Multiple criteria for change detection--e.g., a 1,000
ft change in ceiling, visibility goes from "unrestricted" to
"fog," winds change angle
by x in less than one hour, winds greater than 10 knots, etc.
Observer has to know the amendments list cold.
Sometimes need to look up the threshold rules in a
notebook called the "Quick Ready Reference," when rare things
happen like summer fog - you get rusty.
Or things that don't happen regularly, like fronts in
the summer - the threshold rule is wind change - for the first front in a
season, you are rusty.
The QRR is obviously heavily used (frayed
It would help to keep the information online: it
would be easier if it were all in an electronic medium - you could view
everything in the same format and convert alpha-numerics to graphics.
ASOS gives alerts based on the threshold rules, but
the auditory alert is very soft.
ASOS data can be unreliable and invalid.
The Observation Sheet is a cumbersome table of