WOUK66 EGRR 230939
EARLY WARNING OF SEVERE WEATHER

EARLY WARNING OF HEAVY SNOW


ISSUED BY THE MET OFFICE AT 09:39 ON MONDAY, 23 FEBRUARY 2004.

OVERALL RISK ASSESSMENT: THE PROBABILITY OF DISRUPTION DUE TO
SEVERE WEATHER CONDITIONS IN PART OF THE UNITED KINGDOM WITHIN THE
NEXT 120 HOURS IS 90 PERCENT.

REGIONAL RISK ASSESSMENT FOR THE OCCURRENCE OF SEVERE WEATHER
CONDITIONS BETWEEN 12:00 ON TUESDAY 24 FEBRUARY 2004 AND 12:00 ON
SATURDAY 28 FEBRUARY 2004.

NORTHERN SCOTLAND 80[ PERCENT
EASTERN SCOTLAND 80[ PERCENT
SOUTH WEST SCOTLAND 50[ PERCENT
NORTHERN IRELAND 60[ PERCENT
NORTH WEST ENGLAND 50[ PERCENT
NORTH EAST ENGLAND 80[ PERCENT
THE MIDLANDS 50[ PERCENT
WALES 50[ PERCENT
SOUTH WEST ENGLAND 50[ PERCENT
CENTRAL SOUTHERN ENGLAND 40[ PERCENT
SOUTH EAST ENGLAND 50[ PERCENT
EAST ANGLIA AND LINCOLNSHIRE 70[ PERCENT


THIS WARNING IS THE FIRST UPDATE TO THAT ISSUED AT 10:00 ON SUNDAY,
22 FEBRUARY 2004..

THE MET OFFICE IS FORECASTING A COLD FRONT TO MOVE SOUTH ACROSS THE
UK ON TUESDAY INTRODUCING A STRONG FLOW OF ARCTIC AIR INTO NORTHERN
SCOTLAND IN THE MORNING AND EXTENDING ACROSS THE WHOLE OF THE UK BY
EARLY ON WEDNESDAY. SNOW SHOWERS WILL SPREAD SOUTH ACROSS THE
COUNTRY AND BECOME MOST FREQUENT OVER COASTAL AND UPLAND AREAS
EXPOSED TO THE STRONG NORTHERLY WINDS. ALTHOUGH SNOW COULD OCCUR
ALMOST ANYWHERE ACROSS THE UK THROUGH THE PERIOD, NORTHERN AND
EASTERN AREAS WILL BE MOST AT RISK FROM FREQUENT, HEAVY AND
SOMETIMES SQUALLY SNOW SHOWERS GIVING MODERATE (5-10CM)
ACCUMULATIONS IN PLACES AND HEAVY (AS MUCH AS 30CM) IN A FEW EXPOSED
OR UPLAND AREAS. STRONG OR GALE FORCE WINDS AT TIMES WILL LEAD TO
DRIFTING OF LYING SNOW WHILST BLIZZARD CONDITIONS COULD OCCUR IN
EXPOSED AREAS, ESPECIALLY THE NORTH AND EAST WHERE WINDS COULD GUST
TO 60MPH. DANGEROUS DRIVING CONDITIONS ARE EXPECTED AND IT IS LIKELY
THAT SOME UNTREATED ROADS MAY BECOME IMPASSABLE. IN ADDITION, THERE
IS A LOW RISK THAT RAIN COULD TURN TO SNOW OVER PARTS OF SOUTHERN
BRITAIN LATER ON TUESDAY IMMEDIATELY BEHIND THE COLD FRONT CAUSING
LOCALISED PROBLEMS.


FOR ENQUIRIES REGARDING THIS WARNING - PLEASE CONTACT YOUR REGIONAL
MET OFFICE.
TRANSMITTED BY THE MET OFFICE AT 09:39 ON MONDAY 23 FEBRUARY 2004
THIS WARNING WILL BE UPDATED TOMORROW TUESDAY 24 FEBRUARY.

Only 50% is SE. It's like saying, "well it might or might not". Just keep
looking out of the window!

Shaun Pudwell.


"nguk.." wrote in message
...
WOUK66 EGRR 230939
EARLY WARNING OF SEVERE WEATHER

EARLY WARNING OF HEAVY SNOW


ISSUED BY THE MET OFFICE AT 09:39 ON MONDAY, 23 FEBRUARY 2004.

OVERALL RISK ASSESSMENT: THE PROBABILITY OF DISRUPTION DUE TO
SEVERE WEATHER CONDITIONS IN PART OF THE UNITED KINGDOM WITHIN THE
NEXT 120 HOURS IS 90 PERCENT.

