Model Output Discussion 1200 hrs 30/09/14

[Blessed Weather]

Sorry to use the P word before winter proper has started, but it’s struck me that the PV might be struggling to get its act together this October.
Using today’s GFS 12z N. Hemisphere H500 output for 6^th and 10^th October and comparing it with the same dates in 2010, 2011, 2012 and 2013, it indicates that this year the PV is somewhat scattered around and not an organised entity as in the previous years.

Is this of any significance? It seems to fit with the fact that the “October Pattern Index†is negative at the moment and hopefully bodes for a weak PV over the coming months. Any views guys? Or of no significance at this stage?

Below I've compared today’s GFS output with 2012 and 2013 as illustration:

 

For 6th Oct:

 

2014  2013   2012

 

For 10th Oct:
 

2014    2013   2012

[damianslaw]

GFS showing a different theme this evening compared to yesterday with much more in the way of pronounced height development over Greenland anchoring the trough down on top of the country as opposed to drifting it NW. Indeed strong heights both to the NW and NE will lock the trough in place with nowhere to go.. Things could become quite slack as we move through next week but this would probably enable secondary low development rather than anything settled.

 

Its an unsettled outlook for the foreseeable - very typical October fayre.

[Cloud 10]

Was wondering what the H500 anomalies for September looked like but on visiting the reanalysis page i get this:

 

"At this time (2014/09/29), the NCEP/NCAR Reanalysis is not being updated at PSD as NCEP has halted their distribution. Any of our products or web-tools that use this data will be impacted. Data will be updated when it becomes available. We have no further information as to when that might be."

 

 

 

http://www.esrl.noaa.gov/psd/data/composites/day/

[Frosty.]

Tonight's ECM 12z ensemble mean is painting a very unsettled picture for the next week or so with temperatures much lower than they have been so far this autumn with a marked drop to average levels at last, but having said that, due to the very warm september, it will feel cold in comparison,  a trough to the northwest is in control with rain and showers with strong winds at times, temps a little below average for the NW, around average elsewhere but there are then signs of something a bit warmer, drier and brighter returning to the south / southeast of the uk from around the 10th with a slight pressure rise, however, the north of the uk stays unsettled with atlantic weather throughout...so autumn finally arrives..next stop winter..ding ding..BRING ON THE WINTER FRENZY

[knocker]

Tonight's anomalies. NOAA 8-14 HP western Atlantic with the trough just west of the UK. GEFS HP western Atlantic with the trough more orientated over the UK, low Cyprus and weak HP to the east Further to this weakening of the western ridging and movement of trough westwards On the surface this starts with a slack HP/LP Atlantic split but evolves to generally low pressure in the Atlantic albeit not that active. No particular signs of build up of heights to the SE.

 

The ECM has the same HP to the west but the trough is orientated to the west/south west of the UK with the HP to the east in closer proximity. This evolves into weaker HP to the west, the trough drifting into central Atlantic and progress westwards of the eastern ridge. On the the surface, similar to the GEFs with slack low pressure dominating the Atlantic but closer to the UK of the weakish HP to the east and south east. The jet is in a pretty weakish meridional pattern that could facilitate some build up heights from the east/south east but too early to read anything into that. On the whole it looks a pretty quiet pattern set up.

 

[damianslaw]

Tonight's anomalies. NOAA 8-14 HP western Atlantic with the trough just west of the UK. GEFS HP western Atlantic with the trough more orientated over the UK, low Cyprus and weak HP to the east Further to this weakening of the western ridging and movement of trough westwards On the surface this starts with a slack HP/LP Atlantic split but evolves to generally low pressure in the Atlantic albeit not that active. No particular signs of build up of heights to the SE.

 

The ECM has the same HP to the west but the trough is orientated to the west/south west of the UK with the HP to the east in closer proximity. This evolves into weaker HP to the west, the trough drifting into central Atlantic and progress westwards of the eastern ridge. On the the surface, similar to the GEFs with slack low pressure dominating the Atlantic but closer to the UK of the weakish HP to the east and south east. The jet is in a pretty weakish meridional pattern that could facilitate some build up heights from the east/south east but too early to read anything into that. On the whole it looks a pretty quiet pattern set up.

