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01-11-2012, 09:41   #1
Rebelbrowser
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Christmas 2012 Weather Thread

I know there was already a Christmas weather thread posted last week but it was in the pictures section and seems to be gone now? If not, and if appropriate, Mods should feel free to merge this thread with that...

OK its November so its just about socially acceptable to start thinking of Christmas. Will it be white? Will Sponge Bob get another bbq day this year? Feel free to add your thoughts...

As of now guidance is, inevitably this far out, patchy. Essentially there are some positive straws in the wind this year though (signals for blocking etc.). TWO have had a Christmas weather threading running for some time (they are on their 9th update!). Their latest guidance is posted below. There is no sign yet of Netweather's Christmas Weather page.

I will update as and when appropriate....

"...Christmas weather forecast 2012

Welcome to our dedicated Christmas 2012 weather forecast page. This will update regularly (usually each Saturday) during the run up to Christmas from September 1st and will take into account the weather patterns which develop during the autumn. Please remember that our Xmas forecast is intended to be for fun, as trying to forecast a single day even one week ahead is fraught with difficulty. The forecast is based on what we expect the general synoptic conditions to be like during the late December period.


Forecast - Ninth update
As we approach the beginning of November the latest update increases the chance of a White Christmas in both northern and southern regions to above average. There have continued to be signs of northern blocking persisting in the medium term, and this increases the chance of colder than average conditions in the UK. Although there's a lot of uncertainty about how the weather will develop as we head through November and into December, there are signs of it being more favourable for cold weather than is often the case. So if you're dreaming of a White Christmas keep your fingers crossed!

Probabilities of snow falling on Christmas Day
North of Yorkshire / Lancashire: 30%
South of Yorkshire / Lancashire: 25%....
."
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01-11-2012, 09:44   #2
 
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White Xmas in Dublin? Nah. The land will not be covered in knickers this year.
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08-11-2012, 10:56   #3
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Just to update this. Netweather have their Christmas page up and running now too, joining TWO. Both forecasts are pasted below. Looking as promising as you could hope for (this far out) for snowlovers.

" NETWEATHER - Christmas Forecast 2012

47 days to go! It's that time of year again, the supermarkets have been stocking their Xmas ranges for a month or so (it seems to get earlier every year), we've had the first snow of the season in parts of the UK, and now is the time to start the Xmas countdown proper with our first look at the prospects of a white Christmas in 2012.

Statistically speaking the chance of snow falling somewhere in the UK on Xmas day is actually quite high with over 70% of the last 50 years having seen at least one station reporting snow. If you're looking for the proper winter wonderland with snow actually lying on the ground though it's a different story with less than 8% of those winters having at least one weather station reporting lying snow. The last proper white Christmas was in 2010 when impressively over 80% of the weather stations across the UK reported snow lying during Christmas day...

Before we start with the forecast it's important to bear in mind that at this range we're looking for trends only - it's well too far in advance to start looking specifically at what the weather may bring on Christmas Day.

The chart ( http://cdn.nwstatic.co.uk/images/win.../cfs-xmas1.png ) is from the CFS (Climate Forecast System), and it shows blue air over much of the UK and Ireland which would indicate that it would at least be cold enough for a risk of snow, and this type of scenario has been showing quite regularly. This alongside some other indicators that are pointing toward some chilly weather during December it's safe to say it's a pretty positive start, if you're hoping for some snow on the big day.

There's of course a long way to go yet... We'll be back next week with the next update and will continue to update the forecast right up to Christmas eve. .."


And TWO...

"Christmas 2012: Could be white!

Welcome to our dedicated Christmas 2012 weather forecast page. This will update regularly (usually each Saturday) during the run up to Christmas from September 1st and will take into account the weather patterns which develop during the autumn. Please remember that our Xmas forecast is intended to be for fun, as trying to forecast a single day even one week ahead is fraught with difficulty. The forecast is based on what we expect the general synoptic conditions to be like during the late December period.


Forecast - Tenth update
Into November and the latest update keeps an above average chance of a White Christmas in both northern and southern regions. There have continued to be signs of northern blocking persisting in the medium term, and this increases the chance of colder than average conditions in the UK. Although there's a lot of uncertainty about how the weather will develop as we head through November and into December, there are signs of it being more favourable for cold weather than is often the case. So if you're dreaming of a White Christmas keep your fingers crossed!

Probabilities of snow falling on Christmas Day
North of Yorkshire / Lancashire: 30%
South of Yorkshire / Lancashire: 25%

Forecast issued
Update 1, 01/09/2012
Update 2, 09/09/2012
Update 3, 17/09/2012
Update 4, 26/09/2012
Update 5, 30/09/2012
Update 6, 07/10/2012
Update 7, 14/10/2012
Update 8, 21/10/2012..."


