Tempo
Melvyn
TEMPO can be defined as "temporary fluctuations in conditions during the period, each change lasting not more than 1 hour and existing for less than 50% of the time period stated." This means that conditions should revert to the base forecast when the TEMPO conditions do not prevail and when the defined TEMPO period ends.
It's a common trap to read a TAF with a generally good base forecast and think "it'll be alright as long as I avoid the poorer conditions in the tempos."
- especially if you have multiple poor tempos! Hope this helps>