Improbable spikes in rainfall

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Can anyone explain why I have had, on 2 occasions, improbably huge spikes in the rainfall reading? Three day ago, it registered 1644.90mm. I got a similarly preposterous reading a few months ago. It's been fairly steady and accurate in its reading otherwise. We've been averaging 5-20mm per day in the last week or two.

Is it possible that strong wind, from certain angles, could cause the mechanism to misread?

I'm using a 5-in-1 weather station.

Many thanks—Michael

  
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Michael Shirrefs

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  • Curious

Posted 1 month ago

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SharkFanMI

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I've noticed the exact same issue over the last week or so. Yesterday there were two instances of a huge spike out of nowhere:

And for once this isn't a WU issue- I confirmed the same reading on MyAccurite, it's just easier to visualize it on WU.
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Dwight Haverkorn

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This is simple !  When the wind blows it makes the little dipper cups in the rain gauge rock back an forth, giving a false reading.  I live on the plains in Colorado - not a rain forest - High winds one weekend - NO RAIN - rain sensor registered over 40" of rain.  It is a joke.
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Michael Shirrefs

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Thank you SharkFanMI and Dwight ... I figured there must be some sort of venturi effect, forcing the rain cup down or sucking it up, causing the mechanism to misread. Hard to prevent with that design. Is anyone at Acurite taking note???
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Bart

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I don't think it's the wind causing this. I have (and have had for some time) these false rain readings. It's been reported on numerous occasions from numerous people, and all we get from AcuRite is "our developers are aware of an issue that may be causing this to happen", yet they haven't done anything to fix the problem.

Why I say this is probably not due to wind is this (and yours is the same instances that happen to me, just with different values)...notice how you have 2 instances of this phantom rain, but the values of each instance are identical? That would be a pretty strong coincidence if the sensor was reading correctly, but some environmental factor (wind, etc) was causing it. My phantom rain values have always been 56/100" of rain, with the exception of one occurrence in which that reading was 57/100" of rain. I've had roughly 10 of the phantom rain readings occur.
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Bart

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I should add that this all began for me once I switched to Access. I never had this happen while using SmartHub. It doesn't mean that this isn't happening to people using SmartHub, but that wasn't my experience. Don't know what your setup is, but if you're using Access, that is more than likely the problem. That being said, if you are using Access, I don't think it has anything to do with the weather sensor itself, but rather a problem with Access.
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SharkFanMI

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I would agree that this is likely an Access issue as well. First it was rain resets, now it is phantom rainfalls!
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Drew Shock

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I run both the smartHUB and Access and the Access has on multiple occasions recorded rain when we did not have any. My smartHUB reported no rain correctly.

Usually you can tell if it is wind caused. It will still go up in small increments like .01 or .02 inches at each 5 minute interval. If it's an Access issue it will jump like  .21 inches or more in a 5 minute interval.

It's just one of the many issues Acurite has no fix for with the new Access, bummer. If you one of their old smartHUBs you can hook that backup. They are more reliable.
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Michael Shirrefs

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I have to say that I'm still running a smartHub. So, I can't blame an Access. And for accuracy, the first spike was 1896mm and the second spike was 1644mm, which doesn't really fit a repeated number theory in my case. All I can say is that, if I'd been getting almost 2 metres of rain or just over 1.5 metres ... I'd have noticed.
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Drew Shock

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Michael that is a strange one. My rain spikes were only on my Access. I guess if you had some pretty strong consistent winds maybe? 
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Richard Ingersoll

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My station is on a windy hill in Montana. When there are squalls and the wind gusts over about 30mph I see this phenomenon. The mount and the 5N1 shake badly and I believe the little rocker arm sensor must be activated by the heavy vibrations. I attached cords of rope, staked to the ground attached to the top of the mount by bungie cords under tension in a triangular (tripod) layout. This quelled the vibrations substantially. Now I only get the false readings with winds over about 50mph, which are less common.
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Michael Shirrefs

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The vibration theory is interesting. But in my case, the 5-in-1 is bolted on top of a 4x4inch chunky length of wood, which is concreted into the ground. The station is also backed by a solid piece of steel. It's over-engineered to a stupid degree. We cop some monumental winds, being on a hill which is highly exposed to blasts off Bass Straight, south of us in Victoria, Australia.  
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Drew Shock

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That sounds pretty solid. Maybe some weird electronic interference?

My Texas station used to record rain with gust of 21 mph. We changed the mount from PVC to aluminum and now it takes a gust over 40 to record rain. When it does record wind rain, it's usually just .01 of an inch.
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Richard Ingersoll

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I do believe high winds can affect the little rocker arm, regardless of mounting type, since the construction allows for air circulation and water egress. At some level of wind, with this design, it seems likely the sensor will show artifactual readings. That being said, it is worth investigating other factors. My experience is that I have not seen false readings other than when I was handling or moving the sensor unit, or when the wind was very high and gusty. I have 2 stations, a couple years experience and have used both SmartHub and now Access hubs. Of course I would be interested to know if someone comes up with another expianation.