In Depth Model Discussion, Analysis and Summaries

[weathersupremacy]

The bad news for cold fans it looks very unlikely that the High will get itself into a position to bring cold weather over the UK with anticyclonic gloom being the more likely outcome with temperatures near to or above normal throughout.

Wasn't sure which thread to post this in - this one or the other one you make the exact same post your analysis in.

Gibby, with all due respect, you often claim that you only interpret what the models are showing, but since there's variation so far in FI can you honestly say there's not a mild bias in your post? The FI pattern, I believe, will constantly change in output and I expect further changes and divergences around the new year (and perhaps over the next few days too) period to reflect the weather around 10/15th of January.

Edited December 27, 2012 by weathersupremacy

[Methuselah]

Wasn't sure which thread to post this in - this one or the other one you make the exact same post your analysis in.

Gibby, with all due respect, you often claim that you only interpret what the models are showing, but since there's variation so far in FI can you honestly say there's not a mild bias in your post? The FI pattern, I believe, will constantly change in output and I expect further changes and divergences around the new year (and perhaps over the next few days too) period to reflect the weather around 10/15th of January.

Maybe, the longer-term outlook will change, WS...But, as of now, what Gibby's saying seems fair enough, to me...

[weathersupremacy]

Maybe, the longer-term outlook will change, WS...But, as of now, what Gibby's saying seems fair enough, to me...

Gibby isn't referencing the near future (couple of days) he's referencing FI, where I and others expect many changes in the NWP. What shows tonight in FI will/may show something totally different in the next 12 hours.

[cold snap]

Wasn't sure which thread to post this in - this one or the other one you make the exact same post your analysis in.

Gibby, with all due respect, you often claim that you only interpret what the models are showing, but since there's variation so far in FI can you honestly say there's not a mild bias in your post? The FI pattern, I believe, will constantly change in output and I expect further changes and divergences around the new year (and perhaps over the next few days too) period to reflect the weather around 10/15th of January.

It's right at the very end at 384

Gibby has no mild bias ,sometimes you have to be realistic ,signs may be good ,but gibbys post reflects what's being shown on the models

[bobbydog]

Gibby isn't referencing the near future (couple of days) he's referencing FI, where I and others expect many changes in the NWP. What shows tonight in FI will/may show something totally different in the next 12 hours.

which is why he does a summary update twice a day to reflect what the models are showing . if the models show something totally different in 12 hours, so will his summary.

[Summer Sun]

Gibby isn't referencing the near future (couple of days) he's referencing FI, where I and others expect many changes in the NWP. What shows tonight in FI will/may show something totally different in the next 12 hours.

Gibby is only saying what the models show it may not be what you like but thats the way it goes

ECM in FI is mild so Gibbys spot on

GFS in FI is mild then average then a short lived cold snap before mild air looking like coming back in

A fair summary from Gibby in my opinion

[cerneman]

It's right at the very end at 384

Gibby has no mild bias ,sometimes you have to be realistic ,signs may be good ,but gibbys post reflects what's being shown on the models

Exactly, Only reflecting what the models indicate now, Gibby not mildie or coldie in preparation of his outlooks Edited December 27, 2012 by cerneman

[Methuselah]

Gibby isn't referencing the near future (couple of days) he's referencing FI, where I and others expect many changes in the NWP. What shows tonight in FI will/may show something totally different in the next 12 hours.

Possibly. But, as yet, those changes haven't 'occurred'...

[Gibby]

Gibby is only saying what the models show it may not be what you like but thats the way it goes

ECM in FI is mild so Gibbys spot on

GFS in FI is mild then average then a short lived cold snap before mild air looking like coming back in

A fair summary from Gibby in my opinion

Thanks guys for answering the point for me. I have and never will reflect any bias in my reports mild or cold as it would serve to deflect the whole point of me doing the reports twice a day. I may of course misinterpret things now and again and if I do I am happy to be challenged or corrected. As you rightly say I only report what I see and in 12 hours time if the models paint a different picture then I will report on it and say what I think that may mean for us at the surface. As it is tonight weighing up all the output the High looks to hold a lot of mild and rather cloudy conditions for the UK as we lie on the Northern periphery of the High but of course if it's shown to position in a better location for bringing cold to the UK on the 00zs tomorrow then I will state on what that means for the UK weather tomorrow morning.

Edited December 27, 2012 by Gibby

[suxer]

which is why he does a summary update twice a day to reflect what the models are showing . if the models show something totally different in 12 hours, so will his summary.

