New owner- Pro & con observations

[vidguy7]

This is my first post here, so please go easy on me.

Just a bit of background. I have 2 degrees in meteorology, although I never went into the field. However my interest in the field has always remained high and I’ve always had well-respected weather stations at home.

This is my first experience with the WeatherFlow weather station and I certainly liked the concept. I was aware of some of the issues that were being worked on, but I don’t know what the current state of development of these issues are.

It’s only been a bit less than 24 hours since I installed the Air & Sky units, but we’ve had a decent sampling of weather already. I’ve been very impressed with the unit, I really have. I was not expecting the barometric pressure to calibrate as quickly as it did. My temperature, humidity/DP, barometric pressure and rain totals all seem to be spot on. I was surprised at how accurate the rain totals were as I thought that was initially an issue. if it was, it seems to have been solved.

On the wind side it’s a mixed bag. Prior to the onset of a storm we’re currently experiencing here in N.Y., my winds seemed to be very accurate and comparable to my Davis VP2, but a bit higher, which is good as I’ve always felt the VP2 was reading somewhat low. Additionally, the VP2 often misses gusts that occur outside of the reporting period. As an example, my Sky reported a gust to 30mph and my Davis totally missed it. I confirmed conditions at that time by looking at both the neighboring PWS (which obviously vary hugely in accuracy) and the more trusted NWS/FAA locations. The latter reported similar gusts at about the same time. Kudos to WeatherFlow!

However my wind went downhill once we had a period of moderate to heavy rain. Rain intensity has lessened as I post this info. My unit was reporting frequent gusts of 25 to 35mph when, in actuality, the winds may have been 5mph. I confirmed this by observation (branches on trees hardly moving in all areas and finally, stepping out on to my deck where there was almost no wind at all yet a gust was recorded of 25mph. So the combination of wind & rain is obviously causing an issue. I also confirmed this with neighboring stations, both PWS and NWS.

I seem to recall having read that WeatherFlow was working on a fix for this, but I’m not sure what the current status of this is.

The other interesting thing, and contrary to what I thought others were reporting, is lighting detection. In my case we actually had one of those relatively rare winter thunderstorms. Lightning strikes were reported about 5 miles away and thunder was clearly heard at my site. Yet there was no recording of lightning on my unit. I thought others had lightning detection when there was none, yet here I had none when there was.

Finally the last of my 3 issues is a more minor one, involving graphing. For some reason the graphing of rain rates seems very off. Looking at the actual data from my unit, I show a rain rate of .08"/hr (which is correct), but the graphing of that data shows a virtually constant .55"/hour for over 2 hours. That’s not even close to what’s happening over the past 2 hours where the rain has lessened in intensity. So it seems to be a bug in the graphing software (unless I’m not interpreting this graph properly) since the actual data page seems correct.

Other than those 2 points, I’ve been very impressed with the unit as well as the great staff here! Any information on these issues would be greatly appreciated and I hope I’m posting in the correct area.

[vinceskahan]

I know the rain isn’t “calibrated” yet, but it’s pretty hopelessly inaccurate still for many folks.

My VP2 vs. WF vs. CoCoRaHS manual gauge so far this year…

• WF = 3.27 inches of rain
• VP2 = 2.42 inches
• manual gauge = 2.42 inches

Wind is more reasonable given differences in height and location of the stations

• VP2 = max 45 mph, ave 2.3
• WF = max 42.3 mph, ave 2.1

No ice/snow/sleet to mess up the readings yet this year near Seattle.

Temperatures line up ok…

• VP2 = 28.7 F low, 42.8 mean, 59.5 high
• WF = 28.5 F low, 41.9 mean, 54.5 high
  (WF is very shaded, VP2 gets direct sun much more this time of year)

Humidity and barometer tend to match up nicely.

[vidguy7]

That’s interesting. We just had a bit over an inch of rain here (storm has ended) and my Davis reported 1.14" and my WS reported 1.12. So I’m really happy with those results. The combination of wind with rain is another story. The first 6-8 hours of rain was fine in terms of the wind being reported, but the last several hours resulted in erroneously high wind gusts.

I was really surprised by the relatively nearby thunderstorm that didn’t result in any detections by my Air unit. It seems many owners have had the opposite issue, false detections.

[vidguy7]

A new concern here is a frontal passage that occurred a few hours ago. Winds have picked up, temps have fallen and the air is drying out. My VP2 is currently showing a RH of 83% and most stations in my area are reporting low to mid 80% readings, yet my SF is still sitting at a mid-storm RH of 97% (it actually just went up 1%!). I just looked at several other SF units in my area and they’re all in the mid 70s. So I’m now wondering if this is a ‘calibration’ thing or something else. I know certain temp/humidity sensors can have this tendency to continue to read high as humidity drops, but I’m not sure which one is used in the SF. Either way it’s off by quite a bit, but I do have hope in seeing other SF units with more proper RH.

