Winter Model Discussion - Cold Hunting - 20th Dec

[mountain shadow]

The AO is going very negative, only a matter of time before we can tap in surely.

Meanwhile it will be colder in the North and West with chances of snowfall. The biggest concern has to be the rainfall, its just going to keep coming.

[swfc]

ukmo is the best eye candy this morning screaming arctic blast.

ecm dreadful through out the whole output very messy and mild even above average temps wise.

gfs still cold for the north around christmas but pretty much average in the south,

with the odd above average days but below average futher north with northerlys on the back of in coming low pressure systems.

so all in all scottish sky resports will do well.

i think now the models are in default mode looking for the next trend plenty of time yet bring on jan and hopefully the strat warming event.

hi.why do you think the models are in default mode???They show pretty normal west to east atlantic weather .As for any strat warming id be wary of that being anything than a prospect at the moment.Its pretty obv looking threw most models that a zonal spell of weather is upon the uk imo which is in reality is to be expected.maybe that will change but it is what it is im sad to say.Anyway a merry xmas and try and keep dry Edited December 21, 2012 by swfc

[chiller]

Not a great deal to get excited about this morning for colder prospects. Odd colder incursion post boxing day and GFS gives some possible colder upper air later in the runs. But on the whole ECM and GFS not great with the Atlantic conveyor of lows punching across time and time again. UKMO seems a bit more positive from what I can see with some colder PM air perhaps in the offing. Lets hope late Dec starts showing better prospects. Very volatile and difficult to model me thinks Hard to believe today is the shortest of the year!

[Jason M]

Charts continuing to trend zonal this morning. Looking through the runs and ensembles it seems to me that the clear trend is away from any northern blocking this morning (did we really have any?) Sadly the northern blocking has displaced itself to our south :-)

In response to this the lows cannot sink far enough south and we are left in very wet zonal dirge. I've seen this sort of thing many times over the years and I'd expect the charts will continue to flatten the pattern over the coming days with any northerly having relatively little impact outside of northern Scotland.

I keep reading about warming events, well it looks to me like we're going to experience one over the next few weeks :-)

We read about the beast from the east, but the biggest beast in our part of the jungle generally its to our South or SW (look for the big red blob on the chats).

Jason

[chris55]

Overall a continuation of the unsettled conditions look likely, although turning colder at times with the risk of some snow especially in Scotland and the north. If we are lucky we may see something a little further south.

GFS 00z highlights the small risk of something wintry moving south on Boxing day, all a bit marginal and little support from ECM, but at this range it's not to be taken to seriously anyway. But something to keep an eye on.

[LomondSnowstorm]

hi.why do you think the models are in default mode???They show pretty normal west to east atlantic weather .As for any strat warming id be wary of that being anything than a prospect at the moment.Its pretty obv looking threw most models that a zonal spell of weather is upon the uk imo which is in reality is to be expected.maybe that will change but it is what it is im sad to say.Anyway a merry xmas and try and keep dry

I agree broadly with your analysis of the next 7-10 days as being zonal (albeit cooler/ cold zonal at times here) but the stratospheric warming isn't dependent (the Cohen paper aside) on the tropospheric synoptic pattern, and is still looking on track for a possible SSW around the 7th/8th, which would have a major effect on the pattern and hopefully lead the way to somethin more blocked from mid January onwards.

[Ladyofthestorm]

Actually I am a little less sure the Zonal will continue now past 120hrs. I think finally the atlantic is going to break down its onslaught on the uk and certainly for the Northern parts. The GFS has picked up a change afoot in the teleconnections.... I am going to trust GP thoughts and sentiments on this.

[Froze were the Days]

ECM continues on the mild fairly zonal theme, GFS is only mildly better with Pm air effecting the country briefly next week other than that not a lot but a lot of rain.

Edited December 21, 2012 by Froze were the Days

[Snowmad79]

The AO is going very negative, only a matter of time before we can tap in surely.

Meanwhile it will be colder in the North and West with chances of snowfall. The biggest concern has to be the rainfall, its just going to keep coming.

We need the NAO to go deeply negative. What we are experiencing now is typical of a positive NAO conditions (Increased Westerly flow and a "storm track" aligned with the UK) even though its currently just below.

A negative AO will be useless otherwise tbh.

Look how negative the AO has been and were missing what it has to offer.

Edited December 21, 2012 by Snowmad79

[mulzy]

Poor outlook, albeit with transient cold spells for Scotland. Models not even picking up a pattern change in FI. Azores high in charge for the short and medium term.

