Windy Premium info not accurate vs BOM (AU) Info
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I have just paid for the Windy Premium App and when using the hurricane tracking feature to view the predicted path of Cyclone Ilse off of Northern Western Australia, it shows with latest info at 4.39am AWST 11 April 2023 as a Level 3 intensity number when hitting land on 13 April 2023.
In review of the Australian Bureau of Meteorology App, it shows latest info at 9am AWST 11 April 2023 as a Level 4 intensity number when hitting land on 13 April 2023.
Obviously different information and disappointed the Windy Premium info does not appear current or accurate.
How often does this information get updated please?
Purchased the Windy Premium App to assist me with planning for weather events and not ideal if the information is not updated regularly or is accurate.
Thanks! -
@KCF Can you provide further details about the used layer since I checked the hurricane tracker and saw recent details of the situation.
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@Ondřej-Šutera
Here the information from the Bureau of Meteorology and from Windy tracker this morning. I have added UTC time as local times don’t match of course:
See
http://www.bom.gov.au/cyclone/?ref=ftr
http://www.bom.gov.au/products/IDW60281.shtml
Windy after morning update still shows :
In addition, the BOM is ranking this tropical phenomenon as Tropical cyclone and naming it Ilsa. When Windy is still showing it as the Tropical storm 18.
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@idefix37 @KCF Hi, the storm level is different because we use different scale for displaying them in Windy.
BoM uses this one: http://www.bom.gov.au/cyclone/tropical-cyclone-knowledge-centre/understanding/tc-info/
But we use Saffir-Simpson Hurricane Wind scale: https://www.nhc.noaa.gov/aboutsshws.php
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S Suty referenced this topic on
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I know these different wind scales used for tropical cyclone ranking:
https://en.m.wikipedia.org/wiki/Tropical_cyclone_scalesBut when you show the hurricane tracker according to the BOM prediction, don’t you use the same scale as they do? In this case why the track and wind speed is labelled BOM ?
Could you explain how you can use the Saffir-Simpson scale which is based on sustained wind i.e. the wind speed averaged on 1-minute when global models provide 10-minutes averaged winds and gusts on 3 seconds max.
Or do you use the JTWC prediction?
https://www.metoc.navy.mil/jtwc/jtwc.html -
S Suty referenced this topic on
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@idefix37 I see multiple questions, I'll try to answer them all the best I can.
- But when you show the hurricane tracker according to the BOM prediction, don’t you use the same scale as they do? In this case why the track and wind speed is labelled BOM ?
We're using Saffir-Simpson scale for prediction sources. We will display this crucial information in the user interface in the next iteration of hurricane tracker, hopefully developed during this year. We also want to include link to the forecast source where available.
- Could you explain how you can use the Saffir-Simpson scale which is based on sustained wind i.e. the wind speed averaged on 1-minute when global models provide 10-minutes averaged winds and gusts on 3 seconds max.
This might be oversight from my side. Are you sure the bulletin from BoM provides "wind" as 10-minute average? Below is bulletin from today (2023-04-12) from 0600Z and it contains 10-minute wind as you mention (120km/h) but following prediction hours show much higher wind speeds (from 150km/h up). I'm not sure what to take from this exactly. We might be trying to compare incomparable numbers (as forecast from each source has different meaning for "wind")
- Or do you use the JTWC prediction?
Not yet, we want to add it as new forecast source soon.
- In addition, the BOM is ranking this tropical phenomenon as Tropical cyclone and naming it Ilsa. When Windy is still showing it as the Tropical storm 18.
There are multiple sources for forecast and track history. Each of them usually uses different naming for storms and selection of correct name is not done by human. Unfortunately for TS18, this didn't work as intended soon enough. Now the name is correct as it propagated in the feed of all the sources.
- Windy after morning update still shows: (old update time)
This is another missing information we're to tackle in next HT iteration. Update time is related to last update of storm track (history). Update time of forecast is available in the data feed from backend but isn't displayed to the user yet.
I hope I've explained all the questions asked. Feel free to let me know if not (:
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@Filip_K
Thank you so much for this detailed reply.
I have still some remarks and questions.
The Tropical Cyclone scale used by the BOM is well based on averaged 10-minute wind periods as shown here:
(See paragraph concerning Australia)
https://en.m.wikipedia.org/wiki/Tropical_cyclone_scales
They also include in their scale the gust based on 3-second period, but I don’t know if this parameter is really used for TC ranking.
Also shown here:
You did not answer this question in my previous post:
“Could you explain how you can use the Saffir-Simpson scale which is based on sustained wind i.e. the wind speed averaged on 1-minute when global models provide 10-minutes averaged winds and gusts on 3 seconds max ? “Finally I think it should be necessary to provide more information about the ranking method you use in Hurricane tracker. Otherwise you will get the same questions every time.
As far as I understand now, when selecting BOM, you show the track and wind speeds as predicted by the BOM, but the TC ranking is not that one of the BOM but that one of Windy. Am I right ?Just a last question, what is the meaning of BOM-W and BOM-A?
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@idefix37 More answers:
- Could you explain how you can use the Saffir-Simpson scale which is based on sustained wind i.e. the wind speed averaged on 1-minute when global models provide 10-minutes averaged winds and gusts on 3 seconds max ?
You are correct, we're wrongly using SS scale for 10-minute winds, which doesn't really make sense and is oversight from my side. We should probably use (and explain) different scales for different basins (so it matches locally wide-spread use). Note about comparison is even in the wiki article:
...These differences make direct comparisons between basins difficult- They also include in their scale the gust based on 3-second period, but I don’t know if this parameter is really used for TC ranking.
Gusts are not used for scale or shown to the user, yet.
- Finally I think it should be necessary to provide more information about the ranking method you use in Hurricane tracker. Otherwise you will get the same questions every time.
Agreed. We'll try to incorporate all this knowledge to next iteration of HT.
- As far as I understand now, when selecting BOM, you show the track and wind speeds as predicted by the BOM, but the TC ranking is not that one of the BOM but that one of Windy. Am I right ?
Yes, exactly. As mentioned before, we're applying SS scale to 10-minute winds.
- Just a last question, what is the meaning of BOM-W and BOM-A?
BoM-W, BoM-N and BoM-E are official BoM bulletins (for west, north and east regions around Australia). BoM-A is unofficial forecast from NWP model Access. This information is also not yet available the user and will be, again, in next iteration of HT.
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@Filip_K said in Windy Premium info not accurate vs BOM (AU) Info:
We should probably use (and explain) different scales for different basins (so it matches locally wide-spread use). Note about comparison is even in the wiki article:
“...These differences make direct comparisons between basins difficult …. “
I agree, it is not a good idea to use the same category TC scale in all basins. I don’t think that users make comparisons between basins. They want to get the usual ranking in there area.
In the data provided by each RMSC, is the TC category provided at each future predicted postions? This information does not seem available in the data from the BOM.
This ranking question is not easy as shown by this table of a wiki article, unfortunately for you in French, but you may understand it ( it was available in English but I can’t find it again).
From
https://fr.m.wikipedia.org/wiki/Cyclone_tropicalThank you for your time !
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@idefix37 said in Windy Premium info not accurate vs BOM (AU) Info:
In the data provided by each RMSC, is the TC category provided at each future predicted postions? This information does not seem available in the data from the BOM.
I see it is not available in the public bulletin, but the feed we have from BoM directly does contain this information.
We'll definitely add more info about the data to HT interface soon-ish.
