Model Output Discussion - 1st February Onwards 12z--->

[IDO]

ECM has eventually resolved the period from D6-8 as one HP exits right and another enters left, something the GFS handled days ago!

 

D10 ECM:   GEFS Mean: 

 

The GEFS mean for D12, D14 & D16:

 

  

 

The signal does not look like it is moving towards a HLB, more likely a sinking UK high with N/S split (or NW/SE). Nothing currently suggesting a more meridional flow as we enter the last week of Feb. Temps in FI look like recovering to just above average for the south but still uncertainty on where each HP sits, so week 2 may change in that regard:

 

 

The week 1 high looks to keep it on the colder side of the average, unusually more so for the south

 

So HP dominating till at least D14 IMO though each wedge is transitory so surface conditions will vary at times. Just as many members in FI pushing the 850s towards +10c as going the other way, with the mean uppers for London staying positive from tomorrow to D16. Little sign of rain for sometime and maybe a pleasant period for some if the sun does escape the gloom.

[chris55]

UK high overload lol!! However with a little luck we could be in a much more favourable position if we can get some ridging retrogression undercutting etc. still would prefer to be seeing this type of model outlook with potential rather than raging south westerlies.

[Polar Maritime]

Yes surface conditions will remain on the chilly side, With ground frosts effecting even the far South with High Pressure stuck over the UK for the next 10 days or so, Keeping the Atlantic at bay. This tends to lead to very stagnant air, With conditions for some fantastic cloud inversions and will feel very pleasant. Cool & Dry best sums it up, Great outdoor weather.

 

 

Edited February 6, 2015 by Polar Maritime

[Jason M]

As always things can change quickly but running through last night's 18z run I was struck by its similarity to a Bartlett set up. By this I mean the constant reinforcing of the high pressure cell by another as each one wanes (a traditional Bartlett would be to our SE).

This pattern could last a long time. We could be looking at a very dry and benign late winter and early spring.

Or alternatively by tonight it could all change :-)


Edit: notable how well GFS has been performing in recent days. It has been very very consistent since last weekend.

Edited February 6, 2015 by Polar Maritime
To move discussion on.

[bluearmy]

Troughy spreads pushed well East on the 0z ecm ens suite

Fairly comforting to see good agreement now.

[marksiwnc]

Troughy spreads pushed well East on the 0z ecm ens suite

Fairly comforting to see good agreement now.

And the result of this being?? Sorry ba but I struggle with working this lol

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS.

THE CURRENT GENERAL SITUATION  A large anticyclone will move slowly towards NW Ireland becoming slow moving. A weak front will move South over the UK tomorrow introducing milder NW'ly airs.

MODELS-2 WEEK HEADLINE A lot of benign and quiet weather is expected across the UK with light winds and plenty of cloud but some sunshine or clear spells with some frosts at night especially in the South. Daytime temperatures close to average. Perhaps a little rain in the North later.

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow now climbing North of the UK and being maintained there for the entire run thereon rounding the Northern flank of High pressure in a West to East steady flow driven by the High pressure close to the South of England.

GFS OPERATIONAL The GFS operational today as yesterday shows complete High pressure domination across the UK with the first centre gradually receding SE over Europe next week quickly being replaced by another with further rinse and repeat patterns in week 2. Quiet and benign conditions look relevant for all areas with occasional periods of sunshine and cloudier spells with temperatures close to average by day but with further intervals of patchy frost and fog overnight and very little rain anywhere.

THE GFS CONTROL  The GFS control run offers nothing any different with little significant indication of any difference to the theme offered by the operational at anytime through the period.

THE GFS CLUSTERS The GFS Clusters show 85% of members supporting High pressure remaining close to SW or Southern Britain with sufficient proximity to ward off any attempt from the Atlantic to break through anywhere other than the far North. The remaining 15% of members are more supportive of Low pressure troughs crossing the UK from the West with some rain at times for all.

UKMO UKMO this morning shows High pressure close to Western Britain drifting gently East across the UK and on into Europe next week maintaining dry and benign weather conditions with variable cloud cover and temperatures close to average but maybe a little below in the South next week under a developing South or SE drift with some frost and fog patches by night.

THE FAX CHARTS The Fax Charts are well supportive of the models raw data with a large High pressure area close to Western Britain with a slack Northerly drift down over the UK pushing occasional weak troughs South in the flow.

GEM GEM is a little different this morning as it shows a decline in High pressure to the SE next week allowing the Atlantic door to be open with Westerly winds developing over all areas with fronts crossing East at times delivering rainfall for many in temperatures returning close to average overall.

