Vue rainfall in windy conditions

dionaea · Post by **dionaea** » Mon 28 Mar 2016 11:45 am

I have noticed that in very windy conditions my rainfall more or less fails to be recorded! Presumably the rain is passing more or less horizontally over the top of the gauge. At the moment Storm Katie seems to be at its highest, it is lashing it down with rain & the rainfall has been at 5.8 mm since about 7.00 am BST. Anyone else observed this & any ideas about solving the problem?

Cheers,
Chris

dc1500 · Post by **dc1500** » Mon 28 Mar 2016 3:45 pm

Hi Chris. Looking at it logically if the ground is wet it must be falling vertically at some point! It can't continue horizontally indefinitely so gravity will take over all along that axis and it must fall into the gauge. What it will do is alter the accuracy of the results due to the overall turbulence but it will be the same for standard funnel measuring stations. It's not an exact science.

Tidalwave123 · Post by **Tidalwave123** » Wed 20 Jul 2016 11:45 pm

Many NOAA rain gages are surrounded by 'hanging slats' that can sway with the wind. If you think about it...a typical rain gage is a depression. A strong wind blowing over the depression will cause a decrease in air pressure which can sweep away water. For example, partially fill a spoon with water and blow hard over the spoon...water will be lifted and blown out of the spoon. The slats around the NOAA rain gage greatly decreases the wind speed blowing over the gage, allowing any falling drops to sink into the gage port and down to the tipping bucket.

archae86 · Post by **archae86** » Thu 21 Jul 2016 1:04 pm

Wind effects are a curious topic. In discussing them people tend to focus excessively on the gauge itself and neglect to think about the entire surrounding arrangements.

If you think you have an unusually bad problem, the answer has to be that you have an unusually bad location. You might profit from reviewing other possible locations.

In the end all the rain that falls from the sky has to hit the ground somewhere, but it does not have to hit the ground uniformly irrespective of wind condition. Your goal is to locate the gauge in a place that sees about the average across the range of wind conditions you get.

Experiment! And good luck.

Paragon · Post by **Paragon** » Mon 17 Oct 2016 7:46 pm

I also have wondered if the rain is being properly recorded in windy conditions in my Vantage Vue. I installed a standard plastic rain gauge on a fence post nearby. The two methods agree.

I noticed another problem yesterday. In windy conditions (gusting over 50 km/h, F5 to F6), it registered 20.4 mm of rain when there was none. I have set the today total to zero, now I have to make the other repairs. Clearly there is a pressure difference between the top and bottom of the station and the bucket is being tipped by that difference.

StormCapture · Post by **StormCapture** » Wed 14 Dec 2016 11:35 am

You may have to install Guy wires which are wires that attach to the mounting post that your Vantage Vue is on to the ground or nearby posts to help support it. That will reduce the violent swaying of the station triggering off false rain, fine offsets do this also when no support is there and the gauge is high with the anemometer.

Davis Vantage Vue gauges I'm not a fan of as rain does blow away and collection area is small unlike the pro2 gauge, hence their use of rain errors they have in the Vue console itself.

How high is your Vue off the ground and what is it sitting on?

Cumulus Support