Edited December 21, 2012 by mulzy

[phil nw.]

Yes some realistic posts this morning-cold hard to come by over the next week/10days looking at the 00z runs.

Low heights to our north and that Azores high locking us in to a westerly type of setup.

Nothing far from average tempertaure wise so nothing really mild, with the UK on the polar side of the jet for much of the period.

The slightly colder incursions will be brief it seems before the next low moves in and sweeps in more wind and rain from the west to many areas.

At least a chance of some snow lying in the highlands of Scotland from this setup.

Edited December 21, 2012 by phil n.warks.

[Gibby]

Good morning. Here is the morning review of the output from the 00zs of GFS, UKMO, GEM and ECM for today Friday December 21st 2012.

All models continue to show unsettled weather unabated throughout their output this morning. In the short term a drier interlude today for many Southern and Central areas will be shortlived with renewed heavy rainfall sweeping NE over these areas through tonight and other areas tomorrow. Yesterdays rain and mountain snow has yet to clear from Northern and Eastern areas but here it will become lighter through today but will reinvigorate tomorrow as the new trough pushes in. Temperatures will stay above normal in the South while the NE will still be rather chilly. Sunday and Christmas Eve continue to show very unsettled conditions with further spells of rain in strong and gusty winds continuing the flood risk nationwide.

GFS shows CHRISTMAS DAY as a rather colder day with a slacker NW flow with rain or showers for most. It will be a green Christmas for most rather than white though some wintry showers will occur on Northern high ground with snowfall above 2000 feet in the showers. BOXING DAY shows further showers, wintry on hills give way to drier conditions through the day as a ridge crosses East from the West. Then between Christmas and the New Year the weather remains very unsettled with further spells of rain and some showers, wintry on hills all in association with the passage of successive Low pressures crossing East over Northern Britain. Into the New Year and there is no change with New Years Day itself showing as the only reasonable day as a weak transient ridge passes by before further rain returns from the West by the end of the run.

The GFS Ensembles show more than anything else a very wet few weeks to come as Low pressure remains dominant over the UK. Temperatures in the South especially will fall back to normal values or a little below in the North around the Christmas period for a few days before the trend shows a rise in uppers again later in the run as Low pressure migrates slightly further North with a milder SW flow becoming popular between the members.

The Jet Stream shows a persistent undulating pattern in the vicinity of the British Isles or just to the South for the next week or so continuing to carry Low pressure after Low pressure East in the flow.

UKMO for CHRISTMAS DAY shows Low pressure just to the North of Scotland with a slack SW flow ahead of a trough just to the West of the UK. The big day itself will see showers carried NE in the flow, heaviest near SW coasts and very few in the East. The trough to the West swings East later on Christmas Day with a band of heavy rain or showers for all before BOXING DAY sees rather colder conditions with some showers, wintry on hills in the North and West before cloud approaches the far West late in the evening on Boxing Day with further rain and fresh winds on Thursday. as a new Low pushes East towards Scotland.

GEM shows CHRISTMAS DAY affected by Low pressure drifting slowly East over Southern Britain with rain at times with temperatures falling back to near normal levels in the South. BOXING DAY starts with a chilly NW flow and a few showers before cloud, wind and rain will move NE over the UK again late in the day. In the run up to the New Year the weather continues unsettled and windy with showers or longer spells of rain with temperatures rising above normal at times in the South late in the period.

ECM shows CHRISTMAS DAY with a slack Low pressure over all of Britain with rain at times in slightly colder conditions than of late. BOXING DAY looks like being rather colder in a NW flow with some showers, wintry on Northern hills. Thereafter, a very windy spell sets up with a SW gale and further rain at times, heaviest in the NW before all areas see Westerly winds and further rain at times for New Years Eve.

In Summary this is turning out to be a very disturbing wet spell for many parts of the UK, unwanted for most through the holiday period. All models show an unrelenting attack from the Atlantic with potent rainfall on the cards for all areas in occasionally, strong to gale SW or West winds. This will undoubtedly keep the weather very much in the news as the flooding issues are bound to enhance in the coming few weeks. Temperatures will fall back for a while in the South next week with some snow at times on the higher mountains of Northern England and Scotland but lowland snow looks very unlikely through the period.

[carinthian]

ECM continues on the mild fairly zonal theme, GFS is only mildly better with Pm air effecting the country briefly next week other than that not a lot but a lot of rain.

