There are several weather models (UML/XML) governed by different authorities for different purposes. This page will clarify their respective roles and areas of responsibility.
IWXXM is governed by ICAO and WMO to represent products in ICAO Annex 3 / WMO No. 49. IWXXM 1.0 was released in 2013 and is typically updated in alignment with ICAO Annex 3 updates (every two years). ICAO and WMO are UN agencies tasked with the governance of international aviation and weather, respectively, and therefore IWXXM should be considered the authoritative source for products that are included in ICAO Annex 3. IWXXM 2.0 includes seven products: METAR, SPECI, TAF, SIGMET, AIRMET, Tropical Cyclone Advisory, and Volcanic Ash Advisory. More ICAO Annex 3 products may be added in subsequent releases.
WXXM is governed by FAA and Eurocontrol for international products outside of those represented by ICAO or WMO. WXXM 1.0 was released in 2007, and WXXM is typically updated on 2-year intervals.
WXXM predates IWXXM by several years and initial releases included several products from ICAO Annex 3. All WXXM products that have been officially incorporated into IWXXM should be considered deprecated, as IWXXM is the designated representation for ICAO products. An ICAO METAR, for example, exists in both WXXM 1.1 and IWXXM 1.0. The IWXXM METAR should be used preferentially - WXXM included a METAR representation because IWXXM did not yet exist to carry official ICAO products.
The US and other countries have historically created and disseminated products slightly differently than ICAO. In the case of the US, this mostly comes in the form of additional content in the RMK section (in the traditional TAC formats). IWXXM-US was developed by US agencies (NWS, FAA and others) for representing ICAO products with additional US content. The US disseminates US METARs internally but strips off the extra content when transmitting on ICAO circuits.
On a technical level IWXXM-US extends IWXXM. Therefore IWXXM-US XML documents have elements from both IWXXM (for ICAO standard content) and IWXXM-US (for US-specific ICAO content).
The North-American weather schemas include weather constructs predominantly used and disseminated within the United States, excluding the US specializations of ICAO products from IWXXM-US. On a technical level NAWX extends WXXM with additional content. NAWX is managed by FAA with input from the NWS.
In 2015 NAWX was renamed to USWx to better represent the community of use.
The FAA Weather schemas include many constructs utilized by FAA systems, such as terminal weather (e.g., microbursts) and convective forecasting (e.g., Storm Extrapolated Positions, Growth Trends and Convective Weather Avoidance Polygons).
International Model Releases
A list of model releases is below. Deprecated releases and products are shown in gray.
|IWXXM||Official ICAO/WMO products from ICAO Annex 3 / WMO No. 49|
|IWXXM 2.1||Apr 2017||ICAO METAR/SPECI, TAF, SIGMET, AIRMET, Volcanic Ash Advisory (VAA), Tropical Cyclone Advisory (TCA)||AIRMET and SIGMET fixed to handle multiple OBS/FCST and FCST positions, other bug fixes|
|IWXXM 2.0||Aug 2016||ICAO METAR/SPECI, TAF, SIGMET, AIRMET, Volcanic Ash Advisory (VAA), Tropical Cyclone Advisory (TCA)||Added AIRMET, TCA, and VAA products along with a number of other improvements|
|IWXXM 1.1||Mar 2015||ICAO METAR/SPECI, TAF, SIGMET||Minor bug fixes and improvements|
|IWXXM 1.0||Sep 2013||Online schemas|
ICAO METAR/SPECI, TAF, SIGMET
|Initial release with four products - more to be included in subsequent releases|
