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

[Duane S.]

I tend to agree with Ian Brown as I cannot see any change occurring to this pattern now of high pressure to our south , low over Greenland and relentless westerly winter weather. This winter is pretty much mild now until second half of January at least. It's time in my view to just accept its not going to be a cold winter and just enjoy the sunnier milder weather. I'll be shocked if we get a cold second half of January , my prediction is a mild January now , February average , anyway happy new year folks , let's hope we get a decent summer

Yes Ian is correct if you view his notion of 'longetivity' as being the next 10-14 days. Even then NAO will likely bumble around neutral to slightly positive. In my book that's not long and the NAO at no point looks to go raging positive.

The NAO has returned below average months for every since and including May 2012. January has to be a strong contender to continue that run as I can't see anything but a solidly -NAO second half to January.

As for your comical comment about being "shocked" if the second half of January will be cold. I can only assume you meant 'first half' and yes I'd have to agree with you I would also be shocked if the 'first half' of January was cold. If however (and I assume you couldn't possibly have) have really meant that you would be "shocked" if the second half of January turned out cold, you obviously have access to a lot more information than the rest of us here, perhaps you'd be so kind as to expain your thinking behind that?

[Methuselah]

Aye, GSL. But, whatever happens after mid-month, the scientific knowledge of stratospheric processes will be enhanced as a result...IMO, the upcoming improvements in numerical modelling could be spectacular?

[Timmytour]

Deep in FI there's a low presure system looking to slice the UK in half. Now deep in FI, the actual track of that low, lrt alone its very existence, can't be taken anywhere near face value. But if such a low did come at us, and run a couple of hundred miles south, there's enough in the charts to drag cold uppers over us imo

[Froze were the Days]

I always get a bit concerned (and I know this has been said many times before) when the FI stays in the same range, I know we're not really expecting anything substantially cold if it comes before mid-month but the FI the GFS op runs have been rolling out have been less encouraging over the last couple of days, the ECM op runs have been showing very little either and today's 0z run seems to have a relatively 'flat' zonal picture again becoming established at 10 days and the GFS run isn't far off this either.

CFS model although far more blocked than previous models runs has troughing dominant in mid-Atlantic and not a very favourable position for the U.K. although this is far better than than what the GFS and ECM are showing us at present.

Like to have kicked the year off more positively but I have to say the charts are a tad disappointing in the medium term outlook.

[UV-RAY]

I always get a bit concerned (and I know this has been said many times before) when the FI stays in the same range, I know we're not really expecting anything substantially cold if it comes before mid-month but the FI the GFS op runs have been rolling out have been less encouraging over the last couple of days, the ECM op runs have been showing very little either and today's 0z run seems to have a relatively 'flat' zonal picture again becoming established at 10 days and the GFS run isn't far off this either.

CFS model although far more blocked than previous models runs has troughing dominant in mid-Atlantic and not a very favourable position for the U.K. although this is far better than than what the GFS and ECM are showing us at present.

Like to have kicked the year off more positively but I have to say the charts are a tad disappointing in the medium term outlook.

Agree, this is what all the seasonal models have been alluding too, off course they may all be wrong but what the models are showing is rather worrying IMO. Edited January 1, 2013 by Sceptical Inquirer

[The Northern Ramper]

As with every pattern change the models struggle, we won't have a clue how this will play out until January 10th.

[IDO]

It is a poor start to the New Year for cold seekers. The GEFS trend is to take the 850s closer to the seasonal mean, but really when we have the strat to be forecast to be as it is, then that is the worse I would expect. It appears we have 10 days, or more in the south, of ridging from the Azores High, then we are dragged into another trough. A transitional northerly is possible from there, but basically for the south a poor setup.

The jet is still being pumped up by the PV piece over west Greenland and although in FI the PJ is south of the UK, this again appears to be a temporary feature, as the pattern flattens out again. A cycle by then, of over a month of relatively benign UK weather.

No sign of HLB on our side of the NH: The jet as strong as ever:

The PV set up in it's default 12/13 Winter location:

All in all, when it was suggested that by mid month, we would be heading for cold, its certainly not showing in the hi res GFS runs yet. Maybe it will take the second strat warming to kick start a reset, or the response to the SSW is not as quick as the experts suggested. So we may have to resolve ourselves that late Jan/early Feb may be our new starting point. Anyway time will tell.

Edited January 1, 2013 by i'm dreaming of...

[Bobby]

Not good op runs this morning for cold, however the ensembles , NAEFS have a consistent trend to flatten the pattern and bring back the Atlantic at least to some degree so not much change really, the extent and duration is what is more uncertain.

The anomaly maps into FI of the NAEFS run show low pressure well in charge and the NAEFS has been consistent with this over the past few days

[Jayces]

To those that say they can't see a route to cold or don't think the pattern will change etc, surely there must be something there otherwise the Meto would not hint at it in their extended outlook?

