"Rating" the storm just gone
 

As i read various reports from Hebridean Locals stating that it was the
worst storm they can remember, it is clear that rating a storm that way is
fairly hopeless as one would have to be in the same place and in the same
circumstances for each storm to make a decent judgement. Also, having small
children fairly makes you focus more on dangerous weather etc..

I know that for the relations poor family on Benbecula, the fact that there
were worst storms in the sixties will provide no comfort whatsoever.

As usual if the Met Office don't then the news media will. Maybe if each
"extreme" weather event was put into perspective by the Mo, and I can only
think it would be the MO, then we would have less hysteria and more clear
debate on any change in climate that relates to man?


I know Philip does this regularly in the Telegraph and thank goodness, but
maybe there should be an official MO response?

Maybe they have a policy on this and i am missing it or maybe the
information is available and journos just don't investigate like they
should?

I just think that it seems that the news media want more than they are
currently given and that leads to hyperbole and innaccuracy - how about a
spokesman who deals with the media fulltime. Any thoughts?

brian
enjoying a day of sunshine and calm
aberfeldy

"Rating" the storm just gone
 

"Brian Blair" wrote in message
...
As i read various reports from Hebridean Locals stating that it was
the worst storm they can remember, it is clear that rating a storm
that way is fairly hopeless as one would have to be in the same place
and in the same circumstances for each storm to make a decent
judgement. snip As usual if the Met Office don't then the news media
will. Maybe if each "extreme" weather event was put into perspective
by the Mo,

.... interesting concept: I wonder if some sort of mid-latitude 'index'
of severity has ever been attempted, other than a classification by
central pressure?

Martin.


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

"Rating" the storm just gone
 

"Martin Rowley" wrote in
:

... interesting concept: I wonder if some sort of mid-latitude 'index'
of severity has ever been attempted, other than a classification by
central pressure?

Martin

I'm often thinking about how we should try and rate storms in terms of
their measurable track features. If I had to pick one variable for rating
a mid-latitude cyclone it would be peak 24-hour intensification rate over
central pressure.

I feel that the rapid spin-up systems tend to be the most damaging - i.e.
one storm that is 970mb but took 48 hours of gradual deepening from
1000mb to reach that pressure may not be as damaging as one that took 12
hours to do so. Also there's the forward speed factor too - the
ageostrophic pressure-tendancy related winds will be much higher in a
rapidly deepening, fast moving 970mb system than a static, slowly
deepening 970mb system.

There's a paper in Bulletin of the American Met Society going back to
2002 I think of someone's attempts to classify winter storms and came up
with a severity index that had a number of things combined - including
forward speed, deepening rate and central pressure.

Got me thinking now!!

Cheers
Richard

"Rating" the storm just gone
 

"Martin Rowley" wrote in message
...

"Brian Blair" wrote in message
...
As i read various reports from Hebridean Locals stating that it was the
worst storm they can remember, it is clear that rating a storm that way
is fairly hopeless as one would have to be in the same place and in the
same circumstances for each storm to make a decent judgement. snip As
usual if the Met Office don't then the news media will. Maybe if each
"extreme" weather event was put into perspective by the Mo,

... interesting concept: I wonder if some sort of mid-latitude 'index' of
severity has ever been attempted, other than a classification by central
pressure?

Yes, Hubert Lamb does this in Historic Storms of the
North Sea, British Isles and Northwest Europe, published
by CUP, 1991. He discusses different kinds of grading,
from the objective
windspeed^3 * Area affected * Duration

(choosing windspeed^3 rather than windspeed^2 as
representing wind power rather than simply wind force)

an estimation of total damage to the landscape,
or the number of deaths and injuries
or insurance losses

which are each open to interpretation.

I've been toying with the idea of extending this
to all major weather events ... but the problems of
comparing say a windstorm with a killer smog
are virtually insurmountable. Such an exercise
might be interesting, even of some value, but it
would be pretty subjective.

As far as the news media are concerned, they
are not interested in observations or rankings
for the sake of scientific accuracy ... it's simply
that numbers give the appearance of being
scientific or accurate. No-one was the least bit
interested that a river flood similar to the Carlisle
one happens in one catchment or another once
or twice or three times are year ... but
a local inhabitant quoted as saying that it was the
worst in 40 years is exactly what they want to
hear. Some of us may be in a position to set
the record straight (or maybe just "a bit straighter")
in a rather haphazard way because we have
access to one or two tiny corners of the news
media, but I certainly don't expect the Editor of
the Sun to read my Telegraph column and say
"Oh shucks, we got that a bit wrong, didn't we?"

