Winter Model Discussion - Cold Hunting -12Z 30/12/12

[Southender]

IF and a big IF a block does setup around mid month. Is anyone else concerned that we may end up on the wrong side of it?

[chionomaniac]

Would not be at all surprised to see this run end up the same in the latter stages.

Although its hard to tell where the blocking will set up first there is quite a few hints from the

GFS ens for it to be to our north or northeast.

Yes 6-10 day ensemble mean height anomalies between the ECM and GFS were very similar from earlier runs.

Here are the GFS and ECM 6-10 day H500 anomalies

Moving on to the 11-15 day GFS ensemble means (we are not privy to the ECM ones) we do see a subtle shift - the strong positive UK based anomaly weakens and shifts towards the North west. Will the ECM ensemble suite follow suit?

[Snowman.]

IF and a big IF a block does setup around mid month. Is anyone else concerned that we may end up on the wrong side of it?

Nope not really as it's pointed out after the initial SSW a possible smaller warming will appear over Northern Canada and Eastern Greenland which screams Northern blocking to me.

[East_England_Stormchaser91]

The charts still indicate mild weather for us at the moment though,it could not be any worse for a cold lovers perspective! We have winds coming from the warmest direction possible at this time of the year, the South-Southwest, with feeds as far South as the Azores and Canaries. It has been a long waiting game for cold this year.

In the meantime, N America and Canada will be entering the freezer with record breaking temps.

Lets just hope for something like the 31st January 2003, where many parts of Eastern England saw a blizzard which caused a total whiteout across many parts of East Anglia including Greater London, and causing the M11 and Airports to come to a complete standstill, as it happened very swiftly! I think we in Cambridgeshire received nearly a foot in one night! Not to mention the powercuts we had to get through too all throughout that night and the next day!

[Zenarcher]

Model Summary using the GFS, ECM, UKMO, GEM, JMA and NOGAPS,

Monday to Wednesday 24 to 72 hours - All the models agree on that the start of the week will be mainly cloudy and wet although on Tuesday it will be sunny across England and Wales for most of the day. Gale force winds will affect all parts of the UK on Monday and Tuesday but on Wednesday only the North and North West will see gales.

96 hours Thursday - All the models agree on high pressure building in over the UK this is likely to create widespread fog across the country although the weather will be much drier and calmer than what it has been lately.

120 hours Friday - The models still have good agreement of a large area of high pressure over the UK so dried and settled weather is likely to continue. The ECM, GEM and NOGAPS aren't too keen on bringing the high in too much they place a 1035mb isobar over the far South of England meanwhile the GFS, JMA and UKMO make 1035mb go further North into Northern England and Southern Scotland.

144 hours Saturday - Two things to look at here the high over the UK and the Atlantic lows,

First off the high all models start to show it move away from the UK apart from the JMA which keeps it strong.

What most models show,

Second thing the Atlantic lows we have GEM, NOGAPS and ECM sending a low across the Atlantic the exact positioning and depth varies but they come across a similar picture,

The GFS, JMA and UKMO don't really like that idea too much and don't really develop a low at all or just a very weak one,

168 Hours Sunday and beyond - GFS brings a large deep low into the Atlantic once this moves away we end up with a blocked set up, ECM sends lows and energy over our North so we don't see any blocking occur on it, NOGAPS makes a deep low in the Atlantic but pressure to our East rises, JMA keeps high pressure over the UK.

Strat Warming? - GFS has been keen on this for a few days now this image was from 4 days ago,

Now 4 days later for the same date still positive signs,

Overall - The models have pretty good agreement on unsettled weather to start the week but high pressure will start to move in by the end bringing more drier and settled weather. It seems the ECM, GEM and NOGAPS all show something similar tonight and the JMA, GFS and UKMO are on the other side.

[bluearmy]

The charts still indicate mild weather for us at the moment though,it could not be any worse for a cold lovers perspective! We have winds coming from the warmest direction possible at this time of the year, the South-Southwest, with feeds as far South as the Azores and Canaries. It has been a long waiting game for cold this year.

In the meantime, N America and Canada will be entering the freezer with record breaking temps.

