Hi Joe,
1) It appears there is a mismatch between the time of the
observations and the KML file you are referencing. October 18, 12:53
PM MDT corresponds to 1853 UTC and the 19Z URMA. In the KML files,
the observation value is listed as 60.89F, consistent with the
observation table (61F). I believe you are looking at the KML file
from 19Z on the 17th.
2) Wind speed and gust observations from mesonet providers are
rejected, by default, unless the provider or individual station is
"trusted". In the case you've shown, the observation was
rejected for failing the gross error check. The gross error check
will reject obs if abs(ob-guess)/oberror is greater than a prescribed
maximum ratio (R). For wind speed, R=8.0 for METARS and R=5.0 for
mesonets. For wind gust, R=5.0 for both METARS and mesonets.
3) Yes, you can suggest these additional stations, and we will
see if it is possible to add them. This would require some
coordination and may not be possible for all stations, however.
4) The RTMA is a 2.5 km resolution system, and the values are
intended to serve as an average expected value for the grid box.
Therefore, the slight displacement you see likely isn't having a
significant impact on the analysis.
Please let us know if you have any other questions.
Thanks,
Matt
A few questions I was hoping you could answer for me. I'm trying
to understand the URMA process a little better. I use this site
for viewing which obs are used and which are rejected: https://ftp.emc.ncep.noaa.gov/mmb/rtma2/for_eval/ob_files/
(1) Why are "ob value" and the reported temp often
different? This applies to all parameters. (2) Why are so many
stations NOT used for wind speeds/gusts? (3) Can I suggest
additional stations to use when I don't see them plotted? (4)
For our airport (KBIL), the plotted marker and the actual
location of the ASOS are in different locations that are about
250' of elevation apart...is this causing differences in obs/bg
values? I have attached an image w/ my examples. Thanks!
--
Joe Lester RTMA/URMA Discussion Group Virtual Lab
Forum https://vlab.noaa.gov/web/715073/discussions-forums-/-/message_boards/view_message/32667762VLab.Notifications@noaa.gov
--
Matthew Morris
SAIC at NOAA/NWS/NCEP/EMC
5830 University Research Ct., Rm. 2038
College Park, MD 20740
301-683-3758
