In Depth Model Discussion, Analysis and Summaries

[Gibby]

Good morning. Here is the report on the 00z output from GFS, UKMO, GEM and ECM for today Tuesdat January 22nd 2013.

All models show the rest of the working week looking cold and frosty though amounts of snow will subside over the coming days as Low pressure areas slowly slacken their grip iver the UK, though frost and ice will continue as pressure builds somewhat over the UK. Late in the week and weekend will see a deep Low move into the Northern Atlantic with Southerly winds freshening with rain moving in from the West preceded by snow as it encounters the cold air over the UK.

GFS then shows a couple of troughs crossing the UK over the weekend, the first will more likely bring a spell of snow, turning to rain before clearing briefly before the second more vigorous feature brings gale Southerly winds and heavy rain East across the UK on Sunday. Next week then shows a NW/SE split developing with wind and rain at times while the SE half of the UK are more likely to see drier and brighter conditions with temperatures reaching normal levels or even a little above late in the week. In Far FI winds gradually veer West then North as a mid Atlantic Anticyclone allows a cold Northerly flow to drive cold Arctic winds down over the UK briefly at the end of the run.

The GFS Ensembles show a continuing trend for more average temperatures or a little above for a while next week. Rain at times is prevalent with the wettest conditions is Northern locations. As usual there is plenty of spread at the end with the operational being an outlier in it's cold blip at the end of the run.

The Jet Stream shows a steep rising through the Atlantic of the flow replacing it's current South of Britain location to ride high over the UK in a weeks time.

UKMO for midnight on Monday shows Low pressure crossing Scotland early next week with periods of rain followed by showers in very windy and milder conditions than of late.

GEM shows a cold front sweeping East on Sunday with a spell of heavy rain in cold and strong Southerly winds. The weather then quietens down somewhat as well as become much milder with rain at times, more especially in the North and West with temperatures returning to normal values.

ECM too shows a spell of rain and strong winds through the weekend before milder and drier conditions develop quickly next week in the South and east while Northern and Western areas continue to see mild SW winds and rain at times.

In Summary this morning from the look of all the output the cold spell will end at the weekend. the transition will involve a spell of strong winds and rain with some models showing the risk of snow at the transition point. thereafter it looks like a strong pressure rise to the SE will bring a spell of much milder conditions with rain at times, chiefly in the NW with no immediate sign of a return to cold in the reliable mid term frames this morning.

[Glacier Point]

These tropical developments are beginning to take effect in the sub-tropics. A strong +ve mountain torque has occured and tendency in angular momentum is already postive and likely to spike very positive in the coming days. Overall relative angular momentum similar to November.

Thar she blows...

A big surge in +AAM tendency being registered, with a probable second spike to come in the next 5-8 days. Total angular momentum is really quit impressive at the moment with a large +ve anomaly coming out of the tropics driving us into El Nino type atmospheric response. That spike in relative angular momentum will build amplification into the system with a likely second wave following on behind.

We should shortly see anomalous tropical convection in the central Pacific and Africa, lending credence to GEFS MJO projection for phase 8.

Edited January 22, 2013 by Glacier Point

[bluearmy]

Thar she blows...

A big surge in +AAM tendency being registered, with a probable second spike to come in the next 5-8 days. Total angular momentum is really quiet impressive at the moment with a large +ve anomaly coming out of the tropics driving us into El Nino type atmospheric response. That spike in relative angular momentum will build amplification into the system with a likely second wave following on behind.

We should shortly see anomalous tropical convection in the central Pacific and Africa, lending credence to GEFS MJO projection for phase 8.

I recall a similar post in november stewart which didnt verify as you expected towards the end of the month. any differences this time around to make you more confident?

[Glacier Point]

.. much more substantive +ve angular momentum signal this time round. Note the tropics are just alive with westerly tendency at the moment.

The same posting in November was however a good heads up to the ridge / trough solution that characterised the first half December. That's not to say all of February will be cold, the further we go the more problematic in determining longevity, and I suspect the key variable for us to deal with will be how far west the +ve height anomaly goes.

[jimbo36]

.. much more substantive +ve angular momentum signal this time round. Note the tropics are just alive with westerly tendency at the moment.

The same posting in November was however a good heads up to the ridge / trough solution that characterised the first half December. That's not to say all of February will be cold, the further we go the more problematic in determining longevity, and I suspect the key variable for us to deal with will be how far west the +ve height anomaly goes.

Sorry guys but what does this mean in layman's terms?

[bluearmy]

Sorry guys but what does this mean in layman's terms?

It means feb is probably going to be colder than you might think looking at the predicted output for the first few days of the month. no guarantees but take a look at the recent post in the MOD to see the composite for MJO phase 8. you could also look at the GEFS in the post T300 timescale and pay attention to the runs which are amplified to our west. the risk is currently how far west the ridge might go further west towards canada which opens nw europe up to a west based -NAO, driving sw flow across the uk. as ever, time will tell but the west based - NAO is something flagged up for feb as a possibility in the winter forecast. wouldnt it be typical if we finally get our greeny block and it then heads off west !

[Gibby]

Good evening. Here is the evening report on the 12z output from GFS, UKMO and ECM for tonight Tuesday January 22nd 2013.

All models show a continuation of the very cold conditions for a few more days. Tonight's snowy low pressure in the English Channel will continue to spin an area of snow over Southern England over the next 12 hours or so while areas further North stay largely dry but cloudy with just a few snow flurries in the NE. Tomorrow will see the Low to the South slip slowly away SE taking the worst of the snow with it. Further North a dry day seems likely but still cloudy and cold. Over Thursday all areas become dry and cold under a brief ridge of High pressure before a Southerly wind springs up and brings a band of cloud and rain into the UK from the West during the later end of Friday and Saturday. A spell of snow is expected to precede the rain over the North and East. It will become less cold over the weekend .

GFS shows that once the milder weather gets across the UK the weather enters a phase strong winds and spells of rain especially in the North and West as the basic of Low pressure to the North and Northwest is balanced by High pressure to the South and SE and later the SW as winds turn from a mild long fetch South-westerly to a slightly fresher Westerly flow for a while.