I've said before i think it would be be great if there was a thread dedicated to members summaries,Gibby's,Winters tale,frosty (all excellant) And let this thread hunt for cold

Damn my bad thought we were in hunt for cold thread,more tea please vicar

Edited December 27, 2012 by suxer

[cerneman]

Thanks guys for answering the point for me. I have and never will reflect any bias in my reports mild or cold as it would serve to deflect the whole point of me doing the reports twice a day. I may of course misinterpret things now and again and if I do I am happy to be challenged or corrected. As you rightly say I only report what I see and in 12 hours time if the models paint a different picture then I will report on it and say what I think that may mean for us at the surface. As it is tonight weighing up all the output the High looks to hold a lot of mild and rather cloudy conditions for the UK as we lie on the Northern periphery of the High but of course if it's shown to position in a better location for bringing cold to the UK on the 00zs tomorrow then I will state on what that means for the UK weather tomorrow morning.

Still very much learner and I enjoy reading your reports, Actually read your model summary and try hard to work out your conclusions, Really helping to increase my understanding,,,,,,,,Thank you

[legritter]

The twice per day posts of GIBBY are much appreciated ,they dont always predict what i want but they stick to what the modells are showing .by this time tomorrow we could all be looking at a complete turnabout , the weather is complex and one tiny miscalculation by any modell [computer] will put charts at ten days away miles out . things are on the change probably after next wednesday but how we finish up is still very unclear . we have seriouse weather over the next 3/4 days so alot going on in our complex atmosphere and northern hemisphere in generall . and as i said recently when high pressure sets up it can migrate into a favourable position ,but as always time will tell .cheers gang

[Gibby]

Good morning. Here is the report of the 00z output from the output of the big four giants, namely GFS, UKMO, GEM and ECM for today Friday December 28th 2012.

All models are agreed on events between now and the first couple of days of the New Year. Today sees a fresh to strong SW flow over the UK with a warm front clearing Eastern Britain this morning taking its rain away with it. Left behind will be a broad warm sector with SW winds and a lot of cloud and occasional light rain and drizzle, especially over coasts and hills exposed to the SW. Later today winds will freshen further as a squally cold front moves in from the West with a band of heavy squally rain moving East across the UK later tonight and tomorrow. Following on behind will be brighter and fresher weather with showers, wintry on Northern hills lasting through the remainder of Saturday and well into Sunday. Winds then are shown to back SW as a new depression and troughs move towards the UK from the West with rain reaching the West later on Sunday and moving steadily East over all areas on New Years Eve. Following on behind will be a chilly and showery NW flow which takes us into New Years Day. The first day of 2012 will see a NW flow with rapidly rising pressure and a lessening of showers from the West. It will probably feel quite chilly through the day. By the 2nd a warm front is crossing East over the UK brnging rain and drizzle back East over the UK in temperatures on the rise to normal or above average levels again.

GFS then takes us through the end of next week with a West or just North of West flow under a ridge from High pressure just to the South bringing rather cloudy conditions but much drier conditions with limited brightness. Temperatures would remain well up for early January. By next weekend and through FI the trend is for High pressure to relax away SE briefly as a cold front meanders down from the NW bringing some rain before a new High forms over the South later befre it too drifts slowly away SE at the end of the run. In essence a lot of dry weather would occur in average temperatures by day and the chance of some frost by night should skies clear under the second High but the far SE may see something a little colder briefly as the phase when both High's slip away brings the chance of a temporary feed from Europe bringing some colder Continental air for a short time.

The GFS Ensembles show a very mild slot as we move into next week with drier weather than of late. There is a definitive trend of rather chillier weather developing as we move through the second week with temperatures falling to near average values with some members going for something a little colder but at the same time more unsettled again.

The Jet Stream shows the flow currently over the UK continuing for a while before it balloons to the North of the UK later next week in response to the build of pressure South of the UK.

UKMO for midnight on Thursday shows Low pressure over Iceland and High over Biscay with a typically mild and rather cloudy West to NW flow following a warm front East over the UK with mist and drizzle over Northern and Western high ground following the remaining rain from the front exiting Eastern Britain.

GEM shows a mild and moist West flow for a few days late next week before the High migrates to Europe amalgamating with a Northern European High allowing some colder air to drift NW on it's Southern flank towards the far SE for a time at the end of the run.

ECM shows High pressure building right over the UK later next week behind a weak cold front moving SE over the UK next Friday. Frost and fog patches could well develop in this positioning before milder air encroaches back in from the NW by the end of the run bringing a lot of low level Stratocumulus type cloud making for grey days of anticyclonic gloom in temperatures near to normal or above in the NW.

In Summary a change of weather type is likely as we move into the New Year. Gone will be the persistent train of Low pressure after Low pressure and all their rain and in their place will be a strong build of pressure from the South with dry if rather cloudy conditions developing late next week and beyond. It will never be very cold and with a lot of cloud expected on the Northern periphery of the High, frost and fog is consequently never likely to be widespread. In time there are suggestions that the High will begin to drift away SE allowing the mild Atlantic based weather to drift back down from the NW but more runs are needed to pick up on a pattern of how, if and when this is likely to evolve.

[Gibby]

Good evening. Here is the report on the 12z output from GFS, UKMO and ECM for tonight Friday December 28th 2012.

