TAF's

[Kirk Biddlecombe]

I understand how to 'decode' or make sense of METARS, but am slightly unsure about TAF's; in particular what part of it states when a certain wx condition is predicted...

Here's my example, taken from the Met Office:

LONDON/HEATHROW: EGLL 241630Z 250024 VRB05KT 8000 NSC PROB30 TEMPO 0307 2000 BR BKN003 BECMG 0710 12010KT 9999 BKN040 TEMPO 0919 7000 RA PROB30 TEMPO 1219 12015G25KT 4000 RADZ BKN012 BECMG 1822 18010KT PROB30 TEMPO 1924 BKN014

LONDON/HEATHROW: EGLL 242110Z 242207 VRB05KT CAVOK BECMG 0104 7000


Any help much appreciated!

Kirk

[Barnaby the Bear]

When you see eg 0307 that means between 0300 and 0700, it then moves to
0710. Again 0700 until 1000 etc. So the bits in between each time frame are the predictions.
PROB30 means might happen, but probably not, good to cover bases.
PROB40 more than likely will happen.

So the TAF at the bottom decodes:- Produced 24th at 2110z for the 24th between the times 2200 and 0700 wind VRB05KTS CAVOK BECOMING between 0100 and 0400 7km vis


Hope that helps.

[Kirk Biddlecombe]

Ah, great stuff! You've summed it up very nicely - thanks.

[Honey Monster]

Have a look at

http://users.tkk.fi/~stoivane/metar/

Reg

[XL319]

first is a TAF and second a METAR.....TAFs are issued every 6 hours for normally 24 hours and a METAR is the weather actually observed at that aerodrome every hour. Hope this helps

[lobby]

XL319, I think you will find they are both TAFs.

[chevvron]

Use AVMET; you get METAR and TAF in spoken form.

[howflytrg]

PROB 30 TEMPO 0307 means that there will be a 30% (greatest get out clause in met) chance of said event happening. The TEMPO 0307 means that if it does happen it will be between 0300-0700 for a max of 1 hr at a time and for no longer than 1/2 the time frame quoted.

[Hiro Protagonist]

The FAA's AC 00-45E (Aviation Weather Services) book, available for free download here will tell you all about it.

[tmmorris]

I was told by a friend who flies for a well known national airline that they assume PROB30 = won't happen, PROB40 = will happen, for flight planning purposes.

PROB30 seems to mean - don't blame us if it happens, i.e. you fly and get ripped apart by a CB.
PROB40 seems to mean - don't blame us if it doesn't, i.e. you cancel the flight because of a PROB40 CB and then sit and look at a blue sky all afternoon.

Tim

[Pierre Argh]

I understand how to make sense of METARS, but am slightly unsure about TAF's

I have a problem understanding the Welsh too!

[howflytrg]

PROB30 seems to mean - don't blame us if it happens, i.e. you fly and get ripped apart by a CB.
PROB40 seems to mean - don't blame us if it doesn't, i.e. you cancel the flight because of a PROB40 CB and then sit and look at a blue sky all afternoon.

Tim[/quote]


No UK TAF is complete without atleast one PROB30. THE vis for EGJJ may as well PROB 10/100 FG lol. "Always and never, always and never."
mmmm Think i am going mad.

[paulthornton]

Whilst we are on the subject of TAFs, I thought that as a general rule of thumb, it was a condition changing for the worst that was mentioned in a PROB/TEMPO.

I don't have the TAF to hand, but yesterday morning when I checked EGKK to see if it was worth going out for a trip around Sussex, It had something like this in it: "... 9000 TEMPO CAVOK ...".

Clearly they are saying "Well its a bit hazy and the vis isn't quite CAVOK, but you might get above 10km every so often" - just the first time I'd seen CAVOK mentioned in a TEMPO thats all. Probably old news, nothing to see here, move along now and discuss someone going around somewhere

And they were right too!

Paul