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The World Area Forecast System (WAFS) Internet File Service (WIFS)

Users Guide

By

WAFC Washington

Version 7.0

February 2024

Document Change History

Note: Any section, image or table that's been added or updated from the last version release will have a blue backgroun color.

DateVersionDescription1
24-Feb-101.0Initial draft release.
26-Mar-101.1Incorporated user feedback including: new document change history section, correction to Table 2 GRIB/GRIB2 description, additional descriptions where necessary, section heading changes, and more.
30-Mar-101.2Based on feedback from reviewers, made some changes to the User Authentication fields.
5-Apr-101.2Based on feedback from reviewers, added “WAFC Washington” wording to title, footer, and the Introduction.
26-Apr-101.2Based on feedback from reviewers: (1) section 2 was renamed “Service Overview and Responsibilities of U.S. Government Agencies”, (2) section 3 was renamed “Data Retrieval Process”, (3) backup information was added to section 4, (4) section 7 “Responsibilities of U.S. Government Agencies” was renamed “WIFS Customer Support” and is now section 8, and (5) more information was added to the WIFS Customer Support section including information on a trouble ticket system.
20-May-101.3

Based on technical interchange with customers, the GRIB data is now being served in a concatenated file format. The description of the file formats in Section 6 reflects this change.

Based on feedback from reviewers: (1) Appendix A was added to describe the GNU wget utility, (2) Section 3 was modified to include a reference for Appendix, (3) minor changes were made in Section 4 to clarify back-up roles and responsibilities, and (4) Section 4.2 title was modified.

15-Jul-102.0Folded in the contents of the WIFS Interface Control Document; added Appendix B, Reference Documents; expanded the GNU wget description in Appendix A; updated Section 3 Data Retrieval Process; added Appendix C WIFS Registration; changed link to software providers in Section 3; reorganized Section 4 based on reviewer comments; added new Section 4.3 Suspension of Access; added note to Section 5 that mentions potential harmonization of directory structures.
26-Aug-102.1Changed WIFS help desk phone number.
1-Nov-103.0

Completed Draft Interim Version:

Added introductory information

Reorder sections for logical flow

Added Chapter 2, WIFS Products and Data

4-Jan-113.1Added verbiage on authorization criteria. Updated document after review of v3.0.
14-Jan-114.0Document baselined after final reviews.
28-Mar-114.1Modified Section 5 Data Retrieval Process to make it clearer and easier to interpret; this includes removing the site-specific URLs. Added reference to SADIS User Guide Annexes 1 and 4.
4-Dec-175.0

Removed any mention of GRIB1 data; changed all mention of “trial” forecast data to “harmonized” data, added expected data availability tables to Section 3; removed trial forecast designation for WIFS aviation grids; modified the directory structure in Section 6; modified Appendix A to include more information about how a user can use WIFS; moved GNU wget information to Appendix B. Added GRIB2 details to Appendix C.

FL080 (750 hPa), FL210 (450 hPa) and FL480 (125hPa) were included in the Appendix C table for wind, temperature, RH, and height.

Added sections on SIGWX and PNG corrections.

14-Apr-226.0

Changed Help Desk work hours from 7am-3:30pm to 7am to 3pm.

Updated Appendix C, WIFS directory structure (fig. 6.1) to include 0.25 data, figure 6.3.

Added section 6.2.2

4-Feb-247.0

Updated directory listings to show 0.25 deg data. Added links to API documentation where needed

