Choosing a Weather Station?

[Matt Kearney]

Hey everyone,

I'd like to take my weather interests to the next level by purchasing a weather station and joining CWOP. Which weather stations do you highly recommend? Been looking at stations mainly by Ambient Weather and Davis Instruments so far.

I am having a tough time finding ones that meet the ideal siting recommendations by the NWS, especially getting the wind anemometer high enough (10m high). Do any of you use all-in-one units? If putting the height of the station at 6-7' is it pretty easy to note the height of the anemometer in your data recording for CWOP? Should I really be concerned about not having my anemometer high enough?

Appreciate your guidance!

[chuckda...@gmail.com]

I have two weather stations - a Davis VP2 that I've had up for 15 years and an Ambient WS-5000 that I've had for just a few months.  Both are good to very good.  I'm not particularly concerned with wind readings since I live in trees below a small, protective ridge.  Wind readings would not be useful to anyone for "official" reasons.  Other siting requirements would be more concerning if the readings were "mission critical" to anyone but me  I use them because I want to know what's happening on MY roof at MY house.  Both stations are connected to CWOP and various other networks as well.  These are my impressions of both stations:

Davis VP2

Pros

- I trust the readings more.  I really have nothing to compare it to except my Ambient and their numbers differ slightly.

- Davis will maintain the station (at a cost of course).  in 5 years I've sent the sensor array in for refurb once and the send it back completely cleaned and recalibrated to NIST standards.  

- It has been very reliable and parts are replaced at no net cost.  I've had to replace my anemometer several times and a sensor controller board at no net cost.

- The wired anemometer I have is detached from the sensor array so I can mount it on my roof, well away from the sensor array.

- Every weather network accepts data from the VP2.

Cons

- Expensive.  This goes from initial cost to optional items and sensors.  They're all pretty expensive.

- Relatively few optional sensors.  They're limited to soil and temp/humidity.

- Old "looking" console.  There may be newer ones but I haven't looked.

- No "dedicated" Davis Weather Station site for data collection.

Ambient WS-5000

Pros

- Relatively inexpensive.

- Additional sensors are reasonably priced and there are several.  Additional sensors include temp/humidity, lightning, Air Quality (indoors and outdoors) and soil probes.  I have them all.

- Much nicer looking console with more information displayed.

- Dedicated Ambient Weather Network.  I got this station so I could monitor weather at my children's homes after I bought them Ambient Weather Stations (lower end).

- Ultrasonic Anemometer.  I'm not sure it's better but there are no moving parts that would require replacement.

- Installation, setup and configuration is a breeze

Cons

-  Smaller rain gauge collector.  It doesn't hold as much snow.

- Anemometer is integrated into the sensor array so it can't be mounted on the roof unless I mount the entire array there and I don't want to do that.

- I've only had the station a short time so I don't completely trust the accuracy - yet.  The temp is usually within a degree or so from the Davis but has been 5 - 8 degrees different.

- I don't know what the long-term reliability is and I don't know what it would take to get it repaired.

If the WS-5000 had been available 15 years ago I probably would have started with that.  I'm very happy with the VP2 and trust the readings I get.  If you are a serious enthusiast, the VP2 might be a good choice.  If you're a moderate to serious enthusiast and want lots of options at a relatively low cost, the WS-5000 would be better.

[tucso...@gmail.com]

I'd go with the Davis VP2 or VP2+

Thanks,

James B

[tucso...@gmail.com]

Matt, I forgot to mention that if you go with the Davis VP2 or VP2+, you may want to also order and use the Vantage Vue console with it. The Vue console can be setup to display and send Altimeter Pressure rather than Sea Level/SLP pressure. CWOP/NOAA/NWS requires Altimeter Pressure to be sent in. If your station is at sea level, it really does not matter. But...if your at a significant altitude, sending in Sea Leel/SLP Pressure causes lots of problems. The console you get with the VP2 or VP2+ is hard wired to send Sea Level/SLP Pressure, but can be fooled to send Altimeter Pressure. The Vue console also displays more useful information and, for me, is well worth the additional cost.

Thanks,

James B

DW4536

On Sunday, March 6, 2022 at 2:45:27 PM UTC-7 mattke...@gmail.com wrote:

[Paul]

On Sun, Mar 6, 2022 at 4:45 PM Matt Kearney <mattke...@gmail.com> wrote:

I am having a tough time finding ones that meet the ideal siting recommendations by the NWS, especially getting the wind anemometer high enough (10m high).

