In Depth Model Discussion, Analysis and Summaries

[johnholmes]

Glad the two pdf posts were seen as useful.

[svalji]

Thanks john - fascinating reading. Appreciate the time and effort you put into composing those!

[Gibby]

Good morning folks. Here is the morning report on the 00z output from GFS, UKMO, GEM and ECM for today Friday February 8th 2013.

All models show the UK under a slack and cold Northerly flow currently. Embedded weak troughs are running into the UK from the West decaying steadily. Occasional rain and hill snow will affect parts of the Uk at times over the next 24-48 hours with any sunshine at a premium. Winds though will be light. On Sunday all models show an active trough of Low pressure moving slowly in from the West with the thrust of energy along the trough being SE a Low pressure centre develops along it and moves down to Southern England on Sunday and away SE slowly over Monday and Tuesday. The net result of this will be a very wet day developing Sunday with snow for many Northern and Eastern areas. Later in the day the snow will extend South and West to other areas too, perhaps causing some disruption for a time before clearing away slowly SE over Monday. A spell of East or NE winds is shown by all models for a time then with snow showers in the East and temperatures well below normal. The winds are then shown to fall light by midweek as a ridge of High pressure moves down over the UK from the NW with cold and frosty conditions developing but with bright and sunny days.

GFS then shows less cold weather moving into the Uk from the West later next week as Low pressure to the North pushes a trough East over all areas with rain preceded by a little snow in the East and North. Through FI this morning the weather remains very unsettled and after a few less cold days rather colder weather would develop again with further snowfall over Northern hills extending to other areas too late in FI as the Jet Stream is pushed South and colder air becomes entrained over the UK under Low pressure.

The GFS Ensembles show a run of near average uppers today with some precipitation spikes at times through the period indicating a brakdown to less cold weather behind this weekends snow/rain mix before a hint of things returning rather colder again later in the month.

The Jet Stream shows the flow South over the UK currently breaking up in the next few days before the flow realigns itself on a SE track to the SW of the UK early next week while continuing to move East well South over Europe.

UKMO for midnight on Thursday shows High pressure stretching in a belt from the Azores through Southern England to Northern Russia with a trough moving slowly in towards West areas through the period at the end of the run. A very cold and frosty period would slowly be replaced by cloudier skies from the West the following day with rain and snow edging slowly into the West of the UK.

GEM today shows a couple of milder days later next week as the cold High is pushed East with milder Atlantic winds in association with Low pressure to the North bringing rain across the UK from the West. Towards the end of its run it shows signs of becoming colder again as Low pressure drifts towards Scandinavia pulling a cold Northerly flow down over the UK with snow showers likely.

ECM this morning is much keener to maintain a strong ridge of High pressure from Scandinavia over the UK towards the end of next week and into the weekend with maintained cold conditions with very frosty nights but bright and sunny days. The far SE would continue with a light drift from the East and possibly with the odd snow flurry while the far NW becomes somewhat less cold over the weekend as winds start to pick up from the SW.

In Summary this morning there is still considerable doubt over which areas are going to be most affected by a potentially wintry spell in the opening days of next week. There is definately going to be a spell of wet weather with heavy rain over Southern and Western Britain over Sunday while the North and East are at more risk of snowfall. This still looks like extending to other areas too over Sunday night and Monday but to what degree disruption is likely is hard to call still this morning. The cold wintry weather then slides away SE towards the middle of next week with a relaxing of conditions as a ridge moves SE to give a cold and frosty period. Later there seems a reasonable amount of agreement from GEM and GFS of a breakdown to less cold and rainier conditions at the end of next week while the Euros keep things rather more anticyclonic with frost and cold air much more reluctant to give way until the weekend at least. The tussle between the cold block to the NE and the milder Atlantic winds around an Azores High continues within the output this morning.

[Recretos]

As some of you may know, I am doing the GWO project, making composites for each phase, for each month, for each ENSO phase, and for all amps and amps>1. I will finish the ENSO filtering in about a week or so. So I can start plotting in about 10 days from now. And then the next project will be updated MJO composites.

