expected to occur.
CWA T, G Issued if conditions are at or approaching low IFR (ceiling less than 500 ft
and/or visibilities less than 1 SM).
Forecasts
TAF T, G Included under the visibility group when prevailing visibility is forecast to be
less than or equal to 6 SM.
Aviation Surface
Forecast G Derived from the GFA and includes forecasts of visibility at specified valid
times.
Alaska Area
Forecast T Visibilities of 6 SM or less and obscurations to visibility are included.
Hawaii Area
Forecast T Visibilities of 6 SM or less and obscurations to visibility are included.
Gulf of America and
Caribbean Area
Forecast
T Visibilities of 6 SM and obscurations to visibility are included.
AFD T Describes the weather conditions as they relate to a specific TAF or group of
TAFs, including visibilities.
Tools
GFA Tool G Interactive website that includes visibility.
Flight Service
Interactive Map G Interactive website that includes overlay of AIRMET Sierra and CWAs.
3.4.2.5 Products with Precipitation Information
Table 3-8. Weather Element: Precipitation
Type: text (T), graphic (G), image (I), voice (V)
Precipitation
Information
Contained In:
Type Summary
Observations
METAR and SPECI
(ASOS, AWOS,
ATIS)
T, G,
Precipitation is reported in the body section of the METAR/SPECI when
observed or detected. Some AWOS systems do not report precipitation.
PIREP T, G,
Pilot reports may include precipitation, which in places in the “/WX” section of
the PIREP.
Radar I Radar provides intensity levels of precipitation.
Weather Camera I Precipitation may be seen on the camera.
Analysis
Surface Analysis
Chart G Precipitation is included within the station plot models or when charts are
combined with radar imagery.
Chapter 3, Overview of Aviation Weather Information 3-19
Precipitation
Information
Contained In:
Type Summary
Advisories
AIRMET G AIRMETs are issued when weather phenomena such as precipitation restricts
visibility (less than 3 SM).
CWA T, G May be issued for heavy, extreme, or frozen precipitation.
AWW T
Intended for ground operations at select airports. Criteria may vary depending
on user needs. Examples of criteria that could issue this warning are heavy snow
or freezing rain.
Forecasts
TAF T, G
Included when conditions are expected and indicated by various descriptors
based on the type of precipitation. Intensity is also coded with precipitation
types.
Aviation Surface
Forecast G Derived from the GFA and includes forecasts of precipitation at specified valid
times includes weather phenomena.
Alaska Area
Forecast T A description of significant clouds and weather, including precipitation.
Hawaii Area
Forecast T A description of significant clouds and weather, including precipitation.
Gulf of America and
Caribbean Area
Forecast
T A description of significant clouds and weather, including precipitation.
Alaska Surface
Chart G Includes forecast of precipitation.
Surface Prog Charts G Depicts the type of precipitation and the forecast percent probability of
measurable precipitation.
AFD T Describes the weather conditions as they relate to a specific TAF or group of
TAFs, including precipitation.
MIS T A nontechnical discussion of meteorological events (including precipitation)
causing or expecting to impact the flow of air traffic across an ARTCC.
Tools
GFA Tool G Interactive website that includes precipitation information and overlay of radar.
Flight Service
Interactive Map G Interactive website that includes overlay of radar.
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,
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.
Chapter 3, Overview of Aviation Weather Information 3-21
Fog Information
Contained In: Type Summary
MIS T A discussion of meteorological events (including fog/mist) causing or expecting
to impact the flow of air traffic across an ARTCC.
Tools
GFA Tool G Interactive website that includes fog/mist. Also includes AIRMET Sierra.
Flight Service
Interactive Map G Interactive website that includes overlay of AIRMET Sierra.
3.4.2.7 Products with In-Flight Icing Information
Table 3-10. Weather Element: In-Flight Icing
Type: text (T), graphic (G), image (I), voice (V)
In-Flight Icing
Information
Contained In:
Type Summary
Observations
PIREP/AIREP T, G,
Icing intensity, type, and altitude reported. Noted as an Urgent PIREP or Special
AIREP when severe.
Analysis
CIP G
Computer model’s 0-hour forecast (referred to on the product as an analysis)
depicting five icing analysis products:
- Icing Probability.
- Icing Severity.
- Icing Severity – Probability > 25%.
- Icing Severity – Probability > 50%.
- Icing Severity plus SLD.
Advisories
Convective
SIGMET T, G Possible severe icing is implied within the convective SIGMET area.
SIGMET T, G Non-convective SIGMETs are issued for severe icing.
