superb run down Will

keep up the good work

On 06/12/2011 5:16 PM, Eskimo Will wrote:
Wow is all I can say, this is why I love winter with all its drama.

The deep low set to come over or close to northern Scotland is not even
on the charts yet but it will develop explosively as a shallow wave is
excited on the low-level baroclinic zone in the North Atlantic. This
then phase locks with an upper trough and high PV coming south from west
of Greenland and rapidly deepens late Wednesday into Thursday and is
then steered by the jet towards Scotland. The depression looks like
being warm cored meaning that close to the centre wet-bulb freezing
levels will be up around 400 metres or so asl but deep cold air will be
tucking in round it. Winds could well exceed 70 knots (hurricane force
in northern Scotland) and as the cold air tucks in, blizzards (heavy
snow and severe gales) are likely on hills above 200 metres asl bringing
white-out conditions in the mountains. Given the warm core as part of
the seclusion process the snow is likely to be of the wet sticky variety
and hence poses a significant risk of ice accretion on power lines,
especially Thursday evening when some truly horrific conditions are
likely in northern Scotland and the northern Isles (possibly with power
cuts). The winds will also generate a surge down the North Sea which is
being discussed elsewhere. The London barrier will be raised no doubt
and Holland should worry.

Now the cold front will sweep SEwards on Thursday, the main feature
being a rapid fall of temperature with possibly a short spell of
sleet/snow on its back edge, even on low ground in England. Before then
though the air in the warm sector is quite mild and may give rise to
temporary snow-melt in some upland areas. Then we have a frosty ridge on
Friday.

Meanwhile the very cold (exceptionally cold?) air over Greenland will
continue to leak south lowering North Atlantic SSTs even more and push
the baroclinic zone a notch further south meaning that the next rapidly
deepening Atlantic low could slam further south into the UK early next
week after some respite over the weekend (rain and hill snow but just
normal wind). Further ahead I cannot see any end to this cold westerly
zonality which will tend to get even colder with time due to lowering
SSTs and the time of year!

Phew, I think that's enough from me!

Exciting cheers,

Will
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