Added IWXXM data information

Changed password update information

1 Minor corrections and cosmetic changes are not recorded

Table of Contents

1. Introduction

1.1. Reference Documents

1.1.1. International Standards

1.1.2. Industry Standards

1.1.3. WAFC London Documents

2. Service Overview and Responsibilities of U.S. Government Agencies

3. Products and Data Available on WIFS

3.1. Overview of Service

3.2. Grid Point Data

3.3. PNG Charts

3.4. Significant Weather BUFR Files

3.5. OPMET Alphanumeric Data

3.6. OPMET IWXXM Data

3.7. Administrative Messages

3.8. Sources of WIFS Information Content

4. WIFS User Authorization

4.1. WIFS Registration

4.2. WIFS Password Policy

4.3. Determining Operational and Backup Service Use

4.4. WIFS Backup to SADIS

4.5. Suspension of Access

5. Data Retrieval Process

6. WIFS Directory Structure and File Formats

6.1.BUFR Files

6.1.1. Format of BUFR Files

6.2. GRIB2 Gridded Files

6.2.1. Format of Gridded Files

6.2.2. Format of 0.25 Degree Gridded Hazard Files

6.3. OPMET Alphanueric Data Files

6.3.1. OPMET-HOURLY

6.3.2. OPMET-MINUTE

6.3.3. OPMET-ROLLING

6.3.4. Format of OPMET Files

6.4. OPMET IWXXM Files

6.4.1. IWXXM MINUTE

6.4.2. IWXXM 5MINUTE

6.4.3. IWXXM HOURLY

6.4.4. IWXXM Rolling files

6.4.5. Format of IWXXM Files

6.5. PNG Files

6.5.1. Format of PNG Files

6.6.ADMIN_MSGS

6.6.1. Format of Administrative Message Files

6.7. Announcing Changes in Services or Products

7. WIFS Support Web Site

8. WIFS Help Desk

9. User Troubleshooting Guidelines

Appendix A. Using WIFS2

Appendix B. GNU wget2

Appendix C. WAFS Upper Air GRIB2 Details

List of Tables

Table 3-1 GRIB 2 Data Availability

Table 3-2 SIGWX PNG Data Availability

Table 3-3 BUFR Data Availability

Table 3-4 Administrative Message Types

Table 6-1 Significant Weather PNG Files

Table 9-1 Troubleshooting Guidelines

List of Figures

Figure 2-1 WIFS and SADIS Area Designations

Figure 4-1 WIFS Registration Form

Figure 6-1 WIFS Directory Structure

Figure 6-2 Snapshot of the BUFR folder

Figure 6-3 Snapshot of the GRIB2 folder

Figure 6-3.1 Pre-Set Map Areas

Figure 6-3.2 0.25 Degree Hazard File Snapshot

Figure 6-4 Snapshot of the OPMET-HOURLY Folder

Figure 6-5 Snapshot of the OPMET-MINUTE folder

Figure 6-6 Snapshot of the OPMET-ROLLING folder

Figure 6-7 Snapshot of the IWXXM Folder

Figure 6-8 Snapshot of the IWXXM MINUTE folder

Figure 6-9 ICAO Regions

Figure 6-10 Snapshot of the PNG SIGWX KWBC folder

Figure 6-11 Snapshot of the PNG VOLC folder

Figure 6-12 Snapshot of the ADMIN_MSGS folder

1 Introduction

The International Civil Aviation Organization (ICAO) established the World Area Forecast System (WAFS) system in 1982 to supply meteorological authorities and other users with global forecasts of en-route meteorological conditions in digital form. The U.S. and the United Kingdom (UK) share in the global distribution of the WAFS forecasts required in ICAO Annex 3 and the operational meteorological (OPMET) information specified in the Facilities and Services Implementation Document (FASID) Table MET2A.

The U.S. distribution of WAFS forecasts and OPMET information is provided through the WAFS Internet File Service (WIFS). The UK distribution is provided through systems managed by the Secure Aviation Data Information Service (SADIS) program; formerly known as the Satellite Distribution System. WIFS replaced the International Satellite Communication System (ISCS) and is compliant with ICAO Document 9855, Guidelines on the Use of the Public Internet for Aeronautical Applications. The U.S. WAFS forecasts are provided by the Washington World Area Forecast Center (WAFC). The Washington WAFC is operated by the United States National Weather Service (NWS).

Through access to WIFS, States may wish to meet their obligation under Article 28 of the Convention on International Civil Aviation regarding the provision of meteorological services to facilitate international air navigation. Regarding the use of WAFS products, for example, ICAO Annex 3 specifically notes in Appendix 2, Section 2.1.1: “Aerodrome meteorological offices shall use WAFS forecasts issued by the WAFCs in the preparation of flight documentation, whenever these forecasts cover the intended flight path in respect of time, altitude and geographical extent, unless otherwise agreed between the meteorological authority and the operator concerned.”

WIFS provides access to authorized users as described in Section 4.

1.1 Reference Documents

1.1.1 International Standards

1.1.2 Industry Standards

1.1.3 WAFC London Documents

2 Service Overview and Responsibilities of U.S. Government Agencies

WIFS is a real-time data repository of all OPMET data and WAFS products that are accessible via the Internet to authorized users. The provisions for requesting and approving user access are described in Section 4.

The FAA, as the U.S. Meteorological Authority, identifies the ICAO requirements for the products and services to be provided by the Washington WAFC. The National Oceanic and Atmospheric Administration (NOAA) NWS is the service provider of WAFS products and has agreed to manage and operate WIFS.

WIFS hosts the WAFS products and OPMET data on file servers on multiple geographically diverse web farms. This provides redundancy in case of a networking or system failure. If the primary farm goes down, users will be transparently moved to another farm. For timestamp consistency, only one farm is active at any time.

WIFS and SADIS also provide mutual backup support should there be a failure of either service or failure of user access to either service (see Figure 2-1 to determine areas designated primary for WIFS and SADIS). Section 4.3 describes the criteria for determining operational use and establishing backup service.

Map of WIFS and SADIS areas
Figure 2-1 WIFS and SADIS Area Designations

3 Products and Data Available on WIFS

3.1 Overview of Service

WIFS provides access to WAFS products and OPMET data as defined in ICAO Annex 3, Meteorological Service for International Air Navigation, Chapter 3. These products are provided as follows:

3.2 Grid Point Data

Note: Starting in February 2024, new 0.25 degree grids are available via the WIFS API with 56 vertical levels up to FL600 and 39 forecast times out to T+120. These grids are not available on the legacy WIFS data pages. See the WIFS API page for more details on how to access these new grids.

WIFS provides upper-air gridded forecasts in GRIB2 format including WAFC Washington/WAFC London harmonized forecasts of cumulonimbus (CB) clouds, turbulence (clear air), and icing. Users retrieving this data must have a data processing system, such as the WAFS workstation, which can read, decode, and display the data.

Detailed information concerning upper-air gridded forecasts can be found in ICAO Annex 3, Appendix 2. Specific information related to WIFS gridded data can be found in Section 6.2 and Appendix C. WAFS Upper Air GRIB2 Details. Use Table 3-1 to determine when to expect data to be available.

