Model output discussion - January cold spell ending, what next?

[DanDorsetUK]

Personally I dont see anything to be worried about just yet. For me it's just about downwelling timing. Its clear they are picking up the downwelling but surely this will now increase as time goes on and then reflect in the output. I've not looked lately how much downwelling has acured to todays date and the timeline involved but maybe that's worth a quick look. When the reinforcements hit again give it a delay time then you'll see that reflects in the models. 

[username home]

Consistent that everything looks peachy at T+240...

[ICE COLD]

P7 is an absolute stonker ( but it’s 16 days away ) . Just thought I would post it because of the insane uppers . 

[chris55]

19 minutes ago, Man Without Beard said:

Looking at the clusters D8-D15 

I sense the ECM op is out of kilter with the main thrust of the ensembles. The eventual outcome is a Greenland ridge of sorts by D11, with varying outcomes. 6 clusters. On the T264-T360, the two slightly larger clusters keep a strong ridge to the NW throughout and therefore likely to be very cold. Three other clusters are trending towards west based -NAO so UK cold prospects rely on depth of cold filtered in from the east along with the positioning of the front dividing cold and mild. The remaining cluster weakens the ridge to the NW and would lead to average conditions.

On the whole, cold favoured D8-D15 but not necessarily for all.

 

In the EXTENDED 264 + timeframes I’m counting

22 members with the strong ridge very cold set up, strong north/northeast flow

16 members with a cold set up though not as extreme, perhaps more battleground scenario.

13 with a much milder flow, Azore/Euro ridge holding.

Thats roughly 75% cold, 25% milder. Good set!

 

 

[Frostbite1980]

GFS making more of the low in the mid Atlantic on the 6z what the does down the line....I have no idea

[TEITS]

Almost impossible to figure out what the outlook is going to be. I feel the usual scenario will occur around 12/13th Jan as we see a shift W of the high pressure to our NE and less progress from the Atlantic. Whilst I wouldn't expect this to change to sudden cold E,lys the effects of which have a knock on effect later on.

We then have the added complication of the Arctic high and polar vortex bringing a bitterly cold airmass to NE Europe. The effects on the UK could be a bitterly cold, convective cold spell or a moderately cold spell but with battleground blizzards or even both. l  haven't included the milder option because as I said in the covid thread, I do not want to see a severe cold spell this winter. I bet it will be sods law we get one when this is the last thing the country needs!

[Purga]

Some positives:

At the moment the ensembles are very clearly trending towards another cold spell (The coldest GEFS set yet) and the prolonged turbulence in the stratosphere definitely adds something to the mix..

Hints (again) of a Scandi High trying to build on the ICON 6z & the upcoming GFS 6z (sub 528 across the country again).

There is a second SSW (reversal) due in a couple of days and even a third later on in the month.

The consequences of this are very hard to predict so model volatilty will surely be the order of the day!.

The opportunities remain very much on the table for a decent cold spell, moreso than we've had at this time of year, for a long time.

Edited January 10, 2021 by Purga

[sheikhy]

And again changes early on and front grinding to a halt across eastern areas!!further west than 12z yesterday!!

[feb1991blizzard]

40 minutes ago, nick sussex said:

The frustration continues . 

The ECM op really drops the ball later on and delivers a day ten chart that suggests the SSW was an illusion ! 

We seem to be in the chasing the pot of gold at the end of the rainbow mode.

At some point day ten charts need to start counting down and not left marooned at that stage .

 

It has counted down on the ensembles now to 8/9 ish, remember that mean Atlantic / S Greenland ridge was at one point d12, wouldn't worry about the ops until the ensembles get it within D6 unless the ops are throwing out poor runs every run, in the main the op runs have been pretty good the last few days, If we are to get a proper Greenland block like 2010, the eps and GEFS mean will have to start showing it over the next 24-48 hours i would think, favoured outcome IMO is the GFS 0z at the minute, where the ridge will be far enough North to get some very cold air over us and yes it may look temporary and not as severe as the proper searing cold of some runs, it could re-amplify once we get that far rather than starting to collapse into a MLB like it does on that GFS run, this is what i have in mind as to what might be the closest to verification.

[chris55]

11 minutes ago, nick sussex said:

The ECM on its way to the tragic day ten chart does throw a few teases in but will they still be there this evening and the UKMO looks totally underwhelming upto day 6.

There is a lot of chopping and changing between runs so hopefully it will change once again !

I agree the Euro operationals this morning are poor! But taking all the data together shows a more interesting picture. 
 

EC op was in one of the lesser clusters.

But as you say with everything chopping and changing its hard to pin anything down at the moment. 
 

Will await EC this evening with interest to see which way it goes along with the ensembles.