 

Yes 'quiet' in a wider context in terms of level of mobility, but highly disturbed for our patch of Europe and therefore far from 'quiet'.

[knocker]

Yes 'quiet' in a wider context in terms of level of mobility, but highly disturbed for our patch of Europe and therefore far from 'quiet'.

 

On what are you basing the 'highly disturbed' in the time frame I was discussing?

Edited October 2, 2014 by knocker

[SteveB]

Things still look wet and windy on this mornings GFS, but there is the faint hint that it might settle down a bit in FI.

 

But plenty of wind and rain next week to get through first.

 

 

Temps remain around average throughout.

[knocker]

Interesting development of a plume and some very warm temps. Not quite applicable to the UK. 30C in southern Germany!

Edited October 3, 2014 by knocker

[Gibby]

An unsettled and wet period next week is shown by all models but how long will it last. This is the highlight to discuss today i feel so in a simplistic text form here is my report on the models this morning.

 

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY FRIDAY OCTOBER 3RD 2014.

 

NEXT UPDATE SATURDAY OCTOBER 4TH 08:00

 

THE CURRENT GENERAL SITUATION. An active cold front will move slowly but steadily SE across all of the British Isles over the coming 24-36 hours with a strong SW flow ahead of it veering West to NW behind the front.

 

MODELS-2 WEEK HEADLINE  All areas look like being unsettled and windy with rain at times in cool conditions. Possibly a little drier and less cool in the SE later.

 

THE JET STREAM ENSEMBLE FORECAST A change in the position and orientation of the Jet stream is still shown as it exits Newfoundland and eventually Canada, crosses the Atlantic and over Southern Britain next weekend. It then dips sharply South over the Atlantic and back North to lie well North of NW Europe in the 10-14 day period.

 

GFS The GFS operational splits into two halves with Week 1 showing the well documented slide into wet and windy conditions as Low pressure over or to the NW of the UK dominates conditions across all areas. This is followed by a switch to High pressure, firstly crossing the UK and then moving into Europe and extending a ridge back West across the UK with fine and dry weather with mist and fog night and morning becoming the main features of the weather in continuing cooler conditions than of late.

 

THE GFS ENSEMBLES. The GFS Ensembles are broadly similar in this resolve bringing drier and brighter weather back across the UK slowly through week 2 as the Jet flow returns North of Europe but a way South over the Atlantic in week 2. So a wet and windy week next week should slowly give way to less rain, calmer and quieter conditions again through the second week especially across the South and East.

 

UKMO UKMO this morning maintains a deep Low complex close to or over the UK through the middle days of next week with frequent outbreaks of rain or showers, heavy at times in a generally cyclonic SW flow across the UK.

 

THE FAX CHARTS  The Fax Charts show an active and squally cold front crossing SE over the UK over tonight and Saturday with squally winds and heavy rain for a time. A ridge is then shown to give a quieter interlude across the South briefly before Low pressure and active troughs move in from the West with the active troughs crossing East over all areas to start next week with gales and heavy rain and showers for all, the longer spells of rain most likely across the South.

 

GEM The GEM operational brings unsettled, often windy and wet conditions across the UK next week as Low pressure becomes deep and extensive close to or over Northern Britain with any improvements very slow as it only edges away slowly to the NE later filling slowly with higher pressure and drier conditions edging up across the UK from the SW next weekend and beyond.

 

NAVGEM NAVGEM today is equally unsettled next week as a deep Low close to the UK brings spells of rain or heavy showers to all areas on most days. Pressure is also shown to rise slowly late in the week as the Low to the North fills though rain at times is still likely for most.

 

ECM The ECM operational maintains the basic theme of all other output in bringing a deep Low down towards and over the West of the UK next week with rain and wind at times for all. With the thrust of Low pressure only slowly edging away North later and some reinforcements shown to move up from the SW next weekend there looks less signs of High pressure becoming as dominant later as it's counterpart models with further rain and showers at times possible almost anywhere right out to Day 10.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS There is a slow growth in the theory of  better conditions under High pressure returning to the UK in some shape or form after a week to 10 days of  the coming unsettled and windy period.

