Britain braced for an icy blast from the Arctic
This weekend is a time for thick pullovers
and woolly hats as a taste of winter spreads over much of Britain.
Raw winds sweeping down from far inside the Arctic Circle, even
from the North Pole, will send a collective shiver through the country
today, with heavy snowfalls in Scotland and parts of East Anglia.
The Met Office says that conditions will
deteriorate further tonight as a mass of sub-zero air advancing
from the north collides with warmer, heavy rains from the west.
That clash will send widespread snow showers across Scotland and
from the Welsh Borders eastwards.
An even bigger threat tonight is a rare
and dangerous phenomenon known as an ice storm. This could lay down
a treacherous covering of ice on the roads and anything else it
touches. As cold Arctic air slices under warm Atlantic air, it will
pour with rain that will not have time to turn to snow because the
cold air is shallow. It could remain as freezing rain that turns
to ice when it touches frozen objects such as roads and trees. Ice
storms in Canada and the US are at times so savage that trees and
pylons snap under the weight of the ice.
The menace that we are more likely to face
is black ice - an invisible coating that can turn roads into skating
rinks. Fortunately, most of the snow and ice will melt during tomorrow
morning but there is more bad news on the horizon. The cold spell
looks likely to persist next week and possibly well into December
because of a blocking weather system.
Britain is caught in a titanic struggle between a big block of high
pressure anchored in the mid-Atlantic and low pressure lying over
Scandinavia. Vigorous jet-stream winds a few miles overhead have
developed a kink in their tracks that has trapped the high-pressure
system in a vice-like grip.
So are we heading for a bitterly cold freeze
this winter? Records show that a cold November is no guarantee of
a freezing winter. Three years ago a bitterly cold second half of
November had no ill effects on the following winter and there have
been many similar cases. Similarly, some warm Novembers have been
followed by bitter winters, as happened 80 years ago. The latest
Met Office seasonal forecast still predicts a milder than average
winter, although not quite as mild as last winter. There could be
more cold snaps but there will be bouts of milder weather too.
Forecasters will be focused on a see-saw
in Atlantic pressure systems between lows over Iceland and highs
over the sub-tropical Azores. When these pressure systems become
more extreme, Britain gets milder and wetter winters. When the see-saw
eases off, it brings big freezes.