TAF translation for a newbie....
 

:confused:

for Leeds Bradford (EGNM) today

LEEDS BRADFORD


EGNM 061516Z 061601 15010KT 9999 SCT020 TEMPO 1620 7000 SHRA BKN010TCU PROB30 TEMPO 1620 4000 +SHRA +TSRA BKN008CB BECMG 1720 24006KT BECMG 2023 7000 BKN008 TEMPO 2301 3000 BR BKN003



Can someone explain it please. It has been explained once before to me but not in writing so I can refer back to it and get used to reading them. I understand bits but not other parts.

Thanks in advance

Liam.

If you register free at Met Office: Weather and climate change then log on and go to Met Office: Online services - customer login you will find the answer

Well done G-EMMA that looks pretty good to me!

or
 

Egnm 061516z 061601 Crap Wx

In short, it means you ain't goin' anywhere! :(

Greatest TAF decode I've heard so far:

If the TAF is:

1 line - you can pretty well go
2 lines - Only people with IMC ratings are going anywhere
3 lines - no one's goin' anywhere

As crude as it sounds, it's not often that far off! :)

... and times are given in UTC.

Well done G-EMMA. Just one minor addition. Every "BECMG" and "TEMPO" group supersedes the previous, and in most cases the PROB groups will be aligned with the timing of the BECMG and TEMPO groups so they also supersede the previous.

So if you want to break it down into multiple paragraphs, here's how to do that:

EGNM 061516Z 061601 15010KT 9999 SCT020 <- The general overall picture at the start of the period, so at 16Z. Anything in here that's not superseded later on will remain valid throughout the period.

TEMPO 1620 7000 SHRA BKN010TCU <- Temporary condition between 16Z and 20Z, after which, if nothing else mentioned, it reverts back to 15010KT 9999 SCT020

PROB30 TEMPO 1620 4000 +SHRA +TSRA BKN008CB <- But within this same period it might get worse.

BECMG 1720 24006KT <- Ah, between 17Z and 20Z the wind will become 240/6. But for the rest the previous still applies. So theoretically, if the forecast holds true, at 20Z the conditions are 24006KT 9999 SCT020

BECMG 2023 7000 BKN008 <- And this is what's going to get established from 20Z to 23Z. So at 23Z the conditions should be 24006KT 7000 BKN008.

TEMPO 2301 3000 BR BKN003 <- And from 23Z onwards it will worsen once again.

Oh, and all times are UTC, not local.

I just find it confusing. They put the original TAF text in, suggesting that what comes next is an interpretation of that bit of text. But what they actually do is take the whole TAF into account. That's why you see things like:

Text: EGNM 061810Z 061904 24006KT 9999 SCT020
Forecast period: 1900 to 2000 UTC 06 July 2008

Where does the 2000 UTC comes from? This bit applies to 0400 UTC, doesn't it? Oh no, later on, you'll find

BECMG 2023 7000 BKN008

So that's where the 2000 UTC comes from.

So... Pretty smart analysis algorithm, lousy presentation of the results.

This is the site I like better:

MET'MAP - ORBIFLY FLIGHT SCHOOL - IFR ET CPL AMERICAIN EN EUROPE - FAA IFR AND CPL IN EUROPE

Mouse over a site to see the METAR and its interpretation. Click on a site to make it your personal center of the universe, then bookmark whatever URL is listed for next time. They don't interpret TAFs though, only METARS. But they do give access to both the short and long term TAFs and I also like the color coding to get a glance of flight conditions. Especially if you combine that with rainfall radar or something like that.

I was taught that the longer the TAF, the worse it is to fly...! ;)

Well, I just got proper training so that I could read and understand them the same way I read and understand a book. Oh, and proper training in meteorology, climatology, forecasting, modelling, and so forth too.

How little I knew, eh?

You'll be seeing 4 lines soon... they are going to 36 hour tafs at some places later this year - all the 'times' will extend to be 'day/time', and you can be sure they'll cover every possible option with 'prob30 this and that' within the 36 hours. The decode sites will have to change, wonder how fast that will happen?

