Model output discussion - 20th Feb onwards

[Frosty.]

The Ecm 12z ensemble mean looks very anticyclonic throughout with at least a ridge of high pressure remaining by T+240 hours....all in all, a very good day for those of us wanting a decent spell of settled weather with pleasant spells of strengthening early spring sunshine!

[shotski]

11 minutes ago, Frosty. said:

The Ecm 12z ensemble mean looks very anticyclonic throughout with at least a ridge of high pressure remaining by T+240 hours....all in all, a very good day for those of us wanting a decent spell of settled weather with pleasant spells of strengthening early spring sunshine!

Unfortunately forecast still says no !! Dry, cool and cloudy is what I'm seeing for my location at least. This time next week we will see how it stands. 

Edited March 11, 2016 by shotski

[Frosty.]

2 minutes ago, shotski said:

Unfortunately forecast still says no !! Dry, cool and cloudy is what I'm seeing for my location at least. This time next week we will see how it stands. 

Well I'm describing the uk outlook as a whole, and for many it looks a lot better than the tripe we have been served up from the Atlantic for month after month!

[I remember Atlantic 252]

3 minutes ago, Frosty. said:

Well I'm describing the uk outlook as a whole, and for many it looks a lot better than the tripe we have been served up from the Atlantic for month after month!

that's right Frosty, could be showing horrid NW'lys and low pressure

[knocker]

1 hour ago, Weathervane said:

I have hinted at this before, sometimes clumsily ,but whenever we hear the word SSW, all the normal rules here go out the window, e.g "keep to the models" and "anything beyond day 6 is FI". Instead we look forward to long fetch easterlies or artic blasts whose time frame extends into the far distance.

A look at the current strat thread shows just how tentative our understanding of SSWs and their effect on weather is. Even the current Met quote posted by Knocker seems a bit bold to me. Never the less given the knowledge and enthusiasm of the strat posters and with a lot of us still hungry for cold and snow, doubtless we will be at it again next winter..

To be fair Weathervane not everyone jumped on the SSW bandwagon nor boarded the MJO train and did two quick circuits of the earth.

[knocker]

All i meant by that was, yes the SSW is occurring but the affect on the dynamics of the NH  troposphere, particularly the eastern Atlantic was/is certainly not clear or clean cut so the only sensible course of action is to keep a close eye on the models, including the medium range. Second guessing the evolution on theory in what is uncharted territory without indications of support from the models is jumping the gun probably influenced by the perennial search for cold. Just my opinion of course which is limited by me not having the expert knowledge that others possess.

[Singularity]

  

ECM has the negative tilt to the Atlantic trough at +144 and goes on to produce the most sensible run of the day IMO; yes there is a bit of pressure form the Atlantic but there is little reason to expect that to overwhelm the blocking in the vicinity of the UK. Indeed I am still wary of the high moving NW from the UK before too long.

GFS continues to seemingly tip the balance against the odds shortly past +144 hours. This seems to be due to a shortwave moving through Greenland around that time and in some way enticing the main Atlantic trough to advance NE. The shortwave is non-existent in the ECM 12z run, and clears east much sooner on the UKMO 12z run - so avoiding interaction with the Atlantic trough. I guess this is another one of those moments where a small scale feature defines the path going forward. They don't call it shortwave drama for nothing!

It may not be a great week for southerners, particularly in the east, as the locked-in HP scenario looks likely to feature the high centered far enough north to bring a lot of NE to E flows which are notorious in early spring for bringing a lot of low cloud and murk off the North Sea. It seems to happen for a period in most years either in March or April and is part of the reason why the long-term averages for temperature tend to seem rather low when there is a particularly fine spring month (e.g. the LTA max for April here is only 13.1*C, when I have seen a good number of Aprils in the past dozen years coming in between 14 and 15*C). Funnily enough a cool March in these parts has preceded some of the hottest summers - but my dataset is too small for drawing meaningful conclusions!

