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Trend Forecast (TTF)
Atmajor aerodromes, a statement of trend, valid for three hours (unless
otherwise indicated) from the time of the observation, is appended to the
observation. The TTF relates toweather conditions expected to affect the
aerodrome of origin for the validity periodof the forecast.
Thedecode of the TTF is as per that for theMETAR/SPECI except there is a
statement of trend appended to the end of the forecast. Thismay contain the
following:
• NOSIG is used to indicate that no significant changes to theelements
wind, visibility, weather and cloud, as reported in theMETAR/SPECI, are
expected to occur during the validity periodof the TTF;
• FM (time) indicates that significant changes to a new set ofmean
conditions, from those previously given, are expected to occur at the
trend forecast
2 – me t eorology
CAVOK
VIS
WX Cloud
RVR
Wind
VIS
WX
CLOUD
no
signi cant
changes
signi cant
changes
tomean
conditions
signi cant
variations
frommean
conditions
signi cant
low level
turbulence
METAR
or SPECI
Location Date/
Time
Wind
TTF
TEMP/
DEWPT
QNH Supplementary
Information
Remarks
CAVOK
VIS WX CLOUD
Finish
Time
Start
Time
INTER
or
TEMPO
FMTIME
FMTIME
NOSIG
Wind
BLW............FT
MODTURB or
MOD/SEVTURB or
SEVTURB
Time
TILL