"Michael" wrote in message
.. .
Several Flash Warnings mention "Heavy Snow" of 2 to 5 cm in depth. Now to
me less than 1 inch of lying snow is not exactly a heavy accumulation, I
remember one night in Bradford when we had 5 inches in 3 hours or so. Has
Global Warming made the people of the UK so less used to snowfall ? Maybe
the Met Office needs to tame down their seemingly dire warnings ?

Michael.

(Apologies if this message arrives in duplicate as my previous reply seems
to have disappeared into cyberspace)

According to UKMO Meteorological Glossary 'a rate of accumulation of snow
(in the absence of drifting) greater than 4cm/hour'

I also see Steve Loft's report from Glenlivet of 28cm of snow this morning
which is a greater depth than I have ever recorded here (since 1976)

All the best

--
George in Epping, West Essex (107m asl)
www.eppingweather.co.uk
www.winter1947.co.uk

On Thu, 2 Mar 2006 09:52:19 -0000, George Booth wrote:

According to UKMO Meteorological Glossary 'a rate of accumulation of
snow (in the absence of drifting) greater than 4cm/hour'

Some one needs to tell the the Meto's left hand what the right hand is
saying... But that might be station reports rather than trigger levels
for issuance of warnings. B-)

--
Cheers
Dave. pam is missing e-mail

On Wed, 01 Mar 2006 21:05:00 -0500, Michael wrote:

Maybe the Met Office needs to tame down their seemingly dire warnings ?

http://www.meto.gov.uk/weather/europ...ningguide.html

"Heavy snow - Snow falling at a rate of 2 cm/hour or more expected for at
least two hours."

This is what they base the heavy snow warning on. You might be thinking
of "Very heavy snow - Snow falling at a rate of 2 cm/hour or more
expected for at least two hours, accumulating to 15 cm or more."

Looking at that warning guide page have they re-defined "Blizzard"? I'm
sure it was windier (F7/32mph or F8/39mph) and less visibility (50m)
instead of 30mph/200m.

--
Cheers
Dave. pam is missing e-mail

Dave Liquorice wrote:
On Wed, 01 Mar 2006 21:05:00 -0500, Michael wrote:

Maybe the Met Office needs to tame down their seemingly dire warnings ?

http://www.meto.gov.uk/weather/europ...ningguide.html

"Heavy snow - Snow falling at a rate of 2 cm/hour or more expected for at
least two hours."

This is what they base the heavy snow warning on. You might be thinking
of "Very heavy snow - Snow falling at a rate of 2 cm/hour or more
expected for at least two hours, accumulating to 15 cm or more."

Looking at that warning guide page have they re-defined "Blizzard"? I'm
sure it was windier (F7/32mph or F8/39mph) and less visibility (50m)
instead of 30mph/200m.

--
Cheers

It may not fit with the MO rules, but when I was being taught
professional weather observing I was told that it was almost impossible
to know what rate of snow accumulation was going on, especially for
special reports to ATC that were needed with a change of intensity. I
was told the best guide was reduction in visibility. Snow was slight
until the visibility was reduced below 1500m and heavy if visibilty
fell below 800m.

That may be very unscientific, but it was based on the experience of
the old SO observer, and woe-betide anyone who argued with him.

Dave Liquorice wrote:

Looking at that warning guide page have they re-defined "Blizzard"?
I'm
sure it was windier (F7/32mph or F8/39mph) and less visibility (50m)
instead of 30mph/200m.


The official definition *was* (according to the Meteorological Glossary)
as in the Glossary for this ng:-

http://homepage.ntlworld.com/booty.w...F.htm#Blizzard

The '200m' appears to fit, but 30mph is in the 'Force 6' category ....

Beaufort wind scale:-

http://www.zetnet.co.uk/sigs/weather...s/beaufort.htm

so perhaps there has been some downgrading of the criteria?

Martin.

--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm
and
http://booty.org.uk/booty.weather/metindex.htm

In message . com,
writes
snip
Cheers

It may not fit with the MO rules, but when I was being taught
professional weather observing I was told that it was almost impossible
to know what rate of snow accumulation was going on, especially for
special reports to ATC that were needed with a change of intensity. I
was told the best guide was reduction in visibility. Snow was slight
until the visibility was reduced below 1500m and heavy if visibilty
fell below 800m.

That may be very unscientific, but it was based on the experience of
the old SO observer, and woe-betide anyone who argued with him.

Seems to me to be scientific or at least objective in that is based on
an observable criterion. Connected with the variable being assessed
where that variable cannot be measured. Measurement by proxy?

Ask why information is needed. Immediate practical effects for
livestock, mobility and transport, etc. Also degree of after-effects -
albedo or thaw and perhaps flood. Good information from a proxy measure
of accumulation should be better than no information from uncollectable
dat.a

Oh, and many thanks to Philip Eden for initiating the group ten years
back and all those who still make it a source which I learn from.
--
Peter Thomas

Peter Thomas wrote:



Ask why information is needed. Immediate practical effects for
livestock, mobility and transport, etc. Also degree of after-effects -
albedo or thaw and perhaps flood. Good information from a proxy measure
of accumulation should be better than no information from uncollectable
dat.a


Yes, but the after effects were catered for by the hourly/6 hourly
rainfall totals which were derived from the water equivalent of the
depth of level snow that had fallen. An area had to be kept clear each
hour and the previous hours accumulation melted and measured in the
normal way. This could be a nightmare in strong winds as drifting would
make for a good deal of under-reading.

A level depth of 6 inches.