84th AMS Annual Meeting

Tuesday, 13 January 2004: 9:30 AM
Selecting METARs to verify Ceiling and Visibility Forecasts
Room 3A
Tressa L. Fowler, NCAR, Boulder, CO; and J. T. Braid and A. Holmes
Poster PDF (405.0 kB)
METAR station information is used for verification of ceiling and visibility forecasts. Unfortunately, METAR stations are sparse in many areas and quite dense in others. Additionally, the quality and type of information available from METAR stations may differ considerably depending on whether the station is automated or manual, the location, the type of instrumentation, the level of training and expertise of a manual observer, etc. Thus, in order to reduce the effect of these differences on verification, it is desirable to identify a consistent subset of METAR stations to be used for verification.

A comparison of stations with their neighbors can aid in the identification process. All METAR stations in the CONUS are matched with their neighbors within some radius. The agreement of ceiling and visibility observations between the stations is assessed. Disagreement may imply that one station has an incorrect observation or that the environmental conditions differ considerably over the distance between the stations. In the former case, the bad observation should be eliminated. In the latter, both observations should be included to accurately represent the small scale variation in conditions. Preliminary findings of the neighbor comparison are discussed and presented.

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