When a SSW occurs you can have a QTR (quick trop response). This usually occurs a few days to a week after the SSW.

IIRC this was pretty much what happened in February 2018 which led to the "Beast from the East" event. If memory servies me well, the SSW itself happened around the middle of the month and it only took a couple of weeks or so for the effects of it to filter down from the stratosphere to the troposhere.

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Can / does a SSW have an affect on our weather that quickly? I thought it took weeks to 'transfer'

From what I have read about it, more often than not there is something of a time lag between a SSW taking place and it having any noticeable effect on the UK's weather. However, as I have mentioned in my post above, the events of February 2018 demonstrated quite clearly that this isn't always the case and that sometimes the effects of a SSW on the UK's weather can become apparent fairly quickly.

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Will be interesting to see if ECM copies any of GEM's working-out later.

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Looking like Greenie High on Ecm and UKMO tonight, everything moving rather quickly, and in our favour for once 

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When a SSW occurs you can have a QTR (quick trop response). This usually occurs a few days to a week after the SSW.

True, but the data I’ve seen suggests there’s a disconnect between strat and trop at the moment which suggests any downwelling of an SSW may take longer than usual. We’re in unusual territory here as the sort of warming being modelled currently rarely occurs this early.

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Looking like Greenie High on Ecm and UKMO tonight, everything moving rather quickly, and in our favour for once 

Yes, interesting charts - regardless of any SSW or not, the Trop PV is struggling to get going this year and the purples are all on the Asian side of the Pole for once, instead of in the usual location of Canada/Greenland.

Negative NAO anyone?

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Looking like Greenie High on Ecm and UKMO tonight, everything moving rather quickly, and in our favour for once 

Yes, but it looks far from being a static block. By the end of the ECM run it's weakened and retrogressed to the west of Greenland, which opens up a lot of mild options.

Some interesting prospective synoptics but I think the usual caution applies, i.e. consistency, cross-model agreement and clear ensemble support. Plus, it would be reassuring if the MetOffice was seeing a clear signal for something colder, which at the moment it isn't - they're still backing a basically mobile westerly pattern.

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Yes, but it looks far from being a static block. By the end of the ECM run it's weakened and retrogressed to the west of Greenland, which opens up a lot of mild options.

Some interesting prospective synoptics but I think the usual caution applies, i.e. consistency, cross-model agreement and clear ensemble support. Plus, it would be reassuring if the MetOffice was seeing a clear signal for something colder, which at the moment it isn't - they're still backing a basically mobile westerly pattern.

I think the trend is key - there's clearly an interesting trend evolving in the models.

With regard to the SSW impacts, from what I've read the disconnect Strat to Trop is unlikely to be bridged before mid December.

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I think the trend is key - there's clearly an interesting trend evolving in the models.

With regard to the SSW impacts, from what I've read the disconnect Strat to Trop is unlikely to be bridged before mid December.

Potentially dumb but genuine question - so if there's a disconnect, doesn't that mean that any SSW won't impact on our little bit of the atmosphere?

Normally you'd look for a SSW to disrupt or split the PV but if we're still in a regime where the trop/strat forcings aren't in place then a SSW would presumably do nothing as it won't be able to downwell or whatever the expression is 

 

Model wise and must admit I'm finding it hard to get interested in the usual winter chase for some reason this year - been doing a quick scan of the reliable of the GFS ens and just seems like a slow crawl to slightly above average weather down here with more rain around and the usual 'who knows' scatter in FI.

ECM is interesting but with HP to the NW and E or SE just means for my back yard it's likely to be mild and damp- much more interesting for Scotland though, with colder air in place and some precip too.

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Yes, but it looks far from being a static block. By the end of the ECM run it's weakened and retrogressed to the west of Greenland, which opens up a lot of mild options.

Some interesting prospective synoptics but I think the usual caution applies, i.e. consistency, cross-model agreement and clear ensemble support. Plus, it would be reassuring if the MetOffice was seeing a clear signal for something colder, which at the moment it isn't - they're still backing a basically mobile westerly pattern.

