[wxqc] wxqc Digest, Vol 42, Issue 15

[webmaster]

Hello Phillip,

>If you mouse over the red 'X' you will get an explanation of the reason.
>Typically the green check / red x are a little more strict than the
>thumbs ratings. Also, the thumbs ratings are more heavily weighted
>towards recent observations.

KLVN has been reporting a bad temp for months and months....how can 
it be off an average of 4 degrees forever and get any green 
thumbs?  Is 4 degrees (and a deviation nearly 7 degrees) still "good 
enough" to get two thumbs up?  Sure wish I could get them to fix 
their station....anyone on this list have any pull with the FAA?

>In a nutshell, the thumbs represent the percentage of observations that
>pass the MADIS checks. These are quite coarse (2 mbar, 6 degrees F for
>temperature etc), but do a good job of ruling out really wacky readings.

ah....so being 4 degrees off forever is good enough to get two thumbs 
up but bad enough to deserve a big red X, got it...

>The red/green classification is a tighter set of checks, but is based on
>the average over the analysis period (normally 28 days unless you
>clicked on one of the embedded links to change it). Thus, you might get
>a red X for pressure if your pressure tracked the analysis well, but
>with a constant offset, and the offset was large enough (say 1.5 mbar).
>it could be that none of your readings fail MADIS checks, but
>nevertheless, they are unlikely to be 'right' (for some value of right).

To keep my barometer tracking nearly correct I have to keep manually 
adjusting it which is why I raised the issue regarding what another 
CWOP person told me about the Davis having a known tracking problem 
that can be fixed by cheating.

>For temperature, a separate analysis is done for daytime readings and
>nighttime readings (omitting the hour before and after sunrise and
>sunset). This allows the system to spot problems like solar heating.

That is interesting, but still makes me wonder are all the other 
stations around me hotter than they should be and I am the only one 
that is right?

>The yellow question mark means that the location check failed (and it
>would have displayed a red cross). The problem may be that the analysis
>is being performed for a location other than the actual observing
>location. This will obviously cause a problem.

I mentioned before that the location shown for the station is in the 
middle of the airstrip and I was told that is where they are always 
shown even though we know they would never mount a weather station in 
the middle of the airstrip.  The actual location for their weather 
station is about .2 mile south of shown location.  I got their 
long/lat one day but lost the info.  I was told "they" had to submit 
the proper information and I couldn't correct their information so I 
apparently didn't keep the info.  If their stations are intentionally 
marked center airstrip instead of actual location that might be a 
part of the explanation?

>[Now I reread your message, I don't understand the yellow question mark
>for KLVN -- it looks like some sort of display problem. When I get back
>home, I'll fix this one.]

They do have a location problem and maybe that is why they have a 
yellow question mark?

Thanks!!

Lew


******************************************
Lew - Amateur Weatherman
lew at farmingtonweather.com
Farmington Weather
www.farmingtonweather.com
Farmington, Minnesota, USA