This is the GWO wheel, with marked phases.

Here are February, neutral ENSO, GWO composites, as requested by GP.

Best regards.

[Glacier Point]

Thanks for doing that Recretos. The inference here is that we should see an evolution in hemispheric synoptics as shown here left to right (the two lines are all amplitudes and high amplitudes) starting in the 6-10 timeframe. The starting point is our anomalous ridge over Scandinavia tied into a phase 4 projection of the GWO, assuming a phase 4-5-7-8 type orbit.

GEFS H5 mean anomalies for days 6-10 and 11-15 appear to be in agreement, taking us through a swift evolution from phase 4 through 8:

Once this project gets up and running, would be looking for volunteers to undertake anomaly correlation scores for the hemispheric pattern and composites, so speak up if you think you can help !

Edited February 8, 2013 by Glacier Point

[Recretos]

A very good point. It will be quite interesting to see these composites in action.

If I quote: "assuming a phase 4-5-7-8 type orbit.".

This was the main reason why I wanted to do MJO rather than GWO. MJO is being actively forecasted, so we can kinda anticipate the phases, while with GWO it is a bit more complicated.

EDIT:

I can provide the composites and all kinds of plots, but calculating correlations is a bit out of my league.

Edited February 8, 2013 by Recretos

[phil nw.]

Good work Recretos.

Interestingly 12z GEFS HT. Anomls. are heading that way.Here Days 10 and 15.

shifting the higher anomalies from Scandinavia to Greenland towards the end of week 2.

The NW Euro trough seems ever present.

NAO going negative

Hopefully one last shot of deep cold before Winters end.

[Glacier Point]

Yes, the GWO takes a bit more work, but the rewards are potentially a whole lot greater !

We can use MJO forecasts to help us understand what the tropical component might be 'adding' to the GWO. At the moment the general trend is for the MJO to head into phase 4 (avoiding the +NAO phases 2/3), which couples us nicely with the GWO signal, extratropical and tropical signals as one. With the heat content in the middle part of the Equatorial Pacific really quite high, conditions are ripe for increased cloud cover and tropical forcing on both the western and central tropical Pacific.

This would be consistent with net addition of westerlies, and, in conjunction with previous westerly wind propagation, we should see the whole dynamical synoptic model driven towards the high AAM base state (MJO phases 4-5-6-7- 8 ), where mountain and frictional torques are generally positive. That gives us a reasonable signal for the next 2 weeks to be oscillating between phases 4 and 8 given that overall angular momentum has fallen but generally levelling off.

Edited February 8, 2013 by Glacier Point

[Recretos]

Wow GP, it seems you kinda have it all figured out. For the sake of curiosity, I took the MJO data, and quickly extracted the phase 4 data, and ran it through the same filters as the GWO (Amp>1, neutral ENSO). And I must say that it is not really what I expected, when looking at the existing composite at http://raleighwx.americanwx.com.

I found out, that his composites have the configuration: All AMP and all ENSO phases. That kinda "filtering" is quite easy and I could make plots like that in a day or two. Not to take anything away from those composites or his work. I think they proved very useful. It is just that I think we need MJO composites which will be ENSO and Amplitude filtered.

Here is the filtered phase 4. In total 22 days in the composite. No lags applied. And the comparison. There are some similar features tho.

+7 days lag applied.

Edit: And once I extract and filter the MJO data, it should also prove useful for stratosphere forecasts, in combination with the GWO, since I will have the coded datafiles, and will be able to make many kinds of plots for the usage of stratosphere forecasting, so we wont be limited to just 500mb anomalies.

Edited February 9, 2013 by Recretos

[Gibby]

Good morning. Here is the morning report of the 00z output from GFS, UKMO, GEM and ECM for today Saturday February 9th 2013.

