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Old March 7th 05, 04:43 PM posted to uk.sci.weather
danny \(west kent\) danny \(west kent\) is offline
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First recorded activity by Weather-Banter: Mar 2005
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Default Validation of MRF's - reality checks (Longish)

Hi Dave,
Ok, read your post now ;=) .
I think the best we have is the GFS which I hasten to add to all is from the
AMERICANS and FREE. The only problem with it is interpretting it... There
are 4 outputs from it for every 24 hours and you have to know when a, lets
say, 'less than perfect' output has been released. These Medium range
forecasts from GFS *if* you look at them *over 48 hours*, is as good as it
gets right now.

--------------------------------------------------------------

"Dave.C" wrote in message
. ..
I still have little or no faith in any forecast over 5 days out.
I still see little objective appraisal after the forecast period.
The next bit is meant in good faith to illustrate the problems, it is not
intended to start an anti TWO or anti BG thread, although experience tells
me that may happen. My appraisal is also subjective but at least it refers
to what was originally written. This is a quote made in January and there
have been various congratulatory comments on the TWO winter forecast on
their website.
"TWO winter forecast.
Thanks to those of you have contacted us to say how accurate our winter
forecast is proving to be this year. Although it is looking very good at

the
moment, there is still plenty of time for things to go wrong. So for this
reason we will reserve our judgment until the end of the winter.
Issued 16/01/2005"
The late February cold spell has enhanced this feeling.
So here is my subjective view: -
December
Often quiet and dry conditions are expected to persist through much of

the
first half of the month with temperatures remaining close to the average

for
most of the time.

Quite accurate but when this was issued the HP was already in place and to
forecast otherwise would have been difficult.
The second half of the month is likely to bring a notable change to more
unsettled conditions at first, but then a significant outbreak of wintry
weather bringing widespread and sharp frosts, and also a significant risk

of
snow for many areas, although the north and east of the UK look to be at

the
highest risk. We think the cold snap is most likely to occur shortly

before
Christmas.
The timing of this was very accurate but it was the West which was most
affected and it was barely a cold spell by most criteria with little

frost.
For the month as a whole temperatures are expected to be about 0.5C

above
the Central England Temperature (CET) average. Precipitation levels are
likely to be generally below average.
OK ish

--------------------------------------------------------------------------

--
----

January
Overall we expect a colder January with more snow than has become the

norm
during recent years. The first half of the month is expected to bring mild
and damp conditions for a time before much colder weather becomes embedded
across western Europe and pushes towards the UK probably towards the end

of
the second week of the month. This is likely to mean a high risk of snow

for
much of the UK during the middle part of the month. Our expectation is for
south eastern and eastern areas to experience particularly cold weather
during this period. The cold or even very cold theme looks likely to
continue for a time before milder weather returns towards the end of the
month. For the month as a whole temperatures are expected to be about 0.5C
to 1C below the Central England Temperature (CET) average. Precipitation
levels for the month are expected to be close to average.

This was out on just about every count although there were a couple of
slightly colder spells. I believe this was admitted to being poor.
--------------------------------------------------------------------------

--
----

February
Another rather cold month is expected with wintry outbreaks from time to
time bringing the risk of further widespread falls of snow. The month is
likely to begin with mild and rather unsettled weather across the UK.

After
the first week, a return to much colder conditions is forecast and the

risk
of snow will spread from the east across most of the UK. Frosts will
probably develop widely and become severe in places. Cold conditions may
persist for a significant length of time before milder weather comes back
towards the end of the month bringing rain to most areas. For the month as

a
whole temperatures are expected to be about 0.2C to 0.7C below average.
Precipitation levels for the month are expected to be slightly below
average.

At a glance this may appear quite good. But the cold weather did not

happen
till the end of the month, not after the first week. The frosts weren't
particularly severe. This may seem a bit picky from three months out but

if
I now predict a two week hot dry spell at the end of June and we get one

the
middle two weeks of July would that be good?

So we did finally get that kind of promised Easterly two week cold spell.
But this has been predicted for three years.
All in all my conclusion is that it is neither good nor bad- more
meaningless, which is a shame given the hard work that undoubtedly goes

into
it. The same applies to UKMO monthly outlook and any other MRF's IMHO.

Dave