Page 1 of 1

Rain recording issue

Posted: Wed 03 Dec 2014 11:43 pm
by Warrandyte
I had a challenge yesterday where the rain was just not agreeing across elements in the station.
it was checked an hour after the event (in case of updates), just afetr midnight, and at 0800 the next day (same met day)

Rainfall Rate Max 255.2 mm/hr at 14:32 (quite possible but more likely caused by the wind buffeting the rain guage creating false tips, and nothing can be done about that, just amend the record offline)
Rainfall Today 10.8 mm ((looking at the ground, and the radar this was accurate)

Rainfall Since Midnight 0.9 mm ((ok as it is 0800 hours and there has been a light shower since midnight)

High Hourly Rainfall 21.3 mm at 14:32 If this is true, then why is some of that 21.3 mm not in todays rain, as we are still in the same met day?

any oft he data files are at http://www.warrandytefarm.com/data/ and listing is at http://www.warrandytefarm.com/dir.php
Cheers
Rob

Re: Rain recording issue

Posted: Thu 04 Dec 2014 8:27 am
by steve
The usual reason with Fine Offset stations (as discussed regularly in the Fine Offset section of the forum) is that the station's rainfall counter changed in unexpected ways and Cumulus tried to cope the best way it could. Sometimes this results in today's rain total disagreeing with the other figures, if it has to adjust for the change in the counter; or if, as often happens, the counter suddenly increases, giving a false high rain rate and last hour figure, and then reverts to the correct figure again. Given your apparently incorrect rainfall rate, which corresponds exactly with the high hourly figure, assuming it all "occurred" at the same time, that's the most likely reason in this case. You've said that the high rate was false, so the high hourly figure is as well. If the total is apparently correct, but that rate (and hence the high hourly figure) are false, then Cumulus apparently did a good job in not including that figure in the total.

If you would like me to take a look at what happened to the rain counter, please zip up the diags folder and attach it.