[gizmoev]

@vidguy7

Looking at the actual data from my unit, I show a rain rate of .08"/hr (which is correct), but the graphing of that data shows a virtually constant .55"/hour for over 2 hours.

The graphs are set to specific bins: Light, medium, moderate, etc. That is likely what you are seeing on the graphs. The apps are geared to the general public, not those of us would rather have finer grained graphs.

[vidguy7]

Ah, didn’t realize that gizmoev, thanks.

[gizmoev]

Here is the thread that talks about it: Rain Intensity values

[vidguy7]

David, here’s what doesn’t make any sense to me. Below is David St. John’s explanation of these graphs:

"The blue bar represents the average hourly rate for the time period shown, while the green line represents the daily accumulation (since midnight in the local timezone). The left axis scale applies to both values, but you need to add “per hour” to the rate data. The time period that applies to the blue bar (rate) changes based on zoom level: 1 minute, 5 minute, 30 minute, 3 hour, 1 day. In general the further you zoom in the higher the individual rate values will be, since there is more averaging as you zoom out. Note that when you zoom all the way out, to the 1 day per time step graph, the blue bar (average rate) is not shown"

Now with that in mind, here’s a screenshot of my rain rates during the rain event we had today. If you look at the data, I’m showing an almost constant 0.6" rain rate, yet I never had that much rain in an hour let alone 3 hours (6am-9am). You can see how long that same rain rate occurred, yet my rain accumulation never came close to matching what the rain rate would have implied according to the graph. I’m either confused or the graph isn’t depicting what it should:

[gazzasbees]

@vidguy7

Yet there was no recording of lightning on my unit. I thought others had lightning detection when there was none, yet here I had none when there was.

The AIR unit is very sensitive to orientation, try turning it 45 degrees at a time and then find the sweet spot.
I compare Blitzortung to my AIR and we have a small cell on the radar right now , my AIR has reported 2 strokes locally ( I can confirm as I heard the thunder) and Blitzortung has not reported any within 50km, mine is positioned with the humidity sensor facing due East.

[vtyler98]

If you tap on the graph for the rain rate you’ll see those bars actually represent the “state” of the rain; light, medium, heavy, etc. The bars don’t correspond to the actual in/hr rates but simply what the system classified as “heavy” or “light” rain which is why they’re constant. The line in the graph is the cumulative qpf. Hope that helps!

[gizmoev]

@vidguy7

David, here’s what doesn’t make any sense to me.

Yes, I know. Many of us went through the same thing. What we have to remember is that WF is targeting a market that arent meteorologists, scientists, engineers, mathematicians, etc. I personally would like the actual rain rate graphed rather than a binned value, but then I have to remember that my Physics degree takes me out of the main target market.

[vidguy7]

I’m think you guys are obviously right, but then David’s explanation of the graph was in error when he explained to an owner:

“The left axis scale applies to both values, but you need to add “per hour” to the rate data. The time period that applies to the blue bar (rate) changes based on zoom level: 1 minute, 5 minute, 30 minute, 3 hour, 1 day. In general the further you zoom in the higher the individual rate values will be, since there is more averaging as you zoom out. Note that when you zoom all the way out, to the 1 day per time step graph, the blue bar (average rate) is not shown"

It’s that explanation that threw me because, as you guys are saying, the axis scale on the left does not apply to both values, only total rain accumulation, not rain rate. I think new owners are going to be thrown by that if they read it as I did.

[vidguy7]

Since last night, after our storm passed and a strong cold front went through, I seem to have a new issue. Previously my Sky was reporting winds that were generally higher, but very reasonably so, than my VP2 (my Sky is in the same area, but a bit higher than the VP2 anemometer). At that point things looked great. Of course this doesn’t take into account the issue I previously mentioned when Sky was reporting wind gusts of 30mph when winds were very light during the rain. I think that might have been the water ponding issue, below Sky’s sensors, some have discussed before.

Last night winds in our area were very strong with the onset of cold air advection. Yet my Sky was reporting light winds while my Davis was correctly reporting much higher wind velocities. So during and subsequent to the rain, my Sky seemed confused, reporting high winds when there were none (water ponding for several hours during the rain?) and now reporting very light winds when they’re actually significantly higher. The latter issue is continuing this morning.

Hopefully this can be corrected during the calibration process, but right now it really seems off.

The other thing I’ve noticed is that with large changes in barometric pressure and humidity as we experienced prior to and after the storm, the Air lagged actual readings by a number of hours. Sky’s barometric pressure and humidity took about 5 hours to catch up with actual readings that were displayed on my VP2 and NWS locations hours before.

I wonder if the issue with lagging barometric pressure is the result of the Air being located outside. Typically we have our barometers located inside at a relatively constant temperature. The lagging humidity I’m not sure.