All models continue to be in unity with regard to the pattern of events between now and New years Day. A strong SW flow is blowing across the UK with an active cold front moving East across England and Wales tomorrow. A band of heavy and prolonged squally rain moves East across the UK through the day followed by colder and clearer weather with showers turning wintry on hills in the North and West. Through Sunday further breezy showery West winds back SW through the day with a further band of rain moving in from the Atlantic later on. On New Years Eve a further cold front moves East with more squally winds veering NW on New Years Eve night with New Years Day then one of sunshine and showers in rather cold conditions. The showers die out later in the day in response to a large pressure rise with a warm front moving West to East across the UK on Wednesday with light rain and drizzle and milder winds returning from the West.

GFS then shows a few days of drier and quieter weather with a lot of cloud before unsettled conditions return from the West later in the weekend. In the further reaches of FI the weather remains very much more unsettled with rain and strong winds at times as Low pressure or troughs move East across the UK with rather colder air developing as winds slacken towards the end of FI.

The GFS Ensembles show the High pressure and attendant mild temperatures rather shortlived tonight as temperatures fall back to nearer to normal values and what's less encouraging is the increased risk of rain returning to Southern Britain as the second half of the run progresses.

The Jet stream shows the flow continuing to rise North and fall back South over and to the North of the UK in the coming week. Very late in the reliable jet forecast a strong East surge of the flow from the States at 50 deg N latitude may encourage the High close to the South at that time to be shifted away East by the strength of the flow.

UKMO for midday on Thursday shows a High pressure over the Biscay area with a NW flow over the UK bringing a rather cloudy day with a little rain in places through the period especially to the North and East.

ECM shows a High pressure cell over Biscay too at day 6 which ridges over the UK the following day before toppling away SE late in the run re-introducing SW winds and Atlantic fronts with attendant rainfall to all areas by Day 10.

In Summary tonight the main difference from previous output is the shorter duration of the High pressure moving up from the South shortly after the New Year. It is shown to collapse quite quickly under the pressure from a continuing very active Atlantic with rain and wind returning to all areas by the end of a 3-4 day break. There is consequently little chance of any sustained cold weather showing up on UK shores for the duration of the output tonight.

[Gibby]

Good morning. Here is the report from the 00zs of GFS, UKMO, GEM and ECM for this morning Saturday December 29th 2012.

All models show no changes this morning to the general flow of things between now and the end of next week. The strong to gale SW flow currently blowing over the UK has a squally cold front currently lying North/ South down the western side of Britain moving East carrying a band of heavy rain with it, clearing the far East this evening. Following this mild and windy spell temperatures will fall back to normal levels with frequent showers and brighter intervals replacing the rain. Through the night the showers, heavy in the West will fall as hail to lower levels and sleet or snow on upland Northern areas later. Tomorrow will see a showery day, with the potency of the showers decrease with time as a new area of cloud and rain approaches the West and North later. On New Years Eve the new front carries another band of squally rain East over the UK through the day followed by a colder NW flow for New Years Day with sunshine and showers for the Day itself. On Wednesday the weather turns milder again as a warm front crosses East bringing rain and drizzle to all areas though more especially to Northern and Western areas before drier and rather cloudy weather but for the most part dry conditions affect most areas up to the weekend.

GFS then shows the High close to the South responsible for the drier weather slip away SE with SW winds freshening everywhere as Atlantic fronts bring the return of rain and strong winds to all areas before the new week. The rest of the run shows a period of zonal weather again with periods of rain mixed with spells of sunshine and showers with temperatures rallying overall close to the normal for mid January though this does not exempt the North from some wintry showers behind the cold fronts.

The GFS Ensembles show a few more days of zonal weather before a High pressure cell swamps the UK in warm uppers for 4-5 days when it becomes dry. Thereafter a return to normal values is shown with the increased frequency of rain once more as the Atlantic train rolls in again.

The Jet Stream shows a flow moving over the UK for a couple more days before a strong forcing of the flow North over the British Isles in response to the High to the South. Later next week and weekend a very powerful surge of energy is pulled across the Atlantic towards Europe and it's this that will eventually break the High down SE into SE Europe.

UKMO for midnight on Friday shows a strong Anticyclone circa 1040mbs near NW France with a ridge North over the UK. A slack westerly flow would deliver a rather cloudy and dry day with near normal temperatures for that time of year.

GEM shows the High in a similar location to UKMO at that time pulling it slowly away SE later as troughs wind their way slowly SE later bringing rainfall to the North and West by the end of its run.

ECM too is virtually identical to UKMO with its positioning of the High on day 6, it too carrying it slowly SE, albeit less dramatically so than GFS. Nevertheless, the infiltration of the Atlantic reaches all Northern and Western areas with occasional rain by Day 10.