There's a fundamental tension between rain collection and wind measurement. Rain measurements want mostly calm air  and wind measurements want  obstacle free access to the prevailing wind. While you don't necessarily need a 10 m mast the air movement at 2 m, particularly if there are obstacles like structures, is only loosely related to the prevailing wind. 

If putting the height of the station at 6-7' is it pretty easy to note the height of the anemometer in your data recording for CWOP?

 The weather protocol doesn't include elevation. Station elevation is used for (or to defeat) pressure calculations not wind speed/direction.

Should I really be concerned about not having my anemometer high enough?

This is an interesting question. If you inject bad data into MADIS then best case it's noted in Quality Control (QC) and can be ignored, worst case it can cause good data to be marked as suspect. So if you want to provide NWS with helpful information don't send bad data. That data may be useful to you on  a local level (say you want to compute local ET) even when not helpful at mesoscale.

As an aside: I have a Davis Vue mounted at 2.5 m and VP2 with the anemometer at 22 feet. The wind differences range from similar to dramatically different. My wind data fails spatial consistency all the time but so do the three three airports that surround me.

[Paul]

On Tue, Mar 8, 2022 at 11:31 AM <tucso...@gmail.com> wrote:

Matt, I forgot to mention that if you go with the Davis VP2 or VP2+, you may want to also order and use the Vantage Vue console with it. The Vue console can be setup to display and send Altimeter Pressure rather than Sea Level/SLP pressure. CWOP/NOAA/NWS requires Altimeter Pressure to be sent in.

The software used to query a Davis console (VP2, Vue or Envoy) should read both the LOOP1 and LOOP2 packets to get Station pressure, Altimeter and SLP (Davis formula) readings and send the right one to the aggregator.

[Don Curtis]

Get a weather link live. Much better and easier to read the data from the console and station. You can upload the data to davis' site weatherlink.com directly from the weatherlinkLive and send it from there to any two weather reporters such as CWOP and weather underground every 15 minutes. $0 cost with a basic membership.

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[googl...@tedlum.com]

I'm probably going to just about repeat what others have already said, and that said:

The first choice would be a modular station, like the Davis VP2(+), ahead of all-in-one models. But first take stock of your environment, as it dosen't make much sense to spend a lot of money on a modular station if your site won't allow you to take of the hardware configuration.

Lets go instrument by instrument with "best practice":

Rain gauge:

• Keep it as low as possible
  • Minimizes under-catch caused by wind
  • Makes it possible to perform regular cleaning and removal of the inevitable obstructions
• Keep it 2 x distance from the height of obstructions
  • Obstructions like buildings and vegetation cast a shadow in wind-driven rain, resulting in some under-catch
    
  • Stay 60 feet away from a 30 foot house, or 120 feet away from a 60 foot tree, optimally
  • One caveat is "predominant wind direction". Obstructions down-wind of the typical prevailing wind will have less impact.
    
• Keep it away from surfaces that will result in "splash-in", like the ground and side-walls

Temperature/Humidity

• Should be located above the predominant natural ground cover for the area
  • In cooler, wetter climates that may be grass
  • In warmer dryer climates that may be just sand/dirt
• Avoid the influence of man-made micro-climates
  • Ground irrigation in normally arid climates may produce readings that don't represent what is typical
  • Heat from nearby asphalt surfaces will have some influence if the shield can "see" the surface (radiation), and from the slow drift of heated air (convection)
  • On, over or near a roof is a definite no-no
• Avoid depressions that are likely to have poor air movement and will catch and concentrate cooler air which flows down into it

Wind instruments

• Should be at 10 meters and free of nearby obstructions
• Air which slams into buildings will pick up speed as it's volume will be forced into a tighter space to get around it.
• Air which slams into roofs not only picks up speed but changes it's angle of attack, causing inaccuracy when instruments try to measure that air stream

So, the more of all of that you can manage, the more value a more expensive modular station will have. If your options are very limited to begin with then a modular station probably won't give you much more than a cheaper all-in-one setup. In my area you can tell which stations have the wind instruments closer to the ground and which are up higher - wind readings taken up around 10 meters tend to be about 300% higher then those taken closer to the ground.