REGIONAL RISK ASSESSMENT FOR THE OCCURRENCE OF SEVERE WEATHER
CONDITIONS BETWEEN 12:00 ON TUESDAY 24 FEBRUARY 2004 AND 12:00 ON
SATURDAY 28 FEBRUARY 2004.

NORTHERN SCOTLAND 80[ PERCENT
EASTERN SCOTLAND 80[ PERCENT
SOUTH WEST SCOTLAND 50[ PERCENT
NORTHERN IRELAND 60[ PERCENT
NORTH WEST ENGLAND 50[ PERCENT
NORTH EAST ENGLAND 80[ PERCENT
THE MIDLANDS 50[ PERCENT
WALES 50[ PERCENT
SOUTH WEST ENGLAND 50[ PERCENT
CENTRAL SOUTHERN ENGLAND 40[ PERCENT
SOUTH EAST ENGLAND 50[ PERCENT
EAST ANGLIA AND LINCOLNSHIRE 70[ PERCENT


THIS WARNING IS THE FIRST UPDATE TO THAT ISSUED AT 10:00 ON SUNDAY,
22 FEBRUARY 2004..

THE MET OFFICE IS FORECASTING A COLD FRONT TO MOVE SOUTH ACROSS THE
UK ON TUESDAY INTRODUCING A STRONG FLOW OF ARCTIC AIR INTO NORTHERN
SCOTLAND IN THE MORNING AND EXTENDING ACROSS THE WHOLE OF THE UK BY
EARLY ON WEDNESDAY. SNOW SHOWERS WILL SPREAD SOUTH ACROSS THE
COUNTRY AND BECOME MOST FREQUENT OVER COASTAL AND UPLAND AREAS
EXPOSED TO THE STRONG NORTHERLY WINDS. ALTHOUGH SNOW COULD OCCUR
ALMOST ANYWHERE ACROSS THE UK THROUGH THE PERIOD, NORTHERN AND
EASTERN AREAS WILL BE MOST AT RISK FROM FREQUENT, HEAVY AND
SOMETIMES SQUALLY SNOW SHOWERS GIVING MODERATE (5-10CM)
ACCUMULATIONS IN PLACES AND HEAVY (AS MUCH AS 30CM) IN A FEW EXPOSED
OR UPLAND AREAS. STRONG OR GALE FORCE WINDS AT TIMES WILL LEAD TO
DRIFTING OF LYING SNOW WHILST BLIZZARD CONDITIONS COULD OCCUR IN
EXPOSED AREAS, ESPECIALLY THE NORTH AND EAST WHERE WINDS COULD GUST
TO 60MPH. DANGEROUS DRIVING CONDITIONS ARE EXPECTED AND IT IS LIKELY
THAT SOME UNTREATED ROADS MAY BECOME IMPASSABLE. IN ADDITION, THERE
IS A LOW RISK THAT RAIN COULD TURN TO SNOW OVER PARTS OF SOUTHERN
BRITAIN LATER ON TUESDAY IMMEDIATELY BEHIND THE COLD FRONT CAUSING
LOCALISED PROBLEMS.


FOR ENQUIRIES REGARDING THIS WARNING - PLEASE CONTACT YOUR REGIONAL
MET OFFICE.
TRANSMITTED BY THE MET OFFICE AT 09:39 ON MONDAY 23 FEBRUARY 2004
THIS WARNING WILL BE UPDATED TOMORROW TUESDAY 24 FEBRUARY.

"Shaun Pudwell" wrote in message
...
Only 50% is SE. It's like saying, "well it might or might not". Just
keep
looking out of the window!

Shaun Pudwell.



It was 20% yesterday and some parts of south east
have already had some snow :d

On Mon, 23 Feb 2004 10:08:05 -0000, "Shaun Pudwell"
wrote:

Only 50% is SE. It's like saying, "well it might or might not". Just keep
looking out of the window!

Shaun Pudwell.

Percentage probability indicators are fine but the 50% level is just
another way of saying "don't know". Sometimes standing back and
taking in just what's being said is quote amusing.

50% chance of rain
50% chance of snow

As you say, "it might or might not".

Perhaps I should try this at work... "Well there's a 50% chance I'll
keep within budget" ;-)

--
Pete Lawrence
http://www.pbl33.co.uk
Home of the Lunar Parallax Demonstration Project

"Shaun Pudwell" wrote in message
...
Only 50% is SE. It's like saying, "well it might or might not". Just
keep
looking out of the window!

Shaun Pudwell.