Table 3-1 GRIB 2 Data Availability

Model Time (UTC)Upper-Air Availability (UTC)*Harmonized Data Availability (UTC)*
0003450435
0609451035
1215451635
1821452235

* The expected time under normal conditions. Factors out of our control (such as model delays, network sluggishness and higher than normal system loads) may delay these times by up to 30 minutes.

3.3 PNG Charts

SIGWX forecasts supplied in a Portable Network Graphics (PNG) format are issued four (4) times daily, and are valid at 0000, 0600, 1200, and 1800 UTC for the areas of coverage. The SIGWX forecasts include the elements listed in ICAO Annex 3, Appendix 2, section 1.3.3 (19thedition). Table 3-2 defines the forecast time and the availability of the SIGWX forecasts for use at a fixed schedule.

Table 3-2 SIGWX PNG Data Availability

Forecast Package Time (UTC)PNG Availability (UTC)*
000700
061255
121850
180100

* The expected time under normal conditions. Factors out of our control (such as model delays, network sluggishness and higher than normal system loads) may delay these times by up to 30 minutes.

NOTE:Corrections of PNG graphics will show up with a “_CCA”, “_CCB”, etc., added to the filename after the center designator as in “20161012_1200_JUFE00_KWBC_CCA.png”.

Volcanic ash and tropical cyclone graphics in PNG format are also available on WIFS. These products do not have a fixed schedule other than once the product is issued there are scheduled updates until the product is canceled. These PNG files contain the letters “PFXD” (volcanic ash) and “PZXD” (tropical cyclone) in the filename.

3.4 Significant Weather BUFR Files

SIGWX forecasts are issued using Binary Universal Form for the Representation of meteorological data (BUFR) code form follow the specifications included in WMO Publication No. 306, Manual on Codes, Volume I.2, Part B – Binary Codes. Forecasts of SIGWX prepared by WAFC Washington are issued four times daily, valid at 0000, 0600, 1200, and 1800 UTC. Table 3-3 defines the forecast time and the schedule of the availability of these files in a BUFR format.

Table 3-3 BUFR Data Availability

Forecast Package Time (UTC)BUFR Availability (UTC)*
000700
061255
121850
180100

* The expected time under normal conditions. Factors out of our control (such as model delays, network sluggishness and higher than normal system loads) may delay these times by up to 30 minutes.

NOTE:Corrections of PNG graphics will show up with a “_CCA”, “_CCB”, etc., added to the filename after the center designator as in “20161012_1200_JUFE00_KWBC_CCA.bufr”.

BUFR is a standard binary format approved by the WMO for efficient storage of meteorological features. To produce a BUFR file, two elements are needed: a raw data file and a set of tables containing descriptors. When raw data is encoded, each data value is attached to a descriptor defining what the data represents. The decoding process reads the BUFR file, looks up the descriptor in the relevant table, and writes out the information in the proper format. BUFR does not provide information on how to visually represent data. However, the WAFCs have written guidance on representation, which can be found on the WAFS Operations Group web page (http://www.icao.int/airnavigation/METP/MOG/Pages/default.aspx).

BUFR files contain a set of tables with descriptors. Descriptors must be decoded from a set of common tables on the local machine in order to understand what the values represent. To this end, BUFR messages are very small and machine independent. They can be understood and decoded by any BUFR decoder having the latest tables available.

SIGWX data in BUFR format is independent of the background or projection. Only the information describing the feature is encoded. For example, a CLOUD area is a list of points with the height of bases and tops, and cloud type and amount attributes attached. There are no rules on how the cloud area should be drawn, or how the attributes are displayed. On SIGWX charts this is shown as a box, sometimes with an arrow to the area, but this information is determined by the graphical display program.

3.5 OPMET Alphanumeric Data

OPMET information includes Routine Aviation Weather Reports (METARs), Special Aviation Weather Reports (SPECIs), Terminal Aerodrome Forecasts (TAFs), Pilot Reports (PIREPs), Significant Meteorological Information (SIGMET) reports, Volcanic Ash Advisory (VAA) reports, and Tropical Cyclone Advisory (TCA) messages.

3.6 OPMET IWXXM Data

OPMET information is also available in a machine readable IWXXM (ICAO Meteorological Information eXchange Model) format. Data currently available in IWXXM format includes METARs, SPECIs, TAFs, SIGMETs, VAA reports, and TCA messages.

3.7 Administrative Messages

WIFS maintains a limited archive of administrative messages. See Table 3-4 for details. WIFS administrative messages may contain information on delayed data and products, updates to WIFS file structure and formats, and general information related to WAFS. (Section 6.6 has information on other means of communicating administrative messages.)

Table 3-4 Administrative Message Types

WMO HeaderDescription
FXUS65 KWBC and FXUK65 EGGRThese are used by the WAFCs to alert users to corrections to the WAFC charts
NOXX10 KKCIThese are WIFS administrative messages
NOXX10 KWBCNotice of potential service outages
NOUS42 KWNOAdministrative messages from NCEP Central Operations
FXUS65Notification of SIGWX corrections

3.8 Sources of WIFS Information Content

OPMET, forecasts and data products which are available to users on WIFS are found at:

4 WIFS User Authorization

The United States as a WAFS Provider State has agreed to support the operation of WAFC Washington along with the provision of making WAFS services available to all Contracting States as recognized in ICAO Regional Air Navigation Plans. WIFS is not an open system and requires all users to be approved for access by the:

WIFS access is restricted to those individuals (or activities) who support meteorological services for the conduct or development of international air navigation. The following categories of users may be provided access based on submission and approval of a WIFS Registration Form as described in Section 4.1:

WIFS Users are advised that their account may be terminated if it is determined the account is being used for purposes other than the original intent in support of international air navigation.