In Summary today there is a period of dry and mild weather still on the way for the middle and end of next week. The problem is no model shows the High gaining total control, all models keeping it's centre South of the UK and making for rather cloudy and benign weather conditions with temperatures well up to normal or somewhat above in any brightness. Longer term all models show a breakdown of sorts, especially for the North and West where rain would return by the start of the second week. How far this moves South and East will be firmed up on over coming days. Temperatures look like remaining well up to the normal or above for January with little risk of significant frost and snow problems for Farmers and Growers to worry about in the period, and I'm sure they will be equally relieved that a window of drier weather is on the way.

[Gibby]

Good morning. Here is the report on the 00zs from the big four models, namely GFS, UKMO, GEM and ECM for today Sunday December 30th 2012.

All models show a broadly similar pattern on the sequence of events between now and next weekend. Today will see the sunshine and shower mix give way later today to more persistent cloud and rain coming into Northern and Western areas under a rather chilly and blustery West to Southwest wind. Many Eastern and South-eastern areas may have a dry and bright day. Tomorrow sees an active cold front bring a spell of heavy and squally rain SE over the UK with gales on coasts and hills in temporarily milder weather again. Late on tomorrow clearer, colder and more showery weather returns from the NW with the showers heavy and wintry in the North and West tomorrow night. By New Years Day the showers will be migrating away East as pressure will be rising sharply with decreasing winds backing towards the West on what will of been a rather chilly New Years Day. On Wednesday a warm front crosses East with some rain and drizzle, chiefly in the North. The remainder of the week will see rather a lot of cloud with relatively mild conditions. There may be some brighter spells and if these occur at night there is the chance of patchy mist and fog and a touch of frost but probably not much.

GFS then shows next weekend as remaining mostly dry with High pressure slowly relaxing to the East of the UK. With uppers gently lowering the temperatures at the surface would fall back with the incidence of fog increasing with time and patchy frost too. Later in the run pressure begins to fall with time and a Southerly flow develops with rain spreading from the West by the end of the period in association with Low pressure advancing in from the West.

The GFS Ensembles show a much drier period on the way. As High pressure builds next week from the South there is a guarantee of very mild conditions with rather cloudy skies for a time before temperatures relax back towards the seasonal normal with High pressure in general likely to still be in control with much less rainfall than we have become accustomed too of late.

The Jet Stream shows the flow ridging over the Atlantic and eventually over the British Isles behind tomorrows Low and fronts. The High pressure holds it's own for the most part next weekend as the flow remains steered North over the UK and down over Europe next weekend.

UKMO for midnight on Saturday shows High pressure stretching from Spain to Southern England with a ridge North over the UK. The weather would see relatively light winds, dry weather but with a lot of cloud in places, but some clearer spells too leading to fog patches in places overnight. Temperatures would be generally near or above normal.

GEM shows the High slipping away SE more readily with a moist SW flow bringing extensive cloud cover, increasing winds and eventually rain back across the UK from the Atlantic by the end of the run.

ECM shows a similar pattern to UKMO at day 6 with the High then slipping slowly SE into Europe setting up a NW/SE pattern with mild SW winds over the UK with plenty of cloud with some rain at times in the North and West while SE parts stay largely dry.

In Summary today the weather still looks like becoming more settled from the middle of the coming week. Dependant on the location of the High centre will determine how things are at the surface. However, the main body of models keep the main centre just South of Britain keeping a Westerly drift and feeding a lot of low Stratocumulus cloud around the Northern flank of the high and delivering rather cloudy, benign conditions with temperatures well above normal in any brightness in the East though these same breaks could make way for some overnight mist and fog patches. In the longer term the High is shown to drift back SE into Europe with the likelihood of some Atlantic incursion towards the second week when the North and West at least see the return of wind and rain. These conditions may not reach the South and East though during this period giving the saturated grounds here a chance to slowly drain in continuing reasonable temperatures for early January.

There will be no evening report either tonight or tomorrow night but the A.M. reports will carry on as normal and the full twice daily service will resume on New Years day.

[TonyH]

A look at the week ahead in detail for west Wales and the Midlands:

http://forum.netweather.tv/blog/309/entry-4527-weather-prospects-for-west-wales-and-the-midlands-new-years-eve-to-saturday-6th-january-2013/

[Zenarcher]

Model Summary using the GFS, ECM, UKMO, GEM, JMA and NOGAPS,

Monday to Wednesday 24 to 72 hours - All the models agree on that the start of the week will be mainly cloudy and wet although on Tuesday it will be sunny across England and Wales for most of the day. Gale force winds will affect all parts of the UK on Monday and Tuesday but on Wednesday only the North and North West will see gales.

96 hours Thursday - All the models agree on high pressure building in over the UK this is likely to create widespread fog across the country although the weather will be much drier and calmer than what it has been lately.

120 hours Friday - The models still have good agreement of a large area of high pressure over the UK so dried and settled weather is likely to continue. The ECM, GEM and NOGAPS aren't too keen on bringing the high in too much they place a 1035mb isobar over the far South of England meanwhile the GFS, JMA and UKMO make 1035mb go further North into Northern England and Southern Scotland.

