Author Topic: Davis VP2 Rain Gauge  (Read 1416 times)

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Offline WxLover16

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Re: Davis VP2 Rain Gauge
« Reply #25 on: May 29, 2018, 09:50:13 PM »
Well, yeah...the manual will always be more accurate.

Well, yeah...I'll always be a bit lazy.  Just get me in the ballpark and gimmie a beer...  :lol:

Seriously, though, I can't (don't know how) to automatically pull in manual readings into my website.  So getting as close as I can to an automated reading is very desirable for me. 

The above paragraph sounds rather confusing even to me, and I wrote it.

Off-topic here but just wondering, I see your location is basically due south of Montgomery. Did you get into the eye-wall of Alberto?
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Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #26 on: May 29, 2018, 10:00:46 PM »
but in the end the manual will not under-report.
Not necessarily, splash out has been documented by Valentine WX (Randy) when using the Coco in downpours with it's "smallish" depth of cone.

Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #27 on: May 29, 2018, 10:28:16 PM »
but in the end the manual will not under-report.
Not necessarily, splash out has been documented by Valentine WX (Randy) when using the Coco in downpours with it's "smallish" depth of cone.
You know, I was wondering about that.  It does seem rather shallow, but still seems to do better than the Davis.  :???:

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Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #28 on: May 29, 2018, 10:31:01 PM »
but in the end the manual will not under-report.
Not necessarily, splash out has been documented by Valentine WX (Randy) when using the Coco in downpours with it's "smallish" depth of cone.
You know, I was wondering about that.  It does seem rather shallow, but still seems to do better than the Davis.  :???:
Ain't nothin' perfect...

Online ValentineWeather

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Re: Davis VP2 Rain Gauge
« Reply #29 on: May 30, 2018, 12:12:06 AM »
Ain't nothin' perfect...

Not because of lack of effort. :idea:  I've modified a couple tops to prevent splash out and even catch hail now.
Randy

Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #30 on: May 30, 2018, 12:55:09 AM »
Ain't nothin' perfect...

Not because of lack of effort. :idea:  I've modified a couple tops to prevent splash out and even catch hail now.
For sure. Although not as convenient, one can always just remove the funnel and tube and take the catch and pour it into the tube for measurement later. Problem is, it's later. I like knowing now, at a glance, through the dry side of my window.

Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #31 on: May 30, 2018, 10:13:00 PM »
Well, yeah...the manual will always be more accurate.

Well, yeah...I'll always be a bit lazy.  Just get me in the ballpark and gimmie a beer...  :lol:

Seriously, though, I can't (don't know how) to automatically pull in manual readings into my website.  So getting as close as I can to an automated reading is very desirable for me. 

The above paragraph sounds rather confusing even to me, and I wrote it.

Off-topic here but just wondering, I see your location is basically due south of Montgomery. Did you get into the eye-wall of Alberto?
Yeah, it pretty much wiped it's feet on our front door mat.  Not a big event, though.  A lot of rain, some wind, but nothing as bad as some thunderstorms that come through from time to time...just longer period of rain and wind.  It was very unlike Opal that pretty well bullseyed us...that was one storm that I did get a bit nervous about.  Opened the back porch door and shined a spotlight out onto a 75' or so pecan tree only to see it's top bent over by the wind touching the ground...I closed the door and high-tailed it back to the interior hall.  But, when the first eye wall passed us and we were in the eye I went outside and it was as calm as could be (except for my daughters and wife yelling at me to get back inside! :lol:).  The big pecan tree and a cousin of it both had one side of their rootballs pooched up about a foot or so above ground level.  I went back inside, we passed through the other eyewall and the storm started up again.  Both pecan trees were on the ground the next morning, roof damage, a good bit of timber damage.  I don't want to see that again.

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Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #32 on: June 30, 2018, 10:17:29 AM »
I didn't want to leave everyone in suspense so here is an update. :lol:

I just punched the button on a Rainwise 111 gauge.  It'll probably be here the end of next week and hopefully I'll get it installed in a reasonable length of time (I tend to drag my feet sometimes :roll: ).

