Model Output Discussion 1200 hrs 30/09/14

[Severe Siberian icy blast]

Looking at the ECM and GFS northern hemisphere it's very startling to notice the polar vortex hasn't got the power this year , so many factors contributing to this , with more wave one activity forecast to hit the stratosphere going forward , with both of the big models hinting at Greenland hight rises as we head toward November .
 

Edited October 20, 2014 by Polar Maritime
To remove Winter predictions and thoughts.

[Summer Sun]

The ECM ens is still keen on building pressure as we move towards the final few days of October pleasant by day for England and Wales but an increasing risk of mist / fog developing overnight with frost's also possible especially in the countryside, Scotland remains prone to some rain / showers at first but it settles down by d10

 

[SMU]

Morning

A steady consistent & fairly well defined decline in temps on the ECM extended ens - with even a subzero run in there at the end & 2 snow runs in the mix as well-

To early for the uk - were still around 3 - 4 weeks away ideally -

S

[phil nw.]

Current modelling shows October continuing the warmer than average outlook with the exception of the blip over the next 48hrs.

A warm up again as pressure rises from the south west pushing more tropical maritime air across NW Europe.

Mean charts for day 10 this morning 

 

Jet stream being pushed north of the UK with the driest conditions as usual in the south going forwards as we would expect in that pattern. 

Edited October 20, 2014 by phil nw.

[Purga]

Corkingly mild uppers & settled weather as we finish off the month according to ECM

 

the placement of the HP will make differences of course of the trend is consistent .

[Purga]

Looking at the ECM and GFS northern hemisphere it's very startling to notice the polar vortex hasn't got the power this year , so many factors contributing to this , with more wave one activity forecast to hit the stratosphere going forward , with both of the big models hinting at Greenland hight rises as we head toward November . image.jpg

 

Last year this time the charts looked 'promising' with no strong PV

We all know what happened later don't we!

[Gael_Force]

Last year this time the charts looked 'promising' with no strong PV

We all know what happened later don't we!

 

The good thing about weather modelling - it is unpredictable and has many facets that evolve accordingly - completely unlike your line of comment.

[knocker]

A striking temp anomaly for the Arctic

[Newberryone]

The only subtle difference between yesterdays ecm output and today's is the slight delay in the building of heights from the south, but it certainly gets there in the end. Contrary to popular belief, there's little to suggest these charts won't verify. 

 

In a word...MILD!

[knocker]

As styx noted in another thread some unusual heat in Australia this week.

 

[IDO]

I hope we are not seeing all these stunning Winter synoptics now and miss out in DJF? Again the 06z Control:

 

 

 

Of course not likely to happen like that at D16 but what we would like to see from late November rather than now. A pressure rise from week 2, especially for the south looking likely, just where it centres and its travel arrangements to be firmed up on.

 

Interesting CFS November anomaly:  

 

Ties in with the Control run.

[Cloud 10]

Quite a change in the ECM chart for Saturday on the 12z compared to yesterday with the deep low to the NW much more influential and certainly a leap towards the GFS.

 

today..  yesterday..

[knocker]

The GEFS 12z anomalies are initially going for the the HP UK Arctic connection with a trough western Atlantic and a broader trough area eastern Europe with little amplification in North America.  This giving way to flat pattern and a non dynamic Atlantic, no significant PV and on the surface an unstable HP UK to parts east. A quiet period of weather with temps perhaps a little below average.

[shaky]

Quite a change in the ECM chart for Saturday on the 12z compared to yesterday with the deep low to the NW much more influential and certainly a leap towards the GFS.

 

today..ECM1-120.gif  yesterday..ECM1-144.gif

but heights looking stronger across greenland!!!!

[Cloud 10]

but heights looking stronger across greenland!!!!

 

Even the ECM ensemble mean has made a big swing towards the gfs,which means the removal of

the purples over Greenland!

 

today..  yesterday..

[knocker]

Not a huge difference with the ECM anomaly and NOAA with the GEFS with a very weak jet over N. Europe.At the time of going to press the current thinking would appear to be a slack pattern over the Atlantic with HP over the UK.