I will update this as we go along..........
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08-11-2012, 11:07   #4
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Indeed. But

Quote:
Statistically speaking the chance of snow falling somewhere in the UK on Xmas day is actually quite high with over 70% of the last 50 years having seen at least one station reporting snow.
This is statistically speaking easier in the UK as their HIGHEST weather station in Braemar is at 339m ASL in the Scottish Highlands.

If we could simply relocate Finner from sea level ( more or less) to half way up Errigal we would be a much snowier country, statistically speaking that is.

Once you remove Braemar from the mix I'd say the snow stats in the UK more or less halve on the spot.
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08-11-2012, 12:27   #5
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Indeed. But



This is statistically speaking easier in the UK as their HIGHEST weather station in Braemar is at 339m ASL in the Scottish Highlands.

If we could simply relocate Finner from sea level ( more or less) to half way up Errigal we would be a much snowier country, statistically speaking that is.

Once you remove Braemar from the mix I'd say the snow stats in the UK more or less halve on the spot.
I would say that in a normal year there is a 8-10% chance of falling snow, and maybe a 12-15% of lying snow at one of the airports (to use the usual barometer). This year those stats might be 13-15% and 17-20% (at best) as the set up has a hint of being more favourable. So agree it is ALWAYS a long shot even in the best year.

I can only speak for Cork but in the last 20 years we had falling (and thus lying also) snow in 2004 and lying snow in 2010. Allowing for the fact that Cork is the least likely airport to get snow, I'd say my guesstimates are thus not too far off.

Anyway Sponge Bob, as always your difficulty with Christmas forecasts is that you are applying scientific rigour and logic to the gormless optimisim some of us prefer to rely on at this (upcoming) time of year!
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08-11-2012, 12:42   #6
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Anyway Sponge Bob, as always your difficulty with Christmas forecasts is that you are applying scientific rigour and logic to the gormless optimisim some of us prefer to rely on at this (upcoming) time of year!
I would share your optimism if we could simply relocate a weather station to 339m ASL to compete with the UK..even if we had to use Mount Gabriel instead of Errigal
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09-11-2012, 23:39   #7
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FWIW the research model that I use has a peak in both temperature and storminess on the 27th so would hazard this long-range guess, mild, drizzle or rain strong SW wind developing, highs 8-10 C.
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10-11-2012, 00:46   #8
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Most readers of this thread won't hold you to that MT. Any chance you can briefly explain your peaking theory and the inputs ....as in now in early November. ??
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10-11-2012, 21:26   #9
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Quote:
Originally Posted by M.T. Cranium View Post
FWIW the research model that I use has a peak in both temperature and storminess on the 27th so would hazard this long-range guess, mild, drizzle or rain strong SW wind developing, highs 8-10 C.
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10-11-2012, 22:47   #10
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Quote:
Originally Posted by M.T. Cranium View Post
FWIW the research model that I use has a peak in both temperature and storminess on the 27th so would hazard this long-range guess, mild, drizzle or rain strong SW wind developing, highs 8-10 C.
Whilst I hate the forecast MT I admire the Cohones behind making it this far out. Mind you, I trust you wont take it personally when I say I hope it becomes your Michael Fish moment!
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11-11-2012, 00:14   #11
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Whilst I hate the forecast MT I admire the Cohones behind making it this far out. Mind you, I trust you wont take it personally when I say I hope it becomes your Michael Fish moment!
Ahh My Goldfish - the ultimate and best weatherman of our time. He's a ledge !
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12-11-2012, 16:34   #12
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Netweather's latest offering is below...

Christmas Forecast 2012
Christmas Weather 2012 - Will It Be A White Christmas? - Forecast #2 Sunday 11th November

The chart alongside (from the Climate Forecast Model) (http://cdn.nwstatic.co.uk/images/win.../cfs-xmas3.png ) is showing some air cold enough for snow to the UK on the big day - but remember we're just looking for trends at this stage - it's far too early for any specific forecasts for Christmas.

So, where does all this leave us in terms of the chances of seeing a white Christmas? Much like last our first update it's a pretty positive update with enough signals pointing toward the risk of some cold enough air to be close by to or over the UK during the Xmas period. Still a very long way to go yet though...
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12-11-2012, 18:37   #13
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Netweather's latest offering is below...
Whats that over Cork.??
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12-11-2012, 19:25   #14
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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.
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12-11-2012, 20:50   #15
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Can we have snow on the 6th of January...the Womens Christmas?
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