The GFS Ensembles show uppers rising in a few days time as winds turn into the West. they become briefly quite mild before a return to more average conditions develop thereafter through to the end of the run. All areas are shown to see rain at times.

The Jet Stream shows the flow lifting from its Southern Europe latitude to be near the UK in a weeks time as Low pressure in the Atlantic lifts it over the UK in association with sinking High pressure over Europe in the coming days.

UKMO for midday on Monday shows Low pressure North of Scotland with a broad and chilly West or SW wind bringing showers and sunny intervals in a blustery wind following the rain and the rapid thaw of the previous day.

ECM tonight shows quite a limited warm up with potential for a snowy breakdown for some early in the weekend ( locations to be confirmed). With the first band of rain and snow clearing a second band of heavy rain crosses on Saturday night followed by a cold and windy day on Sunday for many with heavy and squally showers in the West, wintry on hills. Early next week sees the much milder weather arrive with a long fetch SW flow in association with High pressure to the Southeast with rain and strong winds copious in the North and Western high ground. Later in the run things could turn very mild in the South as High pressure over Spain feed very mild Atlantic winds up over the UK from latitudes well South in the Atlantic.

In Summary the weather stays cold for a few more days before an abrupt change to wet and wild weather at the weekend and possibly very mild and drier conditions in the South later next week. GFS Ensembles don't show an overly mild agenda though apart from a few days early next week, and the breakdown at the weekend though guaranteed may be somewhat less straightforward than has been shown in models of late. Whatever the outcome of the weather over the period there are still some interesting synoptics around tonight albeit for 'mildies' rather than 'coldies'.

[Gibby]

Good morning. Here is the latest report on the 00z output from the 00z outputs of GFS, UKMO, GEM and ECM for today Wednesday January 23rd 2013.

All models show universal agreement on a change in the weather in 48 hours or so time. The current cold and snowy spell still affecting parts of the South will die out through the day as the offending Low pressure in the channel fills up. A weak ridge of High pressure will gradually ridge down from the North in association with High pressure slipping South to the East tomorrow. The wintry showers near Eastern coasts will also die out as the High pressure builds but could be replaced inland by freezing fog tomorrow. On Friday pressure will be falling in the West as Low pressure moves steadily in from the West bringing a spell of rain East over the UK on Friday. The rain may be preceded by a spell of snow briefly. As the rain clears temperatures will rise strongly as winds settle SW. Later in the weekend an intense depression out in the Atlantic sends a squally cold front over the UK with a spell of heavy rain followed by squally showers and sunny intervals in a chilly SW wind. Thereafter, all models show an increasingly mild SW flow with rain at times gradually becoming more confined to more Northern and Western regions of the UK later as the South sees pressure build from the South. The above general trend is shared by all models with very little sign of a return to cold from this morning's output.

The GFS Ensembles show a warm up at the weekend with a gradual cooling off to normal values through the end of next week and beyond. Naturally there is a lot of spread between the members but there is little evidence of cross member support showing for a quick return to cold. Plenty of rainfall is expected at times too increasing the flooding risk following the snow melt.

The Jet stream shows the flow crossing the Atlantic on quite Southerly latitudes at the moment. It looks likely it will move slowly North to be around the UK latitude in a week or so time.

In Summary a quick thaw is on the way. Once arrived the emphasis will shift over the weekend and start of next week to flooding especially in the East and SW of England and Wales where a quick snow melt will be accompanied by heavy rain. Longer term amounts of rain will reduce as pressure builds from the South or SE with temperatures into double figures in places by day later next week in the South and East. The North won't be quite as mild though with further rain at times.

[Gibby]

Good evening folks. Here is the evening look at the changes that are soon to take place in the weather over the coming two weeks from the 12z output of GFS, UKMO and ECM for today Wednesday January 23rd 2013.

All models show a change in the weather soon. Tonight will see a cloudy and cold night for most with some snow showers continuing for a while in Southern England before they die out overnight. Elsewhere a few clear spells could develop later with a sharp frost as well as freezing fog patches as pressure gently rises from the North. Tomorrow will probably see a dry day for all with the stubborn grey cloud of recent days breaking to give some sunny spells through the day. It will remain cold though with only a slow thaw in the afternoon. After a frost tomorrow night a trough of Low pressure will approach the West later on Friday with a spell of heavy rain crossing West to East over the UK. The rain will fall as snow for a time, longest in more Northern and Eastern areas where another good 5-15cm is possible in strong winds. Overnight the snow will turn to rain and clear from the West with Saturday being a quieter day with normal temperatures with a continuing thaw of lying snow. Later in the day SW winds will become strong with heavy rain sweeping East over the UK followed by blustery winds and squally showers on Sunday with some snow showers still on high ground in the North.

GFS then moves into next week with strong to gale SW winds and rain sweeping back NE on Monday followed by a broad SW flow with further rain at times in the North and West while the South and East see much less rain and longer dry spells. this weather type is shown to persist until the weekend when a band of heavy rain crosses the UK in developing strong Westerly winds. By the end of Fi following a series of very deep depressions, gale force winds and heavy rain a change is shown to cold and wintry weather briefly at the end of FI as the deep Lows move away East and winds swing NNE.

The GFS Ensembles show a warm up guaranteed now at the weekend with a spell of unsettled weather thereafter with rain at times shown at all locations. Later the uppers gradually fall back to nearer normal values though there is no definitive indication or trend of any return to cold from anything in the GFS output tonight.

The Jet Stream shows the flow to the South of the UK currently but soon to swing its axis to run SW to NE over the UK to Norway in a weeks time.

UKMO for midday on Tuesday shows a strong SW flow over the UK in association with Low pressure out to the NW. There will be spells of rain for all, heaviest in the North and West in temperatures well up to the seasonal normal or above in the sheltered East.

ECM finally shows a mild spell next week too in strong SW winds with spells of rain for many. Late in the run the jet flow appears to be moving South again as pressure rises over Greenland with a renewed surge of cold air waiting in the wings for the UK after a very unsettled day 10.

