Model Output Discussion 1200 hrs 15/11/14

[NorthernRab]

Within the reliable time frame it looks settled with little in the way of wind / notable rainfall as per the GFS & GFSP - some chilly nights to come though! 

 

Looking a tiny bit beyond that, the first signs of considerable cold comes in the form of overnight lows a week from now in Scotland where temperatures will drop as low as -7'C / -8'C. 

 

 

 

All in all the message is settled and chilly in the reliable time frame. 

[Man With Beard]

Some good representations of different charts tonight above, thank you. I think the way things are going are - yes, the models may well have over done troughing over Svalbard, but the result is just a longer path to a mid-latitude high and the possibility of a weak easterly in the SE for a while - there's probably too much ground to make up to hold the Atlantic back completely.

However, a clear possibility is that more trough disruption will occur around the T144 mark. This could prevent the HP ridging in so strongly. This may mean we end up with NWlies coming around the top of the high. Not as cold in general but possibly allowing a Greenland sourced flow a little later down the line.

[Captain Shortwave]

ECM showing the Azores high building in strongly around days 6/7

Polar profile looks good across all the models. Again not the cold set up that many people would want, but it's not that bad overall with dry weather and overnight frost and fog.

Edited November 26, 2014 by Captain shortwave

[mcweather]

Put into the mix the usual poor modelling of arctic high pressure systems within the day 10 period, and add to that the further difficulty in trying to model the transfer of upper vorticity energy across the pole from Canada to Siberia, the usual advice of sitting back and trying not to over- disentangle the mischiefs of each and every intra day face value model operational output suite becomes ever more pertinent. 

 

The pleasantly seasonal rather cold mid latitude high solution advertised in the shorter term looks to be well calculated by the models, but best be wary of reading too much into, and over anticipating, any lasting legacy (if it happens) from flattening out of the pattern to any long-lasting and meaningful extent thereafter with associated westerlies.

 

Whilst this is for sure a distinctly plausible (transitory) response to the energy transport across the pole, we should bear in mind that destination PV Siberia represents the next crucial step along the way with this winters pattern. This is said within the context of a very beaten up and weak polar vortex. It also represents a polar opposite to what happened last year in early December as Siberian energy transferred across to the Canadian sector as part of a centrally organising steroidal vortex that spat deep low after deep low across the atlantic towards us.....

 

Notwithstanding the uncertainties with regard to risks with over progressive model attempts to ditch the high to the east/north east in the short/medium term, the eventual outcome of energy balancing towards the Siberian sector will provide the fresh impetus anyway to the cold pooling SAI feedbacks which have been proven in recent weeks modelling to be in action.

 

We shouldn't fret too much over questioning timing when this next stage in the process is completed - even delayed by a short time. I stated in a previous post that this overall seasonal pattern process, once begun, was likely unstoppable and by the time the up-coming re-shuffling across the polar field has occurred, I would very much expect the next cycle of westward pattern backing to continue with vigour, whatever happens with regard to polar field modelling uncertainties in the shorter term.

 

The upping of the ante in the wave breaking battle as a consequence of this takes us ever closer towards the very back-end of the year and the increasing likelihood of an SSW. Its worth riding a short troposphere/stratosphere bombardment pause while the pattern re-sets

 

@blizzard 81 - will send a pm message

 

As ever Tamara, a sensible and balanced post looking at the much bigger picture. For sure it is that bigger picture that we have to look at to get us to some genuinely wintry weather. The ideas from yourself and Matt Hugo about late December for a possible pattern change to cold have for me always been the ones which were most likely. I thinks perhaps we have been spoilt by Dec2010 especially here in the south. ( It was the coldest December since at least 1879 in south and east Dorset!) into thinking that cold should arrive on the first of December. Never a likely scenario with our geographical position in the world.

 

Year and years of winter weather watching have taught me that patience is the key and now that we are getting to know so much more about how the strat, SAI etc have on shaping our winters it will be interesting to how the signs and signals playout and the global seasonal models unravel. The current holding patterns will have to be got through but come the middle of December I think some very interesting synoptics could start to show up.

[IDO]

We appear to be moving out of the model uncertainty period, with good inter and cross model support for the next 10 days.

 

ECM at D7:  D8: 

 

D9:   D10: 

 

The GEFS FI are also now moving in the general same direction. The D13 members confirm this:

 

 

Timing issues re the Atlantic flow and issues as to where the jets sits and meanders but the long wave pattern fairly consistent. Its now a question of the longevity of this pattern and if & when the strat warming will take effect?

Edited November 26, 2014 by i'm dreaming of...

[swfc]

Quite a change on ecm at 192 hrs.Shows the fluidity of the output atm!!

Edited November 26, 2014 by swfc

[knocker]

A look at the GEFs anomaly for the last three days at 12z starting T240. You can see the marked pattern change, The last chart is a follow through of today's run and the eclipse of the Scandinavian HP

Charts courtesy weatherbell.

