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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

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

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.

IWXXM-US

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).

US-Wx/NAWX

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.

FAAWX

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.


 

Model/ReleaseDateRelease ArtifactsProductsNotes
IWXXM   Official ICAO/WMO products from ICAO Annex 3 / WMO No. 49
IWXXM 2.1Apr 2017

Release bundles

Online schemas

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 2.0Aug 2016

Release bundles

Online schemas

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 1.1Mar 2015

Release bundles  

 Online schemas 

ICAO METAR/SPECI, TAF, SIGMETMinor bug fixes and improvements
IWXXM 1.0Sep 2013Online schemas 

ICAO METAR/SPECI, TAF, SIGMET

Initial release with four products - more to be included in subsequent releases
WXXM    

WXXM 2.0

Mar 2015

Release bundles

Online schemas

 

General purpose coverages

ICAO SigWx

ICAO AIRMET

ICAO Volcanic Ash Advisory

ICAO products are deprecated once they have been represented in IWXXM
WXXM 1.1Mar 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 1.02007 Initial representations of ICAO Annex 3 ProductsDeprecated in favor of WXXM 1.1.  ICAO products have been replaced by the authoritative IWXXM representations

US Model Releases

Model/ReleaseDateRelease ArtifactsProductsNotes
IWXXM-US    US specializations of ICAO products
IWXXM-US 2.0Sep 2016Online schemasUS METAR/SPECI, TAFIncludes US specializations of products present in IWXXM 2.0
IWXXM-US 1.0May 2014Online schemas

US METAR/SPECI, TAF, SIGMET

Includes US specializations of products present in IWXXM 1.0
NAWX   US weather product representations
NAWX 1.5Aug 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 1.4Aug 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-AlphaMay 2010 

Alert, Echo Top Point, Gust Front, Leading Edge, Lightning, Microburst, Storm Motion, Storm Cell, Tornado

Deprecated
USWx    
USWx 1.0Apr 2015 AMDAR, PIREP, AIREPOfficial 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 2.1Nov 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 2.0Jun 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

Product Representations

This section lists the current representation to use for each product.  Last updated 19 April 2016.

ProductModel
METAR/SPECI

ICAO: IWXXM 2.1

ICAO/US: IWXXM-US 2.0

TAF

ICAO: IWXXM 2.1

ICAO/US: IWXXM-US 2.0
SIGMET

ICAO: IWXXM 2.1

ICAO/US: IWXXM-US 2.0
AMDARUSWx 1.0
AIRMETICAO: IWXXM 2.1
PIREPUSWx 1.0
AIREPUSWx 1.0

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 AdvisoryIWXXM 2.1
Tropical Cyclone AdvisoryIWXXM 2.1
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