Recent Posts

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1
You can find 'em with a simple google search so a more targeted search might find what you want  ;)
2
Previously with WL1, you could click on any station on the map and get the "blue sky w/clouds" old display screen. This could be added to a website, or bookmarked, etc.

Now with WL2, you only get a gray box with the data and a link to the bulletin (if you have Pro).

I cannot seem to find an equivalent way to access the "EmbeddablePage URL" for other stations (like mine: https://www.weatherlink.com/embeddablePage/show/36dd565fa0c34d82a26e2ce9c1b38abb/wide )

Is there a way to do this other than trying to get the station's owner to send you the link?

Greg H.
3
Hi guys. Don't post here a lot but have been following this thread closely the last day or two since I have been a loyal Davis customer since 1993 when I got a WMII. Still miss that thing sometimes!

I am also a Contract Weather Observer at KCLT so I have a good bit of experience with ASOS. The reason you do not see 98 or 99 percent readings with ASOS is that it directly measures the DP then calculates RH values using ambient temp where Davis directly measures RH then calculates DP.  For example if ASOS measures 70/69 it calculates a RH of 97%. IF the DP moves up to 70 then of course the calculated RH is 100%. You've got to take the differences in the method of measurement into account when comparing your readings to airports.  As for the sensors reading up to 100% even the expensive ones like the HMP155 can have issues. Back a few years ago our ASOS would rarely hit 100% even in fog with visibilities of 1/4mi. Then they changed the sensor and it hits 100% with relative ease.  I used to obsess about getting to 100% too but don't anymore especially when I can adjust the higher readings using Weather Display. 

As for the SHT31 is was initially excited about its improved accuracy but quickly learned it suffered from the same amount if not more drift towards a wet bias as its predecessors.  I think its more of a moisture problem than a dust problem.  I bought several sensors and when I first installed them I would track  about 1-2 degrees higher than surrounding ASOS stations two if which are within 5-7 miles of me (KCLT, KAKH). I do have a lot of vegetation around my house so I take that into account when comparing DP readings to other places. I also have a Viasala HM46 probe I do spot checks with. RH values would be generally the same < 3% difference.  However I would notice after the first few very humid spells where we would have a day or two of RH values remain 90% or above the sensor would never quite come back to its reading prior to that. Differences in RH between the SHT31 and the Vaisala would be anywhere from 4-8% with the SHT31 higher.  I would buy another sensor and the same thing. 

Doing a little research I learned this is really a technological problem.  Electronics and weather specifically moisture do not mix. Therefore when using electronics to measure moisture there are a lot of problems to overcome to get accurate readings over the long term of say more than two years.  The DTS1 ASOS uses to measure DP comes with features to increase sensor longevity.  Its heated in high RH environments to protect it from condensation.  It also undergoes a high heat cycle I believe once a day to cleanse any chemical vapors that it may encounter. Even so, as has been mentioned prior in this thread the NWS replaces this very expensive sensor every 18 months.  I have recently come across a memo that NWS is looking to upgrade a few sensors for ASOS and the dew point sensor is on that list.

Anyway, bottom line is that if you really want to keep accurate readings in humid climates you need to replace these sensors every year to 18months.  I actually went back to the sht75 as they are very easy to switch out and actually seem to drift slightly less than the board mounted sensors. I wired in a female connector then mounted it through a slot I cut into the sensor plate in the FARS unit. Now when I change out the sensors I simply pull out the old one and replace it with the new about every 18 months.  I still use the Davis filter and replace that every year.  Senserion is phasing out the SHT75 however so I think I'm going to use Jerryg's idea and buy a 31 and replace the Davis filter with the SF2 using plumbers putty to see how that works out.

Thanks for this information very good.
You might consider just doubling the Davis filter to avoid any chemical fumes that can damage sensor. SF2  filters are very small so whatever putty or glue used will surely get into sensor while drying.
4
Thanks, Ken. That seems to be loading again.

Greg H.
5
Well, not to be one to rush things... 

I bought a new Sensiron SHT31 sensor from Ryan back in April of 2016.  It's been enjoying a dark, cool existence in a closet ever since. :roll:

I'm getting ready to replace the old sensor (and the rain gauge) and have been following this thread.  I've seen my heat indexes go out of sight for a while now, just not sure how long it's really been doing that.  My records only go back a year and supposedly the latest readings are the highest so maybe(?) this started since last year(?).  It seems I don't really remember the super-high heat index numbers (120'ish) until this year.

Anyhow, it will be interesting to see how things compare with the new(er) sensor installed...when I get it installed.  #-o

A question here (yeah, I need someone to hold my hand)...  What is the "Davis filter cap"???

