Directory and Filename Structure for Anonymous FTP

There are two different systems used by our file servers in constructing our directory names and file names. One system is an "English descriptive format" used for individually stored forecasts and observations. The other system is based upon a File Name Standard. Files of "WMO bulletins" (note 1) use the Telecommunication Operations Center "File Name Standard" format for storage of meteorological information. There are, therefore, two types of file content formats available on the servers. One is a file of grouped WMO messages available as received from various source communication lines. The other type is files of products or observations that do not contain a WMO abbreviated heading within the file. The second type were either never transmitted as WMO bulletins or were parsed from the original bulletins. The WMO bulletins are structured items for transmission and contain observational data and forecast products. Products which do not use the WMO bulletin format structure but do use the WMO GRIB code for providing the forecast information are also stored under the "File Name Standard". They normally contain large forecast model computer forecast grid field products generated by the NWS/NCEP. The documentation in the access procedures for FTP/HTTP Services web page gives an overview of the data and products available at the Gateway that use this standard. The user must understand the meteorological code formats to be able to decode and display all coded data and forecast products.

The observation files (or bulletin (note 1) collectives of observations) are transmitted, received and stored under the TOC File Name Standard. These files contain data in many standard WMO meteorological code forms depending upon the type of data report. The observations are available "as received" and come from many world-wide sources. You are referred to the Observed Data (Data-Specific Collective Files) web page for details on all data-specific types available on our servers. The WMO collectives of METAR reports are included in these files as a data type under the "TOC File Name Standard". All of the model forecast products are stored under the "TOC File Name Standard" for FTP retrieval. The individual aviation METAR observation and Terminal Area Forecast (called TAF) are also stored under the "English Descriptive Format" in a "parsed" file set for site selective individual retrieval.

There are "Parsed" National Weather Service Forecast Office WARNINGS & FORECASTS stored on the server as well. These products can be found the same way as observations. The file tree is different beyond the /data/ sub-directory. The server user should review the explanation of the various directory trees for a better understanding of how to locate the warnings and forecasts they desire. Remember that the last received product is the only one available and that the warnings and forecasts are file names using forecast "zone" numbers by state. We do not store old data on the server in the parsed files.

Retrieval of Selected Observations

This is a "HOW TO" help guide. It may help to establish a process to pull selected data (such as exampled here for METAR reports) from our "English descriptive format" server resources. You can also pull all of our METAR bulletin files from our server resources using the "TOC File Name Standard" as illustrated later on this page. These procedures focus on retrieving individual observations which were generated in the METAR code. However, the same method can be used for retrieval of individual text forecasts at the Gateway. The aviation data file names are "ICAO Site Identifiers" for the METAR reports and the TAFs. Other information, such as the English language text forecast, is individually stored under NWS zone forecast identifier numbers or with other meaningful descriptive file names. These files contain only the latest available observation, warning, or forecast received at the Gateway. Old observations and forecasts are not available at the Gateway under the "English descriptive format".

Recommended Methods for Retrieval

Several recommended methods are described in the following procedures. The METAR is an hourly observation in the United States and in many other countries around the world. Some countries take METAR observations on a half hourly basis. Constant FTP retrievals to our servers for the latest observation results in service access denial for others. The design of your retrieval processes must consider availability of the data. The METAR data is best requested between 10 and 15 minutes past the hour to account for central processing time.

Decoded METAR Reports

Here is an example on the retrieval of a METAR observation for a selected location. The process uses the standard anonymous FTP protocol. For multiple reporting locations you should use the "mget" multiple retrieval FTP procedure. It is strongly recommended not to open multiple FTP sessions beyond three (3) to five (5) for retrieving data.

1. Use this URL address = ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/ to establish your list of sites to retrieve (you must know the 4-letter site identification)

2. You will be returned a file list (note2) of "4-letter site ID" files with names ending with ".TXT" to select from [be aware that the server is character case sensitive]

3. Establish a list of filenames, by station name (ICAO site Identifier) to use in the FTP, and use the following format of the FTP call in your retrieval program

4. example: URL = ftp://tgftp.nws.noaa.gov/data/observations/metar/decoded/KIAD.TXT for KIAD = Dulles International Airport
(note the site filename is in upper case)

5. You will get, for example, a returned file with a content in this form in ASCII for a decoded METAR from KIAD