with the reference in the TAF below , I was looking for the VIS at 0500 UTC and I was little bit confused because of the " TEMPO "

And the TAF was

LHBP TAF (FT)140400Z 141206 34006KT 9999 BKNO45 
BECMG 2201 1200 BCFG BR SCT002 
BECMG 0104 0600 FG OVC001 
TEMPO 0406 0150 FG VV001

According to the TAF at 0104Z VIS would be 600M, then we can see TEMPO at 0406 with 150 M VIS, so what VIS can we expect? Can we say it is 600M with possibility to be 150 M? Or we can say directly it is 150M?

  • $\begingroup$ Is this a question for an exam, or an actual TAF that you encountered in reality? $\endgroup$ – Steve V. May 3 '17 at 20:09

TEMPO means that there were be fluctuations in the weather in the time period specified, lasting as long as 50% of the time range specified. TEMPO 0406 0150 FG VV001 means that in the period between 04:00 and 06:00 UTC the visibility will at some point go down to 150 in heavy fog, and it could last up to an hour in total.

One thing I would point out is that the time range for the TAF ends at 06:00, so its very likely the fog will last longer than that.

  • $\begingroup$ So if we got that question with two options , is that 600m with possibility to be 150m and only 150 M which one is the best answer ? $\endgroup$ – KM320 May 3 '17 at 8:29
  • $\begingroup$ I don't follow you @KomailMohamed $\endgroup$ – GdD May 3 '17 at 8:30
  • $\begingroup$ It's going to be both, you will have 600m and 150m during that period of time, and ranges in between. For planning purposes assume the least favorable conditions. $\endgroup$ – GdD May 3 '17 at 10:20

Usually, when we translate TAFs we use the word expect. So, in this case, we expect the visibility to drop from 600m to 150m. So when planning a flight you would use 150m.

Also, I find it odd how the time format is different to what I am used to. At my local airport, this is the TEMPO in the TAF.

TEMPO 0302/0307 6000 SHRA SCT030TCU

So this would translate.

Between 0200UTC and 0700UTC on the 3rd, we would expect visibility to be 6000m and for there to be rain showers, and towering cumulus scattered at 3000ft.

  • $\begingroup$ This is the old-style time format, which the United States switched away from six or eight years ago. $\endgroup$ – Steve V. May 3 '17 at 20:10

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