Been looking at that ADDS thing a bit more. There's something seriously wrong with that algorithm. The interpretation is done correctly, as is the presentation. But then the wrong bits of TAF are associated with the presentation bits. Everything is well (excellent, actually) up to the PROB30 bit.

Then comes the following line:
Text: PROB30
And some text suggesting it interprets that line. But what that piece of text actually interprets is
Text: PROB30 TEMPO 1920 4000 +SHRA +TSRA BKN008CB
which is correct, as this is one "block".

The next "block" then seems to interpret the line
Text: BECMG 2023 7000 BKN008
But this line is listed after the block it interprets. Because the line preceding it is the "TEMPO 1920 ..." line which should have been on the PROB30 line.

So past the PROB30 bit, all the content of the "Text:" lines need to be shifted up one block to make things fit. And even then the interpretation block doesn't neatly interprets what's on the "Text:" line, since the interpretation also looks through the rest of the TAF for anything that precedes or supersedes this bit of "Text:" line.

Just guessing what happened: A smart programmer wrote an algorithm to make a linear interpretation of a TAF, from hour to hour, and present it in text form. Which worked flawlessly. And this is no mean feat, because to interpret what the weather is going to be at the end of the period may mean going backwards in the TAF a few "blocks", and to interpret how long the initial weather is going to last may mean going forward in the TAF.

Then a customer request comes along to have the actual TAF text inbetween the interpretation. Which isn't possible in this case since a TAF isn't necessary linear, but the algorithm linearizes the results. So the smart programmer refuses, tries to explain this to his non-understanding management or non-understanding customers, and moves on.

Anyway, request persists, so a less intelligent programmer comes along, willing to take the job (after all, a TAF is in ALL CAPS so it can't be difficult), finds he doesn't understand the code programmer #1 has written so he writes his own algoritm that breaks the TAF into blocks. And then injects these blocks into the blocks that the original algorithm spews out. A quick test by management finds no flaws with this so the thing goes into production.

And the worst thing is that that second programmer probably made a lot of money. First for taking on a job that everybody said was impossible, and secondly for getting it through acceptance testing. In less time than expected.

(Is it true you turn into a cynic after working in the same field for 10 years?:*)

30%? Make that 100% :( I was with friends at Hebden all day and at 17:00hrs we had all of that - TS, heavy rain, low cloud etc. Driving home with the temperature at 11.5C we had radiation fog forming :uhoh: it looked quite pretty floating gently about 6" above the fields and between the trees. It also poured down whilst we spent a couple of hours at Brimham Rocks.
For anyone who may not be too familiar with the geography of the UK, Hebden and Brimham Rocks are places in the Yorkshire Dales National Park. :)

wx is always crap at LBA :}

...
 

most accurate forecast I've heard recently...

The Weather is PANTs........Poor Actuals and Naff TAFs

Well spotted. I think the key issue is that "PROB30 TEMPO" is fairly rare in US TAFs. If you speak SQL, here's the difference between the US and UK interpretations of the WMO's "TAFs for Dummies".


Looking at some of the examples, TEMPO seems to be implied by PROB30 in some cases.

Thus my guess is that the algorithm was not tested on cases where two change words like "PROB30 TEMPO" appear consecutively.

Come to think of it, I like the US system better. I mean PROB30 would imply a TEMPO condition, wouldn't it? In what sort of situations would you have a PROB30 BECMG?

No. There's a big difference between "3000 BKN006 PROB30 0710 0200 FG OVC000" and "3000 BKN006 PROB30 TEMPO 0710 0200 FG OVC000".

In the first case, the airport might well be fogged out for the entire period. In the second case, there should be an opportunity to make an approach at some stage. Don't bet your life on it though.

Thanks for all the replies and discussion.

Great thing t'nternet aint it :)

dont you just hate PROB50 +SHRA

it might rain it might not ..... I can do that type of forecast for free...