Edited November 26, 2014 by knocker

[Summer Sun]

ECM shows things turning progressively cooler next week with the 850's down to -6 by the 5th

 

The week starts with high pressure building so frost and fog overnight if the fog lingers during the day temperatures could struggle to get above 3c around average away from any fog

 

 

By Thursday the high begins to sink south as low pressure begins to move in this allows a north westerly flow by Friday and the 850's falling down to -6 for some and -5 widely

 

 

ECM ends with the high trying to move in again allowing the 850's to rise slightly but still a chilly feel to things

 

 

So all in all a more seasonal start to meteorological winter than last year

 

Edited November 26, 2014 by Summer Sun

[blizzard81]

Not a great ECM for coldies, not unless a semi-northerly toppler floats your boat!

[swfc]

Not a great ECM for coldies, not unless a semi-northerly toppler floats your boat!

Indeed just looks like a bog standard set up be it less unsettled than last year!Guess its suck it and see for the foreseable

[blizzard81]

Stunned silence greets the ECM 12z. The thing that worries me most about this run is that the PV over north east Canada looks just as monstrous at T240 as it does at T72. The other thing that worries me is the ridging of the arctic high over towards Canada at the end of the run. This will help feed the PV over north east Canada and thus push another surge of frigid air into the north east united states. This will in turn ramp up the atlantic - sound familiar? It's for these reasons that I hope this particular run is very wrong!!

Edited November 26, 2014 by blizzard81

[Barry12]

It looks like the block to the NE is coming to an end as we start Winter, which is the most disappointing thing. Still at least theirs no mild weather in sight after this weekend.

Edited November 26, 2014 by Barry95

[blizzard81]

It looks like the block to the NE is coming to an end as we start Winter, which is the most disappointing thing.

Yes Barry, bang on cue! The ECM is most bullish about the block's demise in the earlier time frame so lets just hope it's wrong.

[IDO]

It looks like the block to the NE is coming to an end as we start Winter, which is the most disappointing thing. Still at least theirs no mild weather in sight after this weekend.

Yes it's like clockwork, soon as we enter December the flow flattens and we enter A westerly flow. Luckily the jet is currently forecast to be further north than most of last winter and not as powerful, so more settled at least for the South. Hopefully it won't eat away too much of the winter, and as the experts have reiterated countless times, we must lower our expectancies till maybe late December, as this more zonal flow has been well advertised in the long range models for sometime.

[terrier]

It looks like the block to the NE is coming to an end as we start Winter, which is the most disappointing thing. Still at least theirs no mild weather in sight after this weekend.

Barry the gfs has for a few days been showing the breakdown of the high to the East. And finally it seems to be coming to fruition. Perhaps now we have the Azores moving in we can hopefully reset the patterns as we move into dec. certainly expect to see a dominant atlantic spell as we move into mid dec. then if the ssw plays ball we may see a cold jan.

[Due South]

Barry the gfs has for a few days been showing the breakdown of the high to the East. And finally it seems to be coming to fruition. Perhaps now we have the Azores moving in we can hopefully reset the patterns as we move into dec. certainly expect to see a dominant atlantic spell as we move into mid dec. then if the ssw plays ball we may see a cold jan.

(Certainly) How do you come to that conclusion?

[Barry12]

Yes it's like clockwork, soon as we enter December the flow flattens and we enter A westerly flow. Luckily the jet is currently forecast to be further north than most of last winter and not as powerful, so more settled at least for the South. Hopefully it won't eat away too much of the winter, and as the experts have reiterated countless times, we must lower our expectancies till maybe late December, as this more zonal flow has been well advertised in the long range models for sometime.

 

Yes it has, but it has been 'advertising' the same in FI for the past month. Eventually it was going to be right.

Barry the gfs has for a few days been showing the breakdown of the high to the East. And finally it seems to be coming to fruition. Perhaps now we have the Azores moving in we can hopefully reset the patterns as we move into dec. certainly expect to see a dominant atlantic spell as we move into mid dec. then if the ssw plays ball we may see a cold jan.

 

The models only go out to day 16, so why do you expect this? I wouldn't write off cold for the whole of December, maybe the first week at most.

[ANYWEATHER]

Certainly nothing set In stone yet, , and the beast from the east makes a phantom appearance for a short time , but the main player tonight is the Azores high, well perhaps! To be honest ,I wish the azores high stays well away from the Uk  and  amplify in mid Atlantic allowing some very strong cold fronts to enter the Uk, from the NorthWest and at least give us some Dynamic winter weather.... something the models are picking upon now !

[bobbydog]

Stunned silence greets the ECM 12z. The thing that worries me most about this run is that the PV over north east Canada looks just as monstrous at T240 as it does at T72. The other thing that worries me is the ridging of the arctic high over towards Canada at the end of the run. This will help feed the PV over north east Canada and thus push another surge of frigid air into the north east united states. This will in turn ramp up the atlantic - sound familiar? It's for these reasons that I hope this particular run is very wrong!!