All models show an agreed pattern between now until midweek. A warm front lies North/South across Central UK with outbreaks of rain and sleet with light snow over the highest hills. This will change little through the day. It will feel cold in the East but with temperatures nearer normal in the West. Tonight sees a more vigorous frontal system move into the West of the UK with rain following quickly behind with a strengthening Southerly wind. The rain then marches on North and East across the UK tomorrow turning to snow later in the day across Northern and Eastern areas, possibly giving disruption over Sunday night and into Monday before the whole system pulls away SE clearing the rain and snow away from Southern areas to leave the UK under a cold and raw East flow to start the working week with some wintry showers in the East. By midweek a new frontal system is approaching the West with rain and hill snow reaching the far West of the UK later on Wednesday.

GFS then shows rain moving over all areas with some hill snow in the East on Thursday while the West sees milder weather with rain clearing to brighter weather with perhaps a few rain showers. Through the weekend and start to the following week further troughs move in from the West with more rain at times with the less cold conditions making it just about all the way over to the East removing the risk of further snow even over the hills for a time. Later in FI further disrupting Low pressure continues to slip SE over the UK but thanks to the ever present and strong Azores High the UK lies mostly too far West to see anything of significant wintryness with cold rain at times with just snow over the highest ground in winds from an Atlantic origin for the most part.

The GFS Ensembles show a fairly average spread between the members this morning though there are some colder options on the table. The operational above was one of the milder options for a time after the mid run point with rainfall gradually reducing in amount and frequency later in the run.

The Jet Stream is currently undergoing a realignment over the coming days changing from a North/South flow over the UK to a SE moving flow just to the SW of the UK where it continues to move down to a stronger flow running East over Southern Europe.

UKMO for shows from midweek a front moving East bringing rain and temporary hill snow across from the West followed by a run of Westerly winds and rain or showers to end the working week in temperatures not far from average.

GEM shows milder conditions too spreading down from the NW later next week with the weekend becoming quite mild under a SW flow with Low pressure to the North and High to the South. Some rain would occur here too though Southern areas would likely stay dry and relatively mild if cloudy and breezy.

ECM today shows a further Low pressure midweek bringing rain and showers across all areas around Wednesday and into Thursday followed by a showery NW flow for a time with some wintry showers possible over Northern hills for a time and the SE too later. Thereafter, High pressure from Scandinavia to the Azores link up to form a UK centre when dry and sunny days with frosty nights would develop providing air around the top of the High stays sufficiently cloud free in the light West flow over the North.

In Summary today whichever way you look at it there seems to be a moderation in any cold weather as we move through next week. While the risk of snow is still very real for many Northern and Eastern areas early in the week the trend thereafter is increasing for milder air to eventually win it's way all the way over to the East with rain at times for all. The basic upflow pattern though remains somewhat blocked by the Northern European High with everything shunted East by a couple of hundred miles keeping much of Europe cold and snowy. ECM does buck the trend still bringing High pressure right over the UK keeping things rather colder perhaps but despite frosty nights the days would feel pleasant enough in the ever strengthening sun's power.

[johnholmes]

my quick look at both short term and longer term ideas on the UK weather

summary of immediate and longer ter-sat 9feb.pdf

[cerneman]

my quick look at both short term and longer term ideas on the UK weather

summary of immediate and longer ter-sat 9feb.pdf

Yet again thanks John, Must admit get totally confused when trying to learn from model thread, Just viewing your pdf's help clear the fog, I am saving your posts and refere to them, all part of learning, hope you don't mind? Thanks

[johnholmes]

Yet again thanks John, Must admit get totally confused when trying to learn from model thread, Just viewing your pdf's help clear the fog, I am saving your posts and refere to them, all part of learning, hope you don't mind? Thanks

not at all-I'm very flattered

[xioni]

We can use MJO forecasts to help us understand what the tropical component might be 'adding' to the GWO. At the moment the general trend is for the MJO to head into phase 4 (avoiding the +NAO phases 2/3), which couples us nicely with the GWO signal, extratropical and tropical signals as one. With the heat content in the middle part of the Equatorial Pacific really quite high, conditions are ripe for increased cloud cover and tropical forcing on both the western and central tropical Pacific.

