Christmas 2012 Weather Thread

Hey, I hope it snows like crazy but here's the basic rationale for my milder forecast (aside from the 90% chance that it would verify better than a snow forecast just from climatology).

My long-range forecasts are based on "index values" of research-identified factors taken from a large historical data base. These are synthesized into a forecast (by that guy in the picture above, I think) with some attempt to derive a "scenario" from the blend of index values. When a larger than average number of values peak together, this is taken to indicate a strong energy peak. Such is the case on 27 Dec (as well as a few other dates through the winter) and the index values are running mild then as well.

This gives a basic "scenario" for the period, strong low pressure moving past the northern parts of Ireland and the UK, and looking at the output from about mid-December to the 27th, the scenario appears to be cold modifying around the period 21-23 then a peak of warming 26-27, so it would suggest rising temperatures on Christmas Day with some precip likely to be drizzly, heavier rain to follow.

The method gives two good windows of opportunity for more wintry weather, one in mid-December, and a longer and more significant one in late January and February.

Related to the above, I did a study of pressures at Malin Head in December and January and found a strong tendency to low pressure at the full and new moons of these months, which is expected in the research as solstice full/new moons are coincident with declination maxima (another energy peak in the model). There is a full moon on 28 December at 10z which would place the N Max event on the 27th. This should create an open wave type low with a strong leading warm front from secondary energy on the 25th. Given that the overall flow is indicated to be mild, I would expect this energy to form a double-centered low moving northeast near or south of Iceland. In the cold episode of Dec 2010, the full moon northern max energy peak was around 20th-21st and formed the timing for that epic Dublin snowfall event. This was at least indirectly predicted in the research model and the difference in reasoning there was that the background index values were strongly negative.

This does open up a bit of hope for a snowfall event, if it turns out to be colder than normal by about the 23rd-24th then this energy is going to have to lift the cold air or over-run it, but as I say the indications are more towards a milder pattern already in place by the time this energy arrives on the scene.

A better chance for a December snowfall would be with energy peaks on 12-13 Dec and in the few days thereafter as that appears to be the coldest part of the month.

Clonmel1000 wrote: »

New to here so apologies but its 5 weeks to Christmas. How in the name of God could anyone possibly predict the weather at this stage. 3-5 days is the maximum surely? Anyway after the disaster winters of 2009 and 2010 for hard pressed families with increased heating costs and businesses who are depending on a busy xmas for survival lets hope we get no snow in the run up to Christmas

While I agree with you, that kind of view don't go down too well round these 'ere parts.

Front page of the Daily Express which seems to be taking over from the Mail o the Doom & Gloom front.

http://www.express.co.uk/posts/view/360818/Icy-blast-will-last-a-month

ICY BLAST WILL LAST A MONTH

Some weather forecasters are warning that Britain is line for the worst big freeze in a century

Tuesday November 27,2012
By Nathan Rao

FLOOD-hit Britain will be plunged into the depths of winter tomorrow with Arctic temperatures and a blast of snow.

And experts say that once the big chill takes hold, there will be no let-up in the cold for the rest of the year.

After the torrential rain of the last few days, the first significant snowfall of the winter is expected in the North tomorrow as icy air from the North Pole causes the thermometer to plummet to -15C.

Wintry showers are likely as far south as the Midlands by Sunday. There is even a chance of an early dusting of snow on higher ground in London and the South-east as the whole of the UK prepares for a month of widespread harsh frosts, bitter winds and icy conditions.

Jonathan Powell, forecaster for Vantage Weather Services, said: “Once the rain clears, it is then into a proper cold lockdown.

“Temperatures will fall below freezing across the whole country with some exposed places touching -15C with wind chill. We will see snow in the North, moving further south by the weekend, with the Midlands and Wales likely to see wintry showers. There is even the chance of snow over high ground further south in London.”

He said the first two weeks of December would be “very wintry” followed by a brief mild spell before the cold sets in again.

Jim Dale, forecaster for British Weather Services, said a “Polar front” will send temperatures plunging across Britain this week.

He said: “There is every chance that once we get this Polar air in situ, it is going to take some shifting. People should be prepared for a cold snap.”

Some forecasters are warning that Britain is line for the worst big freeze in a century with “unusually heavy” snowfalls.

James Madden, forecaster for Exacta Weather, said: “The first part of the winter is likely to be very cold and exceptionally snowy. Parts of southern England, Wales and Ireland are also likely to experience a number of snow events that will consist of some unusually heavy falls of snow. It is highly likely there will be disruption to the public transport network.”

Please let it just be chancer weather forecasters being quoted. It's Santa or heat this year and I know which will win but it won't stop the whinging.

I realise that they're writing about the UK but knowing my luck....

Anyone else for a long range guess on how its going to turn out? Snow aside I'd love a nice crisp cold dry couple of days over mild wet and windy muck!

5500 wrote: »

Anyone else for a long range guess on how its going to turn out? Snow aside I'd love a nice crisp cold dry couple of days over mild wet and windy muck!

Exactly my line of thinking ,snow would just be a big bonus. Love the dry crisp weather.