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Aviation Weather Center's Map Service is a web service that provides aviation weather data geospatially. Each layer contains advisories, forecast coverage areas and other weather hazards. These layers are designed for integration into diverse web viewers to assist the aviation industry, emergency management communities, and the general public. By providing timely and accurate forecasts and observations, these services support the protection of life and property and the enhancement of the national economy.
Terminal Aerodrome Forecast (TAF) Layers are weather forecasts for an airport that is used by pilots, air traffic controllers, and flight planners. TAFs are issued by meteorological authorities.
METAR (Meteorological Aerodrome Report) Layers are weather reports that provide current weather conditions at an airport. METARs are important for aviation safety and efficiency.
Pilot Report (PIREP) Layers are reports of the actual critical weather conditions that are encountered by an aircraft in flight. Below are descriptions of how the pilot reports are rendered.
Aircraft Report: Automated reports transmitted directly from aircraft sensors, typically provide routine data such as wind speed, direction, and outside air temperature.
Pilot Report: A standard manual report submitted by a pilot describing non-hazardous conditions such as cloud bases, tops, and visibility.
Urgent Pilot Report: A high-priority report issued for hazardous weather phenomena including severe turbulence, severe icing, tornadoes, or low-level wind shear.
In-Flight Turbulence Reports Layer are pilot reports that categorize the intensity of atmospheric disturbances based on the reaction of the aircraft and its occupants.
This layer is rendered by intensity descriptions listed below:
Smooth to Light: The air is mostly calm with occasional, very slight ripples. It marks the transition from no movement to the first level of light disturbance.
Light: Momentary slight and erratic changes in altitude; some occupants may feel a slight strain against seat belts.
Light to Moderate: Consistent bumps that occasionally become strong enough to jolt the plane.
Moderate: Similar to light turbulence but of greater intensity. The aircraft remains in positive control, but occupants will definitely feel strains against seat belts and unsecured objects are dislodged.
Moderate to Severe: Significant turbulence with sudden, violent "hits" that may cause momentary loss of control.
Severe: Large abrupt changes in altitude as the aircraft may be momentarily unstable.
Moderate to Extreme : A wide range of instability, indicating a transition from manageable bumps to violent tossing where control is lost.
Severe to Extreme: The highest level of warning. The aircraft is being subjected to forces so violent that the integrity of the airframe is at risk.
Extreme: The aircraft is violently tossed about and practically impossible to control, potentially causing structural damage.
In-Flight Turbulence Type Reports Layer are based on Aircraft Reports where there is a Low-Level Wind Shear (LLWS) occurs and there is a sudden change in wind speed and or direction within 2,000 feet of the ground. It is reported when it causes a goin or loss of airspeed (usually 10 knots or more) during the critical phases of take off or landing.
In-Flight Icing Reports Layers are pilot reports that describe icing reports which are the rate of ice accumulation on the aircraft's surface, which can significantly impact aerodynamic performance.
This layer is rendered by ice category below:
Trace: Ice becomes perceptible, but the rate of accumulation is only slightly greater than the rate of sublimation; it is not hazardous unless experienced for an extended period.
Light: The rate of accumulation may create a problem if flight is prolonged (over one hour); occasional use of de-icing/anti-icing equipment removes or prevents accumulation.
Moderate: The rate of accumulation is such that even short encounters become potentially hazardous; use of de-icing/anti-icing equipment or diversion is necessary.
Severe: The rate of accumulation is so rapid that de-icing/anti-icing equipment fails to reduce or control the hazard; immediate diversion is required.
Traffic Flow Management (TFM) Convective Forecast (TCF) Layers are a meteorological product for aviation. The 4, 6, and 8-hour boundaries refer to the forecast timeframes for expected thunderstorms.
TCF Contour Characteristics: These contours do not depict individual thunderstorms; instead they are outlined areas where certain convective weather thresholds are likely to be met.
Coverage: Defined by how much an area is expected to be covered by storms.
TCF Coverage Types:
Sparse: 25–39% coverage (indicated by a broken hatched pattern).
Medium: 40–74% coverage (indicated by a striped hatched pattern).
Line: Greater than 75% coverage (indicated by a thick purple line).
Echo Tops: Maximum cloud heights given in thousands of feet MSL (Mean Sea Level), indicating storm intensity.
For example, the "390" indicates echo tops between 35,000 and 39,000 feet.
The TCF layers are grouped by 4, 6, and 8-hour boundaries that are time boundaries for the three graphical forecasts issued with every TCF product.
For instance, a TCF issued at 0300 UTC will include three separate group layers showing the forecast thunderstorm activity, validated as follows:
4-hour boundary: 0700 UTC.
