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Aviation Weather Handbook

FAA-H-8083-28B Version 2026

Chapter 24

Observations

Cumulonimbus not associated with thunderstorms is coded as CB, followed by the direction from the station, and the direction of movement, when known. The location, direction, and direction of movement entries are separated from each other by a space. For example, a cumulonimbus up to 10 SM west of the station moving toward the east would be coded CB W MOV E. If the cumulonimbus was more than 10 SM to the west, the remark is coded CB DSNT W.

24.4.3.13.19.2 Towering Cumulus

Towering cumulus clouds are coded in the following format: the identifier TCU, followed by the direction from the station. The cloud type and direction entries are separated by a space. For example, a towering cumulus cloud up to 10 SM west of the station is coded TCU W.

24.4.3.13.19.3 Standing Lenticular or Rotor Clouds

Stratocumulus (SCSL), altocumulus (ACSL), cirrocumulus (CCSL), or rotor clouds are coded in the following format: the cloud type, followed by the direction from the station. The cloud type and direction entries are separated by a space. For example, Altocumulus Standing Lenticular clouds observed southwest through west of the station are coded ACSL SW-W.

24.4.3.13.20 Ceiling Height at Second Location

At designated stations, the ceiling height at a second location is coded in the following format: the identifier CIG, followed by the measured height of the ceiling and the specific location of the ceilometer(s) at the station. This remark is only generated when the ceiling is lower than that contained in the body of the report. For example, if the ceiling measured by a second sensor located at Runway 11 is broken at 200 ft, the remark would be coded CIG 002 RWY11.

24.4.3.13.21 Pressure Rising or Falling Rapidly

At designated stations, the reported pressure is evaluated to determine if a pressure change is occurring. If the pressure is rising or falling at a rate of at least 0.06 inch per hour and the pressure change totals 0.02 inch or more at the time of the observation, a pressure change remark is reported. When the pressure is rising or falling rapidly at the time of observation, the remark pressure rising rapidly (PRESRR) or pressure falling rapidly (PRESFR) is included in the remarks.

24.4.3.13.22 Sea Level Pressure

At designated stations, the sea level pressure is coded in the following format: the identifier SLP, immediately followed by the sea level pressure in millibars. The hundreds and thousands units are not coded and must be inferred. For example, a sea level pressure of 998.2 mb is coded SLP982. A sea level pressure of 1,013.2 mb would be coded SLP132. For a METAR, if sea level pressure is not available, it is coded SLPNO.

24.4.3.13.23 Aircraft Mishap

If a SPECI is taken to document weather conditions when notified of an aircraft mishap, the remark ACFT MSHP is coded in the report, but the SPECI is not transmitted.

24.4.3.13.24 No SPECI Reports Taken

At manual stations where SPECIs are not taken, the remark NOSPECI is coded to indicate that no changes in weather conditions will be reported until the next METAR.

24.4.3.13.25 Snow Increasing Rapidly

At designated stations, the snow increasing rapidly remark is reported in the next METAR whenever the snow depth increases by one inch or more in the past hour. The remark is coded in the following format: the remark indicator SNINCR, the depth increase in the past hour, and the total depth of snow on the ground at the time of the report. The depth of snow increased in the past hour and the total depth on the ground are separated from each other by a solidus (/). For example, a snow depth increase of 2 inch in the past hour with a total depth on the ground of 10 inch is coded SNINCR 2/10.

24.4.3.13.26 Other Significant Information

Agencies may add to a report other information significant to their operations, such as information on fog dispersal operations, runway conditions, FIRST or LAST reports from station, etc.

24.4.3.14 Additive and Automated Maintenance Data