In Summary all models are in agreeance that the weather is soon to turn milder with a rapid thaw and some heavy rain to aid the process over the weekend. GFS then shows a period of sustained milder and sometimes stormy weather while ECM shows rising pressure to the NW with cold weather soon to return to the UK beyond day 10. It will be interesting to see whether this trend is reflected in the ECM Ensembles later and extended to future runs taking on board GFS too. If this trend to cold weather occurs and is extended into the here and now remember it was ECM who spotted it first. It will save a lot of debate over which model spotted it first later. It's a long wait and ride to get to it though.

[Gibby]

Good morning folks. Here is my take on the 00z outputs from GFS, UKMO, GEM and ECM for this morning Thursday January 24th 2013.

All models show a cold and static airflow over the UK today and at fiest tomorrow as a weak area of high pressure slips South down the North Sea. After a rather cloudy start for many today the cloud should break latr with some sunshine. It will stay very cold with a sharp frost tonight for many. Tomorrow an active front moves into the UK from the West bringing increasing Southerly winds and rain to Western fringes in the day. Later this extends steadily East turning to snow as it does so, with some heavy and disruptive snow for a time in Northern and Eastern areas. It will clear from the West later and become less cold as winds veer West and decrease temporarily. Through Saturday as this trough staggers away East and decays a new vigorous depression moves into the NW with strong winds and heav rain for all this time over Saturday night bringing a rapid thaw to all before clearer, windy and showery weather arrives from the West on Sunday with some heavy and wintry showers in the North and West in a cold and blustery West to SW wind.

GFS then takes us through next week with a lot of windy weather. It will be come much milder, relative to conditions now with temperatures close to the seasonal normal or a little above in the SE for a time, though always offset by the wind. Rain at times would prevail for all, heaviest in the North and West. Through FI today the trend is to maintain the unsettled and windy theme with temperatures slowly dropping to just below the seasonal normal with further rain at times and no doubt some snow on Northern hills.

The GFS Ensembles confirm what I have stated above with the operational being a good representative of he pack. Rain at times is the order of the period with the Atlantic well in control throughout.

The Jet Stream flow shows an angling of the flow NE in the coming days towards the British Isles and later towards Northern Europe before settling to a typical sine wave style pattern at around 50 to 55 deg North by the middle of next week and beyond.

UKMO for midnight on Wednesday shows deep Low pressure to the North of Scotland with a spell of very windy and unsettled weather well entrenched over the UK. It will be often cloudy with spells of wind and rain driven quickly East over the UK with brighter and more showery spells in between. Temperatures would be near to normal but cold enough for some wintry showers at times on Northern hills.

GEM shows a windy spell of weather too with winds always between South and West carrying troughs NE over the UK with spells of rain followed by fresher showery weather with temperatures well up to the seasonal normal or a bit above in the SE for a time.

ECM this morning shows an unsettled pattern too with a West or SW flow bringing rain at times in normal temperatures. Later in the run the flow tilts more West or just North of West with a trend to rather colder air with some wintry showers on hills later. This trend continues at Day 10 with pressure having fallen in the Med and High pressure in mid Atlantic allowing the next depression to probably slip more SE directing a cold Northerly flow across the UK in the days that follow the expiry of the run.

In Summary the thaw is just around the corner and committed to by all models for late Friday and Saturday. The models then settle us into a milder and windy spell with areas of rain and strong winds interspersed by periods of sunshine and showers.in temperatures very close to normal though it will still feel chilly in the strength of the wind. Longer term GFS show little change to the progressive pattern with rain at times while ECM shows signs of change again late in its run as the jet tilts SE and colder winds from high in the North Atlantic are directed over the UK. Although not as pronounced as last night's 12z output a Northerly could develop behind the incoming depression at Day 10. The only negative though there is no Northern blocking to tap into at this juncture so the UK may have to wait at least two weeks before our next serious shot at real wintry weather again.

[Gibby]

Good evening. Here is the report on the 12z output from GFS, UKMO and ECM for tonight Thursday January 24th 2012.

All models show a breakdown in the cold weather over the next 24 hours. A weak cold ridge over the UK tonight with a severe frost will move away SE tonight. Southerly winds will freshen with cloud increasing tomorrow morning with rain into the West by midday. through the afternoon the rain will move East to remaining areas turning to snow readily over inland Central and Eastern areas later in the day. the rain and snow will clear tomorrow night with a thaw in progress for all. saturday will be less cold and relatively dry to begin with before a new Low brings a set or active fronts into the Uk late in the day with rain and gales for all over Saturday night clearing to sunshine and rain showers on Sunday.

GFS then shows a period of sustained Atlantic based weather with winds blowing from a Southerly or Westerly element throughout the rest of its output. There would be a spell of high winds through the early half of next week with slightly less windy and less mild conditions developing at times thereon. In the second half of the run the Azores High plays a major part in the UK's weather steering West or NW winds and rather cloudy weather with some further rain at times down over Britain, most likely in the North in temperatures close to normal.

The GFS Ensembles show that a milder interlude is on the way. Slowly but surely afterwards the 850 temperatures fall back to levels near to or just below the long term mean for early February in the South and bang on the average in the North. Rain at times is shown as one would expect with an Atlantic influence especially next week.

The Jet Stream shows a NE moving flow over the UK developing in the coming days and continuing in a sine wave pattern at a similar latitude for the following week or so.

UKMO for midday on Wednesday shows Low pressure to the North of the UK with High pressure well to the South. A typical Winters Day Westerly flow will deliver showers and some longer spells of rain across the UK in windy conditions and temperatures close to normal.

ECM tonight shows a series of deep depressions moving ENE to the North of Scotland through next week with showers or longer spells of rain in temperatures close to normal for late January/early February. The Azores High does show signs of ridging NE towards the UK behind an exiting depression over Europe next weekend turning the weather colder with wintry showers for some.

