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TEMPO, INTER, FMandBECMG (AIPGEN3.5)
TEMPO
and
INTER
areused to indicatesignificant variationsof a temporaryor
intermittentnature.
TEMPO
isused to indicatechanges toconditionswhichareexpected to last for
30minutesormorebut less than60minutes ineach instanceandwhere the
aggregateof thechanges isexpected tobe less thanhalf the total period indicated.
INTER
isused to indicatechangesexpected tooccur frequentlyandmoreor less
continuously forperiodsof less than30minutes ineach instanceandwhere the
aggregateof thechanges isexpected tobe less thanhalf the total period indicated.
Thevalidityperiod isgiven in the formatddhh/ddhh inTAFandhhmm inTTF,where
d isday, h ishour andm isminute.
FM
(from) andBECMG (becoming) areusedwhensignificant changes (both
deteriorationsand improvements) from thepreceding informationareexpected
tooccur.
FM isusedwhen rapidchangesareexpectedat thespecified time, and isgiven in
the formatFMddhhmm, e.g. FM301000 (from1000UTCon the30th).
BECMG
isused (inTAFonly)when thechangesareexpected todevelopduring
thespecified timeperiod, and isgiven in the formatBECMGddhh/ddhh, e.g.
BECMG3010/3011 (between10and11UTCon the30th). Inbothcases (FMand
BECMG), thenewconditionswill continueuntil theendof thevalidityperiodof the
TAF, oruntil replacedbyanother changegroup.
CLOUDHEIGHTDATUM
In aerodrome and trend forecasts, cloud heights are given above aerodrome
elevations. In other forecasts, heights are expressed:
• as a flight level; or
• with reference tomean sea level.
FORECASTCORRECTIONS
Corrections (COR) to the TAFmetadata (e.g. validity) are issued as required.
forecasts
FM
TAF
START
TAF
FINISH
2 – me t eorology