What's so special about a forecast?
- it's probably the only forecast of its kind, .
- it's a T+24 DAY forecast
- it's a special weather situation with potentially interesting
developement
- it's experimental and describes the weather variations down to 3
hours.

While completing the series of forecast charts for T+10 day to T+20
days, I came across the chart for 20th November 2003, which attracted
my attention straight away. because of a secondary depression coming
into the country from the SW which had every possibility of bringing
strong winds along with it.

The next step was to check the forecast 500mb-top to see what effect
the surface situation would have in the upper atmosphere. On the day
in question, the 00Z chart showed an upper-air, narrow trough stretching
N-S about the length and width of Britain, placed just down the W
Irish coast.

On the surface at 00Z, the charts show a medium sized depression just
to the W amd NW of Scotland with a trough southwards to the SW of
Ireland. Winds over the whole country are generally from the S. South
of Ireland - and to the SW of England - a secondary depression is
expected to move ENE, across England, and into the North Sea to be near
Holland on 21st November 2003 at 00Z.

According to the charts, I can be sure that a secondary depression.will
be present on or near the position indicated. What is difficult to
forecast, is the strength of the wind. Among other things, the
variation in actual temperature can alter the central pressure of the
secondary depression. The charts do suggest that the stronger winds
should be found over SW England rather than SE England., and that the
secondary depression should fill more and more as it moves into the
North Sea.

Following the depression across the country means forecasting at short
intervals. Usually 3 hour intervals don't show much change - especially
when forecasts such as these are already working at "noise level". But
it is just possible to pick out the position of the depression and this
I have done where some clarity has been evident..

At 0600Z, rain showers should cover N, NW and W Scotland. There is
the possibility of a thin belt of fine weather stretching from Ireland
to NE England. Further south, rain associated with the secondary
depression near S Wales and SW England should move towards the SE of
England. These condition described here are only valid for the time
0600Z. An hour later, features (such as the fine weather in the north)
could, accoring to past experience, change rapidly.

At 1200Z, the secondary depression should form a complex LP system from
S Wales (or thereabouts) to N Scotland. Strong winds should become
evident over S Ireland and SW and S England. How strong, I don't know.
Rainy weather can be expected over Scotland and the W of Britain.
Weather deteriorates from the W over E England.

At 1500Z, the secondary can be identified over the central part of S
England and the central Midlands. Rain showers can be found over most
of the country, but rising pressure and improving weather can be found
over S Ireland.

At 1800Z, the secondary should be approaching E Anglia with winds
turning WSW or W over S England. Heavy rain is possible over Scotland
and N Ireland. The best weather is over SW England.

At 2100 Z, high pressure pushes into the SW of England and pressure
rises generally over the whole country except the extreme W of
Scotland. The secondary should be in the North Sea on its way to
Holland and S Denmark. Fine, clear weather comes into the whole country
from the SW.

The descriptions I have given you are exactly what the charts show. I
know that if I add my own embellishments, the forecast would certainly
come off course. It is only by following the method implicitly that I
can hope the forecast will have some success.

Let's wait till 20th November 2003

Cheers, Keith.

Do you think we will be seeing any scandi or greenland high pressure
influence
at the end of nov or dec?