In Summary by this time tomorrow the cold spell will be virtually over as rain crosses the UK from the West clearing the snow in the East and introducing drier weather for a time. From Saturday night on the weather becomes often wet and windy with temperatures close to normal for most. Local flooding could become an issue in the SW especially as rapid snow melt combined with heavy rainfall develops. Later in tonight's output both GFS and ECM point to something of a cool down though there is little sign of anything significantly cold showing up at the surface in the coming 10-14 days.

[Swave Snow]

Reasonable grounds for thinking that the global synoptic dynamical model is moving towards a third cold pattern this winter (the waning of this present one being well advertised) and the last few GEFS ensemble means have leant support to this idea.

Tropical convection has been focussed in the western Pacific in the last 10 days. This has introduced anomalous westerly winds to the tropical Pacific which in turn has helped lift tendency in angular momentum towards an El Nino type pattern.

Latest TOA Triton data indicates anomalous ocean heat content centred just west of the Dateline and encroaching anomalous westerly winds on the back of the MJO. Trade winds are also decreasing, which is typical of MJO progression towards phase 7/8.

The GEFS MJO forecast has come to life in the last day or so, suggesting a strong amplitude wave to develop in phase 8.This seems reasonable on the basis of favourable conditions for convection due to increased heat avalability and cooling upper atmosphere (especially lower stratosphere).

These tropical developments are beginning to take effect in the sub-tropics. A strong +ve mountain torque has occured and tendency in angular momentum is already postive and likely to spike very positive in the coming days. Overall relative angular momentum similar to November.

The shrewd will recognise that the last uptick in relative angular momentum heralded our first pattern change and cold trough in December, by about 2 weeks lead time as positive (westerly) wind anomalies are fluxed poleward introducing anomalous mind and high latitude ridges and circumglobal troughs (Pacific and Atlantic).

Meantime, our first downwelling wave from a very strong polar stratospheric warming (and sustained reversal in zonal winds) has matured. Stratospheric time scales are extremely long, and we can expect further downwelling episodes lower down in the atmosphere for the next few weeks. Based on Baldwin'c composite of weak vortex events, the next episode of increased eddy activity is due around 28th January although the timing of this is not exact.

The temperature anomaly section shows a reasonable time scale for 'nodal' type propogation extending into February, perhaps more towards mid February. A typical tropospheric response to this would be very similar to an MJO phase 8 projection, so its interesting the atmosphere choreographed in this way.

So teleconnectively we have a reasoned case for anomalous heights to our north end January into February. The timing of this highly problematic as the models were to a degree blind-sided by the first downwelling wave, only latching onto it 2 days before the warming took place. Were this happen again, a sudden turnaround in modelling could well occur.

The last five GEFS mean height anomaly for the extended range has 'hit the target' on all five occasions to varying degrees, which is interesting in itself. Todays GFS super ensemble mean height anomaly....

Putting this together, expect further cold pattern, becoming stronger probability the further we go into February but I wouldn't be suprised to see it pop up from 28th January onwards. Winds from the NE and E the favoured scenario.

Hi GP,

Is it not looking so promising now, or would it be now that or this weekend to expect a sharp turnaround from the models or are they still out of their depth here. Because reading between Gibby and the Met office and some others they all seem to think it is not a fast return to cold weather.

[BlueHedgehog074]

Just some thoughts and summaries regarding the outputs: It looks pretty certain the snow and cold that have invaded parts of the UK will begin to retreat as the models show milder South-Westerly/Westerly winds returning. This looks as though it could get locked in for a while as the various models show High Pressure sitting firmly to the South or South-East, with Low Pressure dominating the North for the next week or so.

But, before then, it looks like the snow will pay us one last visit today as a spell of wintry weather races in from the West thanks to a Low out in the Atlantic knocking the High Pressure block we had over us yesterday, Eastwards. The rain, sleet and snow looks to clear Eastern parts of the UK by early Saturday morning according the the UK GFS precipitation charts. It then looks to gradually turn a little milder as Westerly or South-Westerly winds shown on the charts bring in less chilly air, but with tomorrow, Sunday and even Monday still looking as though it will stay a touch on the cool side. The wind direction for those days generally more on the Westerly side rather than the South-Westerly side - the latter of which would attempt to pump up even milder air from the South.

For Sunday, though, further wet weather looks likely (although details on this could still change slightly depending on the exact positioning of the large Atantic Low out West, but it looks like the airflow will be from a coolish Westerly direction). Any snow that does fall will be likely constrained to hills and mountains, especially to the North, but maybe extending to slightly lower levels in heavier bursts.

From then on, it looks as though places will continue to see further spells of rain and showers brought in on a Westerly or South-Westerly airflow with North-Western areas likely to see the most unsettled conditions being under more influence from Low Pressure systems to the North-West or North. But even Southern areas are prone to being infested with lots of wet weather with High Pressure pushed a little too far South to have much of an impact for these areas. It is possible, however, that as next week goes on, we may see upgrades or downgrades in regards to how far North any High Pressure systems to the South get, but with the 00Z GFS showing quite a powerful stream of the Jet powering right through us with it generally aligned South-West to North-East or West to East, High Pressure may just end up staying put to the South/South-East of the UK with a continuation of a Westerly dominated pattern. It seems like the best of any cool/cold weather we could see would likely come from Polar Maritime airflows with a possibility of wintry showers, especially on high ground. And in fact, the 00Z GFS does show a little more of a cooler theme again for late next week as the winds become more Westerly or North-Westerly.

Although it looks as though the gateway to cold could remain closed for next week (except for those possible Polar Maritime airflows), it's not impossible to see colder, and more blocked patterns suddenly arising from the outputs again, just like what has happened earlier this month. I do feel less invasiveness from the Polar Vortex to the North-West could help to bring back something more blocked, too, along with the Jetstream becoming more broken apart, slower moving and shifting Southwards again. I know the GFS in FI on some of its runs in the last few days has kinda showed Northerly attacks which could be a sign of what could happen in the future. As such a sharp turnaround in the models for the weekend (or maybe early next week) may indeed not be entirely unfeasible.

At least, to be fair, for those who have become fed up with the snow and cold, or who love less cold weather, will be in for a fairly nice surprise once Friday is through with us.