4.1 WIFS Registration

Approving an applicant request for access to WIFS requires submission and processing of a WIFS Registration Form as outlined in the following steps:

Applicant (Completes Steps 1 and 2):

  1. Determines whether WIFS or SADIS is the primary service for obtaining WAFS forecasts for operational use as required in ICAO Regional Air Navigation Plans (RANPs) for their location. (See Figure 2-1: WIFS and SADIS Area Designations).
    NOTE:WIFS provides primary service for North American, Central America, and Caribbean (NACC); and South America (SAM) Regions. WIFS and SADIS share primary responsibility in the Asia and Pacific (APAC) region as listed in the APAC FASID Table 6 (http://www.icao.int/APAC/Pages/edocs-fasid.aspx). Section 4.3 provides further background on factors related to establishing SADIS and WIFS operational and backup accounts.
  2. Completes and submits the WIFS Registration form online (http://aviationweather.gov/wifs). Fields on the form with an (*) are required. Failure to provide accurate information may result in a processing delay or denial of a WIFS account.
    Comments Section: Include a description of the intended use of the WIFS service indicating how that use relates to developing or conducting meteorological services supporting international air navigation.

FAA (Completes Steps 3 & 4 as the WIFS Approval Authority):

  1. Reviews the WIFS Registration request and confirms the State Approval and/or the status of an existing SADIS account if the WIFS access is for SADIS backup.
  2. Approves (or denies) the Registration request.

NWS/AWC (Completes Step 5 as the WIFS service provider):

  1. Advises the Applicant of the status. If approved, issues a Password and User Name; and adds the applicant as an approved WIFS User (primary or backup).

Figure 4-1 shows a snapshot of the current WIFS Registration Form available on the WIFS home page. Upon completion of the registration form, a confirmation screen will be displayed showing that the account was successfully submitted for approval. Review and approval processing normally takes 15-20 business days.

Screenshot of registration form
Figure 4-1 WIFS Registration Form

4.2 WIFS Password Policy

The current password policy is that the password does not expire but may expire with updates to password policy. Users may change their password by going to the WIFS website and clicking on "Manage Account" and clicking on "Change WIFS Password".

Passwords must be at least 12 characters and must contain at least one: one upper case, one lower case, one digit [0-9] and one special character from "!@#$%^&*()".

4.3 Determining Operational and Backup Service Use

In order for the SADIS and WIFS providers to appropriately manage and maintain viable, mutually existing services delivering WAFS forecasts, the following process should be followed within a particular State in arranging to obtain their data.

For Primary Operational Use (see Figure 2-1) from:

  1. WIFS Primary Use:
    • Applicants become approved WIFS Users; follow the procedures in Section 4.1 for establishing a WIFS account.
    • SADIS accounts will be provided to authorized WIFS users by the SADIS Provider State for backup purposes on condition that:
      NOTE: Cost recovery is not required for a backup account provided the SADIS procedures are followed. Additional background is available in the SADIS User Guide/Part 1 (http://www.icao.int/airnavigation/METP/MOG/Pages/SADIS.aspx
  2. SADIS Primary Use:
    • Applicants become approved SADIS Users and participate in the SADIS cost recovery scheme as described in the SADIS User Guide.
    • WIFS accounts will be provided to authorized SADIS users by the WIFS Provider State for backup purposes on condition that:
      • A SADIS account has been authorized and provided;
      • There are no outstanding balances in respect of the SADIS cost recovery scheme and
      • That use is restricted to backup purposes and periodic testing. (See paragraph 4.4 below.)
  3. Either SADIS or WIFS Primary Use:
    For requests coming from the ICAO APAC Region, the State determines which of the two services (SADIS or WIFS) to obtain their primary operational access to WAFS forecasts; follow the appropriate procedures in subsections A or B above.
  4. Both SADIS and WIFS Primary Use:
    In exceptional circumstances, States that have an operational requirement to obtain data from both WIFS and SADIS on a continuous basis will have their requests considered on a case-by-case basis. Under such circumstances a State taking both services will be required to contribute fully to the SADIS cost recovery scheme (unless recognized as a United Nations Least Developed Country).

4.4 WIFS Backup to SADIS

The definition of the threshold for operational versus backup purposes to be used on the SADIS and WIFS Internet-based services was defined and endorsed by the ICAO SADIS Operations Group (SADISOPSG) and is described in the notes below. The policy limits backup access to a maximum of one day in seven. In the event of unavailability of the SADIS service, unlimited access to WIFS will be granted until the SADIS service has been restored.

Note 1. - The specific days/times States/users wish to test their accounts is at the State/user's discretion so long as it does not exceed once every seven days.

Note 2. - Backup accounts will be maintained in a “live” status in order that immediate access is available in the event of a genuine need to access the alternative Provider's service for backup purposes.