Sorry to relate all these issues, but as a new owner I guess I’m at the beginning of a learning curve…or is it my Sky & Air that’s at the beginning of that curve.

[pachuquear]

The interpretation of rain graphs given on 2018-04-18 was changed with the one provided on 2018-09-18.

The latter applies the grouping of “descriptive” intensity rates into categories with a strong bias towards users in temperate areas. This suggests a worldview of uniformity and linearity in nature that doesn’t exist.

Rainfall intensities in the humid tropics are significantly higher than in temperate areas and require different groupings. Likewise, rainfall rates in semi-arid regions are much lower.

Applying the temperate standard globally means that a significant proportion of rainfall events in, say, the humid tropics will fall into the very heavy and extreme categories. It beats me how this is helping “the average user”…

Since the categories defined aren’t universally applicable, it would be better to use the actual rain rates and show the values on a second y-axis.

To guide “the average user” in their interpretation, categories suitable for other regions (e.g. the humid tropics and semi-arid conditions) should be added to the existing temperate groupings.

[pachuquear]

See also the discussion in Change in graphing rain rate

[vidguy7]

Now that explains it perfectly, pachuquear, thanks. I kept seeing that outdated definition. David updated his post. Thanks much!

Now I just need to get my wind speeds sorted out.

I’m curious if others tend to get a long lag with between actual barometric pressure & humidity changes vs when those changes actually settle down on their Air units.

[vidguy7]

I wanted to include a screenshot of my data during the rain we had yesterday. Winds were very light, yet I got a number of high gusts in the area of 30 and above. As I described above, there definitely were no gusts like that in our area. PWS & NWS stations did not show any such data nor did my VP2 which is mounted about 1’ from the WF station at about the same height. I wonder if this isn’t the rain on plate phenomena.

Today my problem is the reverse, frequent high wind gusts in actuality, but my WF is not recording that. My Davis seems to be showing wind speeds 30-40% above what my Sky unit is showing.

[iladyman]

Hi @vidguy7,

1. When I have wild readings in strength and direction following moist conditions I can be pretty certain it is moisture bubbles or similar at the wind sensors. It is a well known problem they are working on with coating experiments. We must be patient with that.
   History is here: Can Rain Affect Wind Readings - Looks like Frost can as well (Updated)
2. When viewing and displaying wind graphs we get a more accurate idea if it is zoomed into maximum 1 min scale. And if you hover the cursor over a point on the graph we can read the scale.
3. If we include our station number others can go in and examine the data in more detail.
   This is how I highlight my scale and readings I might be concerned about:
   
   
   
   cheers Ian

[vidguy7]

Thanks much, Ian! I kind of assumed the issue was the ponding of water, but it’s good to hear you confirm that. This morning I noticed frost on the surface too with our single digit temps, so it makes sense that this too can mess with the winds. Has anyone tried a coating of car wax? I’d think that would make the surface quite slick. I’m not sure if that would prevent frost buildup or dew (although dew often occurs with light or calm winds, so the wind accuracy impact might be moot in many cases), but I wonder if it would make it less likely for water droplets to hang around in a rain event. Maybe we need a drain hole!

Ian, have you noticed the issue I mentioned with a long lag time for humidity and pressure to stabilize after significantly large changes, like some frontal passages? My Davis settled down much more quickly. It took the Air hours to settle in after my VP2. The VP2 has 24/7 fan aspiration, so I assume that played a role. Since the barometer is indoors and not subject to temperature change, I’d assume that might impact that measurement too.

One fascinating thing I noticed today was the impact on wind velocities as I rotated the pole my Sky sits on. When I rotated it 90-180 degrees from the correct N orientation, my wind speeds increased somewhat. It seemed as if the sensors preferred a different orientation which wasn’t correct in terms of wind direction. Weird. I eventually brought it back to the correct orientation at the sacrifice of some wind speed, hoping a calibration would eventually fix this.

BTW, my station # is 6187. Thanks again.

[gizmoev]

@vidguy7

Has anyone tried a coating of car wax? I’d think that would make the surface quite slick. I’m not sure if that would prevent frost buildup or dew (although dew often occurs with light or calm winds, so the wind accuracy impact might be moot in many cases), but I wonder if it would make it less likely for water droplets to hang around in a rain event.

There are several tests going on with different coatings. I put R1 coatings (a hydrophobic ceramic nano-coating) on one of mine and it sometimes helps and sometimes hurts. There are times my stock one does better and times the coated one does better. For example, here is a polar wind graph of the one with the R1 coating. Everything was normal until around 1900 when the wind direction shown changed nearly 180 degrees. My other stations indicated that the wind was still from the SSW direction. When I inspected the unit I noticed that there was a water droplet on the S sensor and a small one on the E sensor besides several on the reflecting plate. After cleaning off just the droplets on the sensors, leaving the ones on the reflector plate, you can see that next few directions were back in the SSW direction, in line with the actual wind direction.