144 hours Saturday - Two things to look at here the high over the UK and the Atlantic lows,

First off the high all models start to show it move away from the UK apart from the JMA which keeps it strong.

What most models show,

Second thing the Atlantic lows we have GEM, NOGAPS and ECM sending a low across the Atlantic the exact positioning and depth varies but they come across a similar picture,

The GFS, JMA and UKMO don't really like that idea too much and don't really develop a low at all or just a very weak one,

168 Hours Sunday and beyond - GFS brings a large deep low into the Atlantic once this moves away we end up with a blocked set up, ECM sends lows and energy over our North so we don't see any blocking occur on it, NOGAPS makes a deep low in the Atlantic but pressure to our East rises, JMA keeps high pressure over the UK.

Strat Warming? - GFS has been keen on this for a few days now this image was from 4 days ago,

Now 4 days later for the same date still positive signs,

Overall - The models have pretty good agreement on unsettled weather to start the week but high pressure will start to move in by the end bringing more drier and settled weather. It seems the ECM, GEM and NOGAPS all show something similar tonight and the JMA, GFS and UKMO are on the other side.

Edited December 30, 2012 by weathermaster

[Glacier Point]

Going to come at the extended range (10th Jan onwards) from a slightly different tack.

Over the last week, tropical forcing (convective activity) has really cranked up in the Indian Ocean. OLR plots depict a moderate to large -ve anomaly in this region.

Tropical activity can be seen as adding westerly inertia to the planetary system. This is registering as a suprisingly +ve tendency anomaly in relative angular momentum over the Equator.

Over time these wind bursts can, if the extratropical circulation is conducive, work their way poleward and contribute to a net increase in total angular momentum.

The most likely initial response from the GWO is a phase 4 projection, which indicates an anomalous mid latitude ridge centred somewhere in the north Atlantic and UK.

This is similar to the MJO projections for phase 6 which shift the balance of probability towards the mid Atlantic for height rises around 10th January.

MJO forecasts (ECM) pretty well aligned on this phase 6 projection by 13th Jan.

I key consideration thereafter will be whether the MJO can migrate eastwards towards phases 7-8 (currently a strong pulse of east winds ahead of the MJO which it will need to negotiate) and the response of the middle and high latitudes, which a stratospheric warming would favour.

It's worth noting that the oceanic heat content in the Equatorial Pacific east of the International Dateline is well above average which might help pep up convective activity ahead of and enhance the MJO in phase 8 in particular. The plot below shows this on the right panel whilst a wall of easterlies lying ahead of the resurgent MJO is shown left panel.

With increasing angular momentum, this favours a GWO phase 8 response, This tends to edge us closer towards an MJO / GWO phase 8 solution for the most likely atmospheric response to the stratospheric warming. I'm going Greenland height rises after mid month. Whether that is too far west or just perfect for a direct hit from the Arctic for the UK and NW Europe we'll have to see but the idea of this being a long-lived warming event which will fundamentally shift the hemispheric pattern (and feedback loops) is one I'd been keen on pushing - so sooner or later would be the message.

Edited December 30, 2012 by Glacier Point

[LomondSnowstorm]

I posted this on the regional thread but realised it would also be appropriate for posting in here (although Stewart has obviously covered much of what my post does but from a slightly different angle perhaps):

Looks like we will be heading into the New Year with a cold northwesterly flow and snow for some:

A white New Year for Glasgow perhaps?

Not going to last too long though, with heights building in from the south. Disagreement on the positioning of this, but this is likely to be the dominant feature of our weather for the next week or perhaps even longer, giving initially mild to very mild temperatures with some rainfall, particularly for northern and western parts:

While this clearly doesn't exactly seem like a great thing, and believe me there is nothing worse at this time of year than a damp tropical maritime flow, it does have two major advantages for us. The first is obvious: while rainfall won't be entirely absent, it will be significantly drier for all of us than under the current regime, which will be a welcome break. The second one is a longer term point, for which we need to delve a little deeper into both the historical analogies and the larger scale signals which are set to dramatically switch around by the middle of the month.

The historical point is one I've made many times before,including in December 2009 and in November 2010, and in both instances this has held true: it all starts with a mid latitude pressure rise.

January 1947:

December 1962:

January 1985:

January 1987:

December 2009:

There are a few exceptions, like 78-79 and 81-82, where the cold was initially driven by a very southerly tracking jetstream even without major heights to the north, but by and large this is how we get the cold in. A few days ago I made a similar post when this became a possibility, and noted that this particular height rise may not last, and could be flattened out by the jet. This remains a strong possibility, and in fact the ECM operational tonight does do that, albeit not entirely flat:

However, we have another possible direction of travel, whereby the pattern is further west and a bit more amplified, which creates either a longer lasting block positioned around the UK or, as in the case of the 12Z GFS, a proper transfer of heights northwards:

Ordinarily, you'd probably back the ECM on this one and say that the high pressure incursion will be short lived. However, there are reasons to believe that this is not going to be the case, and something a little more interesting may be afoot.