Edited January 25, 2013 by DiagonalRedLine

[Gibby]

Good morning. Here is the report of the 00z output from GFS, UKMO, GEM and ECM for today Friday January 25th 2013.

All models show a breakdown in the cold weather today as an active front moves across the UK from the Atlantic. A spell of wind and snow turning to rain will move East across all areas through the day with quite a bit of snow in the North and East for a time. As the rain and snow clears skies will clear and a slight frost could give rise to icy stretches tonight from todays precipitation and thaw. Tomorrow shows a strengthening SSW flow and areas of rain moving quickly across the UK late in the day and overnight with copious rainfall and a rapid thaw of lying snow. On Sunday and much of Monday a strong to gale West or WSW flow is shown with heavy showers for all, more especially in the West with hail and thunder a possibility. Later on Monday yet another spell of wet and windy weather rushes East over the British Isles from off the Atlantic i temperatures close to normal for late January.

GFS then moves through the remainder of its run with a very unsettled spell of weather with spells of rain and strong winds alternating with spells of sunshine and heavy showers. In other words a spell of relatively cool zonality. Temperatures will never be very high nor low for that matter but it will be sufficiently cold for some snow on the hills of the North at times and even occasionally on hills further South too. Frosts would be limited die to the strength of the wind.

The GFS Ensembles show a cocktail of ways to state the same pattern with copious rainfall and winds from off the Atlantic from most members in temperatures never far from normal. Throughout the pack there are no very cold options nor warm ones either making the operational fairly representative of the weather type the UK can expect over the coming few weeks.

The Jet Stream shows the flow pumping NE across the Atlantic over the UK for the foreseeable future driving rain bearing depressions over the north of the UK and attendant strong winds and rain for all.

UKMO for midnight on Thursday shows a Scandinavian Low pressure linked to a further depression West of Scotland with a very showery WSW flow with disturbances running quickly East within the flow. There would be a mix of showers or longer spells of rain, heavy and thundery at times with some snowfall possible on Northern hills in near normal temperatures.

GEM shows no real difference either keeping a supply of low pressure crossing over the North of the UK from the West in strong West or SW winds and normal temperatures. Rain and showers for all the measure of the run.

ECM too keeps things very flat and zonal in its latter stages with all areas receiving copious rain events rushing through on a strong West or SW flow. Temperatures here too look like never straying far from the late January normal.

In Summary this morning there is a very wet and windy spell too come over the next 10-14 days. With the Atlantic wound up numerous depressions and fronts are set to cross the UK in a strong wind and creating further flooding issues not dissimilar to those of early December. With such a zonal pattern it is hard to see this morning where any change to this pattern is going to come from for the time being. All models have lessened the influence of the long fetch SW flow originally offered next week and a hint of rather colder zonality is given by GFS when some unexpected snowfall could turn up briefly in the North but that is the only crumb of comfort for 'coldies' this morning as the old wives tale of 'February Fill Dyke' looks like living up to its name from todays output.

[Gibby]

Good evening folks. Here is the report from my perspective on the 12z output from GFS, UKMO and ECM for today Friday January 25th 2013.

All models spell the end of the cold spell over the next 12-24 hours. A band of heavy rain and snow is currently crossing East over the UK, clearing the SE tomorrow morning. Following on behind will be a quieter less cold period tomorrow before a further spell of strong winds and heavy rain sweep across the UK tomorrow night with a rapid thaw. On Sunday and Monday a showery westerly flow looks likely with heavy squally showers, especially in the West with hail and thunder a possibility as well as snow on Northern hills. A further spell of rain sweeps East later Monday and Tuesday when it could become briefly very mild in the South in very strong winds though.

GFS then shows further Low pressure pushing East to the North of Scotland with further spells of rain up to the weekend when rather colder weather as well as less windy conditions give the UK a welcome breather from the wind and rains of the past week. Thereafter the NW sees a return to rain at times while High pressure comes much more dominant for Southern areas with a continuation of drier weather here with some night frosts and patchy fog in temperatures close to the normal for early February.

The GFS Ensembles show a sustained spell of Atlantic dominated weather throughout its output with no trend towards anything seriously cold shown tonight. Rain at times will continue as depression carrying strong winds continue to be shown to steam in from the West by most members.

The Jet Stream shows a continuation of the flow pumping East over the Atlantic and into the UK and on over Europe with peaks and troughs as various pressure systems pass West to East.

UKMO for midday on Thursday shows Low pressure over Scandinavia stretching West to the North of Britain with secondary depressions west of Scotland and North of the Azores. The far North will be chilly with showers, some of them wintry while most other areas see further rain at times in breezy West winds and temperatures close to normal.

ECM tonight shows a standard Winter setup with a powerful Jet crossing the Atlantic and the UK with the Azores High at home while successive deep Low pressure areas sweep band after band of rain and strong winds interspersed with clearer and somewhat colder conditions with heavy showers. Later in the run temperatures are shown to fall back somewhat as cold zonality briefly tries to take control of the UK weather with wintry showers possible in places in less strong winds before wind and rain return on Day 10.

In Summary a very disturbed spell of weather is set to replace the cold and snowy spell of late. As the Atlantic goes into top gear with a powerful jet stream depression after depression will cross the Atlantic to the North of the UK with strong to gale winds and copious rain events affecting the UK with some regularity. Some brighter more showery interludes will occur too with temperatures near to normal on the whole though some mild interludes could occur in the South early next week and rather chillier conditions generally after next week.

[Gibby]

Good morning. Here is the morning report on the 00z output from GFS, UKMO, GEM and ECM for today Saturday January 26th 2013.

All models show a similar pattern throughout there output this morning which makes my job easy today as I can lump all models into one basic summary rather than look at specifics between them . The weather has taken a complete turn from the cold and snowy outlook of the past week or so. Instead we have a strong Atlantic West or SW flow blowing over the Atlantic and across the UK all courtesy of the basic pattern of High pressure to the South with a series of deep depressions passing to the North. All areas will see periods of rain and showers with temperatures well up to the seasonal normal and a bit above at times in the South. There are tentative suggestions from GEM and from GFS late in FI for pressure to build to the NE as the Atlantic train weakens but these are rather weak signals at this stage with the vast majority of members within the Ensemble group of GFS keeping things at least at normal temperature values after a few milder blips in the early days of next week with a continuation of the Atlantic feed the more likely evolution perhaps with a trend to a somewhat more chilly zonal pattern later on as the Jet Stream which blows strongly over the UK in the next week continues unabated.