[knocker]

The GFS this morning keeps the HP in a pretty favourable position regarding the UK so it should be relatively pleasant for all next week. It does then proceed tp break it down pretty quickly starting on Sunday and in fact in the remaining period introduces two or three quite active depressions that track over the UK. To some extent the anomalies support this scenario with the HP beginning to break down next weekend with zonality ensuing and then a mid Atlantic trough which is running SE from the Canadian vortex. This backs the upper flow a tad and could well introduce some wet and windy weather albeit temps quite positive. One wonders whether this far too progressive so await the ecm take on this.

A quick look at the ecm det. and there is no way it's letting the Atlantic get a sniff as it moves the HP west forming quite an affective block.

Edited March 12, 2016 by knocker

[Frosty.]

Nice outlook for the uk with high pressure domination for the first time in several months. We should all see some pleasant spells of sunshine mixed with variable amounts of cloud and the night's are likely to be chilly with frost and fog forming where skies are clear.

[I remember Atlantic 252]

yeah good charts Frosty! could do with high just a bit further south, for my area (southern areas) but great oop norf

[Frosty.]

1 minute ago, I remember Atlantic 252 said:

yeah good charts Frosty! could do with high just a bit further south, for my area (southern areas) but great oop norf

Agreed, makes a nice change to have an anticyclonic outlook with Atlantic systems well and truly held at bay. 

[shotski]

10 hours ago, Frosty. said:

 Well I'm describing the uk outlook as a whole, and for many it looks a lot better than the tripe we have been served up from the Atlantic for month after month!

Probably the wrong place to ask this so please feel free to move, but where are the forecasts your looking at ? All I'm seeing from the Met office are for average temperatures and grey cloud for both our areas, I'd love some spring sunshine but apart from Sunday I'm struggling to see it in the forecast. Hope your on the money 

Edited March 12, 2016 by shotski

[Frosty.]

4 minutes ago, shotski said:

Probably the wrong place to ask this so please feel free to move, but where are the forecasts your looking at ? All I'm seeing from the Met office are for average temperatures and grey cloud for both our areas, I'd love some spring sunshine but apart from Sunday I'm struggling to see it in the forecast. Hope your on the money 

I'm just trying to bring some cheer regarding our first anticyclonic spell for ages, I don't know how cloudy or sunny it will be, I'm just pleased to see a high over the uk for a change!

[John Badrick]

46 minutes ago, Frosty. said:

I'm just trying to bring some cheer regarding our first anticyclonic spell for ages, I don't know how cloudy or sunny it will be, I'm just pleased to see a high over the uk for a change!

Because we are talking from a IMBY perspective nothing to get excited about in the foreseeable from what I can see, just your bog standard boring weather, so until we can get some proper warmth iam still in winter mode!!

[Frosty.]

31 minutes ago, John Badrick said:

Because we are talking from a IMBY perspective nothing to get excited about in the foreseeable from what I can see, just your bog standard boring weather, so until we can get some proper warmth iam still in winter mode!!

At least it will be DRY and it won't be cloudy everywhere, some areas will have pleasantly warm sunny spells to enjoy!

[mb018538]

Undoubtedly looking pretty cloudy for the most part of the week, could be especially disappointing in my neck of the woods with that nagging easterly all week. At least it'll be dry and not overly windy! Think the GFS has gone a bit mad in FI this morning too.

[Nouska]

1 hour ago, John Badrick said:

Because we are talking from a IMBY perspective nothing to get excited about in the foreseeable from what I can see, just your bog standard boring weather, so until we can get some proper warmth iam still in winter mode!!

