Visibility Reports

[popaviator]

I've noticed that on clear days sometimes the sky condition report varies. Sometimes its 10 and other days it's 20. The last few days the sky condition was reported differently. To me both days we're more or less the same so why the difference in visibility?

 

[FM_Weasel]

Our automated weather reporting equipment only shows a maximum of 10SM. The greatest visibility value you'll get from our ATIS is 10SM, period.

Maybe it depends on the equipment making the observation.

 

[adk]

I believe that if an observer can see a landmark and the distance to it is known, a higher visibility can be reported. If you look at METARs for KBJC you'll see that visibility is reported as 10SM when the report is an AUTO and up to 50SM or so when it's verified by an observer.

 

[PilotChip]

Good question and great responses. I can see how it's confusing. Similar to other facilities, our ASOS reports 10sm and sky conditions below 12,000 agl. As a certified LAWRS observer (Limited Aviation Weather Reporting Station - course and certification required to augment ASOS systems) we can report a visibility that is known at a point or estimated to be beyond that point. For the most part, the ASOS is our official weather reporting system. Only if it is out of service, can we then implement a sole LAWRS observation.