Big Change Monday Onward, much colder, ice and snow later

M.T. Cranium

Snow plow, that's how we spell it, and we actually have them too. :cool:

Well, this is the usual game of marginal snow opportunities from first the east and later the north and northwest. In both cases, the guidance so far brings just about cold enough air to sustain snow, certainly on higher ground there is bound to be some well scattered around the country, whether it snows at lower elevations more difficult to foretell at this stage.

I'm saying in the forecast thread, much of the country will eventually see a bit of snow, so far there is nothing to indicate anything very heavy anywhere but the easterly flow would favour higher parts of Wicklow and Dublin, while the northwest flow favours higher parts of Connacht.

I'm pretty sure it's going to be the usual witches' brew of snow, hail, sleet and just plain rain showers but at least there is some chance, which is far better than many weeks before Christmas when there's basically no chance.

If anything more dramatic develops in terms of the push of colder air, it might prompt some actual snowfall warnings. The problem so far is that the key thickness contour, 522 dm, and the more guaranteed contour, 516 dm, hold back each time and don't make very much contact with Ireland, then there's the tendency to consider that these cold situations almost invariably fail to verify at quite the same thickness as the models show, they always seem to underestimate the moderating powers of the nearby ocean waters (by about 3 dm in my estimation).

So what we need to see is a set of charts with a more vigorous push of the colder air where we get the 510 dm thickness to make contact with the British Isles, then it would be more certain that snow would fall.

yansnow

today is an absolute cracker upgrade over upgrades
MUCH better UKMO this morning

http://www.meteociel.fr/ukmo/run/UN48-21.GIF?15-05

http://www.meteociel.fr/ukmo/run/UN72-21.GIF?15-05

http://www.meteociel.fr/ukmo/run/UN96-21.GIF?15-05

http://www.meteociel.fr/ukmo/run/UN120-21.GIF?15-05

http://www.meteociel.fr/ukmo/run/UN144-21.GIF?15-05

yansnow

look at this one
http://www.meteociel.fr/modeles/geme_cartes.php?&ech=192&mode=0

Cosmo Kramer

yansnow wrote: »

look at this one
http://www.meteociel.fr/modeles/geme_cartes.php?&ech=192&mode=0

OK, I've been following this thread without being any kind of expert on what all the little numbers and charts mean...but that's got to be good, right?!

yansnow

Yea it's look really good the further we go it gets colder and colder,as lows from the artic moves southwards bringing a very cold north to northwesterly winds and lots of precip and from my point of view everyone is expected to see snow.back to the present now as I said a week ago I started a thread about snow this Thursday am still sticking with that am 100% sure the east will see some snow.

Deep Easterly

Latest met.ie outlook seems fairly alright though nothing notable:

Met Eireann wrote:

Outlook

A few wintry showers will persist during Thursday in coastal counties of the east and southeast while the rest of the country will have a mainly dry day with some bright or sunny periods. A rather cold day everywhere with temperatures only reaching between 4 and 7 degrees in a moderate east to northeast breeze. Sharp or severe frost Thursday night.

Friday should be a dry day in all but some coastal regions of the southeast, where the odd wintry shower is still likely. There should be some bright or sunny periods also, but it will be a cold day - temperatures only struggling up to between 2 and 5 degrees and the overnight frost may be slow to clear in places. Winds light or moderate northeast will gradually back northwest. Very cold and frosty Friday night.

Temperatures will be a little higher on Saturday, though it will still feel very cold in a freshening west to northwest wind. Cloud too, will be on the increase from the north and will bring scattered outbreaks of rain or sleet, possibly preceded in places by a little snow, especially over high ground.

http://www.met.ie/forecasts/

Deep Easterly

Latest ECM has me down for a "frost day" this coming friday

jambofc

are all the charts saying the same thing now,in that the high is going to sit over us much longer now and stop the atlantic rubbish breaking through until well after xmas?????
a long sustained cold spell??

Cosmo Kramer

I honestly can't remember ever seeing forecasts as low in Mayo - regularly down to -7 and -8 overnight for the next 10 days, even -9 on the 23rd.

Whatever about snow, it's going to be effing freezing over Christmas, makes a change from the wind and rain anyway.

http://www.yr.no/place/Ireland/Mayo/Castlebar/detailed_long.html

Actually, that can't be right - a daytime high of -4 from the 22nd to the 24th...very unlikely.

force eleven

Deep Easterly wrote: »

Latest met.ie outlook seems fairly alright though nothing notable:




http://www.met.ie/forecasts/

I think that is a hugely disappointing forecast actually,very downbeat for any snow/cold lovers here. Must have been written by Gerry Murphy, 'rain,sleet, possibly preceded by a little snow....on the higher ground' Nothing terribly notable at all this weekend going by that forecast.

