Christmas Day 2008 - Model Output Countdown

Danno

Here is an idea, every day from now until the big day, someone details each model run for the big day and posts it in here... no discussion allowed use the http://www.boards.ie/vbulletin/showthread.php?t=2055433432 thread to comment instead.

For newbies... http://www.wetterzentrale.de/topkarten/fsavneur.html is where the model output comes from.

Perhaps we could use this template...

Model Output by GFS: Thursday December 11th 1800: Ireland is under high pressure, 1030mb. Upper air temperatures are between +2c and -2c. Nearest 528dam line is 400 miles north. A light rain/drizzle band covers the country. Air temperatures range from 8c to 11c. Snow Chance: 0%

Model Output by ENS: Thursday December 11th 1200: Ireland is under influence from Low pressure anchored off South Greenland. Upper air temperatures range from +1c to -3c. Snow Chance: 0%

Addition 1: I state GFS or ENS in the model as closer to the time we can add in details from UKMO, JMA, ECM etc... when they start showing output for 25/12/2008

Addition 2: Could MT Cranium take care of reporting on the 00z model outputs as he, well, will probably be the only regular boards weather forum member that will be online at 4am Irish time! :P :P :P (barring some seriously good charts)

Snowbie

HP over Scandi (1040mb) and the Azores(1024mb).
LP over Iceland
Wind S'ly --> SSE
850mb +3C to -1C
Air 9C to 12C
Thickness 540 to 548
Weather Cloudy with drizzle.
Snow chance 0%

j1979p

Recent GFS models are predicting a high pressure system slightly to the west of ireland building up a few days before Xmas. Cold or not, there will be very little precipitation going on these runs

Danno

Model Output by GFS: Friday December 12th 1200: An egg shaped High centred over Norway draws up a spanish plume. Upper air temperatures exceed +5c and the nearest 528dam line is 600 miles west or east over Poland! Air temperatures range 10c to 11c. No chance of Snow

Model Output by ENS: Friday December 12th 1200: Low pressure off S Greenland feeds in a brisk westerly. Upper air temperatures range from -4c to -1c. Slight chance of Snow in the NW hills

Deep Easterly

GFS 18z 12th December 08 run for Christmas Eve evening, when all the little kids are dreaming their little dreams of snow and santa and all things shiny and sparkly, glittering away.

Little dreams smashed to bits by that chart above, which is quite simply disgusting and unspeakably obscene. Drizzley overcast warmth with heartbreakingly high pressure values that prevents even a decent gale springing up. It is the ultimate voidness. Christ forbid it should turn out like this for Christmas. Because I don't think I could take that.

M.T. Cranium

Greetings from the land that winter did not forget.

I'll mention for starters that my own research model is indicating a gradual change from mild SW to colder NW flow patterns in the next ten days with some chance of a white Christmas, I feel, as there are higher index values for low pressure on the 25th and 27th than most days.

Meanwhile, I had a look at the GFS as requested, and it seems to be showing more of an inversion high situation on the 00z run for 25 December, than previously. The mild pattern (after this weekend's break) goes on for several more episodes through about the 22nd, but then high pressure builds up right over the British Isles, not particularly cold in origins but from previous similar events I would estimate frosty nights of about -4 C and some lingering fog and cold days with this pattern (if it verified -- which it won't, right?) ...

Anyway, be optimistic, I don't think the Atlantic will be too robust because after one or two events the lows coming out of North America here will be weak and quite possibly the sort that will dive under any emerging high pressure from Europe, so this could set up well for a bit of snow at least.