It is, however, beholden on us (as meteo-
rologists and climatologists) to make an
accurate climatological assessment in the
specialist literature so that any subsequent
research does not have to start from scratch.

Philip Eden

"Rating" the storm just gone
 

Hubert Lamb does this in Historic Storms of the
North Sea, British Isles and Northwest Europe, published
by CUP, 1991. He discusses different kinds of grading,
from the objective
windspeed^3 * Area affected * Duration

(choosing windspeed^3 rather than windspeed^2 as
representing wind power rather than simply wind force)

an estimation of total damage to the landscape,
or the number of deaths and injuries
or insurance losses

which are each open to interpretation.

I've been toying with the idea of extending this
to all major weather events ... but the problems of
comparing say a windstorm with a killer smog
are virtually insurmountable.

Philip,

I think you've hit upon the major problem here, any classification is likely
to be very subjective.

The largest sea, and the most damage to the Penzance/Newlyn/Mousehole sea
defences for 40 years was done on 27th October 2004.
The depression itself was nothing really special, and if you lived 2 miles
inland you would have hardly noticed it. It was the track and speed of
movement of the depression, which generated a massive sea from an unusual
direction, combined with an exceptionally high tide which created the
problem. As far as sea conditions are concerned, the reverse of what Richard
Dixon suggests
'that the rapid spin-up systems tend to be the most damaging' that is
normally true.
It's hard to see what classification system would treat it as the major
event it was locally.

Even if you had a 'major coastal event' classification, there would be
difficulties in comparing say the N Cornwall coast where a swell of 10 feet
is not unusual (it was 10-14 feet a couple of days ago at Gwenver north of
Land's End), with a south coast bay where it certainly would be.

Graham

"Rating" the storm just gone
 

What is needed is a parallel to the scales used for hurricanes, eg 1 being
trivial to 5 being devastating.

So Tuesday night's windstorm might have been rated a 4 (as might have been
the October storm of 1987)

I leave it to the experts to decide on the details of the parameters to be
used, but there must be some clues in the hurricane scale that are a good
starting point.

Brian Blair came up with this idea of "ratings" in the first place. Let's
not forget where the rightful credit is due.

Jack

"Rating" the storm just gone
 

"Graham Easterling" wrote Philip,
I think you've hit upon the major problem here, any classification is
likely
to be very subjective.
The largest sea, and the most damage to the Penzance/Newlyn/Mousehole
sea
defences for 40 years was done on 27th October 2004.
The depression itself was nothing really special, and if you lived 2
miles
inland you would have hardly noticed it. It was the track and speed of
movement of the depression, which generated a massive sea from an
unusual
direction, combined with an exceptionally high tide which created the
problem. SNIP

Isn't that the point: i.e. the *effects* (of unusually severe damage,
loss of life etc) are what really matter, rather than a simple comparison
of the "severity" of various events, in terms of windspeed, rainfall,
temperature etc.

Every year, locations at higher altitudes, even in the UK, experience
rainfall and windspeeds that would cause chaos and devastation in lowland
Britain (particularly further south!) but these are unnoticed by the rest
of us, because few, if any, live there, or those who do are used to them
and cope.

Although the press chose to sensationalise it, Mousehole was a case, was
it not, of a topography contributing to a major incident, with injudicious
development (over a very long period, I'll admit) in the narrow valley
exacerbating the effects. There was a large amount of rain in a short
period but when that amount of rain happens somewhere else, less prone to
flooding, not particularly inhabited or with buildings and roads away from
the valley floor, the most we say is that there were a few heavy and
persistent thunderstorms around that day.

Surely it's the severity combined with the unusualness of the event for
that area, coupled with (some might say, leading to) the vulnerability of
the population to that event that is the key, although how you work out
the classification for that is not something I'd like to tackle.

- Tom.

"Rating" the storm just gone
 

The front page intro from Wednesday's Daily Record, Scotlands largest
selling tabloid, read:

"A 124 mph Hurricane hit Scotland last night.."