 

MY THOUGHTS  Low pressure is going to be the main ingredients of the weather over the next week with all models supporting deep Low pressure moving down close to the West and North of the UK with spells of heavy rain and showers for all next week in temperatures much more seasonably average than of late, the feel accentuated by the wind. It's what happens thereafter which has shifted a little this morning towards at least a chance that drier and more benign weather could return over next weekend and beyond as High pressure rebuilds from the SW in response to a shift North of the Jet again over and to the East of the UK. The ECM model is less supportive of this theory and brings further Low pressure up over the UK from the warm waters to the SW with further rain at times to end it's run this morning and while I sense that there is a reasonable chance of improvements in conditions being viable there is a lot of ingredients over the Northern hemisphere next week which have to come together for that to happen and I feel we will see plenty of swings towards and away from better weather shown during the course of the output released over the unsettled and Autumnal period of the next week. One thing that is a given should any better weather develop after next weeks wet period it is unlikely we will see particularly warm weather return as with wet surfaces by then mists and fogs under any High pressure could become a major issue along with the seasonal increase in the incidence of frosts should skies clear. So today looks the last day that any outside tidying of gardens etc ready for the Winter can be accomplished unhindered by weather factors.

[Summer Sun]

Latest rainfall totals to the 11th show some huge variations across the UK over 100mm for some western parts but some of parts of the UK barely see 20mm

 

[Iceaxecrampon]

Latest rainfall totals to the 11th show some huge variations across the UK over 100mm for some western parts but some of parts of the UK barely see 20mm

 

Yes - West Cumbria (Ravenglass) looks promising - really looking forward to a watering.

 

Ian

[Man With Beard]

The ops/ens at T192 are now going the way I was expecting - northern blocking not getting established, the threat of a more westerly influence interspersed with minor Atlantic ridges. All of which keeps next weekend (and probably several days beyond) on the warmer side for the time of year (though 14C-18C will still feel cold compared to recently!), but rain will always be lurking, particularly the further north you are. An outside chance of one last 20C day in the SE at the end of next week?

[gottolovethisweather]

Latest rainfall totals to the 11th show some huge variations across the UK over 100mm for some western parts but some of parts of the UK barely see 20mm

 

 

Indeed SS and could that perhaps be indicative of more prominent ridging towards Southern and South Eastern parts of the UK during the mid to late part of next week? Gut feeling only but the folk in the SE in particular may well end up wondering what all the fuss is about as the strongest winds and heaviest rain will always be outside of this region. I predict a drier than average month for a England upcoming despite the opening up of the Atlantic at least until a broader more active Atlantic comes knocking with its Ex-Hurricanes in the flow, keep a watch in there in the meantime. No denying it will feel much colder though but nearer average in any sunnier spells. Mid to late October is the timescale for this broader change I would say and perhaps Blessed Weather's post from late yesterday is onto something with the current setup of the PV. The progression of the cold as shown in the NH Snow and Ice thread might take a bit of shifting before then too, I suspect.

Edited October 3, 2014 by gottolovethisweather

[knocker]

Spot the PV (wash your mouth out Knocker)

 

 

 

 

Edited October 3, 2014 by knocker

[shaky]

Spot the PV (wash your mouth out Knocker)

 

 

if that is the pv off the west coast of alaska/Canada then that is not where it should be at this time of the year!!!if you ask me things are looking very interesting for the rest of the autumn and maybe even winter !

[Summer Sun]

Indeed SS and could that perhaps be indicative of more prominent ridging towards Southern and South Eastern parts of the UK during the mid to late part of next week? Gut feeling only but the folk in the SE in particular may well end up wondering what all the fuss is about as the strongest winds and heaviest rain will always be outside of this region. I predict a drier than average month for a England upcoming despite the opening up of the Atlantic at least until a broader more active Atlantic comes knocking with its Ex-Hurricanes in the flow, keep a watch in there in the meantime. No denying it will feel much colder though but nearer average in any sunnier spells. Mid to late October is the timescale for this broader change I would say and perhaps Blessed Weather's post from late yesterday is onto something with the current setup of the PV. The progression of the cold as shown in the NH Snow and Ice thread might take a bit of shifting before then too, I suspect.

 

06z following the 00z with not much rain for the SE and large parts of the east, where as over in the west some areas get over 100mm

 

 

Could be a week of large variations rain wise

 

FI sees the PV starting to form

 

[Frosty.]