This would be consistent with net addition of westerlies, and, in conjunction with previous westerly wind propagation, we should see the whole dynamical synoptic model driven towards the high AAM base state (MJO phases 4-5-6-7- 8 ), where mountain and frictional torques are generally positive. That gives us a reasonable signal for the next 2 weeks to be oscillating between phases 4 and 8 given that overall angular momentum has fallen but generally levelling off.

I think your assessment of both the MJO & the GWO are wrong and I think you had done the same mistake back in mid-Dec. The Pacific convection and the heat content near the dateline are currently both high as you say, but there are already strong signs that the Pacific convection is declining, while the Indian Ocean convection is taking over. That's why I think we are going to see a phase 2-3-4-5 circuit of the MJO during the rest of Feb and this is what most models have started showing.

The GWO is always more difficult to predict as it involves extra-tropical features, but a low AAM state (phases 2-3) is easier IMO during the next 2-3 weeks.

Overall these teleconnections suggest that a warm pattern for W.Europe is more likely than a cold one during 20Feb - 10Mar, while cold risks increase again in mid-March if the convection returns to the Pacific.

[Gibby]

Good morning. Here is the report of the 12z output from GFS, UKMO, GEM and ECM for today Sunday February 10th 2013.

All models show an active frontal system and developing depression moving in from the SW today. The fronts have milder weather in association with them but as they run into colder air over Northern and Eastern Britain they will turn the rain, some of which will be heavy to sleet and snow. This will be patchy at first but later in the day as the depression moves SE towards the English Channel colder air will be entrained to more and more areas with rain turning to snow more widely this evening and tonight at the same time as becoming lighter. It will be a cold day in a raw SE wind. Tomorrow shows the Low just to the South of the UK with sleet, snow and rain clearing away South through the day with a cold and raw East wind keeping things rather cloudy with the risk of some wintry showers towards Eastern coasts. By Wednesday a new trough of Low pressure will move in from the West with again a mix of snow and rain for all before it clears East on Thursday with less cold but blustery NW winds and showers the most likely outcome then.

GFS then shows an area of High pressure down to the SW with the remains of Thursdays trough down over the North Sea. Adjacent areas here could see further showers, perhaps wintry while other areas become dry and fine under the influence of slack High pressure. It would likely stay a little on the cold side though. The following week shows weak troughs crossing East to the North and down over the North Sea maintaining the risk of colder weather here with a few wintry showers or light rain at times while the South stays mainly dry and bright near to High pressure. Late in FI the trend is for High pressure to be centred near to the UK with plenty of fine and dry late winter weather with the usual caveats of frost by night and cloud cover encroaching into the NW at times from the Atlantic.

The GFS Ensembles show a period of uppers sustained around normal or slightly above, especially in the North. Though rain at times is shown there are no large amounts shown. The operational was a large cold outlier at the end under the UK based cold High. There is quite a large spread between the members from the middle of the run with values between +9 and -10 in the South and +10 and -10 in Scotland.

The Jet Stream shows the flow continuing to arch over the Atlantic and SE to the SW of the UK then on East from Spain across Southern Europe and North Africa, Later the flow breaks down in our neck of the woods as High pressure becomes prevalent near the UK.

UKMO shows a showery day on Thursday following Wednesdays band of rain and hill snow. It would of become somewhat less cold in the NW flow but there could still be a few wintry showers left in the North and East on Friday before High pressure takes control from Southern Britain to the Baltic and Russia. The South would become dry with bright days and night time frosts while the NW would become milder with rain at times on a SW breeze.

GEM today shows a similar disrupting trough on Wednesday not dissimilar to today with rain and snow becoming lodged over the UK through Thursday before winds swing Easterly and bring wintry showers to the East Coast as the rain and snow slip away South. High pressure becomes strong to the North and then slips down over the UK to end the run with cold and frosty late winter conditions with sharp night time frosts likely for most.

ECM shows a setup not unlike UKMO this morning with a blustery showery day on Thursday following Wednesdays rain and hill snow. High pressure then builds over the South and links to the Scandinavian model which quickly absorbs the UK wing to form a cold Easterly flow over Southern Britain later in the run with snow showers in the South to end.

