Author Topic: Rain gauge underreporting  (Read 794 times)

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Offline arrowspace90

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Rain gauge underreporting
« on: May 09, 2019, 11:53:33 AM »
Due to all the trees in my suburban back yard, I have for a good while had my Davis VP2 wirelessly set up on the inaccessible 2nd story roof.
Of course, besides not being able to get to it, it's rain counts fall significantly under what other stations in my neighboorhood report online.
I have a manual gauge on a side fence with a less than optimum view of the sky between the houses and with trees near but not straight overhead, and even it reports more rain than my fancy Davis gauge up there at 25 feet in the wind.  I read that wind causes the station to under-report.
So, should I move the ISS down to 6 feet and just leave the anemometer up high?  I would have to look into a 2nd wireless transmitter for it.
I thought about a 2nd wireless rain gauge, but this seems to not be supported.

Offline hwcorder

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Re: Rain gauge underreporting
« Reply #1 on: May 09, 2019, 02:10:59 PM »
When it comes to rain gauges fancy doesn't necessarily mean most accurate.

Yeah you may bring the gauge down off the roof because wind can be a problem. Its also possible that dirt or insects have set up shop in there interfering with the tipping bucket mechanism which does happen from time to time. Its a lot harder to check for that kind of thing and when its up on a roof like that but I understand some of us don't have the best yards for weather stations too.

Offline CW2274

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Re: Rain gauge underreporting
« Reply #2 on: May 09, 2019, 02:50:53 PM »
I read that wind causes the station to under-report.
So, should I move the ISS down to 6 feet and just leave the anemometer up high? 
Actually, other than the effect wind has on all rain buckets, in your case, wind will normally cause an over report due to the fact it's causing the spoon to repeatedly tip prematurely from shimmy. The ISS should definitely not be up where it is, so if you've got a place in the yard for it, bring it down. If that cause more of a "rain shield" for your bucket, oh well, at least you'll be able to clean it out when needed, some report is better than none from a clogged bucket. Besides, you've got your manual gauge as well. As far as a second rain bucket, if you are able/want, you can do as some of us here and get a Rainwise 111 and put it in a more optimal sitting place away from the ISS. It's extremely easy to wire into the ISS and reports exactly the same as stock, but with greater accuracy and consistency. Besides, it'll probably easier to level and secure properly than the ISS's stock bucket, also a plus for more accurate rain readings.
« Last Edit: May 09, 2019, 03:49:04 PM by CW2274 »

Offline dalecoy

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Re: Rain gauge underreporting
« Reply #3 on: May 09, 2019, 05:49:42 PM »

,,, move the ISS down to 6 feet and just leave the anemometer up high?  I would have to look into a 2nd wireless transmitter for it.


The anemometer can still connect to the ISS by wire.

Offline Mattk

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Re: Rain gauge underreporting
« Reply #4 on: May 09, 2019, 06:22:45 PM »
Apart from better maintenance access Rain collector would be better down low even if affected by a few tress rather than up high and wind affected

Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #5 on: May 09, 2019, 06:28:57 PM »
I am coming to that reluctant conclusion

Offline Aardvark

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Re: Rain gauge underreporting
« Reply #6 on: May 09, 2019, 07:09:52 PM »
Also the bucket has to be balanced in 3 directions,  that is leveled...

I wouldnt put it up where the wind blows ..  I am assuming that you have the new hour glass bucket?
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Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #7 on: May 10, 2019, 11:49:38 AM »
yes it has the new bucket and it was leveled pretty well. 
This last rain we had 2 days ago, roof reported 1.18 inch.  Manual gauge on fence reported 1.35. 
A previous rain, heavier, about 10 days ago, roof reported 2.43.  Manual reported 3.20.  Pretty big difference?

It really "bugs" me that I cannot regularly inspect that bucket tipper for problems, mostly for bugs. 
« Last Edit: May 10, 2019, 11:51:32 AM by arrowspace90 »

Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #8 on: May 10, 2019, 12:05:57 PM »
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I made this photo smaller so it could be used here.  Would you folks put the ISS in this spot?

Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #9 on: May 10, 2019, 12:11:16 PM »
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This is where it is now.  You can't really tell, but that is up about 25 feet.  The roof is quite steep and a danger to mature (or otherwise) humans.

Offline drew1021

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Re: Rain gauge underreporting
« Reply #10 on: May 10, 2019, 12:34:56 PM »
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This is where it is now.  You can't really tell, but that is up about 25 feet.  The roof is quite steep and a danger to mature (or otherwise) humans.