Note 3. - The SADIS and WIFS Providers will monitor their services to determine user access behavior.

Note 4. - It remains the sole responsibility of the State/user to determine if they require a backup account from the alternative Provider, and if so, to arrange for that account.

4.5 Suspension of Access

WIFS access may be suspended by the WIFS approving authority for unauthorized use of WIFS. Access to SADIS and WIFS as back-up services may be suspended by the WIFS and SADIS approving authorities if user’s primary WIFS or SADIS accounts are suspended.

5 Data Retrieval Process

WIFS does not deliver (“push”) data to the user but requires the user to collect (“pull”) data off the file servers. User access to the WIFS files servers is by a Secure Hypertext Transfer Protocol (HTTPS) session over the Internet. Files can be downloaded across this secure connection using an Internet browser or software tools such as GNU wget. The wget tool is freely available and designed to retrieve content from web-based file servers. More information about how to use WIFS and wget can be found in Appendices A and B.

The minimum recommended Internet connection speed is 64 kbps for OPMET, BUFR and PNG data. The minimum connection speed for GRIB2 data is 512 kbps. Once the data are retrieved from WIFS, users will need software that is capable of processing and displaying WAFS data. A list of WAFS software providers can be found on the Vendors page athttp://aviationweather.gov/wifs. Users should contact specific providers for cost and availability.

WIFS users access the WIFS file servers using thehttps://aviationweather.gov/wifs/dataURL.

6 WIFS Directory Structure and File Formats

Figure 6-1 depicts the WIFS directory structure and the names of the individual folders, with respect to the base URL (e.g.,https://aviationweather.gov/wifs/data).

Screenshot of directory listing
Figure 6-1 WIFS Directory Structure.
Note: updated directories for new data, and removal of discontinued data.

6.1 BUFR Files

The BUFR files are generated every 6 hours and the WIFS BUFR folder contains the past 36 hours of SIGWX forecasts in BUFR format. Figure 6-2 is an example of the files that can be found in this folder.

Example of directory listing
Figure 6-2 Snapshot of the BUFR folder

The file naming convention for these files is:

YYYYMMDD_HH00_TTAAii_CCCC.bufrwhere

YYYY = 4-digit year
MM = 2-digit month
DD = 2-digit day
HH = 2-digit hour of forecast package valid time
00 = Fixed characters
TTAAii_CCCC = WMO header and site identifier
.bufr = File extension

6.1.1 Format of BUFR Files

For details on the format of the BUFR products see WMO Publication FM94 BUFR.

6.2 GRIB2 Gridded Files

Note: Starting in February 2024, new 0.25 degree grids are available via the WIFS API with 56 vertical levels up to FL600 and 39 forecast times out to T+120. These grids are not available on the legacy WIFS data pages. See the WIFS API page for more details on how to access these new grids.

The WAFS GRIB2 files are generated every 6 hours. The GRIB2 folder contains all the forecasts from the past 18 hours. The individual bulletins are concatenated together according to the forecast valid time. Figure 6-3 depicts an example of the files that can be found under the GRIB2 folder.

Example of directory listing
Figure 6-3 Snapshot of the GRIB2 folder

The file naming convention for GRIB2 files is:

YYYYMMDD_hhmmfFF.grib2where

YYYY = 4-digit year
MM = 2-digit month
DD = 2-digit day
hh = 2-digit hour of model run
mm = 2-digit minute of model run
f = Fixed character
FF = 2-digit forecast hour
.grib2 = File extension

6.2.1 Format of Gridded Files

The gridded files are formatted in accordance with WMO code FM 92 (GRIB Version 2), and are described in full detail in "WMO Manual on Codes, Volume I, Part B (WMO No. 306).

Software libraries to decode data in GRIB2 data are provided by the National Centers for Environmental Prediction (NCEP), and can be found at:

http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2/

6.2.2 Format of 0.25 Degree Gridded Hazard Files

These files are available both as a full global dataset and in regional subsets or tiles of data. The tiles are so that the users do not have to download the entire global dataset if they do not need it, which saves bandwidth. The figure below shows the areas covered by each regional tile.

Map depicting pre-defined hazard areas
Figure 6-3.1 Pre-Set Map Areas

The below snapshot shows how the directory looks for the 0.25 degree hazard files. Note the eight smaller regional files.

Example of directory listing
Figure 6-3.2 0.25 Degree Hazard File Snapshot

6.3 OPMET Alphanumeric Data Files

The WIFS server provides OPMET data (METARs/SPECIs, TAFs, SIGMETs, Advisories, PIREPs) in character-oriented format, often referred to as Traditional Alphanumeric Coding (TAC). These data are made available based on the following criteria:

6.3.1 OPMET-HOURLY

Each file within this folder contains all OPMET data that was received by NWS during a given hour. 36 hours of data are continuously maintained, and every hour a new file is generated from the most recent hour’s data, and the oldest file is removed from the WIFS server. Figure 6-4 depicts a snapshot of the files maintained in this folder.

Example of a directory listing
Figure 6-4 Snapshot of the OPMET-Hourly Folder

The file naming convention for OPMET-HOURLY files is:

YYYYMMDD_hh_OPMETwhere

YYYY = 4-digit year
MM = 2-digit month
DD =2-digit day
hh = 2-digit start hour of collected data
OPMET = Fixed text

6.3.2 OPMET-MINUTE

Each file within this folder contains all OPMET data received during a given minute. Thirty-six (36) hours of data are continuously maintained. Every minute a new file is generated from the most recent hour’s data and the oldest file is removed. Figure 6-5 depicts a snapshot of the files maintained in this folder.