IIRC, back in 2009 it wasn't until a few days after the models that we have access to began to consistently show a notable rise in pressure over the Greenland region that the MetO began to mention to possibility of a cold spell in their daily text updates. Prior to that, they had been going for a mostly unsettled and mostly mild outlook for most of December 2009. They seemed to be rather quicker at spotting the likelihood of a notable cold spell in November 2010 than they were the previous year.

I'm not for one second saying that things this year will play out like they did in 2009 in terms of the models leading the MetO, but it shall be interesting to see what the models produce over the coming days.

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Theories abound when a SSW is forecast to occur as to whether it will be a displacement or split, will it downwell or not and if yes how long will it take. Also where will see the cold and where will see the warmth unfortunately NO ONE knows the answer to these questions. It is only by looking at past events plus following NWP models and strat forecast models that a clearer picture develops. Many boffins come out of the wood work professing to know what lays ahead but in truth they are as unsure as the rest of us. Hopefully the picture will become clearer over the coming days.

 

 

I think the trend is key - there's clearly an interesting trend evolving in the models.

With regard to the SSW impacts, from what I've read the disconnect Strat to Trop is unlikely to be bridged before mid December.

is there? The output seems wildly inconsistent beyond day 9 to me, and the only options are mild ones (sadly).

its my annual Christmas pub crawl on 7th, early this year. Could really do with something seasonal as the past God knows how many Decembers have been wet, dull and miserable down here.

 

is there? The output seems wildly inconsistent beyond day 9 to me, and the only options are mild ones (sadly).

its my annual Christmas pub crawl on 7th, early this year. Could really do with something seasonal as the past God knows how many Decembers have been wet, dull and miserable down here.

 

Well, that's quite clearly not the case as even a perfunctory glance at the ensembles would confirm.

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Yes, interesting charts - regardless of any SSW or not, the Trop PV is struggling to get going this year and the purples are all on the Asian side of the Pole for once, instead of in the usual location of Canada/Greenland.

Negative NAO anyone?

 

 

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ECM 12z ensemble for London

http://www.weathercast.co.uk/meteo/eps/ensemble-tt6-london.gif

Still a lot of uncertainty beyond Day 6 but the cold cluster remains - for the third successive run.

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Chances increasing of an Northerly Outbreak,hope the Azores high doesn't spoil the party.Gfs is keen on exactly that happening.

Wouldn't be a surprise
,something nearly always happens to stop cold air reaching the UK.

The 0z doesn’t make me laugh. It somehow managed to build intense cold directly to our north and then finds a way to make sure it misses us and heads all the way to Eastern Europe and you guessed it...Greece.

Still, it’s one run and the trend of building heights towards Greenland remains.

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Yes I had to grin at the gfs 00z with the pool of cold air going to SE Europe. What is of note amongst the chaos is pressure still high over Spain/France by the end of the run and deep cold over Canada..... again! This was also evident on the 18z

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  In GFS, the current LP moves off S-wards on Sat, then LP over the Atlantic moving NE to Norway for the following week, deepest and closest on Thu 28th - that's a repeat of yesterday, though the LP is a bit more reluctant to depart. But new for the whole week of the 2nd, a narrow ridge of HP is sandwiched over the UK between Atlantic southerlies and continental northerlies - would only take slight  movement of LP on either side for this to disappear.

ECM prefers to continue to run shallow depressions across the UK, though there is a suggestion at the end of its run (the 1st) that it may also discover that ridge of HP

No general conclusions from ens runs, you'll need to look them up for your area, but nowhere stays really dry for long, contradicting GFS above.

I'll get excited about SSW when I see it, it doesn't blow my dog whistle.

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The strat warming faction should note that the last few GFS runs have eased off from the sort of temp rises projected recently and the mean is a lot less bullish that the Op this morning.
There is science, serious science and then upper air physics - so anyone hanging their hat on one aspect of many and on what might be an SSW going forward should always be cautious.

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