becoming weather

[danyoren]

Hi
I want to know what weather expected after BECMG for example:


UKBB 160941Z 161212 15004MPS 0400 FZFG VV002
TEMPO 1207 1400 BR OVC003
BECMG 0709 13005MPS 4000 BR BKN007

Tanks
Danny

[redsnail]

Becoming from 0700 to 0900 (and thereafter) wind 130 degrees/ 05MPS (metres per second? not overly familiar with that one) 4000 metres horizontal visibility in Mist (BR), broken cloud, base 700'.
In normal words, wind from the south east at x speed, 4000 metres of vis, misty, cloud from 700' covering at least 5/8 to 7/8 of the sky.
In practical terms, ok for IFR ops, not good for VFR ops.

[Tinstaafl]

Oh, no.....that's great weather for VFR ops here! :sad:

[pigboat]

Always wondered why have wind in MPS. Is there an aircraft out there with the ASI on MPS?
Another absolutely useles measurement is Watts Per Square Meter to express the wind chill factor. I want to know how cold it feels like, not some bs measurement that means absolutely nothing if you ain't a meteorologist.
And don't get me started on oktas. :yuk:

[HotDog]

Have you ever flown in China or Russia? All flight levels in meters, wind in MPS. One Meter per second = 1.944Kts.

[Turbine Cowboy]

Redsnail wrote:


Becoming from 0700 to 0900 (and thereafter)

I want to ask what is the source of all that information? I mean not that you are wrong Redsnail, but where exactly does it specify the time period of the BECOMING?

Is 07-09mans tht the weather forecasted for that period will prevail after 0900?
where is the written (Jepp or ICAO) format decoder?

Thanx

TC:ok:

[Postman Plod]

Oi Pigboat - what you got against Oktas? What they ever done to you?! :8

BECMG is certainly ICAO standard (used it all my meteorological life when I had a meteorological life, now I've just got a life...). It means that the weather is forecast to change in the time period mentioned (0700 - 0900, or 0709) from the previous conditions to the new weather conditions - so its transitional and the weather could be one, or the other, or somewhere in between, and it'll be a permanent change. Like forecasting a front is going to clear, or in this case, the fog is going to lift for the rest of the day.

Could also use FM0900 (From 09:00), where the forecast change takes place from 09:00.

Cant find any online official references (ICAO / Jeppesen), but a simple online search on TAF Decode will bring it all up for you.

Now thats either going to confuse you more, or help...

[HotDog]

Turbine Cowboy, you'll find all the answers in your Jeppesen, but if you don't have one, try this:http://members.tripod.com/pcmuseum/dc3/metar-taf_convertcard.htm

[av8boy]

Have you ever flown in China or Russia? All flight levels in meters, wind in MPS. One Meter per second = 1.944Kts.

Hence, MPS for UKBB (Borispol) I gather.

Dave

[HotDog]

Yes Dave, UKBB-BORYSPIL UKRAINE

UKBB 180000Z 24003MPS 6000 FEW024CB BKN036 03/03 Q1012 18290050 NOSIG

[pigboat]

Oktas always struck me as a little strange. Why use eighths for cloud cover when other weather related items are expressed in tenths?:confused: :D

HotDog, nope never flown in either one. Don't feel deprived.;)

[HotDog]

Nothing strange about it IMHO.

Okta(s): the international unit for reporting cloud amount. Cloud amount is assessed in total which is the estimated total apparent area of the sky covered with cloud.
1 okta is one-eighth of sky covered with cloud. 0 okta = sky clear, 1-2 oktas = few, 3-4 oktas = scattered, 5-7 oktas = broken and 8 oktas = overcast.

[Tinstaafl]

Why Oktas? I'd say it evolved from observers looking at the sky & dividing it into sections to determine coverage.

1st division would be to halve the observable sky, a second into quarters. The next easily done division is to halve the quarters - leading to eighths.

[compressor stall]

Would you be happier with dectas then Pigboat?

[Postman Plod]

Anyway, the only real need for oktas now is in the meteorological world, since aviation moved over to FEW / SCT / BKN / OVC.

[pigboat]

Stallie, lived with dektas fer years. Cloud cover was always expressed in tenths in North America. Seems to have gone over to oktas right about the time Greenwich Mean Time became UTC. ;)

[mstram]

>Anyway, the only real need for oktas now is in the meteorological world, since aviation moved over to FEW / SCT / BKN / OVC.

And what exactly do FEW, SCT / BKN / OVC mean ? :)

I.e. they are just "shorthand" for the oktas anyway !

Mike

[604guy]

Ahhhh... tenths. Makes me yearn for the days of SA's and FT's. A time when the world made sense.

Hey Pigboat...I see that EC has come up with a new formula to express windchill. Thrown the ole watts per whatever out the window and gone back to an equivalent temperature reference. The spokesperson seemed quite pleased with himself. IMAGINE!