1hr and 3hr forecast differ?
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Hi! This is the 1hr forecast for my place, firecast-model is ICON-EU. It does not show any rain in the afternoon:
This is the 3hr forecast, same model, same place. It shows 0.2 rain expected around 4pm:
1hr and 3hr models show different values for certain parameters. This is not the first time I see that. Why's that? I assumed the 3hr model is based on the 1hr forecast which means that if there's no rain expected in the 1hr forecast this should apply to the 3hr too. Am I wrong? What am I missing?
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@plusterwurst
This is similar to this post:
https://community.windy.com/topic/12851/rain-forecasts-issue?_=1615987241156
As Windy displays only rain amounts equal or over 0.1mm in Meteogram, you can cumulate 0.1mm and more during the 3 hours but less than 0.1mm during each of them. -
@idefix37 Okay, that seems to be an FAQ. ;-) Thank you.
Interestingly enough there's that as well:
Symbols at 10, 13, 16, 19hrs show snow/rain but the meteogram does not show any precipitation. Is there an explanation for that as well?
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@plusterwurst
Could be possible rainy/snowy conditions with less than 0.1mm sometime within 3hours... probably?
But you have to note that 0.1mm is almost nothing, so don’t focus too much about it. A chance of more or less nothing, spread over a large area (7km x 7km as forecast by ICON-eu) does not give so much. -
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@idefix37 said in 1hr and 3hr forecast differ?:
@plusterwurst
Could be possible rainy/snowy conditions with less than 0.1mm sometime within 3hours... probably?
But you have to note that 0.1mm is almost nothing, so don’t focus too much about it. A chance of more or less nothing, spread over a large area (7km x 7km as forecast by ICON-eu) does not give so much.@idefix37 Well, if that's the case - if there's less than 0.1mm of rain then there's no bar at the bottom but a rain/snow symbol at the top - we should see the same behaviour in the 1hr forecast as well, right? But as my 1st screenshot shows this is not the case: there's no symbol for rain at around 4pm in the 1hr forecast but rain symbol + bar in the 2nd.
And I know - this amount of rain is not much. But in my city there is a special weather situation. Drifting effects with strong westerly winds direct the showers mostly north or south past the city - but sometimes just above it. And often that's exactly when these small amounts of precipitation are predicted. This helps me to be well prepared for possible precipitation, so I want to be able to interpret the meteogram accurately.
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@plusterwurst
Unfortunately, meteogram is not a very accurate tool. It is useful, for sure, but don’t try to get from it something it cannot give you,... Rain below 0.2mm is hard to notice and not super relevant for a meteogram.
Now, if such a low level of rain is important for you because it can be the sign of something bigger, you should use different tools or maps, like rain/thunderstorms map, to understand the situation and what it could happen over your city -
@yves70 I understand. Thank you.
