Real-time (or close) Wind Speed?

[Tom K]

Hello everyone,

I am looking to measure wind speed so that I can monitor my retractable awning and Auto-close when the wind picks up. I need as close to real-time wind speed as possible. I don’t have a weather station yet, but was hoping that you could provide a recommendation. I see that an Acurite station can provide updates as often as every 18 seconds - can I do better? I use Home Assistant for automation, so planning on feeding feeding wind speed into HA and then controlling the awning from there.

Thanks in advance!

[Greg Troxel]

Based on your requirements, I think you should be setting up the mqtt
extension in weewx, and publishing loop packets, at least for wind.

I have a Davis Vantage Pro2, and it reports data every 2s. However, not
every LOOP packet, as they call them, has every bit of data. I think
wind is quite frequent, as your desire for rapid wind information is not
unusual. Rain, on the other hand, is less frequent, as the tipping
bucket only tips so often.

There are many stations to choose from, and acurite is a popular
low-cost choice. It seems to be one of the more reliable low-cost
stations. Generally, people like the Davis equipment except that they
complain about how much it costs, and that you have to have separate
data logger, and occasionally slight USB flakiness. But other than that
it's great.


I am not sure how your wind is and how real time you need, if you set
your thresholds right. You'd have to look at high-time-resolution data
for your site for a while.

Keep in mind that weather standards call for your wind instrument to be
10m above ground in the clear, but that this is often too hard.
However, you just need to measure wind so you can infer conditions near
the awning and figure out what's too much in your judgement.

[vince]

On Sunday, May 17, 2020 at 4:02:26 AM UTC-7, Tom K wrote:

I am looking to measure wind speed so that I can monitor my retractable awning and Auto-close when the wind picks up. I need as close to real-time wind speed as possible. I don’t have a weather station yet, but was hoping that you could provide a recommendation.  I see that an Acurite station can provide updates as often as every 18 seconds - can I do better? I use Home Assistant for automation, so planning on feeding feeding wind speed into HA and then controlling the awning from there.

A WeatherFlow station can report wind every 2 seconds and has an ultrasonic wind sensor, so it's very sensitive to changes.

They just came out with a new model literally this week, so you might look for a used SmartWeather station perhaps. 

For integrating with HA, you could pick the data off the UDP broadcasts via a program (I wrote one and lots of people use it), you could integrate that with HA pretty easily I think.   My python program can broadcast to MQTT  that HA could subscribe to, or something like that.  I run my listener and HA in Docker containers on a i3 Intel NUC running ubuntu, but a pi3+ or pi4 could easily handle it.

One thing I need to mention about the WeatherFlow stations is tht the rain is 'not' generally accurate in realtime, if that matters to you.   They have a magic thing called 'rain check' where they apply corrections after the fact and you basically can see the previous day's corrected rain via their website.   All the other sensors seem pretty good though.

[Greg Troxel]

Something else I forgot to mention:

weewx sending loop packets to mqtt works fine, by many reports on this
list, as does other things getting those reports.

However, with Home Assistant, what you do is construct a sensor of type
mqtt, and that sensor sees an udpated value every time it receives a
notification via MQTT. There is a notion of storing each update in a
database, so you can graph it, etc.

I am currently sending only archive packets to MQTT, because I don't
want 43200 temperature datapoints in my HA sqlite3 database, because I
think it might cause trouble and I don't feel the need. Perhaps that is
silly of me and it would work 100% fine. And if it were just temp,
that might be one thing, but there are two temps, two humidities,
pressure, rain, wind speed/direction and so on so really this is 0.5M
observations per day.

So, you might want to think of modifying the mqtt sender in weewx to
send wind every 5 minutes, or when it's higher than the last report, or
something like that, so you can get the rapid response you want without
storing tens of thousands of uninteresting data points.

[Tom K]

Thanks - really appreciate the info. One thing you can do with Home Assistant to make sure you are not filling up your DB with lots of sensor data that is constantly changing is to exclude specific sensors from recorder - looks something like this:

recorder:

  db_url: mysql://homeassistant:xxxxxxxxxxx@core-mariadb/homeassistant?charset=utf8

  purge_keep_days: 2

  exclude:

    domains:

      - automation

      - group

      - script

      - adtimer

    entities:

      - sun.sun

      - sensor.i_air

      - sensor.i_bedroom_2_3

      - sensor.i_cooktop_oven_a

[Matthew Gibbs]

I just came across this thread and I thought I'd add that the Peet Bros Ultimeter stations update wind speeds in 0.5 second intervals:

https://www.peetbros.com/ULTIMETERSPECS.pdf

http://weewx.com/docs/hardware.htm#ultimeter_notes

They are pretty simple to set up and I've found mine to be pretty reliable with weewex.

Matt