Good Morning,

Saturated Britain, making the pictures here on the news. Looks like you on on permanent rinse hold. Tomorrow looks like a particularly bad day with more heavy rain and the wind looks also to be a feature in the far north tomorrow with blizzards on the Grampians. Beyond the next 3 days, I would not take a lot of notice of the models and concentration whats in store for this weekend. That Russian block remains subborn and has trapped some very cold air and is also featured on the news here and its here the problem lies,as I think the medium range models are struggling with the variances being progged with this present scenario. As I have said Britain is likely to remain stuck in this never ending cycle of rain and more rain.

C

[Dampdorset82]

I agree nothing too cold showing but again nothing mild either( average I guess) on the models at present but remember only 3 days ago we had a very mild sw flow for xmas day. I would expect to see things change slightly. Im not cold/mild bias but at this point I am dry bias!

Edited December 21, 2012 by Dampdorset82

[Glacier Point]

We need the NAO to go deeply negative. What we are experiencing now is typical of a positive NAO conditions (Increased Westerly flow and a "storm track" aligned with the UK) even though its currently just below.

A negative AO will be useless otherwise tbh.

Look how negative the AO has been and were missing what it has to offer.

An objective assessment of what the AO has done to us thus far. T2 anomalies..

That's a very good manifestation of what would be expected given the modality of this index.

The NAO looks like moderating in the next 7-10 days, which teleconnects to the zonal projection across all NWP. Just how mild or cold will depend on usptream amplification off the Californian coast / Texas and then mid Atlantic. The broad axis of a deep trough just to our east, but with depressions running into the back of the trough periodically introducing milder phases. The fewer the depressions, the deeper the trough to our east and the further south the pM airmass gets.

Further ahead, the linear correlation between NAO and AO rises in January compared to December so we would expect the AO to assume great influence on the North Atlantic domain. That's before you factor in a shifting Pacific pattern, PNA on the turn, increasing angular momentum signal and, stratospheric warming.

[nick sussex]

Maybe they should rename this thread the hunt for 24hrs of dry weather!

Not much change today apart from the models edging the jet further north, this is a natural response to where the PV is located, the ECM is very plausible given the set up.

The Xmas cold blip is hardly there on the ECM and the UKMO/GFS have shortened this so although turning a touch colder Xmas Day into Boxing Day theres the next low waiting to rush in.

If you're looking for positives at least we're not seeing one large PV stuck over Greenland and the PV remains fragmented, sadly one of those pieces decided it wanted a holiday in Iceland!

Still a few better options in the ECM postage stamps so we can but hope one of those is picked up but we need to see the removal of that PV near the UK before even thinking of something colder that can last more than 36hrs.

[phil nw.]

Maybe they should rename this thread the hunt for 24hrs of dry weather!

Not much change today apart from the models edging the jet further north, this is a natural response to where the PV is located, the ECM is very plausible given the set up.

The Xmas cold blip is hardly there on the ECM and the UKMO/GFS have shortened this so although turning a touch colder Xmas Day into Boxing Day theres the next low waiting to rush in.

If you're looking for positives at least we're not seeing one large PV stuck over Greenland and the PV remains fragmented, sadly one of those pieces decided it wanted a holiday in Iceland!

Still a few better options in the ECM postage stamps so we can but hope one of those is picked up but we need to see the removal of that PV near the UK before even thinking of something colder that can last more than 36hrs.

Morning Nick,

Yes a very wet period for the UK indeed.

It`s difficult to find anything wintry in the next week/10days in this pattern-other than some snow for the Highlands .

Like we keep saying a little amplification upstream would help but at the moment it looks pretty flat.

It looks like a waiting game whilst we enjoy our Christmas festivities hoping for that chunk of vortex to take a hike in the New year.

[bluearmy]

Just looking at how the vortex in siberia gets displaced further se. I think we will begin to see news of frigid conitions in korea, ne china and Japan over the new year period.

The growing arctic block with associated -AO is driving the trop split ever wider. our chunk passes to our nw and then ends up around greenland day 10. presumably it should continue, but given the repeated ridging east alaska/west aleutian region, i suspect it will stall. Its possilble that will be too close to greenland to prevent this zonal train stoppng for a while yet. Better hope it gets away from greenland but it would be nice for it to stop still long enough to allow a pattern change to blocked to establish. So far this month, as soon as we have seen promising sypnotics appear, a vortex chunk moves around close enough to the n atlantic to fire up the jet again.

[Severe Siberian icy blast]

An objective assessment of what the AO has done to us thus far. T2 anomalies..

That's a very good manifestation of what would be expected given the modality of this index.

