In article ,
John Whitby writes:

"John Hall" wrote in message
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In article ,
Brendan DJ Murphy writes:
I've always wanted to know how much precipitation (in rain mm) is
required to produce 1 foot of snow.

I've heard statements such as "1 foot of snow is equivalent to 1 inch
of rain" (ie: 12:1 ratio)
Ive also heard "1mm of rain is equivalent to 1cm of snow" (ie: 10:1
ratio)
Which one is correct?
snip

The answer is both/neither. The "drier" the snow, the more air it
contains and so the lower the water content. Dry snow will have the 10:1
or 12:1 ratio you quote. Really wet snow, close to turning to sleet/rain
can have a ratio as low as 4:1.

Harold Brooks in earlier post said

"Several years ago, some colleagues and I looked at the snow/liquid ratio
for 1650 snowfall events from a number of sites in the US. The ratio
ranged from ~2:1 to ~50:1. Our mean was 15.6:1 and the median was 14:1
(we used 6-hour snow accumulation obs-the ratios would be smaller for
longer time periods). The paper is online at "

http://www.nssl.noaa.gov/~brooks/pap...reetal2006.pdf

Yes, I saw that after writing my post. I was surprise that the mean and
median values were so high. I would guess that US experience might be
different from that in the UK, because much of their snow falls at lower
temperatures than we are used to here and so tends to be drier.
--
John Hall
"It is a very sad thing that nowadays there is so little useless
information."
Oscar Wilde (1854-1900)