Help With TAF interpretation

[alexeyf]

Hello,
I need some help with TAF interpretation.

1.
I got this wierd TAF :
TAF LLSD 201350Z 2015/2103 33008KT CAVOK BECMG 2019/2021 14003KT= TAF LLHA 201350Z 2015/2103 33008KT CAVOK BECMG 2019/2021 14003KT

what is the deal with =TAF LLHA (its a different airport)?

2.
When a TAF says BECMG can i asume it will change aproximetly in a linear fashion (i mean wind mainly)?

3.
When some info is missing at a BECMG can i assume it remains unchanged from the previous COMPLETE (or BECMG) line.

Thanks in advance :)

[Katamarino]

1. Looks like another TAF has just been tagged on the end there, guess it's an admin error.

2. I believe it does change in a roughly linear fashion.

3. Yes, you can!

[alexeyf]

Thanks alot man :ok:

[TopBunk]

2. BECMG = indicates an expected permanent change in the forecast met conditions, at either a regular or irregular rate occurring at an unspecified time within the period.

A basic definition with which you should probably familiarise yourself:rolleyes:

[Katamarino]

Ultimately, the forecasts are rarely, if ever, accurate to within that 2 hour period anyway :}

[MFC_Fly]

In message/signals traffic the '=' means 'break', i.e. 'this is the end of one part of the message now for a new part of the message'.

So in the example above there are 2 TAFs in the same message text separated by a 'break'.

[alexeyf]

Hello again,
I'm very new to the TAF interpreting (i'm from paragliding sport) and i want your interpretation on this TAF:

COMPLETE 2315/2403 26015KT 9999 SCT030
TEMPO 2315/2318 BKN025
BECMG 2320/2322 20008KT
TEMPO 2322/2403 BKN022

what the COMPLETE actually means? if the TEMPO overrides it immediately?
Also, does it mean that after the TEMPO it will return to the Complete forecast (with the clouds and wind and all?)

Thanks guys :ok:

[alexeyf]

anyone guys.

[BackPacker]

FWIW it doesn't look like a proper TAF. Normally at that place you'd expect the word "TAF", the ICAO code of the airfield and the time of issue. Like this:

TAF EHWO 241055Z 2412/2421 31009KT 9999 FEW045 SCT350
BECMG 2418/2421 VRB03KT SCT300=

Where did you get that TAF from, and are you sure that there's not some sort of interpretation/filtering going on?

[Mark1234]

A quick google search throws up this, which may be a good starting point:

http://www.ukweather.freeserve.co.uk/metarpg.htm
Or
Decoding a TAF (http://www.basair.com.au/index.php/online-resources/decoding-a-taf.html)

I've not seen COMPLETE before, but TEMPO (and INTER) have specific meanings - for TEMPO, the conditions may persist for up to an hour, INTER up to 30 mins. They do not change the base forecast, they're used for temporary phenomena.

I would read your taf as "COMPLETE... BECOMING" and the tempo's as temporary changes - it's rather odd that the TAF ends at the same time as the second tempo kicks in.

[alexeyf]

I know tha basic TAF interpretations,
what I want to produce is a hour by hour forecast from the TAF.
so what i'm trying ti understand is how should i understand the BECMG?
Should i understand that the conditions are changing within the BECMG time or in that time they are already those (that reported in the BECMG), does they stay the same as in the BECMG after the BECMG period is over? (as i understand in TEMPO they dont).

(btw the complete thingy is mine formating stuff)

[alexeyf]

up up up up up

[Katamarino]

They change during the becoming period, and remain the same at the end of that period (subject to further changes in the TAF of course).

[alexeyf]

thanks :ok:

[bern444]

Each year as we wander round AeroExpo we have a go at the Met people on their stand there, and ask why TAFs and METARs can't be in English instead of obscure code. We don't live in the age of semaphore any more, so we shouldn't need to have to decode gibberish.

The answer was always - "well, its international" , and ours was "NOAA does it, why can't you?". That was the end of the conversation, but someone once promised in an email that they'd do it on the next update. I don't think they have and I didn't see them this year to have another whinge.

B

[alexeyf]

Hi again,
more question :)

first: is the time here -> 2818/2918 is in GMT also?

second: more of a note the forecast time is 19:50Z in the TAF (TAF LLBG 281950Z) and its 22:50 local time but its only 9 oclock here(Israel) :) how can i let them know they have some kind of bias?

Thanks guys.

[Katamarino]

All times are in GMT.

And I don't understand your second question...what bias? Times are in GMT, local timezones are irrelevant...

[alexeyf]

the time the forecast issued is written as 19:50 (and it was an hour ago) now is 19:20 GMT. how can it be?
:bored:

[Katamarino]

Magic :}

Or a typo, or they prepared it in advance but released it a bit early...

[alexeyf]

I want to be sure on something once again...

1) 2915/3003 32012KT CAVOK
2) BECMG 2917/2919 27012G22KT 9999 SCT010
3) TEMPO 2919/3003 BKN010
4) BECMG 2920/2922 22010KT

in the following example in the (4) line the BECMG has no cloud definition,
so, do i assume no clouds OR take the clouds from the (2) BECMG?

thanks guys :ok:

[bookworm]

take the clouds from the (2) BECMG

[alexeyf]

thanks mate :ok:

[IO540]

Everything is "until further notice".

So a TAF from 1000 to 2300, forecasting SCT010, with various OVC005 bits from say 1500 to 1800, will implicitly revert to SCT010 after 1800.

This is because a lot of "weather" involves an air mass of fairly uniform properties, but with temporary muck passing through. After the mucky stuff (e.g. PROB40 TEMPO +TSRA) has passed through, you are back to the original air mass.

One trick to especially watch is a TAF which runs say 1000 to 2300 and with a worsening of weather from 2000 to 2300. It is natural to think the worsening portion ends at 2300 but this is wrong. The whole TAF ends at 2300 and nothing should be inferred beyond 2300!! The worsening portion is likely to continue beyond the end of the TAF.