3.6mm of rain at midday

Big Daddy · Post by **Big Daddy** » Fri 13 Dec 2013 9:53 pm

Hi,
I have suddenly started registering 3.6mm of rain on a daily basis and these tend to occur around midday. It started happening a few days ago and unfortunately right around the time I upgraded to 1.9.4. I am sure the 2 are not related as I have found no other report of this in the forum. Has anybody seen this before or does anybody know what may cause it.

I have attached the rain graph to show. As you can see today it happened but it also was raining at the time so it continued to increase as expected in the normal fashion.

I could check (again) for wildlife inside the rain gauge but I have already taken precautions by fitting wire mesh or it could be an extremely punctual spider.

Many Thanks for any suggestions.

Andy

captzero · Post by **captzero** » Fri 13 Dec 2013 10:17 pm

Hi Andy,
It could be a wind gust or a bird shaking the rain gauge. Do you have wind gusts at around the same time for those days?

Post by **steve** » Fri 13 Dec 2013 10:56 pm

If you zip up the diags folder and attach it, I'll take a look.

Big Daddy · Post by **Big Daddy** » Fri 13 Dec 2013 11:09 pm

Captzero,

My rain gauge is extremely well seated and doesn't normally suffer from wind shake. In the recent St Jude storm it didn't tip once except when it was raining and it was getting battered by 40-50mph wind gusts. However your suggestion pointed me to look at the other graphs and interestingly and oddly enough there are other sudden changes in the weather pattern around the same time. Yes there are wind gusts around this time, even though previous and past this the wind looks fairly calm, sharp drops in humidity and then back to previous levels, sudden sharp increases in pressure even when the trend is falling. I am suspecting that possibly there is an issue with the outdoor sensor / transmitter unit. We have had some icy mornings this last week and I am just wondering if it may have affected the battery's or the actual transmitter unit.

Will investigate tomorrow when its light.

Many Thanks
Andy

Big Daddy · Post by **Big Daddy** » Fri 13 Dec 2013 11:13 pm

Steve,
Our posts must have just crossed.

I have attached the diags as requested.

If I make progress with the battery / sensor unit tomorrow I will let you know.

Thanks
Andy

beteljuice · Post by **beteljuice** » Fri 13 Dec 2013 11:52 pm

.. to look at the other graphs and interestingly and oddly enough there are other sudden changes in the weather pattern around the same time.

Perhaps some radio interference ?

AllyCat · Post by **AllyCat** » Sat 14 Dec 2013 10:08 am

Hi Andy,

Looking at the logs, it appears that the first tip did indeed occur very close to midday on 10th, but at 12.40 and 12.20 on the subsequent two days. You're using a very coarse resolution of the time axis on the graphs, so the exact times are not clear. But the "unexplained" rain appears to be only one tip each day, so your title seems rather misleading.

Personally, I've experienced occasional "phantom" single tips, when it definitely wasn't raining (and I think a few others have reported something similar as well) but not with that regularity (which might be just a coincidence of course).

In my case it appears to be related to a rise in temperature, perhaps even the sun starting to strike the gauge. My guess is that one of the buckets in the seesaw is already very nearly full of water (due to previous rain or perhaps dew) and then the heat either warps the body of the gauge very slightly or some droplets held on the slope of the funnel (due to surface tension) of the gauge are released, casuing the seesaw to finally tip.

However, some other external "interference" (either electrical or physical) might be responsible, so I think you will need to make some more regular observations to see what might be the cause.

Cheers, Alan.

PS: The pressure sensor is located in the Console, so a potential fault with the transmitter is unlikely to be responsible for barometric pressure measurement "issues".

Post by **steve** » Sat 14 Dec 2013 10:15 am

AllyCat wrote:Looking at the logs, it appears that the first tip did indeed occur very close to midday on 10th, but at 12.40 and 12.20 on the subsequent two days. You're using a very coarse resolution of the time axis on the graphs, so the exact times are not clear. But the "unexplained" rain appears to be only one tip each day, so your title seems rather misleading.

Yes, that confused me, too. It's just a single tip. The counter doesn't go back down again, so as far as the station is concerned, it's recorded a tip of the rain gauge.

Big Daddy · Post by **Big Daddy** » Mon 16 Dec 2013 6:11 am

Firstly - Thanks for all your responses and advice and secondly my apologies, I indeed put the . in the incorrect place when typing and it is you rightly say .36mm not 3.6.

On Saturday I realized that when updating Cumulus on my PC that I had to move my weather station console to gain access to my pc. It moved only about 10 inches from where it was originally located. I moved the console back to its original position and everything seems to have settled down again. It could be purely coincidental but I will keep monitoring. It could be it moved into an area slightly more affected by some RF.

Thanks
Andy

nitrx · Post by **nitrx** » Mon 16 Dec 2013 11:14 am

You said you had icey nights wasn't melting dew ?

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3.6mm of rain at midday

3.6mm of rain at midday

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