General purpose coverages
ICAO Volcanic Ash Advisory
|ICAO products are deprecated once they have been represented in IWXXM|
|WXXM 1.1||Mar 2010|
General purpose coverages, contours, gust front, motion vector,
ICAO METAR/SPECI, TAF, AIRMET, SIGMET, VA Advisory
WMO AMDAR/MDCR, AIREP
G-AIRMET, PIREP, CCFP
|Deprecated in favor of WXXM 2.0. Additionally, ICAO products have been replaced by the authoritative IWXXM representations|
|WXXM 1.0||2007||Initial representations of ICAO Annex 3 Products||Deprecated in favor of WXXM 1.1. ICAO products have been replaced by the authoritative IWXXM representations|
US Model Releases
|IWXXM-US||US specializations of ICAO products|
|IWXXM-US 2.0||Sep 2016||Online schemas||US METAR/SPECI, TAF||Includes US specializations of products present in IWXXM 2.0|
|IWXXM-US 1.0||May 2014||Online schemas|
US METAR/SPECI, TAF, SIGMET
|Includes US specializations of products present in IWXXM 1.0|
|NAWX||US weather product representations|
|NAWX 1.5||Aug 2013|
Alert, Echo Top Point, Gust Front, Leading Edge, Lightning, Microburst, Storm Motion, Storm Cell, Tornado,Convective Forecast Polygon, Guidance (probabilistic) TAF, MDCRS
|Added MDCRS, corrected external schema locations. MDCRS now deprecated in favor of USWx AMDAR representation|
|NAWX 1.4||Aug 2012|
Alert, Echo Top Point, Gust Front, Leading Edge, Lightning, Microburst, Storm Motion, Storm Cell, Tornado, Convective Forecast Polygon, Guidance (probabilistic) TAF
|Deprecated. Added GuidanceTAF|
|NAWX 1.2.0-Alpha||May 2010|
Alert, Echo Top Point, Gust Front, Leading Edge, Lightning, Microburst, Storm Motion, Storm Cell, Tornado
|USWx 1.0||Apr 2015||AMDAR, PIREP, AIREP||Official AMDAR and AIREP representations in XML have not yet been developed by the appropriate authorities. If they are developed the USWx representations will be considered deprecated|
|FAAWX||FAA-specific products, such as that used in terminal weather and convective forecasting on the ITWS, CIWS, and NWP programs|
|FAAWX 2.1||Nov 2016||Gust Front Alert, Tornado Alert, Lightning Alert, ATIS Alerts, Contours, Leading Edges, Motion Vector, Configured Alerts, Echo Top Point, Forecast Accuracy, Fronts, Gust Front, Jet Stream, Lightning, Microburst, Runway Configuration, Storm Information, Stream Lines, Terminal Wx, Tornado Detections, Wind Profiles||Minor changes from FAAWX 2.0. Data quality property added to Lightning. Runway Configuration RunwayStatusType changed from string to gml:StringOrRefType and made Ribbon Display Terminal (RBDT) properties optional (minOccurs=”0”)|
|FAAWX 2.0||Jun 2015||Gust Front Alert, Tornado Alert, Lightning Alert, ATIS Alerts, Contours, Leading Edges, Motion Vector, Configured Alerts, Echo Top Point, Forecast Accuracy, Fronts, Gust Front, Jet Stream, Lightning, Microburst, Runway Configuration, Storm Information, Stream Lines, Terminal Wx, Tornado Detections, Wind Profiles||FAAWX version 2.0 is the initial release of FAA weather product extensions of WXXM 2.0 schemas including support for NextGen Weather Processor (NWP) products|
This section lists the current representation to use for each product. Last updated 19 April 2016.
ICAO: IWXXM 2.1
ICAO/US: IWXXM-US 2.0
ICAO: IWXXM 2.1ICAO/US: IWXXM-US 2.0
ICAO: IWXXM 2.1ICAO/US: IWXXM-US 2.0
|AIRMET||ICAO: IWXXM 2.1|
Weakly-typed information, or data without an existing representation
(such as loose collections of point data without a consistent set of values)
|WXXM 2 Coverages|
|Volcanic Ash Advisory||IWXXM 2.1|
|Tropical Cyclone Advisory||IWXXM 2.1|