I guess "A gust of wind measuring 124 mph was measured half way up a light
house, on a cliff, on an uninhabited island in the Outer Herbrides last
night, meanwhile most of urban Scotland experienced gusts of 50-60 mph" -
may not have pleased the Editior so much

Mind you by the same token why not have on the back page

"Rangers 12 Celtic 0" when the score was 1-0 ? - they never seem to get the
footie scores wrong, or say inflate crowds (46,400 saw East Sitrling draw
0-0 at Cowdenbeath etc). I guess it is because they have informed,
interested reporters for football and leave weather to anyone who has got
nowt to do. yet noone has died this year because of football and it is
relevant to only around 1/2 the readership....


"Jack Harrison" wrote in message
.. .
What is needed is a parallel to the scales used for hurricanes, eg 1 being
trivial to 5 being devastating.

So Tuesday night's windstorm might have been rated a 4 (as might have been
the October storm of 1987)

I leave it to the experts to decide on the details of the parameters to be
used, but there must be some clues in the hurricane scale that are a good
starting point.

Brian Blair came up with this idea of "ratings" in the first place. Let's
not forget where the rightful credit is due.

Jack

"Rating" the storm just gone
 

Brian Blair wrote:
The front page intro from Wednesday's Daily Record, Scotlands largest
selling tabloid, read:

"A 124 mph Hurricane hit Scotland last night.."

I guess "A gust of wind measuring 124 mph was measured half way up a light
house, on a cliff, on an uninhabited island in the Outer Herbrides last
night, meanwhile most of urban Scotland experienced gusts of 50-60 mph" -
may not have pleased the Editior so much


I have two views on why these stories are reported in the way that they a

1) Addiction to superlatives - everything has to be bigger, better,
worse, louder (as applicable) than it was in reality.

2) Lack of vocabulary - they do not know what the words they are using
really mean and lack the will to find out.

While o/t, the 'Shipman' case in England some time ago was a rather good
example of both the above, when a news report there suggested that
Shipman was 'the worst mass murderer in history'.

View 1 is demonstrated in their use of 'worst' ... he was a long way
from that ... 'prolific' might be more accurate.
View 2 is demonstrated in their use of 'mass murderer' ... he was not
that. He was of course a serial murderer and they are very different
things.

Perhaps the reason I cannot choose between my two views is that the
reports are usually constructed from a combination of both.

In an ideal world, the news (and after-the-event weather) reports would
tells us the truth, but I am not sure that such a situation has ever
existed. I gave up reading newspapers many years ago ... about the same
time as I realised they would not know the truth if it bit them.

--
Gianna Stefani

www.buchan-meteo.org.uk

"Rating" the storm just gone
 

"Philip Eden" philipATweatherHYPHENukDOTcom wrote:

Yes, Hubert Lamb does this in Historic Storms of the
North Sea, British Isles and Northwest Europe, published
by CUP, 1991. He discusses different kinds of grading,
from the objective
windspeed^3 * Area affected * Duration

(choosing windspeed^3 rather than windspeed^2 as
representing wind power rather than simply wind force)

With many caveats and provisos (and remembering
that Lamb's analysis was for a much, much broader area
than just the British Isles, and included the NE Atlantic)
his " top ten" (actually top 14) for the period 1500-1989
we

Date Index
15 Dec 1986 20,000 (Low 916mbar near Iceland)
10-12 Jan 1792 12,000
4 Feb 1825 12,000
31Oct-2 Nov 1694 10,000
7-8 Dec 1703 9,000 (Defoe's Storm)
22 Oct 1634 8,000
6-7 Jan 1839 8,000
16 Oct 1987 8,000
14-16 Oct 1886 7,000
11-12 Nov 1570 6,000
24-25 Dec 1717 6,000
31 Jan-1 Feb 1953 6,000
2-3 Jan 1976 6,000
23-25 Nov 1981 6,000

I don't have the time to go through post-1989 events
to put them into perspective -- besides, someone may
already have done this and I shouldn't want to repeat
the exercise unnecessarily -- but a back-of-an-envelope
calculation puts the so-called "Burns' Day" Storm at
around 6000, last Friday's at 1250, and Tuesday night's
at 2250.

Philip Eden