Model Discussion 12Z 25/02/13

[lorenzo]

I wouldn't write off a negative NAO showing its hand around 7th March onwards on the charts, this was sniffed out by the JMA MJO cycle a few days back where it went off round the orbit ahead of GEFS, ECM and UKMO into phases predicating negative NAO regimes.

EC32 is looking fond of cold out to St Patricks Day with temps. below seasonal for March by a few degrees. Scandi trough dropping the Northerly cold in and a decidedly Easterly influence thereafter, wonder what decider makes of it..

Although looking at cold temps below seasonal the question just now seems to be can we get enough energy in there to create something of interest or will it be more slack flow and Sc sheets.

[johnholmes]

Any chance of a quick link to this John so us learners can more easily do our homework over the summer?

I am sure someone will come along and give you a link to the Stratosphere thread if you are unable to find it.

Failing that pm chio and ask him for his help?

done it myself it is very easy to find, just 6 or so items lower down on this page

Link is to the first page opened by chio with the links also there

enjoy-it will take a long time to read through it all

Edited February 26, 2013 by johnholmes

[Gibby]

Good morning. Here is today's look at the 00z output from GFS, UKMO, GEM and ECM for today Tuesday February 26th 2013.

All models support the continuation of the UK being governed by High pressure over the rest of the week and weekend. The positions of the High will shift about a bit day to day creating small but subtle differences in amounts of cloud and wind day to day but with it's centre continuing to be over or near the UK throughout this period. Pressure is then expected to fall as we move into next week as the High makes it's move away Easy across Europe early next week with a freshening SE flow developing over the UK. In the meantime the weather will remain largely benign with the cold and cloudy conditions in the South lasting for a while longer before a better chance of clearer conditions occur the weekend when all of the UK become largely dry and bright by day but with frost and fog patches by night.

GFS then shows a chilly and freshening SE breeze developing next week but despite Low pressure edging slowly up from the SW the ingress of any rainfall will be slow with many places staying dry even out to the end of the week especially in the North and East with High pressure building back down from the North later with a return to rather cold weather with the chance of frosty nights returning by the end of the run with winds maintaining an East or SE component.

The GFS Ensembles show a huge spread developing between members fro a weeks time with the operational one of the milder options in the South out to just before the end of the run. In the North the spread occurs even sooner with the dry spell shown to come to an end some when next week.

The Jet Stream shows a continuation of the split pattern with the Southerly arm the most pronounced part of the flow. The Northern arm sinks South and weakens further next week as the UK High slips SE into Europe.

UKMO for the weekend shows High pressure well established over the UK but weakening by the start of the new week as it begins its slide off into Europe. A dry and fine weekend for many looks likely, though rather cold, especially by night when frosts are likely but some compensatory bright days with some sunshine.

GEM today also shows High pressure slipping away East and a chilly and strong SE wind developing by the end of next week. With pressure falling rain will move slowly NE across at least the South and West of Britain by the end of the week with some snow possible on the highest ground further North.

ECM too shows a similar progression through next week with it too showing rain and strong winds into the South and West by late next week as pressure falls over the UK and weak High pressure lies over Scandinavia.

In Summary today this week and weekend looks agreed by all members to see High pressure maintaining a fine and settled theme for all with variable cloud cover and temperatures at the surface near or a little below average. Next week becomes much more complex and although the pattern is agreed by all members that a push of the Atlantic into the UK from the SW looks likely, it's the engagement that has with somewhat colder conditions over the UK and much colder air to the North and NE that is yet to be decided. It could be with a Southerly Jet that the cold bottled to the North has pushed enough cold air down into the UK that could offer a more wintry scenario than that what's currently shown over the next few days. Don't be surprised if there aren't some rather interesting scenarios shown in the output concerning this period over the coming days.

[No Balls Like Snow Balls]

The latest ECM 32 day signals a below ave month temp wise (based on Birmingham)

Temps look set to rise to around average the start of the 2nd week of March before falling away again quite significantly from mid-month. The last 3 weeks of March would also bring above average rain - Winds from a cool NW/W direction then perhaps??.

If the ECM 32 day were to verify then there would certainly be no March "heatwave"

The last ECM update before the above on the 21st Feb also should a cool month with below ave temp and above ave rain.

Edited February 26, 2013 by No balls like Snow Balls

[johnholmes]

my view using the 500mb anomaly charts for 6-10 days ahead, link below

[mushymanrob]

Any chance of a quick link to this John so us learners can more easily do our homework over the summer?

another thing to do is to stick with these model threads over summer. theres far less fantasy posting and the true weather lovers opinions can be found easily.

well the ecm appears to have just about dropped its cold theme, and is now following the gfs in suggesting that a more springlike atlantic based outlook is possible. for my money the ecm has been responsible this year for building up snowlovers expectations with a long seriese of cold/very cold outlooks that never have become reality (or at least to the severity predicted). it showed what many wanted, it seemed plausible, but ultimately over ramped the cold.

the gfs picked up on the 'big thaw' of 2010 long before the ecm or ukmo, the gfs now looks like being the first to pick up on the gradual warming up. when it was first depicted, i thought it was likely to be an outlier, but run after run firmed up whilst the ecm still was championing a severe northerly. the gfs now looks like being the most accurate.