On Sunday, March 6, 2022 at 4:45:27 PM UTC-5 mattke...@gmail.com wrote:

[Paul]

On Fri, Mar 11, 2022 at 5:23 PM Don Curtis <dacu...@gmail.com> wrote:

Get a weather link live. Much better and easier to read the data from the console and station. You can upload the data to davis' site weatherlink.com directly from the weatherlinkLive and send it from there to any two weather reporters such as CWOP and weather underground every 15 minutes. $0 cost with a basic membership.

I'm not sure why you responded to my message but ... I would never use or recommend a remote  ("cloud")  system like Weatherlink or Ambient.  In any case the OP asked about upgrading to a better station not a "better" console. If you feed CWOP your data is ingested by Weather Underground (WU) and PWS Weather and I think either look as good as Davis but, of course, that's a personal choice. You can also go right to the "source" and use findu (or MesoWest). Personally I use a Raspberry Pi to collect station data and upload to CWOP and WU. I point WeatherMate (weathermate.net) at my WU instance and it combines my data with NWS forecasts.

[Matt Kearney]

Thanks everyone, all the advice has been very helpful. Based off your comments and my own research I think I'm going to purchase a Davis VP2 with a WeatherLink Live. I live on about half an acre so that all should work great. I think mounting the anemometer on the chimney will be the most challenging next step once my weather station arrives. Need to determine what mounting hardware I'm using, choosing a ground-wire and installing that, and I'm not sure how exactly it connects to the rest of the weather station/WeatherLink Live, especially if the rest of my Davis VP2 is far out in the yard (200ft from the house/anemometer).

[googl...@tedlum.com]

I'd recommend a Solar-Powered Wireless Sensor Transmitter for the remote wind instruments. It just becomes another station (channel) on the console, and integrates the data seamlessly - you tell it what data each "station" supplies. They should be around ~$120.

• No wires to run
• No chance a lightning strike will take out the rest of the station

If you use a fiberglass mast - or PVC, which isn't as rigid - you are in a better situation than using a metal mast. Since the equipment is wireless and there are no conductors which leave the location, much less enter the house, there really isn't a grounding requirement. Still, if you want to ground it:

• Use #10 copper, or #17 copper-clad steel or bronze, or larger, wire.
• Can be insulated or not, but should be Sunlight Resistant (SR) if insulated - otherwise, the UV will break down the insulation and it'll start peeling.
• Use the shortest, most direct run practicable
• DO NOT run it inside the building - even though the NEC allows it.
  
• Support the wire with standoffs, you do not want it to be in contact with the building. If it needs to do it's job, assume it will instantaneously become the melting temperature of the metal in the wire you've used, which will damage and potentially set fire to anything flammable it's in contact with. Support it with the expectation that a lightning strike will vaporize a section of the wire, and you don't want any of the remaining length to wind up being a hazard.
  
• It must be connected to the nearest point in the buildings "Grounding Electrode System" (NEC 250-81) - meaning, most structures already have a grounding system in place which conforms to NEC 250-81, and this ground MUST be bonded to that. You are not permitted, and it dangerous to have, isolated grounding systems.
  

[googl...@tedlum.com]

Scientific Sales often has one of the best prices. Provantage often does too. Rainman Weather is another one to check. Some offer free shipping, others don't. Search "Davis 6332", and you might find more.

[Karl]

Hi

The chimney, while a good high point, may not be the best location for the anemometer due to turbulence caused by airflow over the house. With the VP2 solar version, the anemometer and temp/rh need to be fairly close together.

What I have done, is purchased 2x 3m (sorry I'm metric!) galvanised or aluminium pipes from my local hardware, plus 2 U-bolts. I've then joined them together with may 40cm overlap, and attached the bottom section to a sturdy fence post as far as possible away from trees. I threaded the cable through the pipes with a little section of exposed cable at the overlap between the two pipes, which protects it from the sun. This way I get about 7m for my anemometer above ground which is pretty good. I have a clear view to the north and the west from where we get most of our wind. The bottom of the anemometer is a good spot for the temperature/humidity sensor, and close enough to the house to send the wireless signal to where the display unit and the Weatherlink unit.

You can see picture on the WOW, WEather Observations Website

https://bom-wow.metoffice.gov.uk/observations/details?site_id=894686001

I hope that helps.

Regards

Karl

[Phil Pasteris]

Karl,

I have had a VuePro 2 fully instrumented since April 2014.  Works great.  I replace the fan motors every couple of years and try to keep the beehive clean.  I bought a flag pole and hoisted the wind system up above nearby rooftops.  I use CUMULUS to read the data logger and I have found it to be a very stable system.

Good Luck!

Phil

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