In Summary this morning the first half of next week looks like being rather cold and raw but with little further snowfall behind our current feature. Midweek looks another tricky time for forecasting as a further front crosses the UK and runs into the cold air with hill snow again a possibility. Behind that there is good agreement on High pressure forming near to the UK but where is crucial to the type of conditions felt at the surface. The Euro's including GEM look favoured to keep High pressure nearer the North or Northeast with ECM setting up a chilly Easterly with snow showers for the South and East while. GFS is not a million miles away but instead parks High pressure over the UK eventually in very cold uppers before sinking it slowly South at the end of the run as the Jet rides over the top but all this far out in FI. There is no real route to mild weather this morning with a cold and frosty spell looking very possible and the chance of at least a little wintriness from wintry showers in the East.

[johnholmes]

my thoughts this morning 6-15 days ahead

Overall its still more blocked than mobile with signs on ec and noaa and even this morning with

gfs

of the block edging south a bit, 500mb flows=

Noaa=just n of west and has the main +ve over Greenland with a ridge of sorts just east of that

Ec=ne this morning with actual upper high to n of uk so that is new-not showing on the others

Gfs

=n of west today (it was s of west on sat with the trough w of the uk its now put it back to the east/med area around italy so hardly consistency there!

To sum up, not great inter model consistency with

gfs

the chief culprit, ec this morning has the idea of an actual upper high and further east than anything on noaa

Overall no sign of a raging Atlantic flow with most indications suggesting some kind of block possibly mixed at times with an unsettled cold westerly upper flow but I would prefer to sit on the fence for a day or two!

[TonyH]

A look at the coming week for Wales and the Midlands:

http://forum.netweather.tv/blog/309/entry-4566-weekly-weather-guide-for-west-wales-and-the-midlands-monday-11th-to-sunday-17th-feb-2013/

[Recretos]

Since it looks like we are going to go (more like speed through) into MJO 2, 3 and 4, I am going to add the phase 2 and 3 composites I made just for this occasion. Now in these composites, there is actually quite a difference when compared to the composites we usually look at, mainly in the strength of the anomalies. The main difference is of course because of the filtering. I cant wait to start the MJO project.

I wrote the conditions on the composite. No lags applied.

@Glacier Point: So I guess that the Feb. phases 2 and 3 actually are supportive for a negative NAO after all.

And here are some forecast anomalies to compare.

The Canadian ENS, and the NCEP analog super ensembles.

And GEFS to finish off.

Any professional opinions?

Best regards.

[Gibby]

Good morning. Here is the report on the 00z outputs from GFS, UKMO, ECM and GEM for today Monday February 11th 2013.

All models show a slowly weakening cold and cloudy Easterly flow over the UK today and tomorrow with occasional drizzle or light sleet and snow in placed though amounts will be inconsequential. Through Wednesday a trough of Low pressure will move East over the UK with rain preceded for snow for some followed by clearer and more showery weather in more Northern and Eastern areas while Southern and Western areas become mainly dry nearer to High pressure to the SW. It will become less cold everywhere later in the week.

GFS then shows a light SW flow over the UK during the weekend with weak troughs around, especially towards the North while High pressure to the South and East keep things potentially brighter and colder here with the risk of night frost. Through FI the milder theme continues with High pressure never far away from the South with winds flowing from between South and West for much of the time. Rainfall will be confined more towards the North and West at times as troughs brush by.

The GFS Ensembles show a milder spell on the way after Wednesday agreed upon by nearly all members. Thereafter, uppers slowly fall back towards the seasonal average. There are a few colder options but the vast majority show temperatures above normal with the operational one of the mildest for the second half of the run. There is some precipitation shown by most members off and on with an Atlantic influence dominant.

The Jet Stream shows the flow arching over the Atlantic and down to Southern Europe to the SW of the UK currently. The pattern moves East towards the UK later in the week before weakening and collapsing to virtually nil over the UK and Northern Europe with a renewed surge of energy moving NE across the Atlantic towards Iceland by the start of next week.

UKMO today shows less cold weather to end the week with some sunny spells but with a night frost on Thursday and possibly Friday night as a ridge of High pressure moves across followed by milder Southerly winds on Saturday with the milder air encroaching East and North slowly over the UK.