 

 

[Kiwi]

12 minutes ago, Rapodo said:

Personally I dont see anything to be worried about just yet. For me it's just about downwelling timing. Its clear they are picking up the downwelling but surely this will now increase as time goes on and then reflect in the output. I've not looked lately how much downwelling has acured to todays date and the timeline involved but maybe that's worth a quick look. When the reinforcements hit again give it a delay time then you'll see that reflects in the models. 

Yes ...the potential is there.

 

[bluearmy]

2 minutes ago, sheikhy said:

And again changes early on and front grinding to a halt across eastern areas!!further west than 12z yesterday!!

The 12z runs certainly took the front well into the North Sea. This 06z returns it back to just off the east coast 

[northwestsnow]

Looks good at 120...

[Catacol]

49 minutes ago, bluearmy said:

not really sure what to think

the warming has been ongoing for almost a week now. the data is well and truly in the models and today, the starting data has reversal almost down to the trop. the broad picture is of an arctic high driving a part of the Asian vortex towards nw Russia. that will introduce frigid air into scandi and probably e Europe ( these areas are going to b v cold anyway before this vortex movement ) 

the question is how close we can get that air to nw Europe and more specifically the U.K

that will depend on how upstream develops.  The period T96 to T180 very uncertain as a weak Atlantic jet  meanders around, especially so in the 4 to 7 day period. That allows the models to do some strange things in the medium term. and are they likely to be in the right place when that frigid air moves sw???

so we really have to just wait for the mid term to resolve itself before we can gain any confidence in how that surge of cold may affect us 

the Atlantic amplification looks solid but this mornings ops show that any greeny height rise could well come to nought. They may be unsupported in the ens and even outliers but whilst they produce output like this they do keep out feet firmly on the ground.

im staying in the v cold camp beyond the 20th ......perhaps even a couple days earlier. The period has been signposted for some time.  However, if the donkey, tail etc etc suddenly disappear again I won’t be searching around for an explanation....... some parts of the mid lats will have an very wintry period. it may just not be our turn ....

Morning everyone - think I can summarise my morning thoughts by suggesting BA has said it all above. The broad context is very good (not quite "excellent" because the vortex didnt shatter) but it is very good and we just need to be patient now while things unravel up top and we get a handle on likely shape of the final third of Jan.

The forcing from the mid strat as we hopefully get a good bit of frictional downwelling is certainly very good.

[sheikhy]

3 minutes ago, bluearmy said:

The 12z runs certainly took the front well into the North Sea. This 06z returns it back to just off the east coast 

And IF it keeps pushing back west it might not even leave mainland england

[Tim Bland]

Cold tantalizingly close to the east. Perhaps some wintry showers for eastern areas day 5.

[bradymk]

Looking colder again earlier on this run.

The cold to the east is further west by the end of the week, with the -8 850’s brushing east coast.

[Jason M]

2 minutes ago, bluearmy said:

The 12z runs certainly took the front well into the North Sea. This 06z returns it back to just off the east coast 

Usually with these scenarios if the front makes it to the East coast you can forget anything but transitory snow. If it stalls just short ie just west of London places get buried. That ECM snow event looks very unlikely just based on experience more than anything. It will either not reach here or it will be rain. Living where you do I suspect you will know where I’m coming from.

[I remember Atlantic 252]

1 minute ago, sheikhy said:

And IF it keeps pushing back west it might not even leave mainland england

Aye, Oadby could be buried, and I'm sweating in 11 degrees

[Gowon]

Could be a big snow event with that low coming in.

[Captain Shortwave]

The front that stalls over the east does turn to snow eventually, though I suspect it would only be a few flurries as the system decays. Looks quite cold by the end of the week. The 06z looks to be cutting the next low through the ridge so the theme remaining cold but probably dry with hard frosts and freezing fog in places.

We certainly need to see improvements in the upstream pattern to encourage potentially severe cold towards Western Europe and the U.K. The ensembles still look good for this at the moment later in week 2.

 

[nick sussex]

More encouraging so far on the GFS 06hrs run .

The pattern is backed west and it will become very cold with stagnant conditions over the UK.

Certainly miles better than the crud the UKMO dished out this morning.

[bluearmy]

When I looked at the ecm day 5, I wondered how much the atlantic profile would have to change to allow the slack scandi ridge to back further west and would it actually be feasible to advent that deep cold west .... it’s very unlikely but given the changes out west, run to run and the weak jet, could we see a rerun of the famous Ukmo day 5 dive se of the upper trough ???

[Notty]

Arctic high stronger earlier GFS 06z

[KTtom]

You couldnt make this chart up...4 lows guarding Greenland from our high trying its best to ridge north!