NAVGEM NAVGEM takes the route of the majority as it too declines High pressure to the SE of the UK next week but follows it up be new High pressure developing again close to the UK reinforcing the pattern of fine and settled weather with some night frosts and fogs but benign days.

ECM ECM differs only in the extent of the second anticyclone developing later next week holding a position close but somewhat further towards the South of the UK which would feed more changeable conditions into the North at times later while the South maintains mostly fine if rather cloudy conditions. Under the Westerly drift mild Atlantic air looks likely to be affecting the UK later.

ECM 10 DAY MEAN The 10 Day Mean this morning indicates that High pressure will most likely lie close to the South of the UK next week and beyond. Conditions will slowly recover to fairly average temperatures and rather cloudy weather overall with any patchy light rain at times restricted to places in the far North.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for High pressure to remain dominant across or just to the South of the UK with little significant signs of Low pressure or rain away from the risk in the far North.

MY THOUGHTS A period of dormant weather remains on the menu this morning as High pressure is shown by all models to hold sway of the weather over the UK for the foreseeable future. Only the GEM operational offers something a little more changeable later as it declines High pressure further to the South allowing the Atlantic mild Westerlies to creep across all areas with some rain later next week. It is the exception though to a very big rule with 85% of the GFS clusters supporting a theme of High pressure close to or over the South of the UK by Day 14 and the ECM 10 day Mean Chart promoting a similar evolution. As is usual in Winter Anticyclones they can be notoriously stubborn to predict the weather within as the positioning and age of the High can play a big part in how much cloud is present and how prevailing winds feel. In this case the High moving away to the SE next week draws a spell of slack South or SE winds up into the UK which could bring drier continental air up from Europe which could be colder and frostier for a time before a new High near the UK brings us back to square 1 by the end of next week with benign and settled weather likely thereon but without anything severe or interesting for weather fanatics to get their teeth into. The one thing that continues to stand out is that despite a wealth of mid latitude High pressure present is the inability of it to ridge sufficiently Northwest, North or NE to set up any risk of an Easterly or even a potent Northerly through the next few weeks. As a result it looks very likely that February is going to be a drier than average month with temperatures probably ending up near to average with nothing noteworthy in terms of mildness or coldness unless synoptics change radically beyond the terms of this morning's output.

Issued at 08:30 Thursday February 5th 2015

[mushymanrob]

I certainly hope not. Here in Peterborough we have only seen 42mm of rain in Dec, 41mm Jan and if the GFS is correct only 4mm in Feb. The other disappointing aspect of the GFS this morning is the boring weather pattern would still require our central heating on as temps during the day are expected to be around 5/6C with frosts at night.

 

frosts will be patchy imho... that will depend upon whether the cloud or where the cloud breaks. its looking mainly cloudy until fi .

 

looks like dismissing yesterdays ecm @240 was justified this morning

 

as that cold northerly seems reserved for europe.

the anomaly charts shifted slightly, the 6-10 dayer supports southern latitude high pressure, bartlett teritory?

 

 

with a second high (as suggested by the gfs) building in afterwards... so a chillier spell perhaps as the high moves in.

 

the gfs in deep fi suggests this high too sinks to a southern latitude, maintaining the dry theme.

temps are varied, it might turn mild, but over the 2 week perion probably averaging out at... average? or slightly below.

Edited February 6, 2015 by mushymanrob

[bluearmy]

And the result of this being?? Sorry ba but I struggle with working this lol

The sluggish block likely to verify out to day 10 at least. The spreads on an upper trough and lower uppers indicated a fair cluster of members against the mean. These are now well to our East so the block looks firm and secure for the period.

[Iceaxecrampon]

This pattern is embedded and hard to shift!

 

HP for the foreseeable then another "reload" - not so much winter over but snow over more so at low level? - especially with the Daffs popping - come on Atlantic the cold is here....

 

Ian

[Summer Sun]

Pretty easy to sum it up this morning GFS 06z is virtually settled through-out which takes us to the 22nd cloud amounts are likely to vary but in any sunshine it should feel fairly pleasant in the strengthening February sunshine.

 

Rainfall amounts as expected with the settled outlook is very low  for large parts of the UK

 

[fergieweather]

The sluggish block likely to verify out to day 10 at least. The spreads on an upper trough and lower uppers indicated a fair cluster of members against the mean. These are now well to our East so the block looks firm and secure for the period.

