Bikers, cyclists

I have been looking at the cloud coverage predictions used in Windy. I commonly find cases where the (total) cloud coverage percentage is less than the Low, Medium, High cloud predictions.

For example, using ECMWF at a particular time I see

Low Clouds 0 %
Medium Clouds 64%
High Clouds 70%
Clouds 54%

I just can't wrap my head around what that means. How can the total coverage be less than both the Medium and High cloud coverage?

In the description of the Clouds layer it says: "Clouds and rain/snow accumulation in the last 3 hours". All I can think of is that this is an average of the clouds in the past 3 hours, whereas the high, medium, low is hourly. Is that what is going on? The sentence is ambiguous at best.

First let me say (again) that I really like the Windy user interface and the types of data it provides. However, I'm trying to reconcile some of the weather data with what I see on other sites.

The other site I have used for a long time is weather.us. I also provides access to the ECMWF forecast with a modest subscription fee. The problem with weather.us is that it has a very klunky user interface. I would love to switch over to Windy as my go-to source of weather.

However, I've noticed that the ECMWF predictions between the two sites can be significantly different and it is not clear why that would be.

1. I have made sure that both are using the same run of the ECMWF model
2. I have made sure the locations are the same (to within a couple hundred meters)

Despite that I will sometimes get temperature predictions for the same hour that vary by 5ºF. As an amateur astronomer, I'm very interested in cloud predictions. I find significant differences between those as well

As an example, I was looking at the weather in a nearby city I'm going to tonight

At 9 PM here are what the two sites say:

(Temp, high clouds, middle clouds, low clouds)

Windy:       51º, 09%, 06%, 0%
Weather.us:  56º, 21%, 01%, 0%

At 12 PM we have:

Windy:      47º, 24%, 34%, 0%
Weather.us: 53º, 28%, 28%, 0%

These are just two examples, but the discrepancies are rampant. They are not huge, but they are worrisome.

I have asked weather.us if they have any ideas why these significant discrepancies would exist. Of course, they didn't really know but did say they apply an elevation correction to some of the data. I wouldn't think that would be done for cloud predictions. It also seems unlikely that an elevation correction would yield a 5ºF temperature difference.

So I'm asking the Windy team if they have any thoughts on this. Unfortunately, I don't know of a third site I could check to see who they agree with.

To be honest, I probably trust weather.us more. It is run by a team of meteorologists and you would think they would know what they are doing. As far as I can tell the Windy site is run by weather enthusiasts.

I would appreciate any ideas about why this difference might exist.

That surprises me a bit. I’m an iOS developer and that kind of change should be extremely simple. It is a change to the app code rather than the web code.

Anyway, I would appreciate it if you could add it to a TODO list to be addressed at some point.

The satellite layer is much appreciated.

There is probably nothing you can do about it, and it is probably in the source data coming from EUMETSAT, but there is an annoying discontinuity running through the central US.

It kind of degrades the beautiful image. If there is anything that can be done about it I'd appreciate you looking at it at some point.

In the iOS app version of Windy, when viewing web pages like the community forums, the Done and navigation button are almost unreadable.

Note that they are more readable here only because of the scaled up image.

Can you either change the tint color of the buttons in iOS, or change the background of the bottom bar to something lighter. I sot of noticed the Done button, but it has only been recently that I realized there was a "back" button on the right.

That’s too bad although it seems to be a common issue in weather apps. Different displays are not synchronized with each other or are using slightly different calculations. However, I can live with it as long as I understand what is happening.

In your opinion, which is to be most trusted? The meteogram or the map layer?

Yes, I have looked at the cloud layers. At 9 PM, it is showing 35% high clouds and 23% medium clouds. That was why I was surprised to not see them in the meteogram.

It depends on what information you want. For the average "guy off the street" I don't think Windy is the particularly easy to use. They just want to see:

• What the current temperature is
• What the predicted high and low temperature is
• Whether and when it is going to rain or snow today

Windy makes that somewhat hard to find. As I posted in a thread yesterday, you have to drill down a bit to find this.

However, for a weather enthusiast, Windy is quite easy to use to use. I find the interface fantastic for digging into what is going to be happening.

I realize there is supposed to be a popup in the upper left that shows a quick 3 day forecast, but I find it doesn't always display for me despite having that option checked. The Quick Forecast also only shows highs whether it will rain sometime that day. That is not quite enough information in my opinion. By clicking it you get the more detailed display, but that is probably more than most people want.

Not every site is going to be all things to all people. The Windy developers have obviously focused more on the "enthusiasts". That is a fine decision but I suspect it means that the bulk of the population will not choose Windy as their "go to " weather site.

@idefix37,

Thanks for the response.

1. Yes, different parts of the world use different units, but we have a choice in the Settings for what we’d like to see. Given space is at a premium on mobile devices, it seems that both might not be necessary. Not a big deal.

2. I understand what the curve is and the pressure labels at the top. My second question was about what FL100 means.

3. It is not that there is never any cloud show, but just that it isn’t always shown in cases where I would think it would be. Here is another example that shows the clouds in some cases:

My question is why are clouds not shown at (say) 9 PM Tuesday. The icon on the second row shows it being partly cloudy. The bottom row shows the cloud base at 28k. Is that too high to display on the meteogram? Although it is not labeled, it look like the top row of the cloud graph might be around 13K. Or does everything above 9km just get stuck there?

Tom,

Thanks for the response. I realize Windy is not your typical weather site, but one common use of weather sites must be to see the current conditions before heading out the door. I will watch for further development along these lines.