Deep Easterly

Cosmo Kramer wrote: »

I honestly can't remember ever seeing forecasts as low in Mayo - regularly down to -7 and -8 overnight for the next 10 days, even -9 on the 23rd.

Whatever about snow, it's going to be effing freezing over Christmas, makes a change from the wind and rain anyway.

http://www.yr.no/place/Ireland/Mayo/Castlebar/detailed_long.html

Actually, that can't be right - a daytime high of -4 from the 22nd to the 24th...very unlikely.

LOL!! That looks tasty! Looks like data my be corrupted for Castlebar.

Forecast for Strade looks closer to the mark:

http://www.yr.no/place/Ireland/Mayo/Strade/detailed_long.html

Su Campu

M.T. Cranium wrote: »

Snow plow, that's how we spell it, and we actually have them too. :cool:

Well, this is the usual game of marginal snow opportunities from first the east and later the north and northwest. In both cases, the guidance so far brings just about cold enough air to sustain snow, certainly on higher ground there is bound to be some well scattered around the country, whether it snows at lower elevations more difficult to foretell at this stage.

I'm saying in the forecast thread, much of the country will eventually see a bit of snow, so far there is nothing to indicate anything very heavy anywhere but the easterly flow would favour higher parts of Wicklow and Dublin, while the northwest flow favours higher parts of Connacht.

I'm pretty sure it's going to be the usual witches' brew of snow, hail, sleet and just plain rain showers but at least there is some chance, which is far better than many weeks before Christmas when there's basically no chance.

If anything more dramatic develops in terms of the push of colder air, it might prompt some actual snowfall warnings. The problem so far is that the key thickness contour, 522 dm, and the more guaranteed contour, 516 dm, hold back each time and don't make very much contact with Ireland, then there's the tendency to consider that these cold situations almost invariably fail to verify at quite the same thickness as the models show, they always seem to underestimate the moderating powers of the nearby ocean waters (by about 3 dm in my estimation).

So what we need to see is a set of charts with a more vigorous push of the colder air where we get the 510 dm thickness to make contact with the British Isles, then it would be more certain that snow would fall.

I totally agree. That's what I reckoned would be the problem, too much modification. The models all have the H850 cold advection consistently die out before reaching northern Scotland, and there hasn't yet been any indication of sub 520dm thicknesses overspreading us. The 00Z models are a huge step down and are beginning to fall into line with that theory. could change again of course, but I reckon there's a less than a 50:50 chance of me seeing lying snow over the weekend (here in Kildare)

eskimocat

I am picking up a distinct impression that our chances of a proper snow are speedily evaporating for Christmas??? Say it ain't so...:eek: ah naw, there must be at least a small to medium snowman due to fall in leitrim over the Christmas surely.... thought might get practice in this weekend too but not looking likely either is it... hearing far too much talk about sleet and rain

Am i following correctly.... someone throw me a snowball here

helimachoptor

Cosmo Kramer wrote: »

I honestly can't remember ever seeing forecasts as low in Mayo - regularly down to -7 and -8 overnight for the next 10 days, even -9 on the 23rd.

Whatever about snow, it's going to be effing freezing over Christmas, makes a change from the wind and rain anyway.

Yeah but it's a dry cold

jenzz

http://www.metcheck.com/V40/UK/FREE/14days.asp?zipcode=wicklow

My white christmas is still hanging in there .... by a thread

maquiladora

Hmmmm, not sure how I feel about our chances this morning. I'm getting that familiar feeling that a gradular downgrade may be at hand, or maybe my eyes are just gone funny from looking at too many charts. :P

Looking at the 06Z GFS roll out, has the high slipping back over us a bit more at 66h and the -5 uppers don't extend as far west. Thursday night doesnt look great for snow showers on this run...

Gonzo

at this stage im expecting very little out of this apart from cold weather and some frost, we may see some flurries as this event is looking very marginal but nothing that will stop us getting about. This thing has been continually pushed back and downgraded over the past week, originally we were supposed to be in a snowfest driven easterly blast by now. Hopefully something good may happen after christmas day, too early to say right now.

leahyl

Gonzo wrote: »

at this stage im expecting very little out of this apart from cold weather and some frost, we may see some flurries as this event is looking very marginal but nothing that will stop us getting about. This thing has been continually pushed back and downgraded over the past week, originally we were supposed to be in a snowfest driven easterly blast by now. Hopefully something good may happen after christmas day, too early to say right now.

maquiladora

06Z also a downgrade for the weekend, snow looks more marginal and its more confined to the north on this run...

Then looking at Monday, double digit temps coming into the southwest...oh dear...

leahyl

maquiladora wrote: »

06Z also a downgrade for the weekend, snow looks more marginal and its more confined to the north on this run...

:(:(!!!!!

pauldry

same ol story

it just goes to show these long range charts are not at all reliable. no forecast is. however exagerating the charts like gfs do is just not on. its not on. its ruined christmas. thanks gfs.

maquiladora

pauldry wrote: »

same ol story

it just goes to show these long range charts are not at all reliable. no forecast is. however exagerating the charts like gfs do is just not on. its not on. its ruined christmas. thanks gfs.

Ah a bit early to abandon all hope. I'd like to see the parallel 06Z run and the ensembles. Also, lets see what the UKMO and ECM do at 12Z. Lets not cancel Christmas because of one run of one model

Edit : It's the 15th, so I believe the parallel run will actually be taking over as the new operational GFS run at some point today.

Villain

Its December a cold run with some nice high pressure around is a lot better than the Atlantic washing us away every day and god knows we need a dry spell.

February is always the best month for snow imo, so this is a good start to the winter no matter what side of marginal we end up on.

But yes expierence will teach you that FI is called that for a reason.

pauldry

pauldry wrote: »

same ol story

it just goes to show these long range charts are not at all reliable. no forecast is. however exagerating the charts like gfs do is just not on. its not on. its ruined christmas. thanks gfs.

Well isn't that what the long timers of
us always tell you on this board.
Never pin hopes on specifics in fi just
the trends.
Also never take one model or one run
in isolation-forecasters don't!
So no need to get despondent yet.

Observe the ukmo and ECM this evening
and watch the BBC forecasts for guidance
at this stage for a short term grasp.

Wibbler

pauldry wrote: »

same ol story

it just goes to show these long range charts are not at all reliable. no forecast is. however exagerating the charts like gfs do is just not on. its not on. its ruined christmas. thanks gfs.

Something very similar happened around Christmas a couple of years ago (2006?). In the run up, it was ramped to the high heavens - 'beast from the east' etc. In Dublin it turned out to be cold and raw for a day or so, with scattered showers of sleet.

I know the event hasn't happened yet, but I'd be truly surprised if this one delivers anything of note for us.

maquiladora

Not much difference betweeen the operational and parallel runs but the parallel does bring the colder air a bit further west for us on Friday :



Waiting for the ensembles to see what suppor the op run had.

Pangea

looks like met eireann are right afterall

maquiladora

Check out the 06Z GFS ensembles, the Op and P runs are mild outliers after the 20th, almost every other member is between -5 and -10 850s until 22nd.

Scubadevils

I think I have somewhat learned my lesson over the last 5 years of part-time weather forum lurking that it only leads to disappointment getting caught up in the excitement on NW, TWO and here to an extent. A quick search back and I found the thread that prompted me to join boards and take part in the December 2004 White Christmas thread!!!

http://www.boards.ie/vbulletin/showthread.php?t=204654&page=2

Which to be fair did result in snow around and on the big day, albeit a slight dusting in my area.

I haven't had the time (or patience) to learn how to read charts but clear trends have certainly emerged from getting to know various posts/members across the forums and the one thing that has become crystal clear at this stage is that getting too excited about FI ALWAYS leads to disappointment.

Pretty much every time signals in FI that show 'a winter like the 60's, 70's, 80's' etc end up coming into the more reliable timeframe where the cold isn't what was initially thought, there is a warm sector mixed in, polar low missed us by 3.4 km, dew points are marginally too high, wind changed direction just as the cold kicked in, etc etc etc!!!

:pac:

Pangea

Pangea wrote: »

looks like met eireann may be right afterall

fixed your post

I must say it's all down to whether the cold air makes it this
far west and that's something that models have always had
difficulty with.
Gfs always historically has had a bias towards resolving difficult
Synoptics with a return to a default pattern.
ECM is the king of models on defining easterlies properly
followed by the ukmo.
So pay more attention to those in the +48 to 96hrs-if they
are wobbling it's curtains...