 

[damianslaw]

Looking towards latter part of the month, ECM remains bullish with its suggestion of strong heights building in from the south to envelop the country as we enter November, GFS less bullish, but it too shows a weak jet and all likelihood heights will get a foothold from the south.

 

Key question is whether these heights will become robust?

 

There are some signs they could do and ridge and build northwards - any milder uppers quickly becoming diluted at the surface to produce fog and frost.

[Nick F]

Have done a new synoptic outlook for the next 14 days:

 

http://www.netweather.tv/index.cgi?action=news;storyid=6238;sess=

 

Synoptic Outlook Discussion - Update 20th October 2014

 

General synopsis over next 14 days

 

The long stretch of unsettled westerlies now looks to continue into early next week and less confidence that pressure will build from the SW as per previous forecasts, though some 50% of GEFS members and ECMWF esemble mean going for some build of pressure from the S or SW from mid-week next week. Once a deep depression (ex-Hurricane Gonzalo) passes NE to north of Scotland tomorrow, the UK looks likely to remain under the influence of persistent low pressure complex to the north near Iceland for rest of this week, over the w/e and into early next week, bringing unsettled conditions and generally mild or very mild conditions with little scope for hill snow. From mid-week, potential for pressure to build from the south, but equally a balance in favour for unsettled westerlies to prevail towards end of the month too.

 

Short Term (5 day outlook)

 

Strong westerly jet streak arrives across UK Monday night, with it a deep depression (remnants of ex-Hurricane Gonzalo) which will track NE to the north of Scotland Tuesday, the low around 975mb close to Northern Isles at noon Tuesday. Active cold front bringing heavy rain sweeps east early Tuesday morning, clearing east coast by mid-morning. Strong/gale force SWly ahead of cold front veering strong/gale/severe gale force NWly colder flow following front. Transient ridge of high pressure quickly builds in from the west by early Wednesday before pressure falls from the NW during Wednesday, with arrival of new Atlantic frontal system across northern Britain, bringing cloud and rain. Then persistent low pressure system remains close to Iceland for rest of the week, driving an unsettled/cyclonic SWly flow across the UK. A cold front, bringing rain, erratically moves SE across the UK on Thursday and Friday, probably clearing SE England Friday afternoon.

 

Longer term (6-14 day outlook)

 

Perhaps drier for southern Britain over the weekend, but closer to low pressure system near Iceland - northern Britain will experience Atlantic fronts and strong SWly flow which will bring cloud and rain at times. Rain persistent and heavy across western Scotland – especially windward slopes.

 

Pressure falling from the NW across all parts early next week, with Atlantic frontal systems making inroads further south and east – bringing threat of some rain to all areas. Not a great deal of confidence mid-week onwards, but 50% chance that pressure will start to build from the south just to the W or SW of UK mid/late week as trough amplifies upstream over Atlantic, which may bring in drier weather to southern parts and/or bring a cooler northwesterly flow by end of the week. The north/south split (drier south/unsettled north) could persist into following weekend (Sat 1^st Nov and Sun 2^nd Nov), increasing risk of frost/fog in south under high pressure while north sees risk of cloud, rain and windy conditions at times.

 

ECMWF/GFS 8-10 day mean 500mb heights (orange = ridging, blue = troughing):

Edited October 20, 2014 by Nick F

[Barry12]

Stronger heights over the arctic on the 18z, the polar vortex is basically non-existent.

 

[knocker]

The EPS ens monthlies update. The temps are around average for month except the Arctic which remains above. Generally unsettled westerlies. Note they haven't quite loaded in the correct order

Edited October 21, 2014 by knocker

[MR EXTREMES]

last night ecm model 

 

gfs

 

gem

 

 

gefs

 

jma

 

 

southern tip of greenland looks a interesting area atm,

 

and possibly into november, the tracking of low pressure systems could well take a more south east route as heights although weak from the models so far build in around southern greenland.