Thanks!

It's the stock filter Davis uses. The thinking is because of aspiration the sensor gets dirty and makes sensor less accurate. Sensirion has its own filter with better filtration but isn't designed for Davis sensor board.

What I've done is double up on stock Davis filter material and looks good in response time, no difference I see. All new sensors come with filter so just added old filter after washing along with new filter. This doubles filtration and hoping sensor will last longer.
I'll probably change sensor each spring anyway as long as price doesn't take off. Don't think it will the actual sensor is $4 and like electrons may actually trend down in price.
6
Hi guys. Don't post here a lot but have been following this thread closely the last day or two since I have been a loyal Davis customer since 1993 when I got a WMII. Still miss that thing sometimes!

I am also a Contract Weather Observer at KCLT so I have a good bit of experience with ASOS. The reason you do not see 98 or 99 percent readings with ASOS is that it directly measures the DP then calculates RH values using ambient temp where Davis directly measures RH then calculates DP.  For example if ASOS measures 70/69 it calculates a RH of 97%. IF the DP moves up to 70 then of course the calculated RH is 100%. You've got to take the differences in the method of measurement into account when comparing your readings to airports.  As for the sensors reading up to 100% even the expensive ones like the HMP155 can have issues. Back a few years ago our ASOS would rarely hit 100% even in fog with visibilities of 1/4mi. Then they changed the sensor and it hits 100% with relative ease.  I used to obsess about getting to 100% too but don't anymore especially when I can adjust the higher readings using Weather Display. 

As for the SHT31 is was initially excited about its improved accuracy but quickly learned it suffered from the same amount if not more drift towards a wet bias as its predecessors.  I think its more of a moisture problem than a dust problem.  I bought several sensors and when I first installed them I would track  about 1-2 degrees higher than surrounding ASOS stations two if which are within 5-7 miles of me (KCLT, KAKH). I do have a lot of vegetation around my house so I take that into account when comparing DP readings to other places. I also have a Viasala HM46 probe I do spot checks with. RH values would be generally the same < 3% difference.  However I would notice after the first few very humid spells where we would have a day or two of RH values remain 90% or above the sensor would never quite come back to its reading prior to that. Differences in RH between the SHT31 and the Vaisala would be anywhere from 4-8% with the SHT31 higher.  I would buy another sensor and the same thing. 

Doing a little research I learned this is really a technological problem.  Electronics and weather specifically moisture do not mix. Therefore when using electronics to measure moisture there are a lot of problems to overcome to get accurate readings over the long term of say more than two years.  The DTS1 ASOS uses to measure DP comes with features to increase sensor longevity.  Its heated in high RH environments to protect it from condensation.  It also undergoes a high heat cycle I believe once a day to cleanse any chemical vapors that it may encounter. Even so, as has been mentioned prior in this thread the NWS replaces this very expensive sensor every 18 months.  I have recently come across a memo that NWS is looking to upgrade a few sensors for ASOS and the dew point sensor is on that list.

Anyway, bottom line is that if you really want to keep accurate readings in humid climates you need to replace these sensors every year to 18months.  I actually went back to the sht75 as they are very easy to switch out and actually seem to drift slightly less than the board mounted sensors. I wired in a female connector then mounted it through a slot I cut into the sensor plate in the FARS unit. Now when I change out the sensors I simply pull out the old one and replace it with the new about every 18 months.  I still use the Davis filter and replace that every year.  Senserion is phasing out the SHT75 however so I think I'm going to use Jerryg's idea and buy a 31 and replace the Davis filter with the SF2 using plumbers putty to see how that works out.
7
The “white house” covering the sensor on the PC Board—see photo attached.
8
Well, not to be one to rush things... 

I bought a new Sensiron SHT31 sensor from Ryan back in April of 2016.  It's been enjoying a dark, cool existence in a closet ever since. :roll:

I'm getting ready to replace the old sensor (and the rain gauge) and have been following this thread.  I've seen my heat indexes go out of sight for a while now, just not sure how long it's really been doing that.  My records only go back a year and supposedly the latest readings are the highest so maybe(?) this started since last year(?).  It seems I don't really remember the super-high heat index numbers (120'ish) until this year.

Anyhow, it will be interesting to see how things compare with the new(er) sensor installed...when I get it installed.  #-o

A question here (yeah, I need someone to hold my hand)...  What is the "Davis filter cap"???

Thanks!
9
Thanks, Ken!  I see you have data available again, so I just made the change you suggested.
10
I suggest changing to data2.blitzortung.org from data.blitzortung.org for the lightning data .. the data server seems to be overloaded at this time.
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anything