So in Summary a sustained spell of windy and less cold weather is shown today with patience having to be adhered too before any specific trend is highlighted towards a return of anything more wintry. There will be plenty of rain and showers for all in the coming spell with some very windy weather too.

[Gibby]

Good evening. Here is the report of the 12z output from GFS, UKMO and ECM for tonight Saturday January 26th 2013.

All models show the UK now under the influence of a strong and mobile West or SW airflow with Low pressure centres Northwest of the UK with a strong west to SW wind with troughs crossing East in the flow bringing spells of strong winds and heavy rain interspersed with spells of rather chillier and equally windy weather with showers, some heavy with snow on Northern hills. This weather then becomes replaced on Monday with another spell of wet and windy weather with severe gales in the NW. On Tuesday the SW flow will become quite mild in the SW with further rain at times before a cold front crosses East on Tuesday night to re-introduce blustery and showery conditions on Wednesday.

GFS then shows further spells of rain through the latter stages of the next working week and start of the weekend before things quieten down somewhat as a ridge topples down from the NW bringing drier and rather chillier conditions for a while though the NW quickly sees a return to the wind and rain. Through FI this more unsettled theme returns South to all areas though not as mild as previously with a trend for cold zonality weather to take control with rainfall falling as snow on hills at times even in the South later.

The GFS Ensembles show a trend to somewhat lower uppers again after the coming three or four days as cold zonal weather looks a feasible option over the coming model run period. The operational and Control Runs were somewhat colder option than most members with all members showing rain at times in a continuing Atlantic dominated pattern.

The Jet Stream shows the flow continuing to pump Eastwards strongly over the Atlantic in a sine wave pattern over and around the British Isles in the forthcoming reliable time frame.

UKMO for midday on Friday shows Low pressure over Scandinavia with a trough SW over Scotland. Cold air lies to the North of the Scottish trough with a showery Westerly flow over the Southern half of the UK. More general rain or sleet is more likely over Scotland through the day.

ECM shows increasingly colder conditions later in the run with Low pressures trending to move more SE across the UK with rain or showers continuing over the UK falling increasingly as sleet and snow over hills at times and more especially in the North and East.

IN Summary there is a trend for rather chillier weather to develop over the UK beyond the early days of next week. It looks like staying very unsettled throughout the period tonight with rain and showers trending to be more wintry, especially over the hills with time.

[Gibby]

Good morning. Here is the A.M. Report on the 00z Output from GFS, UKMO, GEM and ECM for today Sunday January 27th 2013.

All models show a windy and unsettled week to come as the basic pattern of Low to thee North of the UK and High to the South is maintained. Some of the rainfall will be heavy and prolonged especially early in the week when severe gales are likely at times. Flooding could also be an issue as the recent snow melt combines with heavy rain through the week. There will be periods of more showery and cooler conditions like today and again on Wednesday and Thursday when the air might be cold enough for snow on Northern hills.

GFS then shows next weekend with the Azores High moving ever closer to the SW and with pressure having fallen over Europe as a whole a NW flow will set up dragging rather colder but drier conditions SE across the UK though the North and East may see further wintry showers at times, chiefly over the hills. This theme then continues into the middle of the following week when High pressure to the SW splits as a Low pressure divides the High into two bringing rain and wind back in to all areas late in the week to be followed by a quick return to cold and wintry conditions with snow at times, especially in the South as High pressure of sorts builds to the North sending the Jet flow well South of the UK again.

The GFS Ensembles show a trend to rather colder conditions to slowly develop again over the UK as we move through the period. It looks like the trend to develop a situation not unlike the recent cold spell is possible with a weak level of Northern blocking and coupled with a European cold air pool sending Low pressures on a more SE track with sleet and snow possibly becoming more of a feature of the UK by the second week if the path of these depression keep the UK on the cold side of the frontal activity.

The Jet Stream shows the flow blowing strongly across the Atlantic towards the UK for the oncoming 5-6 days before it ridges up in the Atlantic around the Anticyclone just to the SW by next weekend.

UKMO for midnight on Saturday shows Low pressure stretching from the Norwegian Sea to the Baltic with a colder North or NW flow developing over the UK ahead of a toppling ridge of High pressure in the day that follows. There would be wintry showers for many especially in the North and East with snowfall over the hills.

GEM shows a similar set up for Saturday as UKMO moving forward with rather cold zonality bringing spells of rain mixed with wintry showers, especially in the North as we move through to the runs end.

ECM too shows a similar trend, though on this run it keeps our friend the Azores High well in control at this stage keeping the cold and unstable air at arms length over nearby Europe in this time frame with any effects from this mostly felt in the North and East with a lot of benign NW winds and cloud cover likely further SW.

In Summary the trend is clear to see from all the models to aid the return of something rather colder as pressure falls over Southern Europe pulling the Jet South over Europe. The problem for the UK is getting the Azores High to drift far enough away to the SW to allow Low pressures to sink further West in their tracking SE movements encouraging the colder air over Europe into Britain as well as encouraging pressure rises to the North and NW to speed up the transformation to something more wintry such as GFS shows late in its operational. It could be a slow arduous track to a renewed cold spell and it may amount to nothing but there is a definitive trend shown throughout the morning output of the Atlantic winding down somewhat with time allowing more interesting synoptics for 'coldies' to develop.