These guys are after all paid to forecast the weather and hence I hope far better placed to read the charts then most here.

And time and time again small changes in the atmosphere (I think) have led to massive changes down the line. Look at where we are now compared to where we were a month ago where people were looking forward to a raging Easterly from which there would be no quick return to mild, now 4 weeks later it's almost going to be pleasant at the end of the week!

Never underestimate how fickle mother nature is ;-)

[bluearmy]

Bobby, the low naefs anomoly comes in more from the north east than the atlantic which would make it rather a different trough to those we've become used to.

I'm dreamng, the high res gfs goes out to the 9th of jan. would that be showing a solution for mid month yet?

[Methuselah]

True Jayces...But that 'something' could well be the enormous degree of uncertainty involved; or, in other words, that nobody knows?

[IDO]

To those that say they can't see a route to cold or don't think the pattern will change etc, surely there must be something there otherwise the Meto would not hint at it in their extended outlook?

These guys are after all paid to forecast the weather and hence I hope far better placed to read the charts then most here.

And time and time again small changes in the atmosphere (I think) have led to massive changes down the line. Look at where we are now compared to where we were a month ago where people were looking forward to a raging Easterly from which there would be no quick return to mild, now 4 weeks later it's almost going to be pleasant at the end of the week!

Never underestimate how fickle mother nature is ;-)

Where does it suggest in the UKMO 15-29 Jan forecast that cold is on its way?

The initial week (up to 22nd): There is greater than average uncertainty through this forecast period, though it looks likely to start with fairly average climatological conditions, meaning the south and east of the UK will see the driest and brightest weather, while the north and west will tend to be more unsettled. However, there could be some rain at times anywhere across the UK. Temperatures will tend to be close to average for the time of year.

The last week or so: Later, some marked changes of weather-type are possible, and the risk of spells of colder than average conditions increase

As we head to the peak of our Winter the risk of colder weather will increase as a matter of course. It's very wishy washy and I would not raise my expectancies of cold on that, especially bearing in mind the strat potential, and they have to factor that risk in.

Not saying it won't happen, just may take a little longer, which was my point.

[IDO]

I'm dreamng, the high res gfs goes out to the 9th of jan. would that be showing a solution for mid month yet?

Sorry Bluearmy, meant the Op and control runs, rather than the ensemble members (who do go wild and wacky at times).

The short ensembles (850s) showing no trend to cool day up to day 8:

[Jason M]

Where does it suggest in the UKMO 15-29 Jan forecast that cold is on its way?

The initial week (up to 22nd): There is greater than average uncertainty through this forecast period, though it looks likely to start with fairly average climatological conditions, meaning the south and east of the UK will see the driest and brightest weather, while the north and west will tend to be more unsettled. However, there could be some rain at times anywhere across the UK. Temperatures will tend to be close to average for the time of year.

The last week or so: Later, some marked changes of weather-type are possible, and the risk of spells of colder than average conditions increase

As we head to the peak of our Winter the risk of colder weather will increase as a matter of course. It's very wishy washy and I would not raise my expectancies of cold on that, especially bearing in mind the strat potential, and they have to factor that risk in.

Not saying it won't happen, just may take a little longer, which was my point.

The ensemble graphs are of little use at present. It's informative to look through the ensembles in detail though as things are really not as bad in the medium to long term as people think.

By the end most of the ensembles this morning were either cold or headed that way.

Jason

[bluearmy]

Its obvious that the meto 30 dayer has the final caveat sentence added due to the strat situation. It entered the forecast at the same time that shuttler confirmed the ecm extended ens supported a SSW. No one knows what consequences the SSW could have. Without events in the strat, i doubt there would be any comment re 'colder conditions'.

Just looking though the NH plots on the fi gefs today clearly shows the vortex suffering. probably more split/disrupted as each run passes. Maybe we would have been better off if gfs hadnt brought those few quick response op runs at the weekend. I think that raised peoples expectations too much re an earlier onset reaction on the trop.

[Jason M]

Ensembles rolling out and there are a few superb ones in there. Some less good clearly, but the trend continues to gather pace IMO. Personally I'm glad were not seeing great operationals at this point.

The next 7 or 8 days will essentially be very mild overall, but after that we are back in the game.

Jason

[Weathizard]

There's some very nice PTBs in there but some shockers sypnotically with the Vortex still absolutely raging. Don't buy that at all anyway. Will be interesting to keep an eye on the models for the next week or so, could be exciting. I hope..

There are also some absolutely bizzare wacky looking charts in there! PTB12 looks decent for cold *coldhat*

Edited January 1, 2013 by Weathizard

[AWD]

A few very cold FI members in the 06z Ensembles;

The Op a milder solution in FI.

There is a "route to cold". Will we take it?

Edited January 1, 2013 by AWD

[Duane S.]