Example of a directory listing
Figure 6-5 Snapshot of the OPMET-MINUTE folder

The file naming convention for OPMET-MINUTE files is:

YYYYMMDD_hhmm_OPMETwhere

YYYY=4-digit year
MM = 2-digit month
DD = 2-digit day
hh = 2-digit start hour of collected data
mm = 2-digit start minute within the hh hour of collected data
OPMET = Fixed text

6.3.3 OPMET-ROLLING

There are five individual OPMET data files within this folder that are generated from the OPMET_MINUTE files.

Example of a directory listing
Figure 6-6 Snapshot of the OPMET-ROLLING folder

6.3.4 Format of OPMET Files

The OPMET files contain multiple WMO records are formatted in accordance with WMO Publication 386.

6.4 OPMET IWXXM Files

The WIFS server provides OPMET IWXXM data (METARs/SPECIs, TAFs, SIGMETs, Advisories) in XML format. These data are made available based on the following criteria:

Example of a directory listing
Figure 6-7 Snapshot of the IWXXM folder

6.4.1 IWXXM MINUTE

Each minute file file is a collection of products much like the alphanumeric data are. But to preserve the XML nature of the data, each product is put into a file by itself and then added to a tar file. Each minute tar file is a collection of products for that minute only. Then the tar file is gzip compressed. For example, the 20240205_0153_IWXXM_MINUTE.tgz contains:

-rw-r--r-- ldm/ops        4297 2024-02-04 19:53 LAUS23_KWBC_050200.xml
-rw-r--r-- ldm/ops        6845 2024-02-04 19:53 LAUS25_KWBC_050200.xml
-rw-r--r-- ldm/ops        9990 2024-02-04 19:53 LAUS21_KWBC_050200.xml
-rw-r--r-- ldm/ops        4096 2024-02-04 19:53 LAUS24_KWBC_050200.xml
-rw-r--r-- ldm/ops       11450 2024-02-04 19:53 LPUS23_KWBC_050152.xml
-rw-r--r-- ldm/ops       10513 2024-02-04 19:53 LPUS22_KWBC_050152.xml
-rw-r--r-- ldm/ops        4290 2024-02-04 19:53 LPUS24_KWBC_050152.xml

The files use the WMO header to define their content as:

after uncompressing and untaring the file, the individual products may be viewed and decoded. If no new data comes in for a minute, no file will be generated.

Example of a directory listing
Figure 6-8 Snapshot of the IWXXM MINUTE folder

6.4.2 IWXXM 5MINUTE

The IWXXM 5 minute files are a collection of minute files which are then added to a tar file and gzip compressed like the minute files are. For example, the 20240205_0245_IWXXM_5MIN.tgz has in it the following minute files:

-rw-r--r-- ldm/ops        8495 2024-02-04 20:41 20240205_0241_IWXXM_MINUTE.tgz
-rw-r--r-- ldm/ops        1957 2024-02-04 20:42 20240205_0242_IWXXM_MINUTE.tgz
-rw-r--r-- ldm/ops        8371 2024-02-04 20:43 20240205_0243_IWXXM_MINUTE.tgz
-rw-r--r-- ldm/ops        8227 2024-02-04 20:44 20240205_0244_IWXXM_MINUTE.tgz
-rw-r--r-- ldm/ops        4610 2024-02-04 20:45 20240205_0245_IWXXM_MINUTE.tgz

So to get to the data, the tar file must be untar'd into its minute files. Then each minute file must be untar'd to get to the data. It's a 2 step process.

6.4.3 IWXXM HOURLY

The IWXXM hourly files are a collection of 5 minute files which are then added to a tar file and gzip compressed like the minute files are. For example, the 20240205_02_IWXXM_HOURLY.tgz has in it the following 5 minute files:

-rw-r--r-- ldm/ops       31766 2024-02-04 19:05 20240205_0105_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       12327 2024-02-04 19:12 20240205_0110_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       18917 2024-02-04 19:17 20240205_0115_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       15570 2024-02-04 19:20 20240205_0120_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       21336 2024-02-04 19:25 20240205_0125_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops        8305 2024-02-04 19:32 20240205_0130_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       15707 2024-02-04 19:35 20240205_0135_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       11107 2024-02-04 19:42 20240205_0140_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       15843 2024-02-04 19:45 20240205_0145_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       12085 2024-02-04 19:52 20240205_0150_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops       35997 2024-02-04 19:55 20240205_0155_IWXXM_5MIN.tgz
-rw-r--r-- ldm/ops      190237 2024-02-04 20:00 20240205_0200_IWXXM_5MIN.tgz

So to get to the data, it's the same as the 5 minute files except there is one extra step of untaring the hourly file into its 5 minute files.

6.4.4 IWXXM Rolling Files

The files are in the IWXXM root directory (see Figure 6-7). The files have the following contents:

6.4.5 Format of IWXXM Files

The IWXXM format is a standard for interchanging meteorological data using machine readable XML/GML. A XML definition, schema and examples are included in ICAO Annex 3. For more information, see the WMO IWXXM schema directory.

