Winter Model Discussion 12Z 22/1/13 onwards.

[Timmytour]

I expect the snow around me will finally all disappear tomorrow. But that will have been 14 days of lying snow.. Something i could have only dreamed about towards the end of December. So, even if it provides nothing else, this winter will go down as one of the more memorable ones for me. Yet going back to the model thread commencing 13th Jan, I'm not sure there would have been many voices in there expecting the spell we've had to have lasted as long as it did, certainly not from a consistent perpective of what the models were showing.

If looking back teaches you one thing, it's that you can't count on what the models are showing us after a few days and shouldn't get too disheartened or too excited about what they do. Bbut for anyone new to the models, I'd recommend going back to past threads and reading some of the experienced posters thoughts at a moment in time. Yhey are not always right of course....no one who tries to predict the weather days ahead ever is, but it does help you understand why they sometimes elect to decide a model is wrong in what it develops after a period of time, and how they are sometimes right in their projections.

looking ahead I'm a little optimistic that in the coming days the models will show us a more exciting evolution in their outcomes as the PV breaks up to a greater degree and in a different way to what's show at present. But I really need to see the Chinese CMA produce something before I can jump aboard the Winter part two train!

[nick sussex]

If we are to see another cold spell I certainly hope its the convective type and doesn't rely on frontal snow.

What was missing from the recent spell was low night time temps and sunshine for the UK. The problem with frontal snow is that you often end up with warm sectors and marginality.

I think whats been missing in recent years is that convective easterly, for this reason I think UK wide you'd be better off seeing a Greenland high rather than a Scandi one.

That normally guarantees sunshine and snow showers and troughs in the flow.

In terms of the current pattern there is still uncertainty with that low upstream in terms of how deep and amplified it is which does effect Europe.

[Man With Beard]

Don't know if its been mentioned but GEM has an interesting and potentially outcome, with an undercutting low / raised northern heights at T150 which becomes a full on scandi high by T240.

TEITS - I always thought being a bit mentally off was a benefit on this forum, what else would cause anyone to get emotional over a SSW?

[Timmytour]

If we are to see another cold spell I certainly hope its the convective type and doesn't rely on frontal snow.

What was missing from the recent spell was low night time temps and sunshine for the UK. The problem with frontal snow is that you often end up with warm sectors and marginality.

I think whats been missing in recent years is that convective easterly, for this reason I think UK wide you'd be better off seeing a Greenland high rather than a Scandi one.

That normally guarantees sunshine and snow showers and troughs in the flow.

In terms of the current pattern there is still uncertainty with that low upstream in terms of how deep and amplified it is which does effect Europe.

It has been quite remarkable to have had lying snow for two weeks and yet not have lakes and ponds anywhere near frozen enough for even a dog to walk on. In some ways that's a blessing maybe as I haven't heard of any local incidents like the kind there are usually too many of in these circumstances. But I can't remember a similar spell of weather.

Edited January 26, 2013 by Timmytour

[nick sussex]

It has been quite remarkable to have had lying snow for two weeks and yet not have lakes and ponds anywhere near frozen enough for even a dog to walk on. In some ways that's a blessing maybe as I haven't heard of any local incidents like the kind there are usually too many of in these circumstances. But I can't remember a similar spell of weather.

I agree its been unusual in that respect.

The coldest I think was Marham in Norfolk with -13c which came early in the cold spell, after that theres been generally cloudy skies.

It's a shame in one respect because with snow cover and clear skies for several days some places could have recorded some very low night time temps but it did have one positive as you mentioned with people not taking chances with frozen ponds.

Just to add to my previous post the latest NOAA State forecasts for the USA still have low confidence for the end of next week:

FRI...

LOW CONFIDENCE AS THERE IS UNCERTAINTY WITH THE EXTENT OF TROF

AMPLIFICATION OVER THE NE AND POSSIBLE COASTAL LOW DEVELOPMENT

OFFSHORE.

Because this impacts ridging ahead and the movement of the Azores high near Europe then until that gets resolved difficult to say whether the UK can get a cold snap around that timeframe.

Temperatures should dip towards the end of the week but we'd need to see that troughing amplify more to sharpen any downstream low.

Edited January 26, 2013 by nick sussex

[Jason M]

It seems to me that any significant cold spell will be via a scandi high rather than a Greenland one. The odd ensemble has hinted at a Greenland high but given that we see 80 ensembles a day from GFS thats hardlyva surprise. whilst I know others will disagree I can't see any meaninful signal for a Greenland high. There seems a background signal this winter that will simply not allow a Greenland high.

Synoptically the displaced AZH sitting in mid Atlantic with systems moving around the top is very common in Feb and in the medium term i feel that's where we may end up. In this scenario the SE can sometimes get a sideswipe from a cold continent.

