[wxqc] CWOP Information for CW4490 (C4490) in Leander, TX US

[Victor Engel]

You seem to be in a similar situation to me. I have two "official" stations
nearby, KATT, which is at Camp Mabry, and KAUS, which is at Austin
Bergstrom. KATT is closer (3.4 miles, vs. 11.7 miles) and located in an area
more similar to mine than KAUS, so I expect it to track mine more closely.
However, I don't trust it. It frequently has spikes in the data where the
value changes by a millibar from what one would expect from a smooth graph.
There's another station less than a mile from me that tracks mine very
closely. They were even with each other until I made an adjustment last
year. They still track each other closely, but separated by the offset I
entered last year.
http://weather.gladstonefamily.net/qchart/C6155?date=20080601&addnl=AS425&addnl=KATT&addnl=KAUS&Add+to+charts=Add+to+charts&.cgifields=addnl
That close station also uses Davis Vangate Pro hardware.

When I'm really interested in accuracy, for example, around the time I
decided to make an adjustment, I wait for a period of calm winds and
relatively constant barometric pressure. That way I'm less likely to run
into local variability. Then, I rely on the output of KAUS.

Victor

On Sun, Jun 1, 2008 at 4:45 PM, Radiocatus <jhlists at earthlink.net> wrote:

> I, too, have a Davis VP2, and obsessed for a while about variations in
> my readings from the MADIS analysis. I finally decided to use the
> pressure from KONT (Ontario International), about 10 miles away as an
> indicator since should be regularly serviced and calibrated. My VP2
> stays within about 0.2mb of KONT, although the MADIS analysis varies a
> bit due to the several PWS that are included in the analysis.  KPOC
> (Brackett Field) is only about a mile away, but it no longer reports
> temperature, humidity, or rainfall, the anemometer jumps directly from 0
> to 6mph (bad bearings?), and only reports during tower hours. I don't
> trust it.
>
> I've concluded that my temperature and humidity/dewpoint variations are
> due to microclimate variations stemming from my proximity to a large
> reservoir (Puddingstone) about 1.5 miles from my location and upwind
> from me most of the time. MADIS has fits with that.
>
> -Jay AS789
>
> Victor Engel wrote:
> > Please note that when I said I noticed a suspected variation in
> > pressure, I was referring to the difference between my reading and the
> > analysis, not a variation in pressure. I know there is a daily
> > fluctuation in pressure. Presumably it should be the same for everyone
> > in the vicinity.
> >
> > Also, just because a sensor is indoors doesn't mean that it's immune
> > to temperature variations. Such a notion presumes indoor temperature
> > is constant. Over the past 6 months or so my indoor temperature has
> > varied from about 46 to 86. I allow indoor temperature to vary for
> > economical reasons.
> >
> > Anyway, I haven't confirmed the effect I described. It might not even
> > be there. What I seem to notice, though, is that my readings are more
> > likely to be lower than the analysis during warm weather than during
> > cold weather. The difference is slight, since my QC tends to hover
> > between 98% and 100% for barometer.
> _______________________________________________
> wxqc mailing list
> Post messages to wxqc at lists.gladstonefamily.net
> To unsubcribe or change delivery options, please go to:
> http://server.gladstonefamily.net/mailman/listinfo/wxqc
> To search the archives:
> http://www.google.com/coop/cse?cx=008314629403309390388%3Aknlfnptih9u
>
> The contents of this message are the responsibility of the author.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://server.gladstonefamily.net/pipermail/wxqc/attachments/20080601/9b4f7d13/attachment.html