Topic: What exactly is a 'rain event'?

[kbellis]

A single rain event of Biblical proportions: it rained for 40 days and 40 nights. But what about all of the other rain events? How long must we wait between the last rain drop of rain event X, and the first rain drop of rain event Y? When does one event end and the next event begin? How much of a respite must there be in between precipitation events before a new event is recognized?

These questions float to the surface after installing my Stratus Rain Gauge a couple of days ago immediately preceding a rain event that evening and into the wee hours of the next day, and then starting to analyze the data. Another rain event began early this morning and it's been lightly raining and misting all day with the forecast suggesting it won't stop until tomorrow.

 [ You are not allowed to view attachments ]

 [ You are not allowed to view attachments ]

Rain Event X
begin: 20190418 21:00
end: 20190419 04:45

Rain Event Y
begin: 20190420 03:00
end: 20190421 TBA

So why this question? Notice that the WS-2902A judged that 22.25 hours wasn't enough time to separate it into two rain events, but the WS-2000 deemed it enough time. In each case, there appears to be some sort of rule being applied, but clearly the two devices aren't playing by the same rules.

[Mattk]

Different systems treat rain events differently can't help you for your system, I can help you if it was a Davis system, event starts on the second tip and ends when there has been a period of no rainfall for 24 hours.

[galfert]

According to Ambient Weather the following is the definition for a Rain Event which contains a conversion error.
EDIT: The error has now been fixed on Ambient's site. It now reads correctly 1 mm (0.039 in).

• Rain event is defined as continuous rain, and resets to zero if accumulated rainfall is less than 10 mm which should read 1 mm] (0.039 in) in a 24 hour period.  Some weather stations may calculate this slightly differently and the customer should reference the User Manual.

Source:
https://ambientweather.net/help/rain-increment-definitions/

As you can see that definition applies to just about all models including both the WS-2000 and the WS-2902A. The fact that there is a discrepancy in your results probably indicates that something is amiss. It could be the WS-2000 firmware (as in a bug) as rain rate was recently introduced and although that should not have anything to do with rain event you just don't know. Or it could be a missed broadcast caused it to think the rain event was over. Or if you recently upgraded to 1.4.1 perhaps that caused the reset. Or if the WS-2000 got a power outage it would also reset. The WS-2902A has battery backup but the WS-2000 doesn't.

[galfert]

* But there is that disclaimer that some stations will calculate differently. I haven't consulted the manual as it states to do. So it is possible the WS-2000 is resetting at midnight maybe? Or something else? I'll have to consult the manuals.

[kbellis]

Matt and George,
Thank you for your replies.

The defined terms of the rain event; i.e., 0" and <10mm in a 24-hour period for Davis, pg 24 under 'Rain Storm' and Ambient, respectively, are similar with the critical time interval of 24 hours the same, and supports the observed methodology used by the WS-2902A.

As for the WS-2000, and just as a reminder, my WS-2000 was updated to v1.4.1 before any rain event analysis began. There haven't been any power interruptions and both the WS-2902A and the WS-2000 have reported the exact same times and rainfall values.

I cannot say when the non-compliant rain-event-issue with the WS-2000 first began, only that it was first noticed as reported herein this thread, and that firmware v1.4.1 was associated with these observations.

FWIW, this morning's observations show the continuance of the same event on the WS-2902A which began 20190418 21:00, and that the WS-2000 is still tracking the event which began 20190420 03:00.