Has anybody added bird spikes to a Rainwise 111???  I'm sold on them after using the hour-glass, spike-ringed Davis buckets.

Any other modifications that would be good?

Thanks!
Ed

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Offline JCA433

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Re: Davis VP2 Rain Gauge
« Reply #33 on: June 30, 2018, 11:44:22 AM »
The tipping bucket rain gauge part of my VP2 weather station also drastically measured less rainfall compared to the CoCoRaHS rain gauge by about 20 percent.  The recent adjustments I made seemed to have improved the performance to the point that both the VP2 rain gauge and the CoCoRaHS rain gauge are within 4 percent.  However it is too soon to be sure if the VP2 rain gauge will continue to perform well.  Here are the results over the past ten days.


CoCoRaHS gauge             VP2 rain gauge
0.01 inch                                  0
0.01 inch                                 0.01 inch
0.06 inch                                 0.06 inch
0.46 inch                                 0.48 inch
0.01 inch                                 0.01 inch
0.29 inch                                 0.33 inch
0.09 inch                                 0.09 inch
0.15 inch                                 0.15 inch
0.25 inch                                 0.26 inch
0.17 inch                                 0.18 inch
   
« Last Edit: June 30, 2018, 11:57:24 AM by JCA433 »

Offline JCA433

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Re: Davis VP2 Rain Gauge
« Reply #34 on: June 30, 2018, 12:09:52 PM »
I still do not trust the VP2 rain gauge because the mounting pole movement during strong winds increases the error.  Somehow I must prevent the  mounting pole from moving if the rain fall measurement will ever be reliable.  However at least the rainfall measurements are closer.


I forgot to mention that I also replaced the temperature and humidity sensor because it did not for some reason measure humidity over 90 percent.    The new sensor is model 7346.070.  The humidity is often very high here in Miami Dade Florida and maybe this wears out the senor over time?
« Last Edit: June 30, 2018, 12:26:18 PM by JCA433 »

Online ValentineWeather

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Re: Davis VP2 Rain Gauge
« Reply #35 on: June 30, 2018, 01:16:10 PM »
Good deal Ed. You will like the Rainwise. Also glad to see the Davis more accurate after calibration but like JCA433 mentioned the mounting will always be an issue and real test will come with bigger rainfall amounts.

My Texas electronics is main tipping bucket primarily because it has the heater. I trust the Rainwise just as much maybe more  because the TE seems to loose calibration with temperature changes. It works fine in summer but as temps fall calibration gets off while the Rainwise holds calibration down to freezing well. 

Todays rain all gauges were the same TE top gauge Rainwise bottom and both Cocorahs, NWS 8" all came in at .63. This was result when heavy rain doesn't fall the tipping buckets keep up well. 

Just so everyone knows I use a professional calibrator made by Novalynx and go with the recommended rainfall/rate they suggest on tipping bucket gauges. 
Edit: They suggest the 4" per hr. rate which seems high but results speak for itself.
« Last Edit: June 30, 2018, 01:42:11 PM by ValentineWeather »
Randy

Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #36 on: June 30, 2018, 02:55:54 PM »
I just punched the button on a Rainwise 111 gauge. 
=D> Get it level and solidly placed, it'll reward you with excellent accuracy for a tipper.

Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #37 on: June 30, 2018, 02:57:42 PM »
I forgot to mention that I also replaced the temperature and humidity sensor because it did not for some reason measure humidity over 90 percent.    The new sensor is model 7346.070. 
You're gonna love the SHT31. Don't forget the offset if needed.

Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #38 on: June 30, 2018, 10:22:02 PM »
Thanks for the feedback, everybody.  The VP2 ISS is mounted on a 4x4 post so I'm figuring on mounting the Rainwise gauge to the backside of the post.  Will figure out a shelf system for it that is stable.  I'm looking forward to it.  I also need to replace the temp/humidity sensor....got the SHT31 in a box here...somewhere. :roll: 

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Offline DRoberts

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Re: Davis VP2 Rain Gauge
« Reply #39 on: July 06, 2018, 01:52:32 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.


