ICAO ANNEX 3 contains a table, included in our Ops Manual, which states that TEMPO is not applicable for planning for transient conditions (thunderstorms, showers etc) but must be considered for persistent conditions (fog, sandstorm, continuous precipitation) and also that forecast gusts may be disregarded.
Where is it in Annex 3 please? I've only ever seen it (and I think it's the table you're thinking of) in JAR-OPS1 AMC/IEM.