...albeit the continuing EPS signals remain for potential colder/wetter spell into next weekend, with fair number of members having the trough running across us. 00z DET and CTRL are both in middle-upper bounds of ENS spread by Fri-Sat, but rebound of 850hPa temp and GPH remains strongly signposted, so any unsettled phase looks very transient. The renewed block certainly has longevity stamped all over it thereafter (with MJO P8 suspected to at least assist), but combined signals are both in GLOSEA and now also EC Monthly for a more unsettled look to end Feb/start March. Whilst this is the favoured outcome, signals for breaking the block remain v inconclusive. Equally, when confronted with weak synoptic bias (as EC is by week 4), there will be inevitable tendency for model synthesis to return straight to climatology (e.g. much as we also often see with GFS out into Disneyland timeframes). Thus, the block certainly won't exist ad-infinitum (!) but we can't yet be clever about when it will yield to Atlantic mobility (certainly no convincing signs of HLB in GS5, but growing signs for return of cyclonicity from NW into March).

Edited February 6, 2015 by fergieweather

[karyo]

...albeit the continuing EPS signals remain for potential colder/wetter spell into next weekend, with fair number of members having the trough running across us. 00z DET and CTRL are both in middle-upper bounds of ENS spread by Fri-Sat, but rebound of 850hPa temp and GPH remains strongly signposted, so any unsettled phase looks very transient. The renewed block certainly has longevity stamped all over it thereafter (with MJO P8 suspected to at least assist), but combined signals are both in GLOSEA and now also EC Monthly for a more unsettled look to end Feb/start March. Whilst this is the favoured outcome, signals for breaking the block remain v inconclusive. Equally, when confronted with weak synoptic bias (as EC is by week 4), there will be inevitable tendency for model synthesis to return straight to climatology (e.g. much as we also often see with GFS out into Disneyland timeframes). Thus, the block certainly won't exist ad-infinitum (!) but we can't yet be clever about when it will yield to Atlantic mobility (certainly no convincing signs of HLB in GS5, but growing signs for return of cyclonicity from NW into March).

Thank you for your input. Does that imply colder than average temperatures too?

[nick sussex]

I think Ian F has covered things in detail there.

 

It's interesting that the UKMO suspect the MJO into phase 8 because this has been the subject of disagreements between the outputs.

 

You'll see even by looking at the GEFS that a few members dig the troughing further west before the high re-asserts itself. The ECM does looks somewhat of an outlier solution compared to the GFS and UKMO these don't separate upstream low pressure, the ECM splits into two lows at T144hrs and is flatter.

[That ECM]

...albeit the continuing EPS signals remain for potential colder/wetter spell into next weekend, with fair number of members having the trough running across us. 00z DET and CTRL are both in middle-upper bounds of ENS spread by Fri-Sat, but rebound of 850hPa temp and GPH remains strongly signposted, so any unsettled phase looks very transient. The renewed block certainly has longevity stamped all over it thereafter (with MJO P8 suspected to at least assist), but combined signals are both in GLOSEA and now also EC Monthly for a more unsettled look to end Feb/start March. Whilst this is the favoured outcome, signals for breaking the block remain v inconclusive. Equally, when confronted with weak synoptic bias (as EC is by week 4), there will be inevitable tendency for model synthesis to return straight to climatology (e.g. much as we also often see with GFS out into Disneyland timeframes). Thus, the block certainly won't exist ad-infinitum (!) but we can't yet be clever about when it will yield to Atlantic mobility (certainly no convincing signs of HLB in GS5, but growing signs for return of cyclonicity from NW into March).

Thank you for your post although I feel I need to correct one part and in particular a technical point. Disneyland!! It's fantasy island. Honestly what do they teach you professionals nowadays??!! I would now add one of those smiley crossed eyed faces to ensure you know I am joking but I don't know how!

[seaside 60]

Thank you for your post although I feel I need to correct one part and in particular a technical point. Disneyland!! It's fantasy island. Honestly what do they teach you professionals nowadays??!! I would now add one of those smiley crossed eyed faces to ensure you know I am joking but I don't know how!

Above where you type the reply.

There is a row of icons.

Look for the round yellow smiley face, click on it and you will have a choice, like so.

[johnholmes]

My take using the 500mb anomaly charts

As cautioned yesterday the colder n of west flow on EC has disappeared this morning. They are not identical but overall the 3 I use do show a similar idea. That is an upper ridge dominating the UK with no deep cold air able to penetrate. So surface cold or more accurately below average daytime temperatures and dry for most, night time values dependent on cloud cover so watch the sat piccs, visual especially mid afternoon, look at the 900-850mb wind predictions for ideas on how much cloud your area may have.

The idea of a brief input of colder air round the upper ridge is a possibility but I would think no more than a 24 hour event IF it happens.

The above is 6-15 days with the GFS MJO (the only one I use) suggesting no marked cold incursions either.

Beyond that-not my area.