Offline BigOkie

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Re: Davis VP2 Rain Gauge
« Reply #40 on: July 06, 2018, 04:35:55 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.
Interesting. The tipping bucket theory states that the bucket reading should be less.

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Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #41 on: July 06, 2018, 04:40:18 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.
Interesting. The tipping bucket theory states that the bucket reading should be less.

Sent from my MHA-L29 using Tapatalk
The Davis reading less is what I found when I set up the Cocorahs....and that's what prompted me to order the Rainwise bucket.

Btw, the bucket arrived yesterday....hopefully in the next week or so I'll figure out a mounting system for it...

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Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #42 on: July 06, 2018, 04:44:55 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.
Interesting. The tipping bucket theory states that the bucket reading should be less.

Sent from my MHA-L29 using Tapatalk
The Davis reading less is what I found when I set up the Cocorahs....and that's what prompted me to order the Rainwise bucket.

Btw, the bucket arrived yesterday....hopefully in the next week or so I'll figure out a mounting system for it...
Are you going to hard wire it to the ISS?

Offline DRoberts

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Re: Davis VP2 Rain Gauge
« Reply #43 on: July 06, 2018, 04:54:22 PM »
I will have to do a more complete comparison of the two.  My previous post was based on the few observations I have had the opportunity to make. It doesn't rain that often here, and I have had my station operational only since 27 May.

I don't think I have a siting problem with my CoCoRaHS, But I have been wondering about that ash tree.




Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #44 on: July 06, 2018, 05:04:21 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.
Interesting. The tipping bucket theory states that the bucket reading should be less.

Sent from my MHA-L29 using Tapatalk
The Davis reading less is what I found when I set up the Cocorahs....and that's what prompted me to order the Rainwise bucket.

Btw, the bucket arrived yesterday....hopefully in the next week or so I'll figure out a mounting system for it...
Are you going to hard wire it to the ISS?
Yeah, hardwired to the ISS and just have the Davis bucket for back-up (if ever needed) and for spider housing. :-)

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Offline Intheswamp

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Re: Davis VP2 Rain Gauge
« Reply #45 on: July 06, 2018, 05:05:48 PM »
I will have to do a more complete comparison of the two.  My previous post was based on the few observations I have had the opportunity to make. It doesn't rain that often here, and I have had my station operational only since 27 May.

I don't think I have a siting problem with my CoCoRaHS, But I have been wondering about that ash tree.
Keep an eye on it and let us know how it goes.  It seems, from what I've seen, that the usual result is as we mentioned...Davis records lower than the Cocorahs gauges does.

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Offline CW2274

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Re: Davis VP2 Rain Gauge
« Reply #46 on: July 06, 2018, 05:17:57 PM »
Realizing that one measurement does not lead to an indisputable conclusion, I was a bit surprised when both my CoCoRaHS and VP 2 gauges agreed on .29" in a fast hard rain (duration 16minutes).

Usually the CoCoRaHS measures less than the tipping bucket.
Interesting. The tipping bucket theory states that the bucket reading should be less.

Sent from my MHA-L29 using Tapatalk
The Davis reading less is what I found when I set up the Cocorahs....and that's what prompted me to order the Rainwise bucket.

Btw, the bucket arrived yesterday....hopefully in the next week or so I'll figure out a mounting system for it...
Are you going to hard wire it to the ISS?
Yeah, hardwired to the ISS and just have the Davis bucket for back-up (if ever needed) and for spider housing. :-)
You'll like it. I eventually removed the stock bucket and tipping mechanism, not necessary but I didn't see any reason to leave it there, just ma nature's junk collector.

Offline Old Tele man

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Re: Davis VP2 Rain Gauge
« Reply #47 on: July 06, 2018, 05:49:21 PM »
For everyone operating both CoCoRaHS and Davis tipping units, here's a post asking for your help/input:

http://www.wxforum.net/index.php?topic=34669.0
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