[TonyH]

A model and local perspective guide to the weeks weather:

http://forum.netweather.tv/blog/309/entry-4558-weather-guide-monday-28th-jan-to-sunday-3rd-february-2013-west-wales-and-the-central-midlands/

[Thundery wintry showers]

Copied from the model output thread:

It will be a standard Atlantic onslaught this week- sunshine and blustery showers for many today, then grey, drizzly and mild (especially warm in southern Britain) on Monday and Tuesday with a tropical maritime regime, but then brighter and more showery weather returning from Wednesday onwards with temperatures falling closer to average. Winds will be strong throughout the week and much of Scotland may be hit by gales on Wednesday.

A 24-36 hour northerly "toppler" is likely this weekend and the models currently disagree slightly on how potent it will be. The ECMWF version is, to my mind, a bit more potent and long-lasting than the GFS version and may bring wintry showers a fair way inland in the north and east, though with lying snow likely to be restricted mainly to low-lying parts of NE Scotland and higher ground further south:

http://www.wetterzen...cs/Recm1441.gif

Don't expect anything substantial or sustained though- this is pretty much a bog-standard toppler.

Longer-term signals are indicating a mid-Atlantic block, which leaves us open to more short-lived north-westerlies with wintry showers in the north, though we would need a general rise of pressure to the N/NW to bring any advance on topplers.

[Summer Sun]

A few tweets from Matt Hugo and Liam Dutton

Matt Hugo - Given a closer look at medium/long range & my prediction is that blocking/colder weather will become a distinctly possible after 1st of Feb.

Liam dutton - Looks like some colder interludes. A couple of half-hearted toppling ridges. I'm not excited yet... N'lies can be boring. :-)

Matt Hugo Looks that way at the moment but wouldn't rule out a more sustained block. We'll see as ever :-)

I don't mind northerlies to be honest at least they often bring sunshine with them better than the cloudy dull muck we've had for pretty much the past 2 weeks

[snowking]

Ignoring any stratospheric influence and focusing purely on tropospheric signs...

MJO remains insistent on progressing towards phase 8 with a higher amplitude in around 6-10 days time

All apart from the GEM, which is more reluctant:

This helps to explain the developing height anomalies beginning to show their hand in the 6-10 day period:

Pretty solid agreement there for something heading towards an MJO Phase 8 composite for February, and indeed if we roll forward the GFS 6z to days 11-15:

You can't really get a much better match for the UK locale than that with this:

Where as the GEM, given the un-amplified MJO signal, isn't interested at all in the 6-10 day time period:

Though the encouraging sign is that even it, without a strong MJO phase 8 signal, develops something similar in the 11-15 day time period:

In the mean time, whilst we see such a big difference between the GFS and GEM in the mid period, I would suggest that the NAEFS will be a bit 'diluted' in its signal, and might not be particularly useful as a tool therefore.

I think we're looking at between 7-10 days into February for the real cold to return, in the mean time a peak in temperature around Weds/Thurs this week, before a gradual decline. Into the following week, we could end up with a very messy mix of rain/sleet/snow, the snow initially restricted to higher ground, but gradually falling in altitude.

Of course if we were also to factor in lower stratospheric suggestions around the day 10 mark:

Still a pretty strong signal there for a ridge into the mid-atlantic and up towards Greenland, with the Siberian/Scandi PV segment heading south to our East. In fairness this was the initial suggestion from the stratosphere during our current cold spell, so this could be another red herring, but with Ensemble NWP and MJO guidance also in agreement with this, along with the ECM 32 day output (broadly speaking), medium range signals at present nearly all pointing to MJO Phase 8 type setup.

SK

[Gibby]

Good evening. Here is the evening look at the latest 12z output from GFS, UKMO and ECM for today Sunday January 27th 2013.

All models show an unsettled and windy week to come with today's showery Westerly flow backing SW tonight and tomorrow with a further spell of rain moving NE across the UK with renewed gales in the North and West. Tuesday too sees a lot of wind and rain over the UK with some very mild air for a time likely in the South through the day. Wednesday sees the potential for some damaging winds over Northern Scotland while the rest of the UK sees a rather chillier spell both Wednesday and Thursday with showers and bright intervals. By Friday a new Low pressure looks like crossing more Southern areas with rain and strong winds once more followed by a chilly interlude with more wintry showery conditions and the chance of night frosts over the weekend.

GFS then continues to show High pressure down to the SW with a succession of Low pressure areas slipping SE to the NE bringing several spells of rain followed by rather cold and windy NW winds with wintry showers, especially towards the North and East. signs of a more substantially cold Northerly look likely following the last chart of FI.

The GFS Ensembles show a trend towards chillier conditions as we progress through the run though nothing more than average conditions for more Northern locations. Rain though does decrease in quantity the deeper into the run we travel especially in more Southern locations.

The Jet Stream continues tunnelling over the Atlantic towards the UK for the majority of the coming week. It then rides over the Azores High and travels back South just to the East of the UK next weekend and beyond. If cold air is to reach the UK in a meaningful way we need this High pressure to weaken and absorb North to Northern latitudes so that the Jet Stream becomes forced further and further South as it was in the recent cold spell, a process that doesn't look likely in the short term.

UKMO for midday on Saturday shows a ridge of High pressure collapsing SE over the UK with a fair day for many in rather colder temperatures than those of the days previous. It looks as though milder Atlantic winds will spread back over the UK the following day.

ECM also shows the collapsing ridge over the UK next Saturday before it too shows the Atlantic winning back late in the weekend with rain returning from the West. With time though the rain bearing fronts and depressions slip further SE into Europe with the Azores High extending further North through the Atlantic and in response to the Atlantic weakening allows for impending and increasingly cold weather in the days beyond Day 10.

In Summary tonight the weather looks like staying Atlantic dominated for the foreseeable future. The biggest enemy for cold weather fans from tonight's run is the strong Jet Stream riding over the Azores High which is displaced slightly North or Northeast of it's home base at times. As long as that positioning is maintained any cold incursions will be just that with the Atlantic riding over the top of the High courtesy of the Jet flow then delivering the cold zonal flavour to the weather for our European partners rather than the UK. ECM shows what can happen if that High is allowed to ridge North in response in part to a weakening of the Atlantic and Low pressure finding it's way down to the Med.

[Gibby]

Good morning. Here is the morning look at the 00z output from GFS, UKMO, GEM and ECM for today Monday January 28th 2013.