ECM finally shows a lot of High pressure around from the weekend until the end of it's run but it's position this morning is less favourable for notable cold weather for the UK. With no deep Continental feed of air this morning and High pressure sat over or in the vicinity of the UK the best we can hope for is dry and settled conditions with sunny spells by day and clear spells at night with some frost where skies stay clear. Otherwise temperatures by day at least won't be tht far from the seasonal normal.

In Summary this morning the weather looks like becoming High pressure based from the end of this week with a centre either close to or over the UK giving dry and bright daytimes but with some frost at night. Cold weather from the Northern European High is not far away to the East but on this morning's runs it looks less favourable for the UK to tap into anything really cold from there through the model run period. Still at least after the midweek precipitation there looks a strong chance for some drying up of the ground under better evaporation conditions than of late which I'm sure farmers and growers will welcome.

[johnholmes]

So what does the upper air suggest to follow once the more westerly weather pattern sets up later this week?

By 120 hours, see link below all 3 show a suggestion of a fairly marked upper trough well west of the UK.

http://www.netweather.tv/index.cgi?action=modelcomp;sess=

As is often the case the two remaining major centres then diverge in how to deal with this so the surface weather also shows differences. By 168H ECMWF has developed a marked upper ridge over/NE of the country with GFS preferring a flatter variation. This continues out to T+240 with GFS tending to show a surface high over Europe rather than NW of the UK which ECMWF has.

How does this fit in with the 500mb anomaly charts? These are usually much less variable in output whichever one looks at, ECMWF-GFS or the NOAA output. Well the NOAA and ECMWF are not too dissimilar over the past 3-5 days although they are not as consistent as we sometimes see them. As for the GFS version it has had fairly wild swings. The main upper trough has changed twice, from west of the UK, fairly well west at that, to about 20 degrees east with the upper pattern going between fairly mobile westerly to something like a block.

The other two have been much more stable with the pattern very similar to what has been the general flow over the past week or so. Blocking in fairly high latitudes with the 500mb flow tending to split in the Iceland region hence the succession of lows off the Atlantic moving into the country.

The links to both these is given below

NOAA

http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

and the ECMWF-GFS version below

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

As to what to make of these charts then I have to confess I am not very confident in them. As I usually state if they show consistency within their own output and with one another over 3 days or so then I place a lot of confidence in them. When they don’t then that confidence drops. That is how I am this morning. Two out of three are pretty similar in both consistency with themselves and with one another. The odd one out is GFS but in my view we need all three to show consistency.

If I have to give an outlook in the 6-15 day period then it is probably that after a temporary somewhat milder interval, as suggested on most charts from Thursday, then the overall idea of some kind of upper and surface ridge close by the UK seems the form horse. But I would not give anything like the 70-80% confidence I usually do, more like 40-50%.

Uncertain times just now.

[It's just wind...]

The first 40 days of 2013 has seen a remarkably average H5 pattern (left) with analogues hard to come by - my composite on right.

Which suggests this in Feb (left) and Mar (right)

Does anyone post these regularly here or on another (more suitable) thread? Does anyone find this composite method useful?

Cheers, IJW

[Gibby]

Good morning. Here is my review of the 00z outputs from GFS, UKMO, GEM and ECM for this morning Tuesday February 12th 2013.

All models show a very slack and cold airflow pattern over the UK today as pressure gently rises. Most areas will be dry but a few snow flurries are possible just about anywhere. As a Southerly wind stirs the atmosphere later tonight in the West clouds may break up somewhat with rather more of a frost likely. Tomorrow then shows a Southerly flow developing everywhere as a depression to the NW steers a trough slowly East into the West of the UK. Rain will arrive too by the middle of tomorrow and spread East across all areas later and overnight turning readily to snow in many Central and Northern areas for a time before turning back to rain as milder air moves across the UK by Thursday. Winds will of veered towards the NW by then and the weather become drier with just scattered rain showers in the North while the South sees the rest of Thursday and Friday as largely dry days with brighter spells. Through the weekend a lot of dry weather will be around but with weak fronts moving into the UK from the SW some light rain and drizzle is possible, especially on Saturday. A less cold weekend is likely for all but sunshine amounts will be limited.