Snowbie

HP moving across Ireland into UK (1040mb)
LP over Russia, Strong N'ly into Europe
Wind SSE --> SE
850mb 0C --> -3C later
Air 4C to 8C at first
Thickness 540
Weather, Frosty start, dry and sunny
Snow chance 0%

Danno

Model Output by GFS: Saturday December 13th 1800: An extremly high pressure cell of 1045mb sits south of Waterford. Upper air temperatures are above 5c. The nearest 528dam line is near Iceland. Air temperatures range from 6c to 9c. Forget about snow

Model Output by ENS: Saturday December 13th 1800: Low pressure still off SE Greenland, but higher pressure over E Germany pulls in a southerly track from the Azores. What is snow?

M.T. Cranium

The 00z GFS output has delayed the high and downgraded it considerably. Instead, the mild trend for next week seems to continue in subdued form for the days leading up to the 25th, with the details for that day involving a weak warm front and a system moving across Ireland late in the day and on the morning of the 26th. This would imply cloud, periods of rain or drizzle and temperatures rising from about 3 to 8 C.

I remain optimistic. The trend in the models has enough range and uncertainty to allow for a colder turn before the 22nd and then a weak disturbance would perhaps be wintry rather than mild by the 25th.

You can't really lose with these Christmas forecasts, because whatever the weather does, it's at least Christmas.

Snowing here and I'm further south than any of you.

shamwari

I'm not able to copy / paste images, but I ran the GFS output up to the 30th DEC and it looks like it might produce something for the east. Granted its a long way off but it's more promising that the Xmas one!

Snowbie

HP moved across North sea into Scandi (1040mb or a weak block)
1020mb over Ireland in a slack SE flow, slight chance of wintry stuff in south.
Wind SE
850mb -3C to -4C
Air 3C to 6C
Thickness 532 to 534
Weather, Frosty in midlands and north, mainly dry and sunny
Snow chance 10% to 20% (S and SE)

Deep Easterly

ECMWF:
Model Output: December 14th 0000: Rex Scandinavian High deflecting North Atlantic Low northwards. Strong Azores Ridge building towards Ireland:



Run only goes out to 24th. So many options may be possible for the 25th from this one run.

1. Secondary Strom low to develop to the NW or W. (wet, windy & mild in N, W and SW)
2. Azores Ridge to connect with Scandinavian ridge via North Europe or Britain. (Mild in Ireland):mad:
3. Scandi Ridge to develop to the near south of Ireland. (Dry. Frost in places esp South and East.

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2. ECMWF 12z Run from 14th December 08:



Azores High transferred over and just to the east of Ireland. Contains very warm air at height, but frost and more especially (non freezing) fog forecast looks possible for Christmas eve night (contingent on cloud cover) from this one ECM run

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ECMWF 12z run from the 15th December 2008:



Continuing to show Azores Ridge extending northeastwards, this time a little more to the east over Southern Scandinavia. Ireland in a slack, SSE flow, which has a newborn continential influence contained, bringing lower dew points to the eastern half of Ireland, so looking frosty by night in the east and average to cool by day(dependant on cloud cover); with the West, and particulary the coastal fringes, subject to a flirting warm front with more general cloud and possible coastal drizzle. Yuk.

Just one run of course, but 3rd run in a row form ECM showing a build in pressure around Christmas over Ireland. Positioning as ever subject to change.

Also, that chart has potential trough disruption developing close to the SE coast on Xmas day, which could bring thicker cloud (showers/rain/sleet? ) to S and SE coasts.

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ECMWF 12z run from the 16th December 08:

ECM keeping up with the High dominated Christmas, and as mentioned yesterday, positioning of high has change slight on this run for the big day:



In a somewhat more healthier position in that it allows a somewhat drier airflow over Ireland as a whole, so frost/fog more a possibility from this one run on Christmas day/night. Warm upppers of course could promote a lot of level st cu, which would prevent temps from falling below freezing at night. Many more runs needed to get a sense of what and where things are going for Christmas period weather wise.

