Description of weather overlays
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@baldo1191
This is because the level of rain expected is below the minimum threshold.
In general, below 0.3mm you can hardly notice that it is raining -
@yves70 Thanks! I have had the same feeling but the confirm sounds better.
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@yves70 I have another question about rain layer.
I read that the rain and thunder layer shows the sum of the precipitation of the last three hours. If I compare the information from the map (red circle) with the sum of precipitation shown in the meteogram (red rectangle) I have no correspondence. The picker indicates 7.4 mm of rain, in contrast the meteogram shows 9.8 mm of rain (sum of precipitation of 9pm, 10pm and 11pm ). Why do we have this disagreement?Many thanks!
Many thanks!
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@baldo1191
I understand that you can be surprised to see those differences although you should not.
There are different elements :- the figures after the coma have not a lot of meaning so 7.4mm could be easily 8mm and on 9.8mm could be easily 9mm. Of course it could be 7mm and 10mm as well
- what the picker is showing is rain accumulation, this is the equivalent to the data from the map called rain accumulation. The data in the meteogram and data from rain accumulation are both calculated by the model, meaning that by definition you can get different values knowing that on top of this difference, Windy is smoothing the data which will also affect a bit the data.
The conclusion is that you should take that as a nice opportunity to get 2 sets of data for rain accumulation, so in your example you can guess that rain accumulation could be somewhere in the middle so around 8.5mm. It is a bit the same approach as comparing the data from 2 different weather models
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@yves70 Thanks for your indications.
I agree with you both on decimal values and the data smoothing by Windy, but the map and meteogram should be calculated with the same model, isn't it? So, the same information calculated with the same model on the same coordinates on the same time step. If this is true, I can't understand why we see this disagreement. -
@baldo1191
As I said above, data from the meteogram and data from the rain accumulation map, even if they are both coming from the same weather forecast model like ECMWF, they don't come from the same calculation within the model. On top, you have the smoothing effect from the app. Therefore results can be different. This is interesting because if you calculate the same thing by 2 different ways and results are the same, probability is high that the result is correct -
@yves70 Thanks for your information! I didn't understand that the model uses different algorithms, now it's clear! Thanks a lot!
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@gjwolfswinkel it means at what height/altitude (above ground) the temperature is 0 Degree Celsius for the given location/area.
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Please note that the freezing altitude, i.e. the 0°C isotherm, is now sea level (msl).
See this post:https://community.windy.com/topic/16034/isotherm-0-c/5?_=1626989848785
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@yves70 said in Description of weather overlays:
@baldo1191
I understand that you can be surprised to see those differences although you should not.
There are different elements :- the figures after the coma have not a lot of meaning so 7.4mm could be easily 8mm and on 9.8mm could be easily 9mm. Of course it could be 7mm and 10mm as well
- what the picker is showing is rain accumulation, this is the equivalent to the data from the map called rain accumulation. The data in the meteogram and data from rain accumulation are both calculated by the model, meaning that by definition you can get different values knowing that on top of this difference, Windy is smoothing the data which will also affect a bit the data.
The conclusion is that you should take that as a nice opportunity to get 2 sets of data for rain accumulation, so in your example you can guess that rain accumulation could be somewhere in the middle so around 8.5mm. It is a bit the same approach as comparing the data from 2 different weather models
@yves70 Thanks for your interpretation, I've already been confused by this disagreement for a long time, too! Finally find a reasonable answer here.
The one thing I'd like to confirm is whether the rainfall values on the basic forecast and Meteogram still represent the precipitation accumulated from the previous hour (or in the last 3-hr)?And I'd also like to know whether the value of 'rain' in Meteogram actually represents the large-scale precipitation or not? Since the total precipitation is the sum of large-scale & convective precipitation in both ECMWF & GFS, according to their paramter description. It seems that the total amount of precipitation has been split into two parts in the bar graph in Meteogram: the large-scale term and convective term. Furthermore, the sum of 'Rain' and 'Covective' is exact the value in basic list, which might indicate the total precipitation. Does it indicate the term 'Rain' might be equivalent to the large-scale precipitation in Meteogram?
Thanks again!
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@greatkingnan
The rainfall in the basic meteogram, for non Premium users, is the accumulation of the last 3h, for Premium users it can be displayed by 1h
This is the total of rain -
@yves70 Yeah, I know the data in Premium and free version are different (1h v.s. 3h). But the question is...I just want to make sure that the definition of the rainfall value shown on the layers and meteogram is still the same? Thanks for your help!
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@greatkingnan
In the different maps or layers, what you see is the total of rain. In the detailed meteogram, however, you see the split with the convective rain -
There seems to be a certificate error in your blog when trying to view https://blog.windy.com/wind-accumulation on safari
here is the error
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@auweatherwatcher Hello, this URL is not in use anymore. This is our only blog and forum community.windy.com.
Korina
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@korina Good to know. Those links now just go back/redirect to windy main. Perhaps remove the links from the main post to avoid confusion. Unless there was some extra information that might be useful to know.
e.g just show
Wind accumulation: This overlay represents the maximum intensity projection of wind gusts over the next 10 days. Basically, each point on the map represents the strongest or maximum wind forecasted for that place in the next 10 days. This feature is especially helpful for tracking hurricanes and other strong wind events.
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@auweatherwatcher Hello, the certificate error should not happen again.
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@meridies Indeed, this is listed in the Description of Weather Overlays post, but maybe one detail could be clarified.
Waves is described as:
Waves: Significant wave height and its period of all wave types combined (swell and wind waves). Close to the shoreline, the actual height is influenced by the shape of the sea bottom.It would be useful to know how the math used to combine "significant wave height and period its period" from wind and several different sources of swell. The resulting calculation could be very misleading and, in fact, an inspection of these values in Windy is confusing.
For example, as I inspect a point now, I see wind waves listed as 1.0 m, swell 1 at 0.6m and swell 2 at 0.7 m. But the total "wind" value provided in the annotation within the map is 1.2 m. How this is arrived at is unclear.
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@vschmidt
This thread may answer your first question:
https://community.windy.com/topic/3603/different-definitions-for-the-wave-periods-are-shown
And this article too:
https://confluence.ecmwf.int/plugins/servlet/mobile?contentId=131397261#content/view/131397261Concerning your example, what do you mean with ‘the total "wind" value’ ?
If you mean the Wave overlay, it corresponds effectively to the ‘total sea’:
https://community.windy.com/topic/17449/swell?_=1640701282822 -
Would it be possible to have these kind of information in an ad hoc page? Even better if it's shown as a detail when selecting an overlay.
Luigi