Then into next week GFS brings High pressure into the UK from the East and things dry up and settle down with rather more sunshine by day but with patchy frost and fog developing overnight. Later in the week and weekend the dry weather continues with the High drifting more towards the NW with colder Continental air drifting into some Eastern and Southern areas though it would stay largely dry innitially before wintry showers become more prevalent for Eastern areas later under a Northerly feed of air.

The GFS Ensembles show a milder interlude on the way before the trend towards rather colder weather develops into the second half of the run. Rainfall will be small for most areas as High pressure at first to the South and then more towards the North reduces penetration from the effects of Atlantic depressions. There is a large spread as usual in members later in the run with the operational on the cold side of the pack later on.

The Jet Stream currently arching over the Atlantic collapses SE over the UK in the next couple of days after which the flow becomes weak and diffuse in our corner of the World before rejuvenating in the Western Atlantic moving East towards Spain with a weaker limb riding North through the Atlantic.

UKMO shows a large High pressure area covering much of Europe to start next week with a Low pressure area in the Atlantic with troughs waiting in the wings on it's Southern flank. The UK would see light to moderate South or SE winds with dry weather for most in normal temperature values with somewhat colder air from the East gradually infiltrating into the SE of the UK on Monday.

GEM shows High pressure too though it's centre is far more fluid in its movements though generally just to the East of the UK. It would be generally dry and bright at times with overnight frost and fog patches though daytimes would see temperatures generally up to normal values in light winds from a South or SE direction for much of the time.

ECM today shows High pressure in the North Sea on Monday with Low pressure in the Atlantic with a SE flow over the UK feeding gently colder conditions NW from Europe through the day but with some bright and sunny conditions too. Through the following days High pressure extends to Scandinavia and more importantly to Greenland serving up a recipe for some very cold air to develop, first from the East and then the NE as Low pressure is steered SE over the Atlantic into Spain and South through Scandinavia towards Europe leaving the UK in a very cold and potentially snowy weather pattern to end the run with a bitterly cold NNE wind.

In Summary today the weather looks like being High pressure driven over the coming couple of weeks. We all have to get through one more spell of rain and snow in the North before things turn rather milder as High pressure builds from the South. The behaviour of that High becomes paramount then as to where we go with the UK weather over the coming period. Most models indicate a migration to the North or East is likely and ECM whole heartedly takes it North where coupled with an intense Greenland High late in its run brings the UK into the freezer which may be a bit extreme in reality. However, ECM continues to toy with cold synoptics in the latter stages of it's run and shouldn't be discounted with the favoured solution ending up somewhere between what's shown this morning. So plenty of dry weather in the coming weeks with, after a milder interlude a trend towards rather colder weather again with frosty nights but some compensatory sunny days and who knows some more wintriness later.

[johnholmes]

from the model thread as it will no doubt get lost in there

Posted 13 minutes ago

http://www.netweathe...modelcomp;sess=

this shows how the two models in the further range treaat the upper ride and surface high at 12z yesterday and 00z today.

Some similarity in that the surface high is certainly not around 50N but nearer 60N in each case.

Detail of course changes.

looking at the 500mb outputs and NOAA last evening kept the high level blocking shifting it east and n of 60N, ECMWF this morning shows it west of UK and Iceland NNW with an actual ridge. GFS has climbed back on board the more blocked idea with an upper ridge over the UK and NNE.

So on this basis IF all 3 keep this idea supports the link above of blocking somewhere north of the UK but uncertain yet for NW or NE of the UK by T+240?

Any of them would suggest no early spring for the latter part of February.

the NOAA 8-14 chart from last evening

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

and the issue from ECMWF-GFS this morning

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Edited February 12, 2013 by johnholmes

[johnholmes]

This morning wed 13 feb and ec similar again with closed upper high just wnw of uk with n-ne flow over most parts uk, gfs looking much more like this today.

