Wind arrows

[Vagabund]

Hallo,

I am very happy in using zygrib. It gives a good idea how weather will develop the nesxt hours and days.

But one thing I don't understand:

I was tought that the windarrows show lines on the arrow as follows:

- one half line = 1 bft
- one line = 2 bft
- two lines = 4 bft
and so on
- a black triangel on the arrow marks 10 bft

But if you compare zygrib chart-animation and zygrib data (shown left of the chart) one can read different wind strengthes.

So could you please give me the translation for zygrib wind arrows.

Another problem. I just loaded down present zygrib weather information, but there are no wind arrows shown. Which mistake did I do?

Thanks very much and best regards

[DomH]

Another problem. I just loaded down present zygrib weather information, but there are no wind arrows shown. Which mistake did I do?

Hi,
Parameters are in the option menu as shown in the attached image

[DomH]

- one half line = 1 bft
- one line = 2 bft
- two lines = 4 bft
and so on
- a black triangel on the arrow marks 10 bft

But if you compare zygrib chart-animation and zygrib data (shown left of the chart) one can read different wind strengthes.

So could you please give me the translation for zygrib wind arrows.

Hi,
It is not a beaufort scale representation but wind speed in knots

a half line = 5 knots
one line = 10 knots
one line + a half line = 15 knots
etc up to 45 knots

a triangle = 50 knots
a triangle + half line 55 knots
etc...

[Vagabund]

Thank you for your answer,

I have just downloaded the present wind forecast on the north sea.

When you put the cursor on the arrows you also can see that f.ex. an arrow with 3 lines indicate on one position 28.7 knots and on another position 32,2 knots, so in fact the arrows and lines show the approx. wind speed of 30 knots in that case. Is that correct?

Well of course, a wind-speed prediction may not be more accurate and in reality there is also a variantion in wind-speed at a certain position at a certain time.

I'm looking forward to your answer.

Best regards
Vagabund

[DomH]

Thank you for your answer,

When you put the cursor on the arrows you also can see that f.ex. an arrow with 3 lines indicate on one position 28.7 knots and on another position 32,2 knots, so in fact the arrows and lines show the approx. wind speed of 30 knots in that case. Is that correct?

yes.

Suggestion:

If you can read french there is here (viewtopic.php?f=4&t=133) a discussion about interpretation of wind speed in prevision