Well, there are some nations which have to take winter condition reporting serious.
We:
1. Allways report the numbers, and what they are measured with (SFH, SKH etc)
2. It's regulated in the norwegian BSL (equal to your CNO I think) on what, and on how much contamination the different friction devices can be used on. (Don't have the table at hand, but as an example, I think it's prohibited to use the GRT or TAP on wet snow.)
3. It's regulated in what increments each type of contamination is measured, the increment for dry snow is 8mm, slush 3mm etc)
On all the 'proper' airfields we use the SFH or SKH, and if the measurement is fresh, and not 4 hours old, condtions are monstly better then measured in pretty much all conditions. I belive that all incidents with runway excursions due to slippery surfaces in Norway the last 10 years have been due to
1. Late reporting, last snowtam not reflecting the actual condtions. (The watch commander of the field maint. unit not doing his job)
2. Airline SOP not up to scratch, crew landing/departing in conditions well outside aircraft capabilities.
3. Aircrew unfamiliar with operating on contamination, this is allso VERY true when it comes to TWYs and aprons.
(The concept of not trying to make a 90 degree runway exit at the same speed as in the summer etc......)