Firstly, we have the strat warming:

What this will do is give a beating to the stratospheric vortex, which will, hopefully, propagate down the atmospheric to our friend the tropospheric vortex and cause a much more blocked Northern Hemisperic outlook. The response can take time though: with a displacement Sudden Stratospheric Warming of this type we're looking at something along the lines of 3 major propagations over the course of 45 days after the warming, so with the first one making a major impact at the surface around the 15th of January. Sometimes, though, this response can be almost immediate like in late January 2009. There is the chance still, just a chance at this stage, of a more immediate response to the warming, which would occur within the next 10-12 days. While some outputs have hinted at this, and while conditions for downward propagation of the warming to affect our level is very much favourable, I don't feel that this is all that likely, and that it will be a more gradual process with the start of any big cold spell coming around mid month or later. We're certainly not guaranteed of this by any means: the vortex has been shunted over to Greenland and is looking relatively robust, so surely the blocking could easily end up setting up poorly from our perspective? Well yes, there are no guarantees with stratospheric warmings, but then again we have a lot more going for us than just the initial warming. Firstly, even if what remains of the vortex does end up over western Greenland to start with, I don't think it'll be hanging around for too long:

If this does indeed come off as forecast, then it really would be a matter of time before blocking started to develop over Greenland. That's of course far from guaranteed, so we may need a helping hand from our friend the MJO ( http://en.wikipedia....n_oscillation for a basic explanation) which has currently locked us into some very unhelpful phases:

which translates to:

moving into

which combined looks a lot like this:

However, as the chart also shows, the destination of the MJO by the end of the model period is somewhere around phase 6, which for January looks like this:

This is effectively the transitory phase from mid latitude block to Greenland block, and while the MJO isn't always a good match, when the amplitude is as large as it currently is it's likely to not be all that far from accurate. Therefore, my own view is that heights are likely to hang around our latitude up about the 12th, possibly with heights moving east-northeastwards at points and allowing the models to throw up a few easterly scenarios, when a combination of factors is likely to give us a shot at retrogression from mid month onwards.

In summary, then, there is a very clear road map to a cold spell for the second half of January, and while there will be detours, possible delays and maybe even some forward movement of the timescales, things for the moment are broadly going to plan. For the next week, this may seem on the ground like a major step away from cold, but in actual fact this is necessarily the beginning of a journey which will take us from a typical zonal winter pattern to something potentially much more interesting down the line, and if things come off in the right way the considerable patience required to see this through will be rewarded big time.

Edited December 30, 2012 by LomondSnowstorm

[Gibby]

Good morning. Here is the New Years Eve Report on the 00z output from GFS, UKMO, GEM and ECM.

All models show a very unsettled day today with a cold front meandering SE over England and Wales through the day with attendant heavy rain and strong winds. As the front clears winds will turn more towards the NW with colder and clearer weather extending SE to all areas by midnight tonight. New Years Day will be a breezy and chilly day with sunshine and showers the most likely course of the day with many Southern and Eastern areas staying dry. The showers may be heavy and wintry in the North and West, especially in the morning. Through Wednesday the NW flow will of backed Westerly with a weak warm front crossing East bringing cloud with rain and drizzle East over the UK followed by rather cloudy but dry weather with temperatures becoming much higher later in the day. Then from Thursday through to Sunday the weather will be dry for most as a large anticyclone develops close to Southern England with a very mild and moist SW flow across most of the UK. In the West and North there would be plenty of low cloud and drizzle over coasts and hills facing West while Southern and Eastern areas see the best of any brightness with any sunshine in the sheltered East push temperatures as high as 13-15C in places.

GFS then shows a steady decline in temperatures as the High declines and moves gently East allowing a Southerly drift to develop with a little rain in the far West towards midweek next week. Thereafter, the trend towards colder conditions continue as High pressure slowly develops to the North with the desire for Easterly winds to take hold and progressively colder conditions with the chance of some wintry showers or snow should the operational verify, chiefly in the North.

The GFS Ensembles show the operational as a cold outlier later in the run, especially for Northern locations with the likely outcome more a case of lowering temperatures towards normal levels as the large High slips slowly SE with gentler conditions continuing with much drier weather than recently in the South with the NW catching most rain.

The Jet Stream shows the endless flow that has been crossing the UK to the British Isles for so long now ridging North strongly over the coming days directed North to the west of the UK later before returning South over Europe as the High pressure block directs the Atlantic traffic far North than recently.

UKMO for midnight on Sunday shows a large High pressure over Southern Britain with fine weather for all. It will be a case of chasing areas of cloud around trapped under the High with some brighter intervals making way for some mist and fog patches overnight while temperatures remain very much on the mild side at that time point.

