MX alarm email

[freddie]

I had an email from Cumulus when my station generated a spurious gust of 48 knots this afternoon. This is the email text:

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A Cumulus MX alarm has been triggered.
A data spike from your weather station has been suppressed.
Last error: Wind or gust difference greater than spike value - Gust: NewVal=48.3m/s OldVal=23.7m/s - Wind: NewVal=4.9m/s OldVal=4.9m/s

A few points to note:

• I don't have any spike settings enabled
• Units are incorrect in the email.

FWIW I do have the data spike alarm enabled (and the email setting on it).

[mcrossley]

Can you double check the spike settings for me? I'll take a look at the code later.

For some reason all spike checks are done in standard units, not user units.

[freddie]

Spikes are all set to 999.

[mcrossley]

OK, a quick check of the code shows that the spike routine is common with the limit values.

Calibration settings > Limits

You must have a value set for the max speed allowed (it defaults to 90 m/s), I have mine set to 45 m/s (100 mph).

[freddie]

Correct. Mine is set to 40m/s. But that limit wasn't reached.

[mcrossley]

The message says it had a gust value of 48.3 m/s that it ignored?

[freddie]

Yes it did - but the value recorded was 48 knots - which is only about 24 m/s. I actually saw it happen on the gauges, which is how I know it was spurious.

[mcrossley]

"on the gauges" - Which gauges?

You wouldn't see the 48.3m/s (108 mph) in CMX because it was suppressed. The email shows the previous unsuppressed reading was 23.7 m/s (53 mph, 46 knots).
Without a log file including data logging I cannot say what other values were received at the time.

Was anything untoward recorded on wl.com?

[freddie]

Sorry, I don't use wl.com.
By gauges I meant the dashboard gauges - and I saw 48 knots, not m/s.
Attached is the log.

Many thanks.

[mcrossley]

Here are the data packets sent by the station along with the wind speed in mph...

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14:43:17 LOOP: Data - 10: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E3-01-1B = 27 mph
14:43:19 LOOP: Data - 11: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-31 = 49 mph
14:43:21 LOOP: Data - 12: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-31 = 49 mph
14:43:23 LOOP: Data - 13: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-31 = 49 mph
14:43:25 LOOP: Data - 14: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-1D = 29 mph
14:43:27 LOOP: Data - 15: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-2E = 46 mph
14:43:29 LOOP: Data - 16: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-35 = 53 mph
14:43:31 LOOP: Data - 17: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-35 = 53 mph
14:43:34 LOOP: Data - 18: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-35 = 53 mph
14:43:35 LOOP: Data - 19: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-6C = 108 mph
14:43:37 LOOP: Data - 20: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-6C = 108 mph
14:43:39 LOOP: Data - 21: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-6C = 108 mph
14:43:41 LOOP: Data - 22: 4C-4F-4F-3C-00-91-06-C7-73-78-02-32-E2-01-6C = 108 mph
14:43:43 LOOP: Data - 23: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E2-01-30 = 48 mph
14:43:45 LOOP: Data - 24: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E2-01-30 = 48 mph
14:43:47 LOOP: Data - 25: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E2-01-30 = 48 mph
14:43:49 LOOP: Data - 26: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E1-01-30 = 48 mph
14:43:51 LOOP: Data - 27: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E1-01-16 = 22 mph
14:43:53 LOOP: Data - 28: 4C-4F-4F-3C-00-92-06-C7-73-78-02-32-E1-01-11 = 17 mph

All four 108 mph values were discarded.

The highest valid speed recorded was 53 mph = 46 knots

Assuming there was no higher speed that day, that should have been recorded as the maximum gust speed. What does CMX say it was?

[freddie]

The highest valid speed recorded was 53 mph = 46 knots

Assuming there was no higher speed that day, that should have been recorded as the maximum gust speed. What does CMX say it was?

The figure I saw on the dashboard gauge and the wind speeds tile was 48 knots. I ran outside to see what was happening. It was pouring with rain and gusty, but not to the magnitude of 48 knots (I also had the window open and would have heard a 48 knot gust). I then checked my realtime DB table and discounted most of the values captured in the 14:43 UTC minute. So all have been edited (including average speed) to remove the spurious values.

So CMX now says the maximum gust speed was 25 knots, recorded at 14:43 - which fits in with what I was observing at the time. The original highest value was 48 knots.

I've had my current anemometer installed for 10 months. There is an ongoing problem with it in that it refuses to record direction between about 330 degrees and 360 degrees. Thinking about it, there was a spurious high gust last summer during heavy rain which I had to edit out too (73 knots!). I did email prodata last summer but didn't hear back. Maybe it's time to email again!