 

 

i'm optimistic. heres why-

 

lets look at hemispheric profiles and see if something can come from seemingly nothing.

 

heres 216hrs on the ECM-

 

 

spot any similarities with this chart?

 

 

i'll bet if we were looking at that we would say- "no easterlies on the way" "might get a toppler out of it"

 

some might say that the PV is not parked over greenland in this chart. that may be true but as has been pointed out, there is a trend in the models to shift it towards our part of the world.

 

having said that, from the above scenario, we could (actually we do) end up with a chart like this-

 

 

 

look at that PV raging over greenland!!

 

we wouldn't want that would we??

 

guess what happened just 5 days later....... (here's a clue- check the dates)

[mcweather]

i'm optimistic. heres why-

 

lets look at hemispheric profiles and see if something can come from seemingly nothing.

 

heres 216hrs on the ECM-

 

 

spot any similarities with this chart?

 

 

i'll bet if we were looking at that we would say- "no easterlies on the way" "might get a toppler out of it"

 

some might say that the PV is not parked over greenland in this chart. that may be true but as has been pointed out, there is a trend in the models to shift it towards our part of the world.

 

having said that, from the above scenario, we could (actually we do) end up with a chart like this-

 

 

 

look at that PV raging over greenland!!

 

we wouldn't want that would we??

 

guess what happened just 5 days later....... (here's a clue- check the dates)

 

 

 Nice one Bobby dog a clear antidote to all the worrying about the PV  possibly getting established over Greenland.

[karyo]

I watched the 12z gfs at work and felt quite positive but the ECM is rather underwhelming. 

At 192 hours it comes close to delivering a decent northwesterly (which for my location is the best direction) but it failed due to not enough amplification. At least it is keeping the heights in the Arctic throughout the run.

 

Karyo

[Froze were the Days]

Indeed just looks like a bog standard set up be it less unsettled than last year!Guess its suck it and see for the foreseable

 

Agreed cross model agreement in about a weeks time of something drier and more settled - perhaps with some frost but to be honest all pretty bog standard synoptically speaking, don't know where we go from there to achieve any cold, the jet well to the north looks pretty established.

 

Please no more comparisons to the start of last winter (by the way we had a pretty frosty/foggy few days before mid-month in the south east) - like comparing the highest professional football standards to Woking Town.

[BLAST FROM THE PAST]

Why do folk think the models have nailed it until mid Dec onwards now?  The same as they did the week before and last week?  Yes I think we are seeing a change, but that change isn't sorted yet.   I think lots to still look at with arctic HP still being progged.  For me this AZH will assist us...mind you I would say that, but I'm happy with the overall shape of the change.

Lets see where we are in 3-4 days, or indeed 7-14 days before we 'assume' we have to wait until January for cold. 

 

BFTP

[ANYWEATHER]

Agreed cross model agreement in about a weeks time of something drier and more settled - perhaps with some frost but to be honest all pretty bog standard synoptically speaking, don't know where we go from there to achieve any cold, the jet well to the north looks pretty established.

 

Please no more comparisons to the start of last winter (by the way we had a pretty frosty/foggy few days before mid-month in the south east) - like comparing the highest professional football standards to Woking Town.

Pardon, what cross model agreement in a weeks time , I personally don't see anything like this???    

[blizzard81]

i'm optimistic. heres why-

 

lets look at hemispheric profiles and see if something can come from seemingly nothing.

 

heres 216hrs on the ECM-

 

 

spot any similarities with this chart?

 

 

i'll bet if we were looking at that we would say- "no easterlies on the way" "might get a toppler out of it"

 

some might say that the PV is not parked over greenland in this chart. that may be true but as has been pointed out, there is a trend in the models to shift it towards our part of the world.

 

having said that, from the above scenario, we could (actually we do) end up with a chart like this-

 

 

 

look at that PV raging over greenland!!

 

we wouldn't want that would we??

 

guess what happened just 5 days later....... (here's a clue- check the dates)

 

Hi Bobbydog, there are some very important differences on those Dec 62 charts. The one on the 8th is a different kettle of fish to today's scenario

as there is next to no PV over north east Canada and the one on the 21st, whilst at first glance looks terrible for cold prospects, there is a very important

difference in that the energy coming out of the States is much more favourable. The energy is digging south at a very favourable angle and much less likely to rush across the atlantic. Compare this with your chart for this December and you will see that the energy coming off the eastern seaboard of the US is at a much less favourable angle and primed to zip across the atlantic which would be akin to last winter.

The lesson here being you need to analyse all the crucial elements that go into making it possible for UK cold (and there are so many),

not just the general synoptics.

Edited November 26, 2014 by blizzard81