The Run Up To Christmas Based On The 12z Gfs

[TEITS]

Here we go yet again for a look at the run up to Christmas, doesn't a year fly past so quickly!

What im basically going to do is follow the 12Z for the Christmas period which shall include Christmas eve, day, Boxing day. Im including Christmas eve because I always class this as part of Christmas and there are probably some people planning on travelling on this day to see the inlaws!

I shall also be following the 12Z GEFS ensembles and will keep a score throughout this thread i.e how many runs show very cold, cold, average, mild. Hopefully by keeping this score we might be able to pick up on a trend.

Also I will save and post the charts on this thread but I shall only be posting the Christmas day charts because otherwise this thread will become too cluttered.

Finally whilst following the 12Z I shall only post what they actually predict rather than putting my usual spin on them. The purpose of this thread is to find a trend and is not a forecast especially at this early stage. Anyone who doesn't understand the models should appreciate that there is likely to be many different types of weather shown for this period when Christmas is so far away!

I hope you enjoy reading this thread and I shall return later on this afternoon.

[John Cox]

Great idea TEITS

I look forward to following your work on this.

[Shiny_Bottom_1]

Hi Dave.

When I did this last year, I also took the NW figure from the NW 16 day ave temp tracker, and plotted this on to a graph.

You kind of need someone to help post the figure if you are not about, but it worked out quite well.

Dont have the file I used/created, but it was an interesting watch.

Just another idea to add to yours, if you want to take it up.

Good luck, and looking forward to seeing the results.

[BLAST FROM THE PAST]

Dave

You better save me some perishing NE'ly charts!! :lol:

BFTP

[Michael Fishermans Friend]

Nice work! - I'm basing my itinery for xmas on TEITS findings and forecasts.

[LLWA]

like this chart for christmas eve lol

[Guest]

like this chart for christmas eve lol

That will do nicely

[TEITS]

Here we go the first post on this thread looking at 12Z Christmas eve.

General synopsis.

A large area of high pressure measuring 1040mb is centred over Scandinavia and the North Sea.

General description of the weather.

Dry settled conditions for the whole of the UK with mainly light variable winds. The temperatures are likely to be near or slightly below normal although around average towards SW England/Ireland. Some patchy fog could be a problem towards evening and with temperatures quickly dropping this could turn into freezing fog during the latter part of the night.

GEFS ensembles.

A mixed bag as you would expect at this range. Some are suggesting high pressure to be nearby whereas others indicate and more unsettled pattern with low pressure. Very difficult to judge which are cold, average, mild due to inversions from high pressure. So based on these I would give the following scores.

1. Very cold 0

2. Cold 3

3. Average 10

4. Mild 7

From tomorrow I shall only post the charts from Christmas day but shall continue to give a description of Christmas eve also. Hopefully I will have a little more to talk about other than HP centred near the UK!

[TEITS]

General synopsis for Christmas Eve and Christmas day.

A deep area of low pressure in the mid atlantic associated with a deep trough in the Jet stream. A large area of high pressure centred over Europe with the Jet stream running NE of the UK to the west of the UK.

General description of the weather.

A very mild picture is suggested by the 12Z as SSW,lys winds are across the UK. The temps are likely to be on the mild side and in some cases 3 or 4C above normal. Overall fairly cloudy with the best of any brightness likely in SE areas. The NW and parts of Ireland are likely to be more unsettled as fronts sweep across these areas bringing heavy rain at times.

GEFS ensembles.

Again a real mixed bag with no pattern really becoming established. Again we see some ensembles indicating low pressure moving W-E bringing fairly average conditions. We then have some ensembles indicating high pressure some of which would bring mild weather and others bringing cold weather. We also have a few ensembles bringing cold N,lys!

1. Very cold 2

2. Cold 2

3. Average 10

4. Mild 6

[Nick L]

Cheers TEITS, bit of a horror show as far as a White Xmas is concerned!

[TEITS]

General synopsis for Christmas eve, Christmas day, Boxing day.

A large area of high pressure to the south of the UK with low pressure systems sweeping to the north of Scotland keep the UK in a mainly SW,ly airstream.

General description of the weather.

Generally a mild outlook is likely during this period. On Christmas eve it will be rather unsettled with rain at times especially in the NW with SE areas only seeing light rain. The temperatures will be above normal around 10C. On Christmas Day a slightly more settled and cooler day is expected although the far NW may continue to see outbreaks of rain. The temperatures are expected to be around 8C in the south and around 4C in northern areas. Boxing day is expected to be unsettled with further spells of rain with milder temps in the south although remaining fairly cool in the north.

GEFS ensembles.

A slight change in the ensembles tonight compared to recent runs. The ensembles suggest high pressure is more likely than low pressure although the positioning of this it what makes a large difference to the upper temps you see on the chart above. Again we see massive differences with some members bringing high pressure over the UK, whereas others have high pressure centred over Scandinavia bringing a very cold E,ly flow. There are some members indicating low pressure on a mobile W,ly flow but these are the exception tonight.