[nick sussex]

Interesting to see the GFS make less of those shortwaves to the north this morning, both it and the ECM have a tease of some possible snow for northern areas.

Looking at the ECM ensembles for De Bilt theres two clusters forming re whether any cold gets into that region, the majority at the moment is still for milder conditions there but in the set up that could remain the case but northern areas of the UK could still be cold.

Much of the uncertainty will remain whilst the models chop and change with how far east and south the pattern is.

[Frosty.]

Yes it might become interesting across northern scotland later next week with arctic air inching closer, however, for most of the uk it looks like trending milder next week from the southwest and also more unsettled as pressure falls but fairly settled for a while yet with overnight frosts but temps getting closer to average with time.

[stodge]

Morning all

I have to say I'm surprised by how quiet it is on here this morning. The GFS 00Z Operational output looks to be a significant move away from the West based negative NAO scenario which has characterised so much of its recent Operational output and is followed by ECM's 00Z output this morning as well.

As the 06Z is rolling out, I won't paste the link but a cut-off low moves north of Labrador and disrupts the large HP forming to the west of Greenland re-building the ridge to the east.

I certainly don't yet regard a transition to a SW'ly Atlantic-driven regime as a given at this point. Indeed, GFS keeps us in a SE'ly even veering back E'ly in early FI. I'll be looking at the 12Z output to see if any of the other models start backtracking on the west-based negative NAO in favour of something more neutral.

[TEITS]

Rather easy to sum up the output at the moment.

Between +168 to +240 a SE,ly could be replaced by an E,ly with much colder air arriving in the far N. Now the big question is how far S will this manage to get? My own personal feeling is whilst it may take a while for this to occur I can eventually see much of the UK being cold into the 2nd week of March.

Key dates to keep an eye out for is the 9th/10th March.

[No Balls Like Snow Balls]

Some milder Southerly winds showing up in deep FI (not for the 1st time), Mild uppers and mild daytime temps albeit not particularly dry and sunny.

Edited February 26, 2013 by No balls like Snow Balls

[Panayiotis]

The 00z has many more members going for cold after the 4th March than yesterdays 12z/18z, will be interesting what the 06z ensembles show...

Also the CFS is v.interesting at 168hrs, high over us splits, one part moves to Greenland and the other moves swiftly (something which the other models are not keen on doing!) away into the Turkey/Belgium region, result:

Too bad its the CFS and the transaction looks to 'clean' to be true however there is a little more positivity I feel on this thread today than yesterday

Edited February 26, 2013 by Panayiotis

[Purga]

Yes it might become interesting across northern scotland later next week with arctic air inching closer, however, for most of the uk it looks like trending milder next week from the southwest and also more unsettled as pressure falls but fairly settled for a while yet with overnight frosts but temps getting closer to average with time.

Yes and once the HP sinks SE the ECM ENS mean shows a -ve NAO setting up with the bulk of the UK in a mild S/SE flow.

Although at T240 the cold does edge further South towards N Scotland - hopefully it may trend further South in the more relaiable timeframe.

Edited February 26, 2013 by Purga

[Man With Beard]

my view using the 500mb anomaly charts for 6-10 days ahead, link below

Thanks John, really helpful. I think your charts demonstrate how there is still a small chance that something wintery could develop for the UK. However, the relative silence on here today reflects a lack of willingness to chase yet another less likely outcome at T192+. Though Scotland still very much in the game for marginal snow. Another possibility, of course, is weaker blocking to the north allowing a push of warmth from the south - I wonder if this is how things will go?

[snowmadchrisuk]

Does the CFS need some serious work doing to it or what .... It still shows a serious Cold setup and at a very early time frame it is different to the main Models. For example by the 5th of March look what it shows ...

The difference is at 72-96 hours the Low on the Main Models that sinks our High , on the CFS it sends it well South into Southern Europe under cutting our Block and sends a section of the displaced P/V diving South into the North Sea with really Cold uppers while at the same time building a wall of Height's strongly over Greenland.... It is actually showing the perfect solution anyone could hope for ... I notice there is a cluster of ensembles once again supporting a Colder Solution . I just wonder if there's any chance it is on to something ...

Edited February 26, 2013 by snowmadchrisuk

[Frosty.]

I think we will need a trigger low to push that frigid arctic air further south, it looks very slow progress on the gfs and ecm 00z and only reaches the very far north, there is no driving force to it, and then we have to keep an eye on the lows to the southwest as pressure begins to fall and winds become Sly to SEly and temps lift up to average at least which would be relatively much milder than recently, temps are up a notch on yesterday, at 4-6c today, tomorrow a notch higher, nearer 6-7c and with brighter skies pushing south and east tomorrow but on the flipside of the coin, n.ireland and western scotland will be clouding over as a weak front edges in from the atlantic. The general pattern beyond tomorrow until and including the weekend is for the weather to remain settled and with sunny spells and overnight frosts but cloudier in the far nw and north for a time.