From the last few days models my own view in order of likelihood as the dominant pattern is

1. Displaced AZH. Effectively the circular blob sitting in mid Atlantic

2. Zonal

3. Scandi heights

4. Greenland high (and 4th by a distance)

Jason

[mulzy]

It has been quite remarkable to have had lying snow for two weeks and yet not have lakes and ponds anywhere near frozen enough for even a dog to walk on. In some ways that's a blessing maybe as I haven't heard of any local incidents like the kind there are usually too many of in these circumstances. But I can't remember a similar spell of weather.

It's been a decent spell here in London but definitely not remarkable. Been on he wrong side of marginal at times and after 4 days of lying snow, a slow thaw set in with temperatures struggling to get below freezing. I hope the next cold spell is more to what Nick S eludes to.

Some positive signs in the model output this morning but he ECM 0z is a worry.

[Methuselah]

My biggest single 'cause' for optimism is what the models are consistently not showing: there are no real signs (that I can see, anyway) of what really kill-off winter: a Bartlett (or a faux-Bartlett, even a misplaced faux-Bartlett), or anything along those lines becoming dominant; and, equally as important, there's not much to suggest an intense, singular Polar Vortex becoming entrenched any-time-soon, either?

So, when I combine those notable absences to the fact that, after about 7 days' out, the models generally are in la la land (and I've not got a crystal ball) the weather could do just about anything??

Hence the MetO highlighting increased levels of uncertainty...

[J10]

If we are to see another cold spell I certainly hope its the convective type and doesn't rely on frontal snow.

What was missing from the recent spell was low night time temps and sunshine for the UK. The problem with frontal snow is that you often end up with warm sectors and marginality.

I think whats been missing in recent years is that convective easterly, for this reason I think UK wide you'd be better off seeing a Greenland high rather than a Scandi one.

That normally guarantees sunshine and snow showers and troughs in the flow.

In terms of the current pattern there is still uncertainty with that low upstream in terms of how deep and amplified it is which does effect Europe.

Indeed, even though we had heavy snow here, the snow was in places thawed from the grass underneath, as this was never frozen at any time in the spell.

Ironic that in past years especially around Christmas, there have been bitterly cold spells with severe frosts and no snow.

[Tom D]

It's been a decent spell here in London but definitely not remarkable.

Not far from London here in Herts it's been fantastic IMO. We've had snow on the ground for 14 days, up to a depth of 14cm last Monday and currently still 5cm in places. It's been consistently -2c to 2c for two weeks too, with the odd overnight -10c or -8c. What is most remarkable in my view is the lack of sunshine - it's been almost completely overcast and grey during the spell. This morning was refreshingly bright. Also IMO what is remarkable is that, despite a lengthy cold spell for most of the UK, the CET will probably recover to only just below average because of the swing between much milder and much colder than average conditions.

Anyway, back to the models and it's hardly encouraging to see charts like this coming into the +144 timeframe. I hope others agree there's potential BUT given the strength of that vortex over Canada/W Greenland we may be stuck in this new regime for a while.

Edited January 26, 2013 by Tom D

[Jason M]

Not far from London here in Herts it's been fantastic IMO. We've had snow on the ground for 14 days, up to a depth of 14cm last Monday and currently still 5cm in places. It's been consistently -2c to 2c for two weeks too, with the odd overnight -10c or -8c. What is most remarkable in my view is the lack of sunshine - it's been almost completely overcast and grey during the spell. This morning was refreshingly bright. Also IMO what is remarkable is that, despite a lengthy cold spell for most of the UK, the CET will probably recover to only just below average because of the swing between much milder and much colder than average conditions.

Anyway, back to the models and it's hardly encouraging to see charts like this coming into the +144 timeframe. I hope others agree there's potential BUT given the strength of that vortex over Canada/W Greenland we may be stuck in this new regime for a while.

I think the biggest problem though is that we have Iberian heights again. While this persists we won't get the trough far enough south and the colder air will be deflected into the Low Countries.

[alexisj9]

It seems to me that any significant cold spell will be via a scandi high rather than a Greenland one. The odd ensemble has hinted at a Greenland high but given that we see 80 ensembles a day from GFS thats hardlyva surprise. whilst I know others will disagree I can't see any meaninful signal for a Greenland high. There seems a background signal this winter that will simply not allow a Greenland high.

Synoptically the displaced AZH sitting in mid Atlantic with systems moving around the top is very common in Feb and in the medium term i feel that's where we may end up. In this scenario the SE can sometimes get a sideswipe from a cold continent.