The Ecm 00z ensemble mean shows a prolonged unsettled outlook, no sign of the weather settling down again in the next 10 days. coolest, windiest and most unsettled across northern uk but the south also generally unsettled and showery with a risk of persistent rain at times, temperatures around average for the south which is a heck of a lot cooler than so far this autumn, it will feel pleasant in any sunny spells but overnight where skies clear and winds fall light, there is a higher risk of fog forming and cold enough for slight frosts but the overall theme is cooler and unsettled, the last bit of warmth in the SE today before the much cooler air spreads in behind an active cold front bringing a band of heavy rain southeastwards.

[Bobby]

06z following the 00z with not much rain for the SE and large parts of the east, where as over in the west some areas get over 100mm

 

 

Could be a week of large variations rain wise

 

 

This is a a fairly typical distribution of rainfall for this time of year, NW/W regions experience up to 3x or more rainfall than the E/SE in October on average.

Edited October 3, 2014 by Bobby

[Yarmy]

Spot the PV (wash your mouth out Knocker)

 

 

 

I know it's a hackneyed term, but it's going to be difficult to discuss winter synoptics without mentioning it explicitly. 

 

Are we ever going to get 0-72 back on Meteociel for the UKMO?

[Summer Sun]

I know it's a hackneyed term, but it's going to be difficult to discuss winter synoptics without mentioning it explicitly. 

 

Are we ever going to get 0-72 back on Meteociel for the UKMO?

 

Fairly unlikely I'm afraid from the info I was given

[IDO]

The signal earlier this week for things to improve for the S/E/SE after D5 again showing up on the 12z GFS op. It shows a slack setup up till D10:

 

D8:    D10:  

 

Temps from mid-week look average or above for the S/SE.

 

It is not till D11-12 that the next LP system approaches from the NW. It is another slow moving stalling system on this run: 

 

It eventually ends with an Atlantic trough and Euro heights (a continuing signal): 

 

That ties in with the JMA update.

 

GEM is not dissimilar to the GFS with a slack setup as the LP system moves away from mid-week though it develops a short wave low in the warming trough around D9, something the GFS has been flip flopping with in the last few runs (not 12z):

 

 

Certainly still no sign of a prolonged Atlantic onslaught, especially for Eastern (SE) regions and the long wave pattern still looks more meridional than zonal. So October could well be again an above average month for temps especially for the SE/S.

 

In the short term the cold front moving SE during tonight will fizzle out as it reaches the far SE so my area looking like it continues to avoid the washout weather:

 

Accumulated precipitation end Saturday:

 

Expecting more as the LP system moves in on Monday/Tuesday for the SE as 2-3 fronts move eastwards, but no where near as much as further NW. Then looking like 5-7 days of relatively dry weather for the South/East/SE, with maybe showers if the GFS is correct; a lot wetter if the GEM LP system develops.Worse of the rain W/NW.

 

 

[IDO]

...ECM also now similar to GFS in not modelling the LP at D10. This morning's run:  Tonight: 

 

So some continuity between the main two models for a quieter period after D5 for some. After D10 the GEFS for London show continued uncertainty and more runs needed:

 

 

The forecast AO moves from negative towards neutral during this slack period but appears to go negative again straight away so a further attack from the NW looking likely around D12 and where the UK falls within that pattern is what the GEFS are struggling with:

 

Edited October 3, 2014 by i'm dreaming of...

[knocker]

The anomalies tonight are all evolving towards a low pressure dominant Atlantic albeit with a fairly slack pattern. The HP in the west perhaps slipping a tad south. The main difference is the GFS shows little sign of any influence from the HP to the E and SE whereas the ECM certainly pushes it further west so still leaving the door ajar, This perhaps suggested by the different orientation of the jet as the GFS has it much stronger and further south than the ECM.

 

This really still up in the air as at the moment it could resolve into quite a wet unsettled pattern ( probably favourite) or a drier one, in the south especially

 

There is nothing like a bit of fence sitting and covering all the angles.

 

[knocker]

just a brief digression as this chart reminds me of the joy of being  on Weather Station Julliet at 52.30n, 20.00 west.

Edited October 4, 2014 by knocker