[The Enforcer]

I suspect that the current short term outlook for predominantly dry weather will suit as many Net-Weather members as those wishing for snowy weather. With the jet profile remaining so far south on repeated runs, I can't really see any move away from this anticyclonic dominated weather, in spite of some of the outcomes being portrayed for outside the 5-day period. Of course, it doesn't follow that this means that it is a foregone conclusion that it will turn colder once more, as several complex factors have to align to allow polar maritime air access to the UK, but it seems equally unlikely to me under the current scenario that tropical maritime air would be able to make any significant inroads towards us either.

[mushymanrob]

Rather easy to sum up the output at the moment.

Between +168 to +240 a SE,ly could be replaced by an E,ly with much colder air arriving in the far N. Now the big question is how far S will this manage to get? My own personal feeling is whilst it may take a while for this to occur I can eventually see much of the UK being cold into the 2nd week of March.

Key dates to keep an eye out for is the 9th/10th March.

happen it might, but what will it bring? id be surprised if it wasnt another repeat of what we have now, as this is appears to be the most likely weather type when we get a march easterly.

but the trend appears to be a shift towards milder weather, but even if it does become milder next week (and the northerly or easterly cold chances disappear) im sure there will still be more cold weather with frosts and even snow, thats normal for march and the models dont suggest anything but normal is likely.

[Frosty.]

I suspect that the current short term outlook for predominantly dry weather will suit as many Net-Weather members as those wishing for snowy weather. With the jet profile remaining so far south on repeated runs, I can't really see any move away from this anticyclonic dominated weather, in spite of some of the outcomes being portrayed for outside the 5-day period. Of course, it doesn't follow that this means that it is a foregone conclusion that it will turn colder once more, as several complex factors have to align to allow polar maritime air access to the UK, but it seems equally unlikely to me under the current scenario that tropical maritime air would be able to make any significant inroads towards us either.

The lack of posters on here speaks volumes for what most think will happen, a milder and unsettled trend next week looks like the form horse but when I say milder, I mean temps creeping back to average rather than anything particularly mild and still that small risk of colder air pushing south into the northern isles of scotland next wednesday/thursday.

[legritter]

Afternoon gang ,i still think something will turn up before full on spring arrives .alot of cold air hanging around to our far north .later frames of ECM still teasing us .iv just fathomed out how to put an avator on my profile ,my grey matter working ok today .it would be nice if all of us could get to see somemore magical snow before we all become obsessed with thunderstorms etc .catch up with you all later .

[Thundery wintry showers]

High pressure is set to relocate a bit further west over the next few days. At present, skies are overcast over most of England but are clear over most of Scotland, and this implies that the clearer, sunnier weather will extend southwards over the next couple of days. It looks likely that the sunny weather will get at least as far as the Midlands and East Anglia, but with a persistent easterly flow over the far south of the country, it may remain cloudy near the south coast. Temperatures are likely to recover to near-normal values by day, but will be rather below overnight, with frosts.

For the long-term the high pressure is projected to slip away eastwards but we then evolve into a rather unusual synoptic situation with slow-moving low pressure to the north and a strong southerly tracking branch of the jet. This chart from the ECMWF at T+192 is quite typical:

http://cdn.nwstatic..../ecm500.192.png

The implication is that southern areas will probably turn warmer by night, while becoming cloudy and wet, while northern areas may hold onto relatively quiet, dry weather for longer, but with increasing amounts of cloud heading in off the North Sea following about five or six days of mainly sunny weather, and with cool days and warm nights. Because of the large uncertainty over positioning of low pressure, though, there is plenty of scope for the rain belts and the boundary between cold and warm air to be revised northwards or southwards as we get nearer the time, but it is looking unlikely that we will get any widespread snowfall, or notable warmth accompanied by bright sunshine, this side of the 10th March.

Edited February 26, 2013 by Thundery wintry showers

[ANYWEATHER]

happen it might, but what will it bring? id be surprised if it wasnt another repeat of what we have now, as this is appears to be the most likely weather type when we get a march easterly.

but the trend appears to be a shift towards milder weather, but even if it does become milder next week (and the northerly or easterly cold chances disappear) im sure there will still be more cold weather with frosts and even snow, thats normal for march and the models dont suggest anything but normal is likely.

Tbh, I dont see a returning to above average temps for a good while, and whilst the southern half of the uk may see something milder than of late we may well see some battleground situations ie mildvscold over central Britain in picticular. Its very hard to pick up any trend from the models at the moment, and I certainly would not rule out another bash of cold weather over the Uk during March. If youre one to go by the latest metoffice update for March, they say that March is likely to be below average temperature wise. Anyway lets get this mundane,non discript weather out the way, and perhaps later in the week we may see a definiate trend whether it will be milder or colder from the models.....!

[Panayiotis]

06z ensembles still trending colder, past the 7th....

[Panayiotis]

Anyone ready for another let down?

[smoggyjester]

this is just a thought, so please dont run me down,. but last year i feel that autumn arrived late, then winter arrived late, maybe winter may hang on in to march????? like i say just a thought as last year our weather seemed all over the place in terms of timing