From the last few days models my own view in order of likelihood as the dominant pattern is

1. Displaced AZH. Effectively the circular blob sitting in mid Atlantic

2. Zonal

3. Scandi heights

4. Greenland high (and 4th by a distance)

Jason

I don't have a problem with a Mid Atlantic high, who knows it may even move North up into Greenland.

[Summer Sun]

Well if GFS 06z is to be believed we could see a decent settled spell as we enter February after a very unsettled end to January

After this low pressure returns but thats 5 successive rain free days there on the 06z with temperatures likely to be average in the south and maybe slightly below average in the north at times

The main reason for the settled charts is the low pressure further north allows the Jet stream to head north thus allowing high pressure to build

Edited January 26, 2013 by Gavin.

[Froze were the Days]

Yuck! those above charts just remind me of the 2nd half of last February which became largely settled and very mild and completely turned over the deficit in terms of the cold spell the first 10-12 days in the south east. Wouldn't surprise me at all if it happened as it seems to me the 2nd half of February over the last decade or so has become increasingly spring-like.

[rory o gorman]

personally i would take a spring like February over a stormy zonal pattern that is battering Ireland right now .

[Jason M]

I don't have a problem with a Mid Atlantic high, who knows it may even move North up into Greenland.

The problem though is that I'm not talking about a high ridging up to Greenland. My thoughts are for the mid Atlantic 'blob'. Ie a great big circular lump of high pressure. This is very different to a blocking high. Think of a boulder in the middle of a river where the water just flows around the side. In this case low pressure systems flow around the top leaving the uk bathed in returning tropical air from the NW.

Jason

Edited January 26, 2013 by Jason M

[cooling climate]

naefs is interesting in week 2. following on from ecm ens at day 10, there is a gradual sinking of the jet further sw to allow the low euro anomoly to work west and establish itself close to our se. at the same time, a weakish mean upper ridge appears to be intent on strengthening svaalbard/iceland/nw scandi. sound familiar ?? similar timing to jan aswell.

This would of course add instability to the airflow meaning more more precipation in the east and south

tying in with what the Meto are saying. A possible very snowy airflow for eastern and southern areas

could result with the low heights pepping up convective activity.

[Gary_R_Walker]

Please delete if this is in the wrong place, but could someone let me know if this Forecasting Model Discussion part of the forum is only about finding cold and snowy weather. If it is ignore this next bit. I was wondering if the extremely high winds expected on Monday could possibly cause a storm surge down the North Sea in a southerly direction, and can any of the weather models help to predict this type of event.

Edited January 26, 2013 by Gary_R_Walker

[summer blizzard]

The problem though is that I'm not talking about a high ridging up to Greenland. My thoughts are for the mid Atlantic 'blob'. Ie a great big circular lump of high pressure. This is very different to a blocking high. Think of a boulder in the middle of a river where the water just flows around the side. In this case low pressure systems flow around the top leaving the uk bathed in returning tropical air from the NW.

Jason

It is the likely outcome in my opinion given the SSW which favours Atlantic High's but the position of the vortex which is still strong to the west.

It was actually a dominant pattern from November through to Mid-January 2005 so it can stick around but the advantage is that it is a very dry pattern and the later in the season we get the sunnier it may be. Given that stratospheric temperatures are still well above average i wouldn't be surprised to see a retrogression either.

[Summer Sun]

GFS is out to t78 now and theirs little change so far remaining unsettled and windy

UKMO is out to t72

Again very little change unsettled and windy and turning milder for a time

Edited January 26, 2013 by Gavin.

[Bobby]

Please delete if this is in the wrong place, but could someone let me know if this Forecasting Model Discussion part of the forum is only about finding cold and snowy weather. If it is ignore this next bit. I was wondering if the extremely high winds expected on Monday could possibly cause a storm surge down the North Sea in a southerly direction, and can any of the weather models help to predict this type of event.

I don't think so, I think you'd need more of NWly flow but the winds are forecast to be more SWly.

I think the Met Office do tide heights and so on and maybe the Environment Agency too.

[samadamsuk]

this is based on the GFS - swell and surf forecasts for the uk - http://magicseaweed.com. Looks like the north sea isnt going to be that effected at the om -

cheers, Sam

[Jason M]

Shame really. The Iberian heights just won't allow the northerly ........

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=138&mode=0

Jason

[Gary_R_Walker]

this is based on the GFS - swell and surf forecasts for the uk - http://magicseaweed.com. Looks like the north sea isnt going to be that effected at the om -

cheers, Sam

Thanks for that.

[SnowObsessor90]

I think this might one another one of those occasions where the Models have duped some people with the slightest 'faux' potential (myself included) but no matter there's still plenty of time to go yet