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What exactly is the difference between RA, SHRA and TSRA in METAR and TAF reports? I couldn't find a source where they were all compared together.

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2 Answers 2

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Short answer:

  • RA: Moderate rain
  • TSRA: Thunderstorm with rain
  • SHRA: Shower(s) of rain

How this is constructed is detailed below.


From WMO Aerodrome Reports and Forecasts, abbreviations for precipitations are:

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A type of precipitation is RA for rain. It can be associated with a one or more qualifiers, e.g. TS for thunderstorm, SH for shower, + for heavy, etc. No qualifier means moderate.

Definitions

  • Thunderstorms: One or more sudden electrical discharges, manifested by a flash of light (lightning) and a sharp or rumbling sound (thunder). Thunderstorms are associated with convective clouds (cumulonimbus) and are usually accompanied by precipitation. The associated cumulonimbus has vertical updraughts that may reach 30 m/s in the more vigorous cells. Downdraughts also occur, especially in the later stages of development, with speeds of about half of those for updraughts.

  • Showers: Precipitation, often short-lived and heavy, falling from convective clouds. A shower is characterized by the suddenness with which it starts and stops, and generally by large and rapid changes in precipitation intensity.

Use

  • The qualifier TS shall be used whenever thunder is heard or lightning detected at the aerodrome within the 10-min period preceding the observation.

  • When an automatic observing system is used and when showers (SH) cannot be determined with a method that takes account of the presence of convective cloud, the precipitation should not be characterized by SH.

  • The descriptor SH (showers) cannot be associated with ice pellets (PL).

Examples

  • RA: (Moderate) rain
  • +SHRA: Heavy showers of rain
  • TSRA: Thunderstorm with rain
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    $\begingroup$ Note that TS can be used with other precip, for example TSSN, or with no precip, as VC TS. Note also that the intensity modifier applies to the precip, so +TSRA means "thunderstorm with heavy rain" and NOT "heavy thunderstorm with rain." $\endgroup$
    – randomhead
    Dec 21, 2023 at 15:15
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    $\begingroup$ @randomhead: One or two qualifiers can be used with any single weather phenomenon (SH, +, ... are qualifiers, not weather phenomena). Generally, qualifiers cannot be used alone, but TS is an exception, it is both a qualifier and a phenomenon (though this is not visible in the table). $\endgroup$
    – mins
    Dec 21, 2023 at 16:16
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TS stands for thunderstorms, so TSRA means rain associated with thunderstorms.

RA means steady and continuous rain. SHRA means rain showers. Showers stop and start abruptly and can vary in intensity.

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