GEM shows the High relaxing a little further South late in its run with the North seeing a return to occasional rain while the South maintains mostly dry and mild weather though still with large amounts of cloud floating about.

ECM for next Sunday shows a similar scenario with High pressure persisting near Southern Britain in varying shapes and forms. The North will see occasional rain as weak troughs pass over and the cloud from these will become trapped under the High at times giving cloudy and misty conditions further South. For the most part the UK will remain in mild conditions, though temperatures would likely fall back somewhat, especially in the North and East as weak cold fronts cross SE before returning as warm fronts later on.

In Summary this morning there is firm agreement on today and tomorrow being the last of the deeply unsettled spell. Gone will be the gales and heavy rain of recently to leave the UK in quiet and anticyclonic days with a lot of cloud cover and temperatures well above normal for a time. In general the trend thereafter is for the South and East to maintain dry, relatively mild and rather cloudy conditions with the North and West likely to see a return to cloud and some rain but here too, lengthy dry spells seem likely. The GFS operational evolution to a changed synoptic pattern and a colder continental feed late in the run looks a little isolated in the grand sheme of things and will have to be seen as unlikely at the moment given it doesn't have much support from it's own members or other models. It will be interesting to see whether it is replicated in the following runs or just a blip so unless support spreads to the other models and outputs over the coming days I will not make much further comment on it at the moment.

Remember there will be no report again this evening but will be back to the twice daily reports as from tomorrow 2013. I would like to take this opportunity to wish all my readers on my website and forun a VERY HAPPY AND PROSPEROUS NEW YEAR and may all your meteorological wishes come true.

[johnholmes]

my ideas on what the upper air pattern may look like in 10-15 days time, usual pdf format, sorry if any cannot open this type of file.

Upper air ideas 6-15 days ahead on Mon 31 dec 12.doc

[Zenarcher]

Model summary using the GFS, ECM, UKMO, JMA, NOGAPS and GEM.

Tuesday to Thursday - 24 to 72 hours - All the models agree within this time range and show clear and sunny conditions across England, Wales and Eastern Scotland on Tuesday, elsewhere will be cloudy but dry. Wednesday will be cloudy all over the UK with fog and mist being widespread as well. Thursday will continue to be cloudy and misty for the UK but the very far North of Scotland may see some sunshine. Gale force winds on Tuesday for all but on Wednesday and Thursday only gales in the North.

96 hours Friday - All the models agree on a large high pressure to stay over the UK we can expect this to bring further cloudy and misty weather to the UK.

120 hours Saturday - As the models showed yesterday high pressure still remains over the UK but it's showing signs of weakening and moving away this is something all the models show,

The Atlantic lows yesterday is where the question mark was at this very point, today we have a slightly better idea, all models place a low in a similar place just entering the Atlantic,

144 hours Sunday - This is where it start's getting interesting here all the models have picked up that perhaps the high pressure over the UK will return again although this time not as strong,

And all models also go for low to be at the South of Greenland although its deepness varies,

168 hours and beyond the changeable outlook - The GFS for most of the time keeps high pressure over the UK but eventually brings in the Atlantic weather, the ECM which for the last two runs have shown to be poor for those looking for blocked and cold weather is an improvement and weakens the Atlantic and builds high pressure to our North East, JMA builds high pressure up as well.

Overall - Some interesting changes today in the models they are clearly struggling with the changes at the moment. The ECM is a positive change from what it has been showing lately. Yes the GFS FI isn't too great today but what has it shown a lot over the last few days a blocked outlook which is a trend it has built up one run that disagree's is not end of story.

Edited December 31, 2012 by weathermaster

[Gibby]

Good morning and a Happy New Year to everyone. Here is the first report of 2013 on the 00z output from GFS, UKMO, GEM and ECM for New Years Day Tuesday January 1st 2013.

All models show a rather cold NW flow over the UK with pressure rising rapidly everywhere. There will be some showers near Northern and Western coasts through the day, wintry on the higher Northern hills . These will lessen through the day as a ridge of High pressure crosses East over the UK tonight. There will be clear skies and a touch of frost for Central and Eastern areas before cloud spills in from the West to many Western areas and places further East tomorrow morning. Some rain will follow, possibly heavy in the Northwest but light and patchy in the South as a warm front crosses East over the UK. After a chilly start in the East the warm front is shown to bring much milder air back in off the Atlantic. The following three days see high pressure close to the South with a very mild westerly flow over the UK carrying a lot of cloud over all areas with some drizzle near Western hills and coasts, especially in the Northwest.

GFS then shows another weak trough crossing East on Sunday with a band of rain and drizzle in places, again chiefly to the North while maintaining the cloudy and mild theme. Then through the following week something of a North/South split develops with the North close enough to Low pressure crossing East to the North to allow rain at times while the South stays largely dry, mild and still rather cloudy though not without the chance of a little rain at times. In FI this morning the trend is for rather more unsettled conditions to gradually spread down from the North to all areas with rain at times and rather colder weather too with rain and showers for all areas by the end of the run with sleet and snow showers at times on Northern hills.