6.5 PNG Files

Portable Network Graphic (PNG) images of the Significant Weather ICAO area charts are stored in the PNG folder of the WIFS file system. The WMO messages in Table 6-1 are retained in the PNG folder for 36 hours. Additional information pertaining to the areas referenced in Table 6-1 can be found in Figure 6-9.

Table 6-1 Significant Weather PNG Files

WMO HeaderArea
PGEE05 KKCIICAO A
PGIE05 KKCIICAO B1
PGGE05 KKCIICAO F
PGAE05 KKCIICAO H
PGBE05 KKCIICAO I
PGJE05 KKCIICAO J
PGDE29 KKCIICAO M
PGNE14 KKCINorth Atlantic Ocean Region


Figure 6-9 ICAO Regions

Volcanic ash and tropical cyclone graphics in PNG format are also available when advisories are issued. These products will have a WMO header starting with PFXD (volcanic ash) and PZXD (tropical cyclone). Figure 6-10 and Figure 6-11 depict snapshots of the files maintained in the SIGWX and VOLC folders, respectively.


Figure 6-10 Snapshot of the PNG SIGWX KWBC folder


Figure 6-11 Snapshot of the PNG VOLC folder

The file naming convention for these files is:

YYYYMMDD_HH00_TTAAii_CCCC.pngwhere

YYYY=4-digit year
MM = 2-digit month
DD = 2-digit day
HH = 2-digit hour of forecast package valid time
00 = Fixed characters
TTAAii_CCCC = WMO header and site identifier
.png = File extension

6.5.1 Format of PNG Files

For detailed information on the PNG format, see the W3C Portable Network Graphics (PNG) Specification (Second Edition) (http://www.w3.org/TR/PNG).

6.6 ADMIN_MSGS

Administrative messages are retained on WIFS for 36 hours. Each file contains a single message. Figure 6-12 is a snapshot of the administrative messages found on the WIFS servers.

Example of a directory listing
Figure 6-12 Snapshot of the ADMIN_MSGS folder

The file naming convention for these files is:

YYYYMMDD_hhmm_TTAAii_CCCC.adm where

YYYY = 4-digit year
MM = 2-digit month
DD = 2-digit day
hh = 2-digit hour of message issuance time
mm = 2-digit minute of message issuance time
TTAAii_CCCC = WMO header and site identifier
.adm = File extension

6.6.1 Format of Administrative Message Files

The Administrative message files contain a single WMO record formatted in accordance with WMO Publication 386.

6.7 Announcing Changes in Services or Products

Any routine changes to the WIFS Directory structure, content, or the formats of the WIFS files will be communicated at least 30 days in advance of the scheduled implementation via an “NOXX10 KKCI” Administrative message and to the user’s registered email on file. In addition, requirement changes that are agreed upon and announced at the ICAO Met Panel (Working Group-Meteorological Operations Group) and other regional meetings may result in modifications to the file content and data structure. Examples of new WIFS content and formats will be made available for WIFS User testing to identify any impacts to user WIFS processing or display systems.

WIFS Customer Support will be available to assist WIFS Users in resolving any issues with user logins, data timeliness, and network outages.

7 WIFS Support Web Site

The WIFS support website can be accessed by opening the following link in a web browser:http://aviationweather.gov/wifs.

The intent of this web site is to provide users with an online portal for information pertaining to WIFS. The web site has the following key capabilities:

8 WIFS Help Desk

The WIFS Help Desk is available to address issues Monday through Friday between the hours of 7am to 3pm US Central Time. To contact the WIFS Help Desk:

9 User Troubleshooting Guidelines

Table 9-1 provides an initial set of troubleshooting guidelines to help users with possible issues. This information can also be found on the WIFS Support web-site which may be updated with more troubleshooting guidelines.

Note: Users can check the status of all WIFS files by visiting https://aviationweather.gov/wifs/#status.

Table 9-1 Troubleshooting Guidelines

SymptomProbable CauseActions to Take
Data are out of date, cannot be retrieved, is not being properly displayed, or missing on the workstationWAFS data retrieve process failedTest the internet connection1
Check the data retrieve log file for errors2
Contact the WAFS workstation support team
Data on WIFS is out of dateTest the internet connection1
Check the WIFS status page https://aviationweather.gov/wifs/#status.
Browse to the WIFS online file list and check to see if data are up to date3
Contact the WIFS Help Desk. See Section 8 for procedure.
There is a WIFS data ingest problemCheck the Advisories page for new advisories pertaining to data outages.
Contact the WIFS Help Desk. See Section 8 for procedure.

Notes:

  1. To test your internet connection, try to connect to a known website on your browser. If it does not connect, contact your system administrator or your Internet Service Provider for assistance.
  2. If you do not know where this file is or how to access it, contact the WAFS Workstation Support Team.
  3. In your browser type in the WIFS URL (i.e., http://aviationweather.gov/wifs/data). Click on the appropriate category and find the data you are looking for. Take note of the file name with the latest date/time.