So now got all 3 with upper ridge/centre close by uk

Noaa e of Iceland, ec close by nw western isles, gfs shows ridge centre is ne/nne of uk

Ec has unsettled wly well south of 50n, gfs still has trough about 20w with flow s of w into uk

Noaa fairly similar to ec, but wly flow is further north

Naefs at 240h also has ridge centre ne of uk then moves it west to be just n of Iceland by 384h

On the 00z net wx comparison charts ec is fairly consistent in developing the high, as it has been for 24-36 hours now, gfs less so, comparing the ec position at 00 168h to the 12 192h and it holds the high closer to the nw part of the uk than before, very similar to its 500mb anomaly idea

This gives considerable support to the idea of upper and surface high pressure cells being somewhere between Iceland and the far nw part of the uk by day 10

Link to net wx comparison charts

http://www.netweather.tv/index.cgi?action=modelcomp;sess=

and below the link to noaa last evening 6-10 and 8-14

http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

overall hp dominated and n-nw of the uk is certainly the form horse 6-15 days from now, maybe a day or so earlier?

[Gibby]

Good morning. Here is the report of the 00z output from GFS, UKMO, GEM and ECM for today Wednesday February 13th 2013.

All models show a change to milder conditions over the next 24 hours or so. There is a slack and cold air pocket over the UK at the moment but this is being stirred by a freshening Southerly wind through today in association with a set of troughs moving in from the West. Rain turning to snow as it moves East will continue it's progress Eastwards through the day giving accumulations of snow in the North for a time before it all turns back to rain tonight as much milder air moves in. Tomorrow and Friday sees winds having swung into the NW with unusually for a NW flow much milder air with just scattered showers over Thursday and dry and bright conditions on Friday. As a ridge moves across the UK at the start of the weekend winds back SW with a little light rain and drizzle likely as a warm front moves NE leaving the UK under a slack and mild SSW flow to end the weekend.

GFS then shows next week governed by High pressure to the SE of Britain with relatively mild and rather cloudy SW winds with any rain restricted to the far NW. Through FI winds back SE and High pressure relocates to the North of the UK with Easterly winds developing though with no cold air to tap into things would stay reasonably mild until the end of FI when colder air infiltrates over Western Europe and moves slowly West into the South of the UK.

The GFS Ensembles show almost universal agreement for a much milder spell with temperatures near or above normal for a considerable time before things steadily shift back down towards the seasonal average. The operational was both a mild and then cold outlier through the mid and end sections of the run respectively. There is minimalist support for anything really cold by any but a few members this morning. It will be mostly dry though for much of the time through the next few weeks.

The Jet Stream shows a steadily weakening flow over the next few days though the general pattern will remain similar before a relocation well to the SW of the UK of the flow takes place early next week as it moves East towards Spain.

UKMO shows High pressure over Europe and Low pressure in the Atlantic with a Southerly flow backing SE as Low pressure weakens and disrupts in the Atlantic. This allows a High pressure belt to build down from the Norwegian Sea to the North Sea at the end of its run with an increasingly chilly SE flow developing though still largely dry.

ECM shows a similar development to UKMO today though somewhat more pronounced with an Easterly flow developing by next Tuesday and pulling colder weather into Southern Britain as High pressure centres close over the North of the UK with dry and frosty conditions likely for all in a renewed blocking situation.

In Summary there is a contrast between the Euro's and the Americans today as the former show a slowly developing blocking High pressure setup again to the North of the UK with dry and colder weather likely with time while the American models prefer to hold High pressure to the SE keeping milder winds wafting over the UK supported well by the GFS Ensembles. So it's a case of take your pick which evolution you support today as either one could conceivably happen. The one constant between all models is that it looks like becoming largely dry which will be a relief to many stricken by waterlogged fields as the drainage and evaporation processes look quite able to take place.

Incidentally, those trying to view my forecasts on my website will notice they have not been updated since yesterday morning. My web hosting company has a server issue linked to my site and are supposedly working on it. Needless to say that I will be pestering them again through today. The live parts of the site are working fine though. Apologies for the inconvenience.