 

links

ECMWF-GFS

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

NOAA

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

GFS MJO now and predicted

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

and the 500mb anomaly charts based on the MJO phases

http://www.americanwx.com/raleighwx/MJO/MJO.html

Edited February 6, 2015 by johnholmes

[bluearmy]

It's a fair cop! In my rush this morning I only looked at the day 10 spread and with it being very low, I assumed there was little point looking at days 7-9.

Ian has rectified this.

The spread does reveal a system going nw/se through the North sea next weekend.

Looking at the london graph, i would estimate a 20/25 percent chance that this spread occurs.

as Ian says, even if it does come through, it looks short lived.

[fergieweather]

 

It's interesting that the UKMO suspect the MJO into phase 8 because this has been the subject of disagreements between the outputs.

 

 

It's currently in phase 8 (as signalled both in latest EC and GS5 output). UKMO note that it'll remain at low amplitude, "...but still supportive of a –ve NAO out to day 15."

[nick sussex]

Regarding the MJO, yesterdays statistical models only had the CA one going into a decent amplitude phase 8. Now today theres agreement across the 3 statistical models for this to occur quite quickly.

 

 

At the moment the suggestion is that the MJO will play some role but not enough to get the high in a much more favourable location for cold potential, there is a time lag with the MJO impacting on the outputs but I would have expected to see something if the MJO Phase 8 was going to verify, it could be other variables muting out the signal somewhat.

 

Still waiting for the dynamic models to update, we'll see if they do indeed go into that phase 8.

 

PS thanks for that update Ian, its quite surprising because the UKMO a few days back had the MJO going into the COD, this divergence across the model suite has been evident across the last month.

 

Its interesting that you mention a negative NAO because that's been very difficult to get so far this winter.

Edited February 6, 2015 by nick sussex

[seaside 60]

On what I have read in here, shouldn't that mean we should be experiencing, more in the prospects of "colder weather" types or at least knocking on our doorsteps.

 

Ok, Nick S has sort of answered that....

Edited February 6, 2015 by seaside 60

[Cheshire Freeze]

Regarding the MJO, yesterdays statistical models only had the CA one going into a decent amplitude phase 8. Now today theres agreement across the 3 statistical models for this to occur quite quickly.

 

statphase_full.gif

 

At the moment the suggestion is that the MJO will play some role but not enough to get the high in a much more favourable location for cold potential, there is a time lag with the MJO impacting on the outputs but I would have expected to see something if the MJO Phase 8 was going to verify, it could be other variables muting out the signal somewhat.

 

Still waiting for the dynamic models to update, we'll see if they do indeed go into that phase 8.

 

PS thanks for that update Ian, its quite surprising because the UKMO a few days back had the MJO going into the COD, this divergence across the model suite has been evident across the last month.

 

Its interesting that you mention a negative NAO because that's been very difficult to get so far this winter.

 

Personally I'm just wondering when the switch in the modelling will be flicked. A UK high for nigh on 2 weeks we shall not see....that I'm sure of.

[nick sussex]

Personally I'm just wondering when the switch in the modelling will be flicked. A UK high for nigh on 2 weeks we shall not see....that I'm sure of.

Well if there are going to be changes in the NWP as a reaction to the MJO phase 8 they should happen quickly. With Ian now confirming that its already in phase 8 the question is whether the models are reacting to a low amplitude signal. What if the true signal ends up being closer to the statistical modelling, although this is not very strong its certainly stronger than I think the UKMO are expecting.

 

The last ECM forecast had the MJO going into phase 8 at around the same strength as the statistical models however looking at its output its not really picking up the baton.

[Cheshire Freeze]

Well if there are going to be changes in the NWP as a reaction to the MJO phase 8 they should happen quickly. With Ian now confirming that its already in phase 8 the question is whether the models are reacting to a low amplitude signal. What if the true signal ends up being closer to the statistical modelling, although this is not very strong its certainly stronger than I think the UKMO are expecting.

 

The last ECM forecast had the MJO going into phase 8 at around the same strength as the statistical models however looking at its output its not really picking up the baton.

 

Quite. The ECM of yesterday morning was probably a fair reflection of where we'll be mid month. Just waiting to see which model flinches first. How many times have we seen a supposed 2 week long spell of UK high scenario erode into something a lot different? Quite a few is the answer!

[nick sussex]

Quite. The ECM of yesterday morning was probably a fair reflection of where we'll be mid month. Just waiting to see which model flinches first. How many times have we seen a supposed 2 week long spell of UK high scenario erode into something a lot different? Quite a few is the answer!

I think high pressure is likely to be close by but its just where exactly it sets up that's more uncertain. Further nw of course brings some colder potential for the UK.

 

It might be CC that the MJO may well be muted out somewhat, we'll know over the next few days because if somethings going to happen in the NWP then I'd expect it to show very soon.