Info in UAV forecast

HumbearKS · Mar 20, 2020

Has anyone ever noticed in UAV forecast that a specific day (like today, March 20th) is listed twice in the section for the detailed forecast - with two very different forecasts. Trying to fly my drone here today but it turns out much windier than forecasted for the whole week for today. Overnight it added the second, different forecast for today but the initial forecast for today is still available right under the new one. Seems odd...

sar104 · Mar 20, 2020

Can you post a screen shot?

HumbearKS · Mar 20, 2020

Here are the screenshots.....thanks for your feedback, SAR104...note both screens were posted for the same day just different figures

sar104 · Mar 20, 2020

HumbearKS said:
Here are the screenshots.....thanks for your feedback, SAR104...note both screens were posted for the same day just different figures

You may have noticed that those forecasts also have different sunset and sunrise times, by one minute. That means that although they look like the are for the same location, they must not be.

HumbearKS · Mar 20, 2020

I noticed that but the only thing that makes sense is if they were for two different spaces still in the same area/city since I did not move much around over the last few days. Yet wind gusts and cloud cover are very different numbers. Not sure how to explain that...

sar104 · Mar 20, 2020

HumbearKS said:
I noticed that but the only thing that makes sense is if they were for two different spaces still in the same area/city since I did not move much around over the last few days. Yet wind gusts and cloud cover are very different numbers. Not sure how to explain that...

It cannot be that close. The 0620, 1830 times are correct for Kansas City. The sunrise one minute earlier at 0619 and sunset one minute later at 1831 times are a location substantially to the south.

HumbearKS · Mar 20, 2020

There is no way since I had not been searching for a different location forecast nor had I traveled to a different location so that it could be triggered that way...otherwise it would make sense...

OurAngryBadger · Mar 20, 2020

I have a weather app I made for photographers and working on putting a drone forecast in it. So let me take a guess because I'm a little knowledgeable in it.

To me, looking at both photos, it seems about 2 hours apart?

Forecast is not totally likely to change a whole lot in 2 hours, but it can happen, especially as more weather data comes in from the sources. I believe Dark Sky is the weather data service UAV forecast probably uses (I do as well) and although they don't provide info on where they collect the weather data from, it's most likely a mix of observational and forecasted data from local weather services, NOAA, and observational data from airports. As time goes on, more accurate data may be available and they may switch their sources to provide a more accurate forecast.

As far as sunrise/sunset time discrepancy, it can be a few things:

1. Your GPS signal was a bit off and it had you at a location further away, and it affected the sunset time enough to meet the threshold to consider it 1 minute, even if it was only a few hundred meters off.

2. There may have been a connection issue contacting the server and they may have a failsafe built into the app to calculate sunrise and sunset time even when you have no internet connection. This is easy to do with mathematical formulas but for some reason I've seen different results by 1 minute too.

3. Going off number two, there may have only been a problem connecting to tge dark sky server (they provide sunrise/sunset) and maybe it connected to the TimeAndDate.com server instead as a failsafe, I have also seen their numbers differ between both services for whatever reason.

sar104 · Mar 20, 2020

HumbearKS said:
There is no way since I had not been searching for a different location forecast nor had I traveled to a different location so that it could be triggered that way...otherwise it would make sense...

Either that or their system is producing both random sunrise/sunset times and random forecasts. I rather doubt that.

sar104 · Mar 20, 2020

Photogad said:
I have a weather app I made for photographers and working on putting a drone forecast in it. So let me take a guess because I'm a little knowledgeable in it.

To me, looking at both photos, it seems about 2 hours apart?

Forecast is not totally likely to change a whole lot in 2 hours, but it can happen, especially as more weather data comes in from the sources. I believe Dark Sky is the weather data service UAV forecast probably uses (I do as well) and although they don't provide info on where they collect the weather data from, it's most likely a mix of observational and forecasted data from local weather services, NOAA, and observational data from airports. As time goes on, more accurate data may be available and they may switch their sources to provide a more accurate forecast.

As far as sunrise/sunset time discrepancy, it can be a few things:

1. Your GPS signal was a bit off and it had you at a location further away, and it affected the sunset time enough to meet the threshold to consider it 1 minute, even if it was only a few hundred meters off.

2. There may have been a connection issue contacting the server and they may have a failsafe built into the app to calculate sunrise and sunset time even when you have no internet connection. This is easy to do with mathematical formulas but for some reason I've seen different results by 1 minute too.

3. Going off number two, there may have only been a problem connecting to tge dark sky server (they provide sunrise/sunset) and maybe it connected to the TimeAndDate.com server instead as a failsafe, I have also seen their numbers differ between both services for whatever reason.

Sunrise/sunset does not change by one minute in opposite directions over a few hundred meters.

OurAngryBadger · Mar 20, 2020

sar104 said:
Sunrise/sunset does not change by one minute in opposite directions over a few hundred meters.

You are right. What I am saying is that the weather data APIs do not report in seconds, only minutes, so in theory (although this is just an educated guess) it may gave changed enough to consider it a whole minute even though it isn't.

Actually I took a more closer look at the photos and there's few things that bother me.

While the wind speed can change for forecast in 2 hours time, the temperature should not change that much if at all!

This is looking more like a wildly inaccurate GPS location retrieval.

But what bothers me more is that the KP has been changed so much between the 2 hours. KP data only comes from the SWPC and they don't update it frequently (or at least didnt used to, I havent worked with them in a while) so Im not sure how to explain that

MavicDelight · Mar 21, 2020

Photogad said:
I have a weather app I made for photographers and working on putting a drone forecast in it. So let me take a guess because I'm a little knowledgeable in it.

To me, looking at both photos, it seems about 2 hours apart?

Forecast is not totally likely to change a whole lot in 2 hours, but it can happen, especially as more weather data comes in from the sources. I believe Dark Sky is the weather data service UAV forecast probably uses (I do as well) and although they don't provide info on where they collect the weather data from, it's most likely a mix of observational and forecasted data from local weather services, NOAA, and observational data from airports. As time goes on, more accurate data may be available and they may switch their sources to provide a more accurate forecast.

As far as sunrise/sunset time discrepancy, it can be a few things:

1. Your GPS signal was a bit off and it had you at a location further away, and it affected the sunset time enough to meet the threshold to consider it 1 minute, even if it was only a few hundred meters off.

2. There may have been a connection issue contacting the server and they may have a failsafe built into the app to calculate sunrise and sunset time even when you have no internet connection. This is easy to do with mathematical formulas but for some reason I've seen different results by 1 minute too.

3. Going off number two, there may have only been a problem connecting to tge dark sky server (they provide sunrise/sunset) and maybe it connected to the TimeAndDate.com server instead as a failsafe, I have also seen their numbers differ between both services for whatever reason.

What apps have you written that are available?