POLAR VORTEX WARNING: Latest winter weather models show UK faces MONTHS of heavy snow

Flashback:

– Snowfalls are now just a thing of the past (Independent, March 20, 2000):

(Click on image to enlarge.)

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Britain is facing one of the coldest winters on record

– POLAR VORTEX WARNING: Latest winter weather models show UK faces MONTHS of heavy snow (Express, November 12, 2014):

hocked forecasters warned tonight the latest high-tech weather models point to a CATASTROPHIC big freeze in late 2014 with THREE MONTHS of blizzards and Arctic gales.They fear a lethal and unprecedented combination of low pressure, above-average rainfall and a freak Polar vortex will come together in a perfect storm of misery for Winter 2014.Moist air from the Atlantic currently causing the mild, wet and windy weather threatens to collide with bitter Arctic winds.

It means a dramatic plunge in the current mild temperatures will turn torrential rain to blizzards capable of smothering the ENTIRE COUNTRY in feet-deep snowdrifts.

The big chill could arrive as early as this month although some models show the colder flow of air will be held at bay until the New Year.

However when it arrives, it threatens to rival the historic winter of 1947 which saw snow fall EVERY SINGLE DAY between January and March.

Crippling snow drifts of up to FIVE METRES  ground swathes of the country to a standstill while the armed services were drafted in to drop emergency air supplies to stranded communities.

In a terrifying similarity to this year, the killer whiteout of 1947 started with suspiciously mild conditions persisting into early winter.

Worried experts have warned Britons not to be lulled into a false sense of security by the current benign conditions.The very latest weather models show a unique set of circumstances coming together to create an extreme whiteout driven by violent snowstorms.

James Madden, forecaster for Exacta Weather, said a strongly negative Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) this winter are main driving factors.

Both phenomenon are governed by atmospheric sea pressure and when in a negative phase they allow cold air to flow in from the East – the so called blocking effect.

Mr Madden said due to recent warming in the Earth’s stratosphere, both the NAO and AO are “excessively” low pointing towards a severe freeze.

A separate measure derived from air flow patterns in the upper atmosphere called the October Pattern Index (OPI ) also points towards a negative Arctic Oscillation.

The resulting weak jet stream, which usually holds the cold at bay over the North Pole, will give way to a blast of freezing air which will sweep across the UK.The OPI was devised by scientists Riccardo Valente and Professor Judah Cohen with this year’s readings dangerously similar to those taken during the catastrophic winter of 2009/10 – the coldest in 31 years.

Experts say a crippling big freeze could be as close as the middle of this month and has the potential to last until spring.

Mr Madden said: “The important pieces are now becoming grouped together to form blocking episodes throughout the second half of November and the upcoming winter period.

“This is reflected upon with the obliterated Polar Vortex and the downward trend of the ‘excessively abnormal’ Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) values, due to recent stratospheric warming and higher than normal pressure across the Arctic region.

“When the AO is in its negative phase, it allows for an easier intrusion of cold Arctic air to lower latitudes such as the UK.

“When the closely related NAO is also in a negative phase, it allows for cold easterly winds and much cold winters to develop.”

He said heavy early snow over Siberia is another indicator that Britain could be in for a mega-freeze.He said: “The impressive Siberian snow cover for this year also offers a high correlation for a negative AO throughout much of the upcoming winter and into next spring.

“We can therefore expect a significant amount of colder intrusions and prolonged diversions of the jet stream/blocking within this period.

“The majority of weather models are now also starting to support a cold easterly/north-easterly developing for next week, and if we combine this with a number of other factors this is likely to bring a number of potentially widespread snow events and much colder weather at times throughout the second half of November and into early/mid December.

“As we progress throughout this period we are also likely to see widespread frosts and stubborn fog patches becoming more of a frequent feature as blocking becomes more prominent.

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