Reminds me of this thread :-

http://groups.google.com/groups?hl=e....svr.pol.co.uk
or
http://tinyurl.com/yqj86

Jon.

On Mon, 23 Feb 2004 10:08:05 -0000, "Shaun Pudwell"
wrote:

Only 50% is SE. It's like saying, "well it might or might not". Just keep
looking out of the window!

Well... no!

I reckon the probability of *disruption* from snow in Central Southern
England for a randomly chosen 5 day period in the Winter is about 5%
and for my location near the Coast nearer 1%. That is, if you issued a
series of 5 day forecasts throughout the Winter (90 days), and
forecast disruption from snow every time, you'd be wrong 95 to 99% of
the time.

So it's quite exciting down here when the probability increases to
40%! OK, that's probably an average for the region and for my location
it would be, perhaps 20% or less. But that's a heck of a lot higher
than the normal 1% to 5% !

--
Dave
Fareham

Yn erthygl , sgrifennodd
Pete Lawrence :
Percentage probability indicators are fine but the 50% level is just
another way of saying "don't know". Sometimes standing back and
taking in just what's being said is quote amusing.

Somewhere in the mountains of Scotland, the chances are doubtless 100%
of snow. Somewhere around the mediterranean probably around 0%. Somewhere
in between has to be a 50%. Would you rather know that it was a 50% chance
or would you like them to toss a coin and tell you that it will definitely
snow?

Personally I appreciate the percentage certainties.

Adrian
--
Adrian Shaw ais@
Adran Cyfrifiadureg, Prifysgol Cymru, aber.
Aberystwyth, Ceredigion, Cymru ac.
http://users.aber.ac.uk/ais uk

On 23 Feb 2004 21:05:42 -0000, (Adrian D. Shaw) wrote:

Yn erthygl , sgrifennodd
Pete Lawrence :
Percentage probability indicators are fine but the 50% level is just
another way of saying "don't know". Sometimes standing back and
taking in just what's being said is quote amusing.

Somewhere in the mountains of Scotland, the chances are doubtless 100%
of snow. Somewhere around the mediterranean probably around 0%. Somewhere
in between has to be a 50%. Would you rather know that it was a 50% chance
or would you like them to toss a coin and tell you that it will definitely
snow?

Part of me does and part of me doesn't.
--
Pete Lawrence
http://www.pbl33.co.uk
Come and visit the "Lunar Parallax Demonstration Project"

"Pete Lawrence" wrote in message
...
On Mon, 23 Feb 2004 10:08:05 -0000, "Shaun Pudwell"

snipPercentage probability indicators are fine but the 50% level is
just
another way of saying "don't know". Sometimes standing back and
taking in just what's being said is quote amusing.

50% chance of rain
50% chance of snow/snip

I think you'll find that the warning is of 50% risk disruption due to
severe weather, heavy snow in this case. It's not saying that there is a
50% risk of snow. Maybe you should you read the explanation behind the
warning i.e 'Snow falling at a rate of approx. 2 cm/hour or more
expected for at least two hours' before dismissing it so lightly.
If it were the case of just a snow forecast, the percentages would be
much greater.

Dave L

On Tue, 24 Feb 2004 10:47:06 -0000, "Dave L"
wrote:

50% chance of rain
50% chance of snow/snip

I think you'll find that the warning is of 50% risk disruption due to
severe weather, heavy snow in this case. It's not saying that there is a
50% risk of snow. Maybe you should you read the explanation behind the
warning i.e 'Snow falling at a rate of approx. 2 cm/hour or more
expected for at least two hours' before dismissing it so lightly.
If it were the case of just a snow forecast, the percentages would be
much greater.

Actually Dave I was being a bit more general. My comments were aimed
at various weather forecasts available to the general public which do
indeed state things like "50% chance of rain".

However, there's still the point that 50% risk of disruption means
"there could be disruption, but it might not happen". For someone that
doesn't want disruption that's a bad thing. For someone hoping for a
day off work it's a good thing.

I'm not saying that percentage indicators are a bad thing so long as
they are interpreted correctly.

It's all a matter of perspective. From the 0% perspective, 50%
probability is pretty good odds that it's going to happen. However,
from the 100% perspective 50% probability is pretty good odds that
it's not.

In reality, a balanced view can only be made if the relative
probabilities are assessed from the 50% point. In other words, it's
likely that it will rain today or it's unlikely that it's going to
rain today. The 50% point then becomes the origin of measurement.
The zero confidence or "don't know" point ;-)

--
Pete Lawrence
http://www.pbl33.co.uk
Home of the Lunar Parallax Demonstration Project