The GFS Ensembles show a very mild spell to come with high 850's for January. The trend is then a natural progression to more normal uppers to bring more normal January temperatures at the surface with time but also the return of some rather more unsettled conditions at times too. The downward slope of the graph shown from the ensembles this morning masks the fact that there is still only a very limited chance of cold snowy bound weather to come soon with the first impression looking more favourable for cold than it actually is due to the very high uppers over the coming 3-5 days from tomorrow.

The Jet Stream shows a strong ridging North over the UK for the next week or so with each weak return South to the flow thwarted as a new push North occurs in response to the High pressure to the South of the UK.

UKMO for midnight on Monday shows a slackening ridge over the East of the UK with a slowly freshening SSW flow over the West and North in association with Low pressure in the Atlantic. The mild and rather cloudy theme conttinues though there could be sufficient breaks in the cloud to the East to allow some mist and fog patches for a time. Some rain would probably run North up the western side of the UK soon.

GEM today shows a similar look as UKMO at 144hrs gradually pulling a trough East over the coming days with some rain for all before High pressure re-establishes near Southern Britain with some fine, dry weather returning in rather colder uppers with perhaps some fog and patchy frost to the South. At the end of its run it looks like the High is relocating to the Atlantic with Day 10 seeing a cold Northerly setting up in response.

ECM is having none of the Northerly thoughts though despite at Day 6 showing similar synoptics to GEM and UKMO. Instead it eventually brings a trough across from the West with some rain before flattening the pattern out and probably bringing a High pressure back in across at least Southern areas after day 10 with a North/South split the most likely conclusion after day 10.

In Summary this morning the start of the New Year two weeks look very favourable to those who like relatively mild and largely settled weather. Throughout the period there looks to be High pressure close to the South of the UK at times with a lot of dry benign conditions down here with just the odd patch of rain as weakening troughs pass by. In the North after some reasonable days late this week the weather turns more unsettled here with more outbreaks of rain and temperatures returning to near normal. There is no easy way out of this pattern as long as pressure remains High either near the Azores or Spain and the continuation of the mobile Atlantic train, albeit much further North towards Iceland through this period than has been the case for so long this last 6-9 months.

[Gibby]

Good evening. Here is the review of events from the 12z outputs from GFS, UKMo and ECM for today New Years Day Tuesday January 1st 2012.

All models show a warm front approaching the UK from the West tonight replacing the rather chilly remains of a NW flow, still over Eastern areas at midnight. The warm front is shown to cross the UK, clearing the East Coast later tomorrow. A mild and light to moderate Westerly flow follows with plenty of low, grey cloud and hill and coastal drizzle in the West and NW. Over Thursday through Saturday this general pattern persists with some brightening of the sky to the lee of high ground to the West where it will become very mild with temperatures everywhere well above normal for early January.

GFS moves forward showing the ridge of High pressure over the UK giving ground on Monday with a SW flow developing and rain and drizzle to the West and North for a time early and again late in the week with a dry and quiet spell in the middle of next week. The rest of FI shows a return to windy and unsettled conditions with time as Low pressure moves in close to the UK from off the Atlantic. It would also become much colder, especially in the North with sleet and snow developing at times here.

The GFS Ensembles show a week of dry and fine weather in the South from the developing High pressure before a return to more mobile Atlantic weather returns with rain at times for all in temperatures returning to nearer the normal for mid January.

The Jet Stream shows a strong ridging of the flow over the UK over the coming 5-6 days before the trend develops to begin to move the flow back slowly South by the middle of next week.

UKMO for noon on Monday shows a ridge of High pressure previously over the UK slipping away SE as Low pressure from off the Atlantic freshens up the SW wind and brings rain back to the North and West, extending slowly SE in rather mild conditions.

ECM for the same time point shows a similar story to UKMO with a trough crossing East early in the week with a spell of rain in tow to be followed by dry and fresher weather with frost and fog developing by night as High pressure settles over the UK and later near Scotland by which time daytime temperatures will be on the decline to rather cold levels by the end of the run.

In Summary there is continued support for High pressure to be dominant in the forecast models over the output period. In the short term mild and cloudy High pressure looks likely from it's position just to the South of the UK with ECM developing a new centre further North later next week spliced by a little rain from weak Eastward moving troughs at the beginning of next week. This would mean a drop in temperatures with frost and fog developing for many with time towards the second weekend. GFS doesn't show a continuation of High pressure through FI preferring a return to unsettled weather with rain at times and colder air too, especially in the North where snow could develop at times. The ECM solution could progress on to see more interesting conditions for cold lovers if it drifts a little further NE from Day 10 into Scandinavia. It will be interesting to see where we go with ECM in subsequent runs in view of the SSW forecast of late.