I'm in Spring mode - the birds, blossom, and light levels tell me that. As far as temperature is concerned, the models tell me that I will have winter mode in the early morning and even summer mode in the afternoon when I can do some sun bathing on a sheltered south facing terrace. Isn't weather wonderful - should be something to please everyone .....  depending on viewpoint. ;0

[weirpig]

1 minute ago, Nouska said:

I'm in Spring mode - the birds, blossom, and light levels tell me that. As far as temperature is concerned, the models tell me that I will have winter mode in the early morning and even summer mode in the afternoon when I can do some sun bathing on a sheltered south facing terrace. Isn't weather wonderful - should be something to please everyone .....  depending on viewpoint. ;0

Think you may be dissapointed.  afternoons certainly wont feel like summer not even indoors.  some areas will struggle to hit double figures.  But hey it will be dry might get to the grass

[TomDav]

15 minutes ago, mb018538 said:

Think the GFS has gone a bit mad in FI this morning too.

Seems to me a plausible solution, considering we have had an unprecedented SSW event that I doubt has been fully assimilated by the models yet

[Nouska]

2 minutes ago, TomDav said:

Seems to me a plausible solution, considering we have had an unprecedented SSW event that I doubt has been fully assimilated by the models yet

Exactly what I thought when looking at the GFS output and it will give some hope to those who have been following the AER blog. What I don't see is a steering mechanism (as yet) to bring it in to the UK.

[John Badrick]

53 minutes ago, weirpig said:

Think you may be dissapointed.  afternoons certainly wont feel like summer not even indoors.  some areas will struggle to hit double figures.  But hey it will be dry might get to the grass

I was gonna say, where are you Nouska, the Caribbean??? Yes at least I can tackle the overgrown jungle that my garden has become after such a mild winter

[knocker]

The main features of the ecm day ten anomaly.

Firstly it's still hanging on the ridging over the UK (rather supports the ops if not the position of the surface high which is a variable feast anyway) and then we the Russian trough in situ still in NE Europe, a trough mid Atlantic and not without importance our old friend the Canadian vortex troughing down eastern N. America. So we are still hanging on to the good weather at that stage.

This soon changes in the ext EPS period. By T300 the HP has replaced by zonality with the trough over the eastern N. America swinging east to be orientated SE over the western Atlantic. This westerly flow will produce periods of unsettled weather with temps varying around average. By T360 the trough is in the central Atlantic which backs the upper flow and looking at the 850mb streamlines we are looking SW winds and quite pleasant temps in Cornwall although the downside would some wet and windy interludes.

The European trough is now a weak area of low pressure north of Finland with no cold air applicable

Edited March 12, 2016 by knocker

[Frosty.]

High pressure rules throughout next week, still anticyclonic by next weekend on the Gfs 6z...so the main theme is dry and quiet with variable amounts of cloud but with spells of pleasantly warm sunshine too and chilly nights with a risk of frost and fog where skies clear.

[I remember Atlantic 252]

3 hours ago, John Badrick said:

Because we are talking from a IMBY perspective nothing to get excited about in the foreseeable from what I can see, just your bog standard boring weather, so until we can get some proper warmth iam still in winter mode!!

I don't mind boring, when we had gales and rain which completely suck, was wishing on anticyclonic gloom! mild and dry is great any time of year but especially March, Frosty right as well, some cloud breaks will appear, I think best of Spring weather far north and far west where sunshine could be unbroken

[Singularity]

Hmm - the models have trended towards waking up the MJO again in phase 5 as opposed to 3 or 4.

 

Contrast the phase 4 analogue with the phase 5 one:

  

...and you can see where GFS is getting it's idea of a push from the west from. You can even see how it could be leading to those height rises in the high-Arctic - as opposed to the SSW which continues to be modelled as having unusually little impact in the troposphere.

ECMF is less active in phase 5, and the bias-adjusted one still kicks off in phase 3/4, so less of an attempt to produce a zonal regime is evident in that model. 

GEFS fancy a trip to phase 6 later in time, which appears to favour air flows from the SE or similar. We've seen that sort of thing cropping up in recent GFS runs too.

 

Really, a large part of the past 4 months has been governed by to what extent the MJO is active, and where, due to an apparent stratospheric disconnect. If we knew more about the EPS mechanism that may be responsible (see latest page of stratosphere thread) then this could perhaps have been anticipated pre-season. Perhaps.

Edited March 12, 2016 by Singularity