Aviation Weather Decoder

IMPORTANT: If you haven't already done so, be sure to read the overview document that contains information relevant to all of the NCEP decoders!

The NCEP Aviation Weather Decoder parses reports of the following formats into the NCEP Decoder Interface Format:

• METAR - WMO FM 15-XII
• SPECI - WMO FM 16-XII
• SAO - Surface Aviation Observations, Federal Meteorological Handbook Number 1 (FMH-1), FCM-H2-1994, August 1994.

Known Deficiencies:

• For METAR/SPECI:
  • Supplementary information:
    • Recent weather phenomena of operational significance (Group REw'w') are not decoded.
    • Wind shear in the lower layers (Group WS RWYD_RD_R or Group WS ALL RWY) are currently not decoded.
    • State of the runway (R_RR_RE_RC_Re_Re_RB_RB_R) is not decoded.
  • Trend forecast fields are currently not decoded.
  • Remarks fields (Group RMK ......):
    • Fields from stations in countries other than Mexico are currently being checked for possible decoding, but this decoder does not decode every field following the RMK group.
    • Fields from Mexican stations are checked only for the presence of the sea-level pressure (SLP) field.
• For SAO:
  • Observation types of Record Special ('RS'), Special ('SP'), Urgent Special ('USP'), and Routine Delayed Report ('RTD') are not decoded.
  • Sky conditions of 'CLR BLO XXX' are not decoded.
  • Visibilities preceded by a '+' or trailed by a '+' are not decoded.
  • Squall winds (those prefixed by a 'Q') are not decoded.
  • In the Remarks section of the report, the only parameters which are decoded are:
    • Synoptic cloud types (C_L, C_M, C_H);
    • Depth of snow on ground and water equivalent of snow depth;
    • 3-hr pressure change and tendency;
    • 3-hr, 6-hr, and/or 24-hr precipitation amounts;
    • Maximum and minimum temperatures;
    • Minutes of sunshine.

Related Documents:

• The NCEP Decoder Interface Format - a fairly detailed description of the output format that is used by all of the NCEP decoders, including examples of how to easily re-encode this output into your own desired final format.
• Interface Output from the NCEP Aviation Weather Decoder - a tabular listing of all of the decoded values available within the interface format output from the NCEP Aviation Weather Decoder.

Change History Log: