Model Outlook Thread: January 2010

Scubadevils

opr wrote: »

The more qualified people here and the Irish MET seem to be saying very little about Sunday while other people are playing it up as snowmageddon! Why ?

Opr

Really down to the quote in my last post, it would seem something like this is extremely difficult to forecast - still three days away, they have trouble forecasting snow 6 hours out!

opr

Felixdhc wrote: »

Really down to the quote in my last post, it would seem something like this is extremely difficult to forecast - still three days away, they have trouble forecasting snow 6 hours out!

I completely understand that but usually when an event this big seems to be on the cards we would at least get posts/opinions from the more qualified people on the forum but they all seem to be staying remarkably quiet and given the potential of the event it just seems strange.

Opr

MilanPan!c

I predict 100cm of snow between Sat and 2012.

Scubadevils

opr wrote: »

I completely understand that but usually when an event this big seems to be on the cards we would at least get posts/opinions from the more qualified people on the forum but they all seem to be staying remarkably quiet and given the potential of the event it just seems strange.

Opr

We have had some thoughts already from Snowaddict and I would expect he will give a detailed update this evening... no pressure Snowaddict!

I'm sure Weathercheck etc will be around this evening too with their thoughts.

nacho libre

munsterlegend wrote: »

did she mention sky news predicted doomsday on sunday?

no.
However, Pat Clarke, on the radio forecast just now, mentioned a strong easterly airflow taking hold over the weekend with showers over much of the country by Monday.

joe316

On snow, Gerry "Sunny Fiesta" Murphy is on RTE atm

maquiladora

opr wrote: »

The more qualified people here and the Irish MET seem to be saying very little about Sunday while other areas are playing it up as snowmageddon! Why ?

Opr

Gerry Murphy was just interviewed on the news and they showed charts for Sunday/Monday that had constant precipitation, we just dont know if it will all fall as snow or not yet, if it does, then it could be a snowfest.

maquiladora

12Z ECM

typhooner

Would i be correct in saying that this chart would result in widespread Blizzard conditions...

http://www.meteociel.fr/modeles/ecmwf/run/ECM1-144.GIF?07-0

maquiladora

typhooner wrote: »

Would i be correct in saying that this chart would result in widespread Blizzard conditions...

http://www.meteociel.fr/modeles/ecmwf/run/ECM1-144.GIF?07-0

Dont think temps would be high enough, wind and rain I would say.

Su Campu

It would seem that we are now in the start of a global pattern shift that should mark the start of the end of this prolonged cold setup, and bring us back to normal January levels.

With the north Atlantic upper high cutting off and joing up with the Scandi high, and the persistent cold trough over North America becoming replaced by a ridge, the global circulation resumes its progressive pattern and allows the Atlantic to restamp its authority on Western Europe with a positive NAO.

All today's models - ECMWF, GFS, GEM, NOGAPS and NCEP CFS are in good agreement with this change, and the CPS (for what its worth) has a positive NAO right through to the end of the month.

The imminent advancement of the Atlantic High eastwards this week effectively cuts our umbilical chord to the arctic source and its low heights, and brings with it a dam rise of some 20dms by Tuesday, signalling the end of the month-long Arctic influence.

maquiladora

18Z GFS rolling out, showing snow showers for the east and southeast almost all day Saturday :



Which continues on Sunday morning with some more ground covered by the showers in the south and east :



As darkness falls in the early evening, precipitation would spread deeper into the northeast, midlands and southwest :



By midnight the situation looks the same, widespread snow inland but temps rising slightly on the east coat may turn it to sleet or rain in places :



Monday morning and the picture is the same precipitation falling in many places, in the east and southeast this would mark 48 hours of what appears to be almost constant precipitation. Temps rising in the east may turn this increasingly to rain and sleet but further west it would probably still fall as snow :



Beyond this the precipitation continues but the temp rise also continues slowly turning all the precipitation to rain during Tuesday, expect perhaps on high ground in places.

Deep Easterly

Su Campu wrote: »

All today's models - ECMWF, GFS, GEM, NOGAPS and NCEP CFS are in good agreement with this change, and the CPS (for what its worth) has a positive NAO right through to the end of the month.

.

Something to watch alright. Tonight's ECM shows Ireland in classic battleground territory during the middle of next week:



Source: http://www.ecmwf.int/

with a more normal Atlantic stream developing thereafter. Of coarse, there is always the chance that the Arctic Block will prove stronger that is forecast so we need to see some sort of trend developing over the next few days to be sure either way.

rc28

Su Campu wrote: »

It would seem that we are now in the start of a global pattern shift that should mark the start of the end of this prolonged cold setup, and bring us back to normal January levels.

With the north Atlantic upper high cutting off and joing up with the Scandi high, and the persistent cold trough over North America becoming replaced by a ridge, the global circulation resumes its progressive pattern and allows the Atlantic to restamp its authority on Western Europe with a positive NAO.

All today's models - ECMWF, GFS, GEM, NOGAPS and NCEP CFS are in good agreement with this change, and the CPS (for what its worth) has a positive NAO right through to the end of the month.

The imminent advancement of the Atlantic High eastwards this week effectively cuts our umbilical chord to the arctic source and its low heights, and brings with it a dam rise of some 20dms by Tuesday, signalling the end of the month-long Arctic influence.

Then why are the real forecasters so certain that there's no end in sight to this cold spell? On the nine and 6 news gerry murphy was quite certain he couldn't see a breakdown coming.

Su Campu

rc28 wrote: »

Then why are the real forecasters so certain that there's no end in sight to this cold spell? On the nine and 6 news gerry murphy was quite certain he couldn't see a breakdown coming.

Maybe they're taking the opinion that one swallow does not a summer make, ie. they may be waiting for further model runs to confirm or deny this change. But with all models saying pretty much the same thing, it's looking a likely outcome

Snowaddict

Hi Su Campu,

At the start of a global pattern shift - Yes. Upstream signals are changing and are somewhat mixed. To suggest however that there is unanimous mulit model continuity on the pattern is incorrect of you this evening. GFS is entirely different to ECWMF towards Day 7, as indicated by Deep Easterly above.

There is not solid conifdence on a positive NAO signal, some models suggest this, some don't. GEM continues to suggest an undercutting motion with southeasterly winds to T+144. Yes, it won't be as cold with a vast diurnal range. But near average everywhere - Not if the GEM or ECMWF evolution verified exactly today out to T+144.

CFS is worth, well not very much, as we know. I do agree that a large scale pattern change is beginning to develop and the formation of the Scandi High itself cuts off our cold source as deeply cold air is unable to circulate around the High and back westwards into Western Europe.

All output considered tonight, the breakdown is not as rapid as you suggest above. If you consider GFS in isolation, then it quite possibly is.

It would seem that we are now in the start of a global pattern shift that should mark the start of the end of this prolonged cold setup, and bring us back to normal January levels.

With the north Atlantic upper high cutting off and joing up with the Scandi high, and the persistent cold trough over North America becoming replaced by a ridge, the global circulation resumes its progressive pattern and allows the Atlantic to restamp its authority on Western Europe with a positive NAO.

All today's models - ECMWF, GFS, GEM, NOGAPS and NCEP CFS are in good agreement with this change, and the CPS (for what its worth) has a positive NAO right through to the end of the month.

The imminent advancement of the Atlantic High eastwards this week effectively cuts our umbilical chord to the arctic source and its low heights, and brings with it a dam rise of some 20dms by Tuesday, signalling the end of the month-long Arctic influence.

maquiladora

Ive edited my post of the previous page to show precip charts from Saturday to Monday to show just how longlasting the 18Z GFS is forecasting the precip to fall (looks light most of the time but its the sheer length of time it goes on for thats interesting).

ninebeanrows

I think that is a very premature call Su Campo.

Many models show potential for PV to be re injected to our east with
that high not going anywhere, the temperature does modify during midweek yes.

maquiladora

18Z GFS stalling a low to our southwest on Tuesday?

Stalls it there till Thursday in battleground mode then cold air extends back over us again?

Pushes the "real" breakdown back to 200 hours...?

Heh. Pub run.

Snowaddict

maquiladora wrote: »

18Z GFS stalling a low to our southwest on Tuesday?

Stalls it there till Thursday in battleground mode then cold air extends back over us again?

Pushes the "real" breakdown back to 200 hours...?

Heh. Pub run.

Great analysis there Maq, summed it up in a nutshell

Yes & while Su Campu is right to a great extent in his post above, which is very informative about the large scale pattern, it's very difficult to predict as to whether it will be a straight through breakdown or something similar to GFS 18Z. The cold pool will be very strong & it will require some power to break it down.

Diurnal range decreasing into Monday but still feeling very cold, with low day time maxima.

SA

Deep Easterly

Snowaddict wrote: »

Diurnal range decreasing into Monday but still feeling very cold, with low day time maxima.

SA

Very true, and this possible wind chill effect cannot be underestimated. It will continue to feel bitterly cold despite a very slow increase in temps due to the forecast increase in wind for next week.

nacho libre

but it seems you all agree that it will breakdown:( the dispute is as to whether it will be progressive or swift. i wonder will we be hearing from the guy from predictive solutuions again after he said it would last into March.

well, as i've stated previously if it must end let it not end with a wimper!

pistolpetes11

If and its a big IF , we were to get a substantial amount of snow over the coming days , would this have a significant input on the breakdown of this cold spell ?

maquiladora

nacho libre wrote: »

but it seems you all agree that it will breakdown:( the dispute is as to whether it will be progressive or swift. i wonder will we be hearing from the guy from predictive solutuions again after he said it would last into March.

well, as i've stated previously if it must end let it not end with a wimper!

Dont forget its only the first week of Jan! Who knows what late Jan and all of Feb might bring?

Su Campu

I hear what y'all are saying, and yes it is a big call at this stage. But upwind changes are already in motion, and I do think that the models are much in unison in taking these changes forward.

As I pointed out in a post on Sunday, I think it was, the cutting off of the Atlantic high this week was going to be a crossroads in our future - that has happened, we're losing the Greenland high, there's a total replacement of airmass taking place over the weekend, our blood supply to the Arctic is gone, and to my eye doesn't look to be coming back any time soon.

It's just my opinion of the large scale picture. Yes, in the mean time there will be small scale risidual cold pools debris remaing over the weekend, but very soon these will modify and remove the barrier to the Atlantic.

That's how I see it on a global scale, only time will tell if it's right or wrong

M.T. Cranium

I recall that the models were trying to shift the cold before Christmas a little too fast, and when it did shift, the milder conditions were hardly any better than near normal, and actually made things worse by adding to the melt/freeze cycle and ice production.

This looks to me like a pattern that could evolve into a major winter storm; as long as high pressure stays planted over Scandinavia, it likely won't warm up much beyond 2-4 C at sea level, which keeps higher elevations open to snowfall, but if another surge of upper level cold rotates around this Scandi high and collides with some moisture-laden lurking system like the one being sketched out for Tuesday, then you might get into some serious snowfalls.

Sunday looked a bit better on the GFS 18z than the 12z, with the lower thickness values hanging around a bit longer, and scraps of marginal thickness continuing to show up at times even through the week, suggesting that perhaps with a reality check, the cold spell may not really moderate that much at all.

Energy peak of 14th-15th may be the battleground scenario to set up a winter storm, keep an eye on that period for further developments.

Deep Easterly

Not sure how reliable these forecast maps are or what model they are based on, but they do show a gradual warming over the mid to late Jan period.

Will be interesting to see the model runs tomorrow and to see will they be in the yay or nay camp regarding this.

Edit: Just to add, the above charts have been predicting a warm up since the last 3rd of December 09. They will be right at some stage!

Deep Easterly

Not much change at 144hrs on this morning's ECMWF run:



Ireland under slack trough which divides the cold polar continental airmass and relatively milder Atlantic air, with not much happening inbetween.

By 192hrs, this model has somewhat milder Atlantic air breaking through:



although certainly milder, the real Atlantic warmth still a couple hundred miles to the west of Ireland on the western side of an upper ridge.

by 216hrs, the real milder air attempts an attack from the southwest:



To far out to be even speculated on though, but it would seem a tentative trend is developing on the models this morning of somewhat milder breaking through towards the 3 quarter of January.

So will it or won't it? time will tell...:)

jambofc

do these chart's look good to you with more knowledge,to me they say cold enough for snow to start with then becomeing marginal but you never no,the amount of precip is amazing,it cant all end with 3 n half weeks of dry cold(localised snow)weather and then just rain for day's could it????

jambofc

this one would'nt attach to my last post.