Ensembles rolling out and there are a few superb ones in there. Some less good clearly, but the trend continues to gather pace IMO. Personally I'm glad were not seeing great operationals at this point.

The next 7 or 8 days will essentially be very mild overall, but after that we are back in the game.

Jason

Agreed. Whether or not the operationals go with things is of little consequence out that far. We are seeing a growing trend of cracking charts that simply weren't there a week or so ago.

Another couple of charts of interest for the 15th.

No raging heights beneath us there...

[Catacol]

All in all, when it was suggested that by mid month, we would be heading for cold, its certainly not showing in the hi res GFS runs yet. Maybe it will take the second strat warming to kick start a reset, or the response to the SSW is not as quick as the experts suggested. So we may have to resolve ourselves that late Jan/early Feb may be our new starting point. Anyway time will tell.

Rather misleading.

Your image is from somewhere over 300h on the GFS - that is not high resolution by any means. If you read what the strat experts tell you they will all state that the tropospheric response is some time after a SSW event occurs. Therefore as the warming is forecast to start mean wind reversal on about the 5th Jan we should not expect much of a tropospheric response for a fortnight or more afterwards, and the GFS op run at 300h plus is likely to wander all over the place until it gets a handle on this.

You are correct in your late Jan/early Feb statement... but then again both GP and RJS were saying this back in November - so there is nothing in today's output which should worry any long term forecaster at the moment.

[Bobby]

Ensemble mean from the 06z for the start of the second week of January not exactly inspiring

Looking at the individual runs there seems to be a sign that a piece of the PV will be ejected towards us (from around the Greenland area generally) around the second week of January?

There are quite a few a few more runs looking like that, we've had some OP runs hinting at this. This would also fit in with the NAEFS mean/anomalies

NAEFS mean

A piece of the PV coming down could be good depending on where it sets up, perhaps giving us a big Northerly blast, but it could also very unsettled.

A little trend I have noticed...

[nick sussex]

Looking at the models I think realistically any change to colder conditions is unlikely to arrive before the 12th at the earliest with the 15th possibly more likely if things go well.

The ECM isn't too bad at 240hrs but its ensembles look underwhelming although I think BA mentioned this might be to do with its start conditions re any strat warming.

We really need to see the upstream pattern amplify and the operationals look rather reluctant to do this. It's all well and good seeing some decent ensemble solutions but I'm always wary of those till the operational switches.

I really do hope the models get a move on with this as I'm fast losing patience with seeing day after day of dross dished up with any interest over recent days being dropped next run, the ECM in particular has been useless in terms of continuity between runs and the GFS continues to toss a few crumbs at day 15!

We're all tired of crumbs we want cake!

Edited January 1, 2013 by nick sussex

[joggs]

Happy new year to you all n have a safe 1.

[bluearmy]

Looking at the models I think realistically any change to colder conditions is unlikely to arrive before the 12th at the earliest with the 15th possibly more likely if things go well.

The ECM isn't too bad at 240hrs but its ensembles look underwhelming although I think BA mentioned this might be to do with its start conditions re any strat warming.

We really need to see the upstream pattern amplify and the operationals look rather reluctant to do this. It's all well and good seeing some decent ensemble solutions but I'm always wary of those till the operational switches.

I really do hope the models get a move on with this as I'm fast losing patience with seeing day afer day of dross dished up with any interest over recent days being dropped next run, the ECM in particular has been useless in terms of continuity between runs and the GFS continues to toss a few crumbs at day 15!

We're all tired of crumbs we want cake!

Normally nick i'd take no notice of gfs op in low res but it runs at more layers than the ens so i wonder if it shoud have a better handle on strat/trop interactions? the overall judgement may well be that looking at the output beyond a week, either operational or ensemble maybe a complete waste of time until any affects from the initial warming have become clear.

[IDO]

Rather misleading.

Your image is from somewhere over 300h on the GFS - that is not high resolution by any means. If you read what the strat experts tell you they will all state that the tropospheric response is some time after a SSW event occurs. Therefore as the warming is forecast to start mean wind reversal on about the 5th Jan we should not expect much of a tropospheric response for a fortnight or more afterwards, and the GFS op run at 300h plus is likely to wander all over the place until it gets a handle on this.

You are correct in your late Jan/early Feb statement... but then again both GP and RJS were saying this back in November - so there is nothing in today's output which should worry any long term forecaster at the moment.

Interestingly Simon Keeling has blogged on the upcoming strat, and has reservations to its capacity to deliver very cold weather:

http://www.weatherweb.net/wxwebtvsimonnew.php?ID=567

So with this seemingly not a perfect strat warming event and the UK only 60/40 to benefit in any case, these factors, along with the UK's poor starting position, would to me suggest that we are far from certain to get the benefits of such an event, snow/cold wise. We are bound to get some cold and the north some snow but I believe the expectations from many members here is for a much colder prolonged wintry landscape.

A bit of luck needed I suspect.