Appendix A. Using WIFS

Once you are authorized to use WIFS (see Section 4) you can begin downloading data at any time. The basic technical requirement for using WIFS is a computer system equipped with the following components:

  1. Connection to the public Internet
  2. Software capable of issuing Hypertext Transfer Protocol Secure (HTTPS) GET commands to download the data (see Appendix B for details about the recommended software GNU wget).
  3. Sufficient storage to store the products you want to download.
  4. Software capable of reading, decosding, displaying, and manipulating the data according to the user’s specific purpose. To see a list of software providers, point your browser to http://aviationweather.gov/wifs and click on Vendors.

Use Case Example 1 – Downloading a single file using the web browser

Below is a use-case scenario for how a fictitious user (John Smith) identifies a single file he wants and uses his web browser to download it from WIFS. In this case, John knows he wants a Significant Weather PNG chart.

  1. Using his web browser John navigates to http://aviationweather.gov/wifs/data
  2. When prompted he enters his WIFS user ID and password
  3. He clicks on the PNG->SIGWX->KWBC folder in the folder listing
  4. He locates the file of interest
  5. He downloads the file from the browser. For example, in Internet Explorer he right clicks on the file name and chooses Save Target As to download the file to his computer.

Use Case Example 2 – Downloading a single file using the GNU wget tool

Below is a use-case scenario for how a fictitious user (John Smith) identifies a single file he wants and uses wget to download it from WIFS. In this case, John knows he wants a Significant Weather PNG chart.

  1. First John must identify the file he wants to download. The only thing he knows is that he wants a PNG file.
  2. John issues the following command to download a PNG directory listing from WIFS:

    wget --user=johnsmith --password=wxdude https://aviationweather.gov/wifs/data/PNG/SIGWX/KWBC/

  3. The “index.html” file for the PNG data folder will be downloaded to the current working folder on John’s computer. John can then open this file in his browser or a word processing tool to see the directory listing.
  4. Once John identifies the exact file he wants, he downloads the file using wget:
    On the command line from his computer, John types the following command:

    wget --user=johnsmith --password=wxdude https://aviationweather.gov/wifs/data/PNG/SIGWX/KWBC/20100715_0600_PGEE05_KKCI.png

  5. John’s file will be downloaded to the current working directory on his computer.

Use Case Example 3 – Downloading multiple files at once

Below is a use-case scenario for how a fictitious user (John Smith) uses Wget to download multiple files at once from WIFS. In this case, John knows he wants all of the PNG charts.

  1. First John changes his current working directory to the directory where he wants the files to be stored.
  2. On the command line from his computer, John issues the following command:

    wget --user=johnsmith --password=wxdude --recursive --no-directories https://aviationweather.gov/wifs/data/PNG/SIGWX/KWBC

All of the files in the PNG directory will be downloaded to the current working directory on John’s computer.

Appendix B. GNU wget

GNU wget is a free software package for retrieving files using HTTP, HTTPS and FTP, the most widely-used Internet protocols. It is a non-interactive command-line tool that can be executed from programs, scripts, and cron jobs. GNU wget has many features to make retrieving large files easy, including:

To download GNU wget, navigate to http://ftp.gnu.org/gnu/wget/.

GNU wget documentation can be found at http://www.gnu.org/software/wget/manual/.

The structure of the command including only the required arguments is described below. The wget utility is powerful and includes the capability of performing recursion, statistics, logging, and much more.

wget --user=<user> --password=<password> <URL>

where

user = your WIFS login name
password = your WIFS password
Note: password may need single quotes around it to prevent shell from mis-interpreting the password

Appendix C. WAFS Upper Air GRIB2 Details (Web only)

Note: Starting in February 2024, new 0.25 degree grids are available via the WIFS API with 56 vertical levels up to FL600 and 39 forecast times out to T+120. These grids are not available on the legacy WIFS data pages. See the WIFS API page for more details on how to access these new grids.

The following data sets are provided for T+6, T+9, T+12, T+15, T+18, T+21, T+24, T+27, T+30, T+33 and T+36.

1.25° Resolution0.25° ResolutionFlight Levels
U-component WindFL050, FL080, FL100, FL140, FL180, FL210, FL240, FL270, FL300, FL275, FL300, FL340, FL360, FL390, FL410, FL450, FL480, FL530
V-component WindFL050, FL080, FL100, FL140, FL180, FL210, FL240, FL270, FL300, FL275, FL300, FL340, FL360, FL390, FL410, FL450, FL480, FL530
TemperatureFL050, FL080, FL100, FL140, FL180, FL210, FL240, FL270, FL300, FL275, FL300, FL340, FL360, FL390, FL410, FL450, FL480, FL530
Relative HumidityFL050, FLOSO, FL100, FL140, FL180
Tropopause Height(tropopause)
Tropopause Temperature(tropopause)
Maximum U-component(height of jet stream)
Maximum V-component(height of jet stream)
Geopotential Height of Standard LevelsFL050, FL080, FL100, FL140, FL180, FL210, FL240, FL270, FL300, FL275, FL300, FL340, FL360, FL390, FL410, FL450, FL480, FL530
Icing SeverityFL060, FL 100, FL140, FL180, FL240, FL300
TurbulenceFL100, FL140, FL180, FL240, FL270, FL300, FL340, FL390, FL450
Cb Hortizontal Extentn/a
ICAO Height at Cb Basen/a
ICAO Height at Cb Topn/a
Note: removal of 1.25 deg hazard grids.

Notable Grid Characteristics:

Issuance times:

Grid details:

File sizes: