Hi all! I just got my Tempest over the weekend (a very rainy one here in eastern Pennsylvania), and have been trying out some locations around my yard using a tripod. Interested in feedback on whether it’s more important to get a clear view of the area around, or better to be higher vs. surrounding terrain.
My yard, as shown, has a lot of trees along the eastern edge (mine) and southern border (neighbors). The yard also slopes down appreciably. The area around the shed is probably 8-10 feet lower in elevation than the northern fence line. The house is a walk out basement, so the deck is 10 feet above even ground level. I marked in red a few locations I’m considering.
#1 has the clearest view in terms of obstacles or trees. However, it’s in a lower area of terrain compared to other spots.
#2 gets the sensor 8-10 feet higher on the terrain, but will see northerly wind blocked by the house. Prevailing winds at my property are southerly and westerly, though.
#3 gets higher still and moves away from my house but I’m concerned about wind-tunneling effect between my house and the neighbor. My RV provides additional blocking.
#4 About 50 feet from the house and the nearest trees (tall arborvitae which definitely block some wind at/near ground level). I’m also a bit concerned that when we have a fire in the fire pit I may cause erroneous temp readings in the Tempest.
I could go on the roof as well, which would get it a good 20 feet AGL from the front yard, which is probably 30-35 feet higher above surrounding terrain than location #1. I’m concerned about accessing the Tempest for servicing in that case.
Any insight would be greatly appreciated. I read through this entire thread and still haven’t been able to make my mind up.
Hi Bob,
I vote location 1. My reasoning is your wind speeds will always be difficult unless it is higher than everything, so you have to accept your wind speeds can not be accurate, unless on a very tall pole, which is very difficult and introduces vibrations in strong winds. So then all your other values including rain will be best in my opinion at location 1. Where it is surrounded by as much grass area as possible. Where the air temperature can flow without buildings creating microclimates.
Cheers Ian
Hello and welcome to the family!
The general rule of thumb is higher is better, the NWS standard sensor height is 33 feet AGL over grass if at all possible. Vegetation absorbs IR and will give a truer temperature reading. If you placed it on the roof, since it is black, the roof will heat up a lot during sunny calm days and give elevated temperature readings. Obstructions to wind such as buildings and trees will disrupt the wind for a surprisingly long distance down wind and will give reduced wind velocities and will cause the wind direction to fluctuate because of the eddies created. You would have to place the sensor a good 20 - 30 feet above the obstacles to ensure it is in “clean air”. For most of us that just isn’t practical, so we take what we can get. Given all that, I vote for location 1 and get it up as high as you practically can. Use either a sleeve in the ground to be able to pull up the pole for access and pin it to prevent the pole from turning, or make a pivot mount to allow swinging the pole down for access. Go for as stout and high a pole as your budget will allow. If vibrations cause false rain you can try topping the pole with a few feet of heavy wall PVC. The rain sensor seems to work at high vibration frequencies and PVC resonates at much lower frequencies than most steel poles.
The standard for the wind sensor is about 10 meters (about 33 feet) above the average ground height within a radius of 500 feet for an ASOS mounted at an airport (with some potential exceptions depending on potential site specific requirements like nearby buildings, trees, etc) which is where most official reading come from in the US. For temperature sensors the standard is 5 feet AGL (or higher if the average maximum snow depth is above 3 feet) … nominally 2 meters. For precip, the “collector” (in quotes, because ASOS standards don’t really handle haptic rain gauges) needs to be as close to ground level as possible. So, any kind of “all-in-1” station like a Tempest pretty much can only be mounted to one standard.
Thank you all for the feedback and recommendations! I’m going to go with location 1. I’ve had the Tempest on a tripod at that spot all week at about 7’ AGL and it seems to be a good spot. Hopefully in the next weekend or two I can sink a pole or post to permanently mount the unit. Thanks!
Sounds good. I would suggest setting a short piece of pole in the ground that sticks up a foot or so. Either a sleeve or a piece with a tapered/reduced end that you set the main pole in/on. Then drill a hole through the joint and pin it with a sheet metal screw or bolt all the way through just to prevent the pole from rotating at the joint. It would also be a good idea to put a few inches of gravel at the bottom of the hole to set the sleeve on to allow water to drain away. Then it will be much easier to service the Tempest should you need to.
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