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ECMWF 12z run from the 17th December 2008:



ECM continuing to show a high dominated Christmas day. As earlier progged by this model, Azores being absorbed into newly formed Scandinavian ridge. This shows high with and increasing continental undersource, which suggest fog/frost where skies remain clear at night, and possible very sunny by day. This run has also done away with weak warm frontal activity near the west coast, although NW coastal districts my still be at risk of some general cloud. Also, a weak trough still cannot be ruled out near the south coast also. While not set in stone yet, the consistancy of this set up is encouraging, and also GFS is showing this also. My fingers are crossed and my heart is racing.

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ECMWF 12z run from the 18th December 2008:



Not much change from previous runs from ECM with regards Christmas day. Western flank of High centered over of just to the east of the country. Warm uppers suggesting st cu still, but where skies clear, frost and fog possible. Hard to say where this would occur at this stage, but E and S still seem most favoured. Weak troughs still possible near western and southern coasts.

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ECMWF 12z Run From the 19th December 2008:



ECM maintaining High pressure based Christmas with slight continental underflow. Min Level ST Cu still a real possiblity, but clearer skies cannot be ruled out, again, it does look like east and south have higher chance of frost and fog if cloud breaks. But cannot be ruled out anywhere really. Weak trough cannot be ruled out either, again South and Northwest coast most at risk, and also, that high my have a weak front embedded that may meander over the country, but too far out to say just yet.

Quite Christmas skies over Ireland is all be nailed on at this stage with ECM.

Snowaddict

Just though I'd post an update for Xmas Day based on today's:

Sunday 14 Dec 2008 GFS 12Z Perturbations


For Xmas Day, 25th December, 12 Noon

Quie a number of solutions offered up by the perturbations, however the following runs suggest a cold to very cold and possibly wintry setup, from either the east or north / northwest...


Number 1, 2, 3, 6, 7, 9, 10, 13, 18, 20.


However, they are also subject to frequent change, although Xmas day does not look to bad in the overall scheme of things, based on the ensembles. Indeed 50% go for a cold to very cold and potentially wintry setup. 50% is not bad at all in my opinion.

M.T. Cranium

GFS showing mostly mild scenarios through the 25th, ECM showing buildup of a massive inversion high that looks like it could be very frosty at night (-2 to -5 C range) and therefore foggy in some areas all day, some weak sunshine in a few spots. Will either one of them be right? Or will the flow go its own way?

Danno

The 12z today from GFS shows Ireland with a cold front passing through. Daytime temperatures are around 10 to 12c but down to 5 or 6c that night with showers. -5 upper air approaches the west coast by midnight... perhaps a bit of snow for highland in the west and northwest.

The ENS at 06z today shows Ireland firmly planted under a strong high pressure cell of 1035mb. Although the high pressure is southerly sourced, I would expect a strong inversion to deliver fog and ice at night with cool chilly days... perhaps a white christmas by fog and ice?

The GEM a 00z shows an easterly high pressure exerting influence over Ireland. The airflow extends to Ireland from the Ukraine via, northern Balkans, Austria, NE France... perhaps it could be bitter cold if the continent cools down enough over the next 240 hours.

The ECMWF shows a rather milder SE wind under influence from an easterly high pressure. Probably more Med air than cold air in the mix.

With four models predicting from here on, it can begin to get a bit clearer as to what we can expect for the big day. Three of the four above agree on eastern blocking with the finer details to be added next week, the GFS with the most recent output seem to be ploughing a lone furrow, will the others catch on or will the GFS turn to the eastern blocking? Stay tuned for the next overview around 10pm tonight!

Danno

GFS 15th Dec 18z A Eurotrash High feeds in a spanish air mass. We get a warm front crossing the north coast. Very mild with 10c widely.

GEM 15th Dec 18z A whiteout... litterally. No data.

ENS 15th Dec 12z Very similar to GFS.

Snowbie

Danno pretty much sums it up. 10C widely but as high as 13C maybe a 14C in places according to this run.

M.T. Cranium

The ECM was showing a stronger high on its 00z run, and if that verified it would perhaps be white from frost rather than snow. Quite warm at upper levels but with a 1040 mb high the inversion factor has to be considered.