The NAO looks like moderating in the next 7-10 days, which teleconnects to the zonal projection across all NWP. Just how mild or cold will depend on usptream amplification off the Californian coast / Texas and then mid Atlantic. The broad axis of a deep trough just to our east, but with depressions running into the back of the trough periodically introducing milder phases. The fewer the depressions, the deeper the trough to our east and the further south the pM airmass gets.

Further ahead, the linear correlation between NAO and AO rises in January compared to December so we would expect the AO to assume great influence on the North Atlantic domain. That's before you factor in a shifting Pacific pattern, PNA on the turn, increasing angular momentum signal and, stratospheric warming.

Well thankyou for that voice of reason there Stewart , by the sounds of things you don't expect the Azores to be a big player then? If we can sink that south then the jet may go south with it , which will limit any milder interludes, it's good to see the signals for January ,so we should see more of a blocked Atlantic by the sounds of things , but in the mean time the chart you posted looks mouth watering , so although it may not be as cold as that charts looks , we are likely to have a fairly cool/cold period which offers snow for some , after all it doesn't need to be sub -10 850s to have snow m which is what a lot of us search for.

[TEITS]

Have to say the medium range is looking rather disappointing to me.

So it seems we shall have to wait until we are into January before any significant cold spell could affect all of the UK. However despite all the promising teleconnections/stratosphere predictions I would advise members to be cautious until this actually appears on the model output. Another reason why im saying this is the Met O predicted the 2009, 2010 cold spells from some distance away and yet their 16-30 day forecasts continue to suggest more of the same i.e zonal. So whatever positive signs some are detecting on here the Met O don't agree.

[Radiating Dendrite]

Well thankyou for that voice of reason there Stewart , by the sounds of things you don't expect the Azores to be a big player then? If we can sink that south then the jet may go south with it , which will limit any milder interludes, it's good to see the signals for January ,so we should see more of a blocked Atlantic by the sounds of things , but in the mean time the chart you posted looks mouth watering , so although it may not be as cold as that charts looks , we are likely to have a fairly cool/cold period which offers snow for some , after all it doesn't need to be sub -10 850s to have snow m which is what a lot of us search for.

Not what the EC32 is showing for January according to Matt Hugo.

To be honest, everything seems to be contradicting at the moment!

Just keeping everything crossed that GP is right!

[mountain shadow]

It would be difficult for the azores high to influence with a negative AO.

A negative AO would push the jet stream further south which in turn would keep Azores high further south.

Sobering to note how negative the AO has been yet delivered nothing.

[NickR]

Not what the EC32 is showing for January according to Matt Hugo.

To be honest, everything seems to be contradicting at the moment!

Just keeping everything crossed that GP is right!

I'm not sure why Matt Hugo persists in tweeting the latest from the ECM 32-dayer with such gusto... it's been a complete waste of time so far this season.

[trickydicky]

Good Morning,

Saturated Britain, making the pictures here on the news. Looks like you on on permanent rinse hold. Tomorrow looks like a particularly bad day with more heavy rain and the wind looks also to be a feature in the far north tomorrow with blizzards on the Grampians. Beyond the next 3 days, I would not take a lot of notice of the models and concentration whats in store for this weekend. That Russian block remains subborn and has trapped some very cold air and is also featured on the news here and its here the problem lies,as I think the medium range models are struggling with the variances being progged with this present scenario. As I have said Britain is likely to remain stuck in this never ending cycle of rain and more rain.

C

I like the sound of the Austrian news, and they say we are weather obsessed.

I am sensing a slight IMBY-ism in some model interpretations today. A coolish North Westerly flow is being thought of as about as welcome as a punch in the face to those in the Essex/Kent/Sussex quadrant, but as being not at all bad to those within striking distance of a gradient in the North and North West. From my backyard, I would prefer it if we had a North Westerly flow delivering cold right down to Dover too, because if its cold down there, it will definitely be cold enough for snow up here. We'd all like a big fat Greenland high, or an easterly screaming in from Kamchatka for those in the south east, but this is better than a raging south westerly, although to anyone flooded out there house it probably makes no difference.

[Summer Sun]

Latest from Matt Hugo on twitter

Pretty much every 00Z EC ensemble member shows a very unsettled theme continuing throughout the opening week of January

EC32 day maintains an unsettled theme as well right to the 20th of Jan, with lower than average pressure near the UK & wetter than average.

As a disclaimer, don't forget the EC32, as with other models, failed miserably at predicting the E'ly so could be wrong re; January.

At the moment Scot, Ireland and N Eng may see wintry showers on high ground by the end of Xmas Day overnight into Boxing Day.

https://twitter.com/MattHugo81