Lets just hope for something like the 31st January 2003, where many parts of Eastern England saw a blizzard which caused a total whiteout across many parts of East Anglia including Greater London, and causing the M11 and Airports to come to a complete standstill, as it happened very swiftly! I think we in Cambridgeshire received nearly a foot in one night! Not to mention the powercuts we had to get through too all throughout that night and the next day!

That was caused by a potent toppler and a slow moving trough in the flow. I would think that if there is a cold consequence for nw Europe from any change, it would be rather more sustained than that was. I did enjoy your post from a schizofrenic perspective!

[UV-RAY]

Still not much sign of a pattern change to colder weather as far as I can see, thankfully at least high pressure builds in and gives those fed up of being flooded a rest bite. Stlll think some places could reach 16c at least come Friday onwards.

[Zakos]

IF and a big IF a block does setup around mid month. Is anyone else concerned that we may end up on the wrong side of it?

Where is the logic in that?

There is always the risk that this will happen, hence forecasts for cold are made on a probability basis. I thing High Latitude Blocking of sorts is a virtual certainty now.

A severe cold spell was predicted in mid jan by the experts on net-weather weeks ago, and as it draws closer it is looking more and more likely that they will be correct.

Also from what I am hearing, it looks probable that it will setup in a favourable position.

[UV-RAY]

Where is the logic in that?

There is always the risk that this will happen, hence forecasts for cold are made on a probability basis. I thing High Latitude Blocking of sorts is a virtual certainty now.

A severe cold spell was predicted in mid jan by the experts on net-weather weeks ago, and as it draws closer it is looking more and more likely that they will be correct.

Also from what I am hearing, it looks probable that it will setup in a favourable position.

I don't see any severe cold in any charts for mid January, I think the latter end of the month will be more likely.

[East_England_Stormchaser91]

That was caused by a potent toppler and a slow moving trough in the flow. I would think that if there is a cold consequence for nw Europe from any change, it would be rather more sustained than that was. I did enjoy your post from a schizofrenic perspective!

With UK weather, you have to look at the benefits both ways, as anything looking good can just completely go down the pan!

[Duane S.]

IF and a big IF a block does setup around mid month. Is anyone else concerned that we may end up on the wrong side of it?

I would be more concerned if we didn't have a strong strat warming about to hit followed potentially by a further one later in the month. What will be will be but this gives us a great chance for some sustained cold. What more can we ask for?

It's like saying my football team is playing well at the moment and that as a result they have a really great chance of promotion but I am really worried that they will just miss out. Got to be better than watching your team rubbish all season with no hope of promotion?

[Zakos]

I don't see any severe cold in any charts for mid January, I think the latter end of the month will be more likely.

mid/late jan onwards sorry I should have been more clear.

I certainly think we will start to see big changes in the hemispheric pattern by mid jan though

Edited December 30, 2012 by Zakos

[Methuselah]

I don't see any severe cold in any charts for mid January, I think the latter end of the month will be more likely.

Well, not being blessed with clairvoyance, I can't 'see' anything in charts, mid month?

[UV-RAY]

mid/late jan onwards sorry I should have been more clear.

I certainly think we will start to see big changes in the hemispheric pattern by mid jan though

That I agree with, hopefully we will start to benefit from those earlier rather than later. I think late January/February is when things could get very interesting for coldies.

[UV-RAY]

Well, not being blessed with clairvoyance, I can't 'see' anything in charts, mid month?

Tut, tut RP, you know full well what I was implying you tinker.

[Jaffusmaximus]

Quick question, if we got a substantial SSW mid Jan would there be enough winter left to get a good spell of cold over our Islands?

[Radiating Dendrite]

Quick question, if we got a substantial SSW mid Jan would there be enough winter left to get a good spell of cold over our Islands?

The SSW is due to start on the fifth, with a projected second warming happening soon after.

We should have plenty of winter left! We still have two months left the last time I checked!

[Uncle_Barty]

Still not much sign of a pattern change to colder weather as far as I can see, thankfully at least high pressure builds in and gives those fed up of being flooded a rest bite. Stlll think some places could reach 16c at least come Friday onwards.

A what???

Sounds painful!

That 16c will need a good bit of sunshine to achieve - a lot will depend on how much cloud is round this high. SW'lys under HP can be pretty cloudy in winter.

[Radiating Dendrite]

I think he means respite

[UV-RAY]

I think he means respite

Stupid iPad spellchecker, well that's my excuse anyway.

