Morning all.

This is how I see things panning out in broad terms. I'll leave the detail
to the official Met Office forecasts later.

High pressure is now building over Scandinavia in response to the deep low
west of Ireland in association with a southerly jet thrusting low potential
vorticity polewards. On Saturday this high will nudge west and as there are
no more Atlantic lows the gate will open to the cold air from the east to
start to flood westwards. Deep cold air will arrive on Sunday with
thicknesses below 528DAM and this will be very unstable to sea temperatures
with CB tops up to 15000 feet bringing heavy snow showers to the east which
will settle. These will then spread westwards on Sunday night as organised
PV filaments form troughs in association with the cold pool bringing quite
widespread snow due to release of upper level instability. Meanwhile during
Monday warm advection to the SE over Europe and also some PV forcing will
encourage low pressure to form over SE England and this will then meander
westwards into England on Tuesday and Wednesday with bands of sleet and snow
rotating around it, air will be a little warmer at this stage so rain is
possible near coasts in the SW. By Thursday this low will have merged with
the Atlantic low complex and this is where the key to the cold spell lies.
If the low merges a long way west then that will open the gate to milder
southwesterlies into the south spreading north as per some model solutions.
Consensus allows a merging over Ireland which will then mean some digging of
cold air down from the north on Friday and Saturday in response to warm
advection over eastern Canada and western Greenland. We then get into a cold
northerly type which will either collapse as per ECMWF or reinforce. If the
low stays put over England and Wales then a stronger northerly could come
down later and then we would enter a prolonged severe cold spell as per
earlier runs.

That's the way I see it ATM, it is quite a finely balanced setup longer
term. Short term is cold no question about that with snow for many.

Ciao, :-)

Will
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