AIRMET T, G AIRMET Zulu depicts areas of active or expected moderate icing.
CWA T, G May be issued for moderate or greater icing.
Forecasts
Aviation Clouds
Forecast G Includes a depiction of icing AIRMETs.
Alaska Area
Forecast T May includes a description of icing not meeting AIRMET criteria otherwise
“NIL SIG” is noted if no significant icing is forecast.
Gulf of America and
Caribbean Area
Forecast
T A description of moderate or severe icing conditions.
Medium-Level
SIGWX G Areas moderate or severe icing are depicted.
WAFS G Global icing forecasts provided in a grid point format.
Chapter 3, Overview of Aviation Weather Information 3-22
In-Flight Icing
Information
Contained In:
Type Summary
FIP G
Five icing forecast graphics derived from computer model data for the
following:
- Icing Probability.
- Icing Severity.
- Icing Severity – Probability > 25%.
- Icing Severity – Probability > 50%.
- Icing Severity plus SLD.
MIS T A discussion of meteorological events (including inflight icing information)
causing or expecting to impact the flow of air traffic across an ARTCC.
Tools
GFA Tool G Interactive website that includes in-flight icing (PIREPs, FIPs, AIRMETs,
SIGMETs, and CWAs).
Flight Service
Interactive Map G Interactive website that includes icing.
3.4.2.8 Products with Freezing Level Information
Table 3-11. Weather Element: Freezing Level
Type: text (T), graphic (G), image (I), voice (V)
Freezing Level
Information
Contained In:
Type Summary
Observations
PIREP/AIREP T, G,
V Included when reported.
Analysis
Freezing Level
Analysis G Depicts the height (MSL) of the lowest freezing level.
Advisories
AIRMET T, G
Contains one or more of the following:
- Areas of multiple freezing levels.
- Range of freezing levels over the area.
- Lowest freezing levels at intervals of 4,000 ft MSL.
Forecasts
Alaska Area
Forecast T A description of significant clouds and weather that includes freezing levels.
Gulf and Caribbean
Area Forecast T A description of significant clouds and weather that includes freezing levels.
Low-Level SIGWX G Freezing level at the surface are depicted.
Alaska SIGWX G Freezing levels are shown for the surface and at 2,000-ft intervals.
Upper Air Forecasts G Computer model outputs for freezing levels at select height levels (available
levels vary depending on the model).
Chapter 3, Overview of Aviation Weather Information 3-23
Freezing Level
Information
Contained In:
Type Summary
Tools
GFA Tool G Interactive website that includes freezing levels.
Flight Service
Interactive Map G Interactive website that includes freezing levels.
3.4.2.9 Products with Turbulence Information
Table 3-12. Weather Element: Turbulence
Type: text (T), graphic (G), image (I), voice (V)
Turbulence
Information
Contained In:
Type Summary
Observations
PIREP/AIREP T, G,
Turbulence reports include location, altitude, and aircraft type. The pilot
determines the degree of turbulence, intensity, and duration. Severe or extreme
turbulence is reported as an Urgent PIREP or Special AIREP. The vast majority
of AIREPs are automated and include turbulence reports derived from the
aircraft’s motion.
Radar I Convective weather on radar could indicate potential areas of severe turbulence.
Satellite I Potential turbulence areas may be inferred from certain cloud patterns by a
meteorologist or trained specialist. CB always implies severe turbulence.
Analysis
GTG G Product provides a computer analysis of turbulence based on multiple computer
algorithms. Graphic also depicts any turbulence PIREPs.
Advisories
Convective
SIGMET T, G Possible severe turbulence is implied within the convective SIGMET area.
SIGMET T, G Issued for severe turbulence not associated with thunderstorms.
AIRMET T, G AIRMET Tango depicts areas of active or expected moderate turbulence. The
product is divided into high and low altitude at 18,000 ft.
CWA T, G May be issued for moderate or greater turbulence not covered by an existing
AIRMET or SIGMET.
Forecasts
TAF T, G Low-level mechanical turbulence could be inferred when strong and gusty
surface winds are forecast.
Alaska Area
Forecast T
Expected turbulence conditions are included along with the following
information:
- AIRMET information for turbulence or LLWS.
- Turbulence not meeting SIGMET/AIRMET criteria during the six to 12-
hour period.
- “NIL SIG” is noted if no significant turbulence in forecast.
Gulf of America and
Caribbean Area
Forecast
T Moderate or greater turbulence is noted at the end of forecast bulletin.