All models show a broad West or SW flow over the UK through the working week in association with a series of Low pressures North of the UK and High to the South. Troughs will moves quickly NE or East over the UK from time to time bringing spells of rain and strong winds, heavy at times. Temperatures will be generally well up to normal through the week and above tomorrow in the South as a warm sector passes through. It will be cooler in the showery spells with a little wintriness in the blustery winds associated with the showery spells. By Friday things begin to become a little more interesting.

GFS brings a deepening Low pressure across the South of the UK and on its Northern flank some cold air will be drawn into its circulation with some rain, sleet and snow possible for a time at the start of the weekend. By Sunday a weak ridge collapses down over the UK with a fine and cold day leading into a return to milder Atlantic winds to start next week. FI today shows a continuation of the mixed pattern between milder Atlantic winds blowing from the West or NW with rain in places mixed with further cold incursions from the North when widespread wintry showers would occur with temperatures dropping below normal for several days at a time before the Azores High topples another ridge down over the UK cutting of the cold feed for a time especially for Western and Southern areas.

The GFS Ensembles show an agreed trend into rather colder territory as we move through next week. There will be rain at times this week in generally mildish conditions and a cold dip at the weekend in association with the depression over the South at the weekend. Things then trend more difinitively colder next week as successive cold pushes from the North work their way down over the UK.

The Jet Stream shows the flow still moving East over the Atlantic towards the UK before ridging further North over the Azores High later in the weekend and next week as it inches closer to the UK.

GEM today shows a depression at the weekend exiting Eastern England and leaving a brief cold Northerly over the UK before returning polar maritime air cuts off the flow around a High pressure area to the SW. This general pattern of cloudy damp weather mixed with brighter, colder and more wintry showery type weather then continues to the end of the run.

ECM too shows an even deeper area of Low pressure close to the SE on Friday with a couple of cold and potentially wintry days at the end of the week and start to the weekend. A ridge then topples SE over the UK with a return to somewhat milder weather with occasional rain before the next cold front sweeps SE continuing the theme of colder interludes mixed with milder incursions around the Azores High to take us to the end of the run.

The pattern seems quite well agreed upon today with this week totally Atlantic based with wind and rain at times. A depression on more Southerly latitudes at the very end of the week could spring a few wintry surprises for many Southerners before the general theme of High pressure to the SW and Low pressure over Europe sets up with winds from the NW for much of the time. Due to the proximity of High pressure close to the SW the colder incursions behind cold fronts will be most felt to the North and East of the UK while the South and West see more modified conditions while that High stays so close. In any event each cold incursion remains relatively short lived as pressure takes a long time to build further North through the Atlantic, cutting off the Atlantic train and Jet stream from riding over the Azores high. Patience is going to have to be a virtue for sustained cold from this set up though the trend is there for something more sustained for 'coldies' longer term.

[Gibby]

Good evening. Here is the evening look at the 12z output from GFS, UKMO and ECM for tonight Monday January 28th 2013.

All models show the rest of this working week as being unsettled and often windy with rain or showers at times for all. Tomorrow looks particularly wet as a warm front scoots NE over the UK followed by a cold front late in the day, all bringing spells of rain in a gale force SW wind. At least it will be mild in the South for a time through the day. Through Wednesday and Thursday more showery weather is likely but some of these will be heavy and prolonged especially on Thursday. By Friday a new wave depression or deeper Low ensures the end of the working week stays unsettled and wet, especially in the South before a drier and colder interlude feeds down from the NW over the weekend with a welcome 24-48 hours of dry and rather chilly weather over the weekend with a slight overnight frost likely for many.

GFS then brings milder maritime air down over the UK through Sunday with rather cloudy and benign conditions early next week with some light rain possible in the North for a time as a front passes by bringing slightly colder air back to the NE by midweek. FI tonight repeats the process of weak troughs toppling SE over the UK at times followed by a toppling ridge too for most if not all of its latter stage output as High pressure lies close to the SW for most of this time. At least the SW would have a chance to dry up somewhat as only small amounts of rain would occur here.

The GFS Ensembles show a gentle cooling to levels just below the long term mean as a more NW influence to the winds over the UK take hold next week. There is little evidence of any significant cold shown on tonight's output from GFS members for the UK though no really mild weather is likely either. Amounts of rain will reduce beyond this week as the displaced Azores High to the SW of the UK diverts the majority of frontal rains towards Europe.

The Jet Stream shows the flow blowing strongly over the UK ridging North over the Atlantic later this week over the top of the Azores High before returning South over the UK.

UKMO for midday on Sunday shows a strong Anticyclone to the SW of the UK, Northeast of the Azores. A warm front is shown crossing the UK from the West through the day. The likely weather would be an early frost in the East and South giving way to milder and drizzly weather as the weak warm front crosses East through the UK later in the day.

ECM tonight shows a much more potent Low on Friday than the other models with rain and gales in the South giving way to colder and brighter conditions to start the weekend. The overall pattern is back on track by Sunday with ECM following UKMO in bringing a warm front East over the UK on Sunday with rain and drizzle on recovering temperatures due to a large and strong Azores Anticyclone parked to the SW of Britain. Later in the run a few days of milder Atlantic Westerlies bring rain at times for many before a deep Low moves across the Atlantic to Scotland and on Day 10 across to NE England. Cold NW winds are then shown to sweep South over all areas with wintry showers for all the hills and low ground too in the North.

In Summary tonight the pattern look like changing a little as we move into next week. After this weeks relatively mild, windy and wet conditions a change to rather colder conditions looks likely next week . Of more importance to lower lying locations some of the output suggests rather drier conditions, especially to the SW where winds blowing from the NW around a displaced Azores High keep meaningful troughs away, but further North and East those same troughs bring some rain and wintry showers at times with a more full blooded attempt at something more universally cold for the UK from ECM in 10 days time. We really do need that Azores High to weaken or become displaced further NW or West as well as ridging North to allow the Jet flow to buckle, weaken and to relocate further South, something that ECM is showing on that day 10 chart.