6-hour boundary: 0900 UTC.
8-hour boundary: 1100 UTC.
Center Weather Advisories (CWA) Layers are an aviation weather warning for conditions meeting or approaching national in-flight advisory (G-AIRMET, SIGMET or SIGMET for convection) criteria. The CWA is primarily used by air crews to anticipate and avoid adverse weather conditions which are en route and terminal environments. It is not a flight planning product because of its short lead time and duration. Additionally, the CWA should be meteorologically consistent with other products and reflect conditions at the time of issuance and/or in the near future.
CWAs are valid for up to two hours and may include forecasts of conditions expected to begin within two hours of issuance. If conditions are expected to persist after the advisory's valid period, a statement to that effect should be included in the last line of the context. Follow-up CWAs should be issued as appropriate. Notice of significant changes in the phenomenon described in a CWA should be provided by a new CWA issuance for that phenomenon. If the forecaster deems it necessary, CWAs may be issued hourly for convective activity. CWAs should be issued for any of the following events when they are expected to occur within two hours and have not been previously forecasted by AWC or AAWU products, or to supplement the AWC and AAWU products.
Center Weather Advisories Events, are as follows:
Conditions meeting convective SIGMET criteria
Icing - moderate or greater
Turbulence - moderate or greater
Heavy or freezing precipitation
Conditions at or approaching Low IFR
Surface winds/gusts >30 knots
Low Level Wind Shear (surface - 2,000 feet)
Volcanic ash, dust storms, or sandstorms
G-AIRMET Layer is a graphical advisory of weather data that may be hazardous to aircraft, but are less severe than SIGMETs. They are only valid at specific time "snapshots" and the nearest valid time snapshot is displayed on the interactive map (Note: This could be a forecasted time). Forecasters create graphical objects depicting the areas and attributes of G-AIRMET hazards, which are distributed in BUFR file format then AWC converts into GeoJSON. These GeoJSON are converted to feature classes which are displayed in this map service. G-AIRMETs are issued at discrete times three hours apart for a period of up to 12 hours into the future (00, 03, 06, 09, and 12 hours). They are issued at 03:00, 09:00, 15:00 and 21:00 UTC (with updates issued as necessary). G-AIRMET are issued by the AWC for the lower 48 states and adjacent coastal waters.
The Aviation Hazards depicted in the G-AIRMET Layers are:
Turbulence: Areas of moderate turbulence, other than convectively induced, including the vertical extent.
Low Level Wind Shear (LLWS): Wind shear below 2000 feet AGL, other than convectively induced resulting in an air speed loss or gain of 20 knots or more. LLWS potential information is included after G-AIRMETs for moderate turbulence and/or sustained surface winds greater than 30 knots or statements indicating no significant turbulence is expected.
Strong Surface Winds: Areas of sustained surface winds greater than 30 knots. The direction and speed of the wind are not depicted; only the area where sustained surface winds greater than 30 knots will occur.
Icing: Areas of moderate airframe icing, other than convectively induced including the areal extent.
Freezing Level: The lowest freezing level above the ground or at the surface as appropriate. Freezing level information is included after G-AIRMETs for moderate icing or statements indicating that no significant icing is expected. Freezing levels are delineated using high altitude VOR (VHF Omnidirectional Range) locations describing the location of the lowest freezing level above the ground or surface as appropriate. Freezing levels above the ground are delineated at 4000 feet intervals above mean sea level. Multiple freezing levels above the ground are delineated by high altitude and low altitude VOR locations. The range of freezing levels across the forecast area is also included.
Instrument Flight Rules (IFR): Areas of cloud ceilings with bases less than 1000 feet above ground level and/or areas of surface visibilities below three statute miles, including the weather causing the visibility restriction. The cause of the visibility restriction includes only widespread sand/dust storm, Precipitation (PCPN), Smoke (FU), Haze (HZ), Mist (BR), Fog (FG), and/or Blowing Snow (BLSN).
Mountain Obscuration: Areas of widespread mountain obscuration where visual meteorological conditions cannot be maintained, including the weather causing the obscuration. The weather causing the obscuration includes only CLDS (Cloud or Cloud Cover Blocking peaks), Precipitation (PCPN), Smoke (FU), Haze (HZ), Mist (BR), and/or Fog (FG). These obstructions may cause parts of the mountain to not be visible.
Update Frequency: The data in this service updates every 10 minutes.
Link to graphical web page: https://aviationweather.gov/gfa/#pro
Link to data download: https://aviationweather.gov/data/api/
Questions/Concerns about the service, please contact the DISS GIS team.
Time Information: This service is time enabled.