Personally I would get everything off the roof. Why you might ask,

1. Too difficult to get at for performing routine maintenance
2. Heat from the roof will cause a large warm bias during the warmer months.
3. Could act as a lightning rod during storms.

I don't know what size your lot is but if possible move it out at least 50' in an open space with as much sun exposure as possible.
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Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #11 on: May 10, 2019, 01:07:11 PM »
Unfortunately, though I agree with your points, 50 feet not available.  My large backyard is completely under a canopy of big oak trees.

Offline drew1021

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Re: Rain gauge underreporting
« Reply #12 on: May 10, 2019, 01:10:26 PM »
Unfortunately, though I agree with your points, 50 feet not available.  My large backyard is completely under a canopy of big oak trees.

I have to ask. How about the front yard?
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Offline CW2274

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Re: Rain gauge underreporting
« Reply #13 on: May 10, 2019, 02:51:25 PM »
My large backyard is completely under a canopy of big oak trees.
Still better than the roof.

Offline JudinNorman

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Re: Rain gauge underreporting
« Reply #14 on: May 10, 2019, 03:07:03 PM »
Unfortunately, though I agree with your points, 50 feet not available.  My large backyard is completely under a canopy of big oak trees.

Stop whining. Chop the trees down, move or be happy with crap data.  Choice is yours. Not much us members can do.

Offline dalecoy

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Re: Rain gauge underreporting
« Reply #15 on: May 10, 2019, 03:37:08 PM »
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I made this photo smaller so it could be used here.  Would you folks put the ISS in this spot?

Yes, but leave the anemometer on the roof.

Offline CW2274

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Re: Rain gauge underreporting
« Reply #16 on: May 10, 2019, 03:53:59 PM »
[ You are not allowed to view attachments ]

I made this photo smaller so it could be used here.  Would you folks put the ISS in this spot?

Yes, but leave the anemometer on the roof.
That pic isn't very revealing but I'm assuming it's the front yard, if so, even with a fence, the ISS may be ripe for vandalism.

Offline drew1021

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Re: Rain gauge underreporting
« Reply #17 on: May 10, 2019, 04:50:51 PM »
VP2 with 24 hour FARS. WU: KNCLEWIS2. CWOP/APRS: DW4712, COCORAHS: NC-FR-7

Offline ocala

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Re: Rain gauge underreporting
« Reply #18 on: May 10, 2019, 05:04:42 PM »
As Dale said leave the anny up on the roof.
Drop everything else to your backyard and put that cocorahs gauge in your front yard.
Unfortunately because of your backyard situation your rain bucket is now a paper weight.
Just use the coco gauge as your official gauge.
Urban siting can be a huge dilemma.

Offline CW2274

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Re: Rain gauge underreporting
« Reply #19 on: May 10, 2019, 05:20:14 PM »
Just use the coco gauge as your official gauge.
Or, as I stated up top, get a RW bucket and stick it in a good place. Having accurate, automated rain counting is really nice.

Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #20 on: May 11, 2019, 12:37:00 PM »
Rain last night recorded on roof as .74 inch.  Manual gauge (it's a nice one) recorded .95.  Significant difference.  I will be trying to line up a guy to remount just the anemometer on the current roof stand with a dedicated transmitter and bring the ISS down to that fence in the photo (it's on the side of the house, NOT behind a security fence).  It's a low crime neighborhood, so hopefully it won't be thieved, though it's a risk.
I can't stand sending out under-reported rain totals!

Offline CW2274

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Re: Rain gauge underreporting
« Reply #21 on: May 11, 2019, 03:26:40 PM »
(it's on the side of the house, NOT behind a security fence).  It's a low crime neighborhood, so hopefully it won't be thieved
I was actually more concerned about short humans...
Ya know, if you put the ISS in the back yard and get the RW to place in a clearing, like maybe next to the manual one, that would solve your problem. Anny remaining on the roof is excellent.

Offline arrowspace90

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Re: Rain gauge underreporting
« Reply #22 on: May 11, 2019, 03:42:58 PM »
I think it will go where the manual one is now.  That one is getting a more accurate total, and I could regularly inspect it.
Hopefully no one will come in the night and steal it or vandalize it just because.

Offline CW2274

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Re: Rain gauge underreporting
« Reply #23 on: May 11, 2019, 03:50:15 PM »
I think it will go where the manual one is now. 
Hopefully no one will come in the night and steal it or vandalize it just because.
Obviously your call, but your faith is certainly stronger than mine, the ISS ain't cheap and people will take anything. It'll certainly cost more to replace it than to get a RW for ~$70 and stick the ISS somewhere safe. Just sayin'...

 

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