[Nick F]

Looking at the CPC 8-14 day H500 outlook - the indications are for a +ve height anomaly stretching from the arctic south all the way down across the UK and on to Iberia while -ve heights persist from Baffin down across the NW Atlantic sector:

http://www.cpc.ncep....14day/500mb.php

Though this pattern is pretty much where we are at at day 5 - so a stagnant pattern of high pressure blocking over W Europe seems likely - the ECM deterministic could be a little too progressive in returning the UK under a more mobile flow by t+240.

Unless we see any major changes in this pattern, I really can't see an easy route to cold and snow that many are after, as it will require mid-latiude blocking likely over NW Europe to shift favourably - and we all know how difficult that it is. The persistence of the PV over NE Canada and height rises over NW Europe and to our north suggests to me that we should look towards the east or northeast for cold later this month ... unless the SSW blasts the PV to the NW to pieces and totally changes the flow pattern over the Atlantic.

Edited December 30, 2012 by Nick F

[nick sussex]

Quite a scatter in ECM ensemble solutions from the 9th January with a colder cluster developing towards the 12th.

The majority still look more average for that time, I'd say its around 40/10 but at least theres some interest showing up there.

Following on from Nick F's post, if you look at those anomalies we really need the pattern to retrogress and a sharpening of any troughing to the west, you need to see this elongating and digging further south on the outputs, this can happen as a result of more amplification upstream.

Edited December 30, 2012 by nick sussex

[Bristawl Si]

Looking at the CPC 8-14 day H500 outlook - the indications are for a +ve height anomaly stretching from the arctic south all the way down across the UK and on to Iberia while -ve heights persist from Baffin down across the NW Atlantic sector:

http://www.cpc.ncep....14day/500mb.php

Though this pattern is pretty much where we are at at day 5 - so a stagnant pattern of high pressure blocking over W Europe seems likely - the ECM deterministic could be a little too progressive in returning the UK under a more mobile flow by t+240.

Unless we see any major changes in this pattern, I really can't see an easy route to cold and snow that many are after, as it will require mid-latiude blocking likely over NW Europe to shift favourably - and we all know how difficult that it is. The persistence of the PV over NE Canada and height rises over NW Europe and to our north suggests to me that we should look towards the east or northeast for cold later this month ... unless the SSW blasts the PV to the NW to pieces and totally changes the flow pattern over the Atlantic.

So, Nick, does your analysis basically contradict some of your 'colleagues' on here who are placing emphasis on a favourable outcome of a SSW?

[Nick F]

So, Nick, does your analysis basically contradict some of your 'colleagues' on here who are placing emphasis on a favourable outcome of a SSW?

I would find it difficult to agree with anyone who's confident to say that the SSW will definitely land us in a favourable outcome for cold/wintry weather for all, especially given the current and predicted pattern from NWP - which would take some major tweeking to get cold and snow our way.

Although it's fun trying to predict cold outcomes that the models may not be picking up on, at the end of the day, we have to wait and see what comes our way. Nothing is guaranteed in weather, no matter how favourable the stratosphere, MJO, GWO etc appear.

Of course, I do hope the SSW does bring us a favourable outcome for the sake of sanity on this thread!

Edited December 30, 2012 by Nick F

[damianslaw]

Quite a scatter in ECM ensemble solutions from the 9th January with a colder cluster developing towards the 12th.

The majority still look more average for that time, I'd say its around 40/10 but at least theres some interest showing up there.

Following on from Nick F's post, if you look at those anomalies we really need the pattern to retrogress and a sharpening of any troughing to the west, you need to see this elongating and digging further south on the outputs, this can happen as a result of more amplification upstream.

Forgetting the potential affects of stratospheric warming, the key to a pattern change is greater amplification in the atlantic flow, we are already seeing signs of amplification now, with height rises building from the azores into the south, admittedly these height rises for now are in the wrong place for colder weather.. but the atlantic flow is becoming less flat and the activity less intense than over the past couple of weeks and this in itself bodes well for mid atlantic height rises as we move further into the first half of January.

Amplification tends to increase as we move into the second half of the winter with a much weaker atlantic.

Back to the models, not much to say, all in full agreement of a drier mild spell of weather as we move through the first few days of the month, potentially very mild for the time of year, it looks a cloudy dull affair though.