Author Topic: Cocorahs gauge compared to NWS gauge funnel droplets  (Read 706 times)

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Offline JudinNorman

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Cocorahs gauge compared to NWS gauge funnel droplets
« on: June 25, 2017, 03:45:31 PM »
Does anyone else notice this?  My cocorahs stratus gauge readings are always 0.01" lower,  sometimes 0.02" if the rain was showery type with dry period in between.  I first thought there was more evaporation taking place out of the cocorahs gauge compared to the NWS gauge however I have gone out to the gauge right after the rain has stopped to confirm that's not the case. I have noticed much more droplets on the funnel of the cocorahs compared to the NWS gauge.  The other day after a rain had stopped I took my finger and swept the cocorahs funnel clean and made the droplets go down in the cylinder.  That seemed to add about 0.01" to the measurement.  I have noticed on the days when my NWS gauge measures 0.01 or 0.02" of rain and the cocorahs gauge just shows a trace. I'm now convinced the funnel of the coco gauge retains more water droplets than the NWS gauge,  even after a water and soap cleaning it still does.
Has others noticed this before?
What type of polish would be good to allow the funnel not retain the large amount of droplets?

Jud

Offline WheatonRon

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Re: Cocorahs gauge compared to NWS gauge funnel droplets
« Reply #1 on: June 25, 2017, 05:21:25 PM »
If my readings from my CoCo gauge and my Davis VP2 were off by only .01 or .02, I would tear down the goal posts in celebration. I have two VP2s, a CoCo gauge and a Rainwise 111 and one day last week my CoCo gauge showed .30, the Rainwise .28, VP2a ..24 and VP2b .18! My differences are not right and being off .01 or .02 I wouldn't worry about it! All four gauges are close to each other and about the same height from the ground.
« Last Edit: June 25, 2017, 05:23:16 PM by WheatonRon »
Davis VP2 with 24 hour FARS, SHT31 (3 complete systems-2 for uploading to the internet the other system for test and play); CWOP--CW5020 and FW3075; WU--KILWHEAT17 and KILWHEAT36; WeatherCloud.net; CoCoRaHS--IL-DP-132; Rainwise 111

Offline ocala

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Re: Cocorahs gauge compared to NWS gauge funnel droplets
« Reply #2 on: June 25, 2017, 06:49:14 PM »
I would agree with the above that if you are off by .01-.02, your doing good.
As for the droplets maybe some RainX or some car polish might do the trick.

Online ValentineWeather

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Re: Cocorahs gauge compared to NWS gauge funnel droplets
« Reply #3 on: June 25, 2017, 09:56:29 PM »
Funny i've noticed the cocorahs records .01 faster than my metal 8" NWS gauge which has a wetting factor of about .005 before it will measure on the stick. A little Rain-X for plastic or car wax on the funnel should increase beading and roll off faster. 
Randy

 

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