Question: Liquid Accumulation

[jhemak]

Describe the issue

Hi @cloneofghosts - I hope you don't mind me creating an "issue" to ask a question. But, do you happen to have a good suggestion for tracking cumulative weekly rainfall? I was thinking of creating a Utility Helper using sensor.pirateweather_current_day_liquid_accumulation that resets weekly, however I'm confused why the amount seems to go down at times (see picture), and I don't know how to configure the helper to produce the expected cumulative total. Maybe you have already found a better way? Thanks in advance!

Home Assistant version

No response

Integration version

No response

Troubleshooting steps

• I have updated my Home Assistant installation to the latest version.
• I have updated the Pirate Weather Integration to the latest version.
• I have gone through the documentation before opening this issue.
• I have searched this repository and API Repository to see if the issue has already been reported.
• I have restarted my Home Assistant installation.
• I have queried the API in my browser to confirm the issue is not with the API.
• I have not included my API key anywhere in my issue.
• I have written an informative title.

[jhemak]

Here is how I configured my helper:

[cloneofghosts]

Outside of the daily resets I'm not sure why exactly it goes down during the day. I know it's from the NBM 1h forecast so I would think it should stay consistent throughout the day. Will ping @alexander0042 to see why that might be happening.

As for the weekly accumulation I'm not sure. I'm not a HA expert but maybe @alexander0042 might have an idea or you could ask on the community forums?

[alexander0042]

Hi- thanks for opening this.

It's a great question, and the "going down during the current day" behavior definitely isn't intuitive, so very worth thinking about. What's happening on that front is that the current_day_liquid_accumulation variable is calculated from adding up all the hourly accumulations from midnight until the current time. On the surface, this should be simple, but under the hood it ends up relying on forecast models that can bounce around a bit. Easiest to explain with an example:

At 5:00 am, you check the forecast and the current day accumulation is 7 mm. This is coming from a combination of 00Z, 01Z, 02Z, and 03Z model runs, using the 1 hour forecast for 0-3, and the 2 and 3 hour forecast for 4:00 and 5:00. Here's what the data looks like:

• 00:00 | 1 mm 00Z model run
• 01:00 | 0 mm 01Z model run
• 02:00 | 2 mm 02Z model run
• 03:00 | 1 mm 03Z model run
• 04:00 | 1 mm 03Z model run; 1 hour forecast
• 05:00 | 1 mm 03Z model run; 2 hour forecast
  Current time, so current day accumulation is 6 mm
• 06:00 | 0 mm 03Z model run; 3 hour forecast
• 07:00 | 0 mm 03Z model run; 4 hour forecast

Now, at 7:00 am you check again, and the current day is now is 4 mm!?! What's happened under the hood is that the 04Z and 05Z model runs have now been ingested, and you know what, the model shifted (probably due to new radar data) and now there's no precipitation during those periods. So now the data looks like:

• 00:00 | 1 mm 00Z model run
• 01:00 | 0 mm 01Z model run
• 02:00 | 2 mm 02Z model run
• 03:00 | 1 mm 03Z model run
• 04:00 | 0 mm _04Z model run_
• 05:00 | 0 mm _05Z model run_
• 06:00 | 0 mm 05Z model run; 1 hour forecast
• 07:00 | 0 mm 05Z model run; 2 hour forecast
  Current time, so current day accumulation is 4 mm

Long story short, so while this isn't' intuitive behavior, it's also not unexpected. What I'd like to do is switch to observed conditions instead of model data some day for time in the past, but until that happens, this sort of thing is pretty unavoidable.

With respect to the home assistant integration, what if you used the hour 1 accumulation sensor instead of the daily one? I'm not super familiar with this helper,, but I think that would give you accumulating hourly precipitation. Let me know if it works, since I'll add it to the documentation in case anyone else is interested!

[jhemak]

Thanks, @alexander0042, for the explanation ... that is very helpful!

This seems to be one of those situations where what seems like it ought to be a simple task (answering the question "How much rain have we had over the past 7 days?") ends up being harder than expected. That always makes me think I am missing the more simple/elegant solution.

In case it's helpful to others, I wanted to share what I am doing:

I was unable to use current_day_liquid_accumulation with a Home Assistant Utility Helper due to the behavior described above where the value can decrease over the course of the day.

So, I ended up creating a trigger based template sensor that stores the day's current_day_liquid_accumulation at 11:59:59. I then have a Utility Helper that resets weekly using this template sensor as its source. So far, it seems to be working. Will report back here if I end up having to make any further tweaks.

- trigger:
    - trigger: time
      at: "23:59:59"
  sensor:
    - name: Daily Rainfall
      unique_id: <value removed>
      state: "{{ states('sensor.pirateweather_current_day_liquid_accumulation') }}"
      unit_of_measurement: "in"