1. Very cold 4.

2. Cold 7.

3. Average 4

4. Mild 5

[Nick L]

Thanks again TEITS. Let's just hope that the mild FI stays in FI!

[I remember Atlantic 252]

more promising 11-9 in favour of cold, would like to see an easterly shown on 0perational, every operational FI has been mild mush since xmas eve/day appeared on charts

[chionomaniac]

TEITS, Thanks for doing the rundown to the Christmas No 1! I see we are edging in the right direction.

What we need to see is 1 ensemble member to move to very cold every day, and come Christmas day we will be pretty much there. Let's hope Santa brings some sleighs!

Looking at the cumulative totals after 3 days we are:

1. Very cold 6/60 or 10%

2. Cold 12/60 or 20%

3. Average 24/60 or 40%

4. Mild 18/60 or 30%

Keep up the good work.

c

[ukmoose]

Good idea Teits.

I remember Bill Giles being completely caught out by the cold, snowy spell just after Christmas 2000. He forecast very mild weather (and the synoptics clearly showed this) less than a week before the snow arrived.

All to play for yet...

Moose

[Guest]

General synopsis for Christmas Eve and Christmas day.

A deep area of low pressure in the mid atlantic associated with a deep trough in the Jet stream. A large area of high pressure centred over Europe with the Jet stream running NE of the UK to the west of the UK.

General description of the weather.

A very mild picture is suggested by the 12Z as SSW,lys winds are across the UK. The temps are likely to be on the mild side and in some cases 3 or 4C above normal. Overall fairly cloudy with the best of any brightness likely in SE areas. The NW and parts of Ireland are likely to be more unsettled as fronts sweep across these areas bringing heavy rain at times.

GEFS ensembles.

Again a real mixed bag with no pattern really becoming established. Again we see some ensembles indicating low pressure moving W-E bringing fairly average conditions. We then have some ensembles indicating high pressure some of which would bring mild weather and others bringing cold weather. We also have a few ensembles bringing cold N,lys!

1. Very cold 2

2. Cold 2

3. Average 10

4. Mild 6

Maybe but the thickness levels don't look too encouraging.

[TEITS]

General synopsis.

A large area of high pressure centred over the UK covers all of this period.

General weather description.

Very easy to sum up Christmas eve, day, Boxing day as being settled, dry, and cold. I would think fog could be a problem and as temperatures are likely to be very low some of this could be freezing and linger all day. The temperatures are likely to be well below normal and in some locations under freezing fog are unlikely to reach above freezing.

GEFS ensembles.

Still not pattern in the ensembles except that high pressure is more likely than low pressure. Also very difficult to say which are cold due to upper temps being misleading when under an area of high pressure.

1. Very cold 4.

2. Cold 6.

3. Average 5.

4. Mild 5

Edited December 11, 2008 by THE EYE IN THE SKY

[Nick L]

Wouldn't mind that at all! 2nd preference behind snow. Thanks TEITS.

[TEITS]

Wouldn't mind that at all! 2nd preference behind snow. Thanks TEITS.

Glad you appreciate the thread Nick.

I would love the 12Z to show similiar to the 06Z because it would be very enjoyable describing the actual weather.

[TEITS]

General synopsis.

A large area of HP to the south of the UK on Christmas eve will build north on Christmas day before transferring east to Scandinavia on Boxing day.

General description of the weather.

Christmas eve is likely to start on a wet note for Scotland but the remainder of the country will largely dry and settled. The temperatures are likely to be around average although milder across SW England, Wales, Rebublic of Ireland.

Christmas day is likely to continue with the settled, dry weather as high pressure builds across the UK. The temperatures will be around average but again milder in SW England and Ireland.

Boxing day is likely to be colder with the chances of fog persisting all day in some locations. The temperatures will be slightly below normal and cold where fog persists. Again SW England and Ireland will be milder.

GEFS ensembles.

The same trend continues today and that is the suggestion from the ensembles of high pressure being more likely than low pressure during this period. There are 2 different types of cold spells being shown on the ensembles, 1. cold surface temps via an inversion, 2. cold temps due to cold upper temps. There are obviously milder ensembles with LP dominating but based on the 12Z these are the exception.

1. Very cold 4.

2. Cold 8

3. Average 4.

4. Mild 4.

[azores92]

shame it couldnt be the 06z you were describing :lol: , anyway foggy would be my second preference. good forecast as always.

Edited December 12, 2008 by azores92

[BarnetBlizzard]

Could be looking at an easterly a few days after x-mas if we are lucky

[Nick L]

Glad you appreciate the thread Nick.

I think it's great of you to do this, I wouldn't have the time or patience to do it, I already have no Christmas with all the "presents" my teachers have given me in preparation for Jan exams! :lol:

[Snowaddict]

Excellent post again TETIS, really appreciated.

I agree with your view about Xmas completely, several of the ensemble members are very promising still.

Nothing should be discounted as of yet.

Regards,

SA.

[yamkin]

Could be looking at an easterly a few days after x-mas if we are lucky

Don't be surprised if mother nature brings a cold Easterly during the Xmas period