Getting a little late in the game for a large-scale pattern shift now, but things upstream remain rather uncertain, so some potential for a shift over Europe before the final approach.

arctictree

All models seem to be going for a settled spell starting early next week. Misty cold days and frosty nights.

Snowbie

HP 1048mb in Scandanavia and fronts pushing in from the Atlantic.
A possible block?
Wind SSE generally
850mb 5C decreasing later
Air 7C to 9C falling later
Thickness 5480m
Weather, Dry and cloudy at first clearing later from the east
Snow chance 0%

M.T. Cranium

The 00z models were still going with the strong inversion high situation, I guess that would mean fog and frost in some eastern and central parts, a milder day on the west coast?

It snowed here, not that this will help in any way.

nacho libre

sod it anyway. i just hope we get a decent snow event in January

Snowbie

HP 1038mb centred over Scotland
A slack SE flow over Ireland but mainly calm
Wind SE or calm
Thickness 5480m
850mb 6C
Max Temp 6C or 7C
Min Temp 0C or -1C
Weather, Dry and cloudy with some breaks
Snow chance 0%

M.T. Cranium

The model trend is still towards colder high pressure with the east and central parts of Ireland being most affected, more likely to have severe frost or lingering daytime fog. With the guidance we have from various models at present, I think there is a fairly good chance of even colder weather towards the 27th and beyond, with two possible outcomes, a gradual development of a very wintry period, or a glancing blow of potential flurries on SE winds followed by a slow warming trend again.

The whole thing hinges on whether the Euro-high continues to retrogress towards Iceland and whether it can set up far enough north to induce a really cold northeast or northerly flow after about the 29th. If it does, then sub-freezing temperatures are in the mix. If it settles in closer to Donegal and then perhaps shifts back into western Europe, then there are just slight chances for snow in the holiday period and a return to somewhat milder weather after New Years.

I back the colder option because retrogression seems more likely than stagnation. Things would have to speed up considerably to get a real white Christmas but some places might be white with hoar frost at least. Snow is in the mix for the 26th in parts of southern England, I would think it might be an outside chance for one or two parts of Ireland by late 26th or 27th.

Snowbie

HP extends from Scandi 1040mb
A slack E'ly flow over Ireland sets in
Wind E to SE
Thickness 5480m decreasing later
850mb 0C in east to 3C in West falling later
Max Temp 7C
Min Temp 0C
Weather, Dry and mostly cloudy
Snow chance 0%

Pangea

any updates guys?

Supercell

Pangea wrote: »

any updates guys?

Lack of updates are because it looks very much set in stone at this point.
Christmas day will be cool and dry in most places.
Cloudy and cool with a chance of coastal drizzle in the east and south east in some unlucky spots.
Further west you go the more likelihood of sun.
Basically a cool settled day, not the worst if you are out and about visiting relatives I suppose.

M.T. Cranium

Here's your white Christmas, old MTC grabbed it and won't let go ...

view from my front window this morning ...

http://www.easternuswx.com/bb/index.php?showtopic=182718&st=120&gopid=3336995&#entry3336995

Snowbie

M.T. Cranium wrote: »

Here's your white Christmas, old MTC grabbed it and won't let go ...

view from my front window this morning ...

http://www.easternuswx.com/bb/index.php?showtopic=182718&st=120&gopid=3336995&#entry3336995

We have to register to view the pics M.T.
Can you insert the image in the tags please.:)

Supercell

M.T. Cranium wrote: »

Here's your white Christmas, old MTC grabbed it and won't let go ...

view from my front window this morning ...
-IMAGE LINK: Sorry, Guests cannot view images.-

Any chance of a glimpse for us non guests there?

M.T. Cranium

(ahh, there it is ... )

Okay, sorry guys, that's what I wanted to do but I couldn't figure out how to post pictures here. Will try this ...