Edited October 21, 2014 by emotional rollercoaster

[MR EXTREMES]

gefs

 

 

low pressure being pushed more se at 180hr ok its a long way out but its a good sign that the vortex so far is not throwing the kitchen sink.

id be very surprised if the ecm does not show some eye candy with block building around southern greenland.

[Gibby]

Good morning. The Westerly bandwagon largely goes on within the models this morning.

 

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY OCTOBER 21ST 2014.

 

NEXT UPDATE WEDNESDAY OCTOBER 22ND 08:00

 

THE CURRENT GENERAL SITUATION. A Low in the Northern North sea will move away East. A strong NW flow will back slowly Westerly and decrease from the West tomorrow.

 

MODELS-2 WEEK HEADLINE  Changeable weather with rain at times but some drier and brighter periods across the South. Near or slightly above average temperatures. Rather windy at times in the North.

 

THE JET STREAM ENSEMBLE FORECAST The Jet flow running SE currently across the UK will undulate north and South over the coming days as troughs and ridges pass West to East. The flow simplifies to a West to East motion across the Atlantic and the British Isles through the second week.

 

GFS The GFS operational today shows a basic pattern of Westerly winds across the UK over the coming few weeks. there will be ebbs and flows in the strength of this pattern and with High pressure predicted to be not far from the South of the UK at times there will be a fair amount of cloud at times here with occasional rain. In the North the westerly flow is shown to be more active and strong with more frequent bouts of wind and rain followed by brighter, cooler and more showery conditions. With a Westerly flow throughout temperatures should be held close to the average overall.

 

THE GFS ENSEMBLES. With only daily specifics marking any difference between the operational and it's ensembles this morning the same mix of westerly winds and occasional rain and showers is the main focus of conditions shown across the UK over the next few weeks with the most rain and wind over the North.

 

UKMO UKMO this morning shows pressure High just to the South and Low to the North early next week with dry and bright conditions likely in the South with windy weather further North with occasional rain or showers in average temperatures for all.

 

THE FAX CHARTS  Warm sector conditions with cloudy and drizzly conditions will develop over the coming days with less wind than today. Cold fronts cross SE across Britain at the weekend with some rain followed by scattered showers then likely.

 

GEM The GEM operational is also showing a long spell of Westerly winds in response to High pressure to the South and Low pressure to the North. Occasional rain and strong winds as a result particularly over the North will continue with longer dry and mild spells further South. A shift towards colder NNW winds at the end of the run is shown.

 

NAVGEM NAVGEM shows a typical Autumn synoptic setup with Low pressure dominant near Iceland and High pressure to the South and SW with a Westerly flow across the UK with rain at times from troughs over the North and west and longer drier spells further South f rather cloudy. It will be generally quite mild over the period. 

 

ECM The ECM operational today looks a lot less settled in the longer term as the recent build of pressure from the South next week has been replaced by further Low pressure moving in from the SW or West with rain at times in generally mild conditions. There are though some colder incursions from the NW shown to affect the North at times with showers.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The general trend remains for a North/South split in the weather over the next few weeks in a typical Autumn setup.

 

MY THOUGHTS  The Westerly pattern of weather over the UK through the next few weeks has again been endorsed this morning as most models like the idea of holding High pressure to the South of the UK and Low near Iceland. This amounts to the continuation of a broad Westerly flow across the UK and troughs in association with the Low pressure to the North will cross many areas with occasional rain. The most rain will always be towards the North with the best of the drier periods across the South. With a Westerly flow temperatures will never be cold and temperatures could be a little above at times across the South and below in the North in occasional polar maritime air. The ECM operational throws something of a curveball this morning in removing High pressure from the South of the UK as the Jet Stream slips South and allows Low pressure to make inroads into the UK from the SW as well as NW with rain at times a more universal commodity across the UK by then. It will be interesting if this is a new trend from the model or a blip as it recently has been dogged in showing High pressure moving up across the South later next week up until this morning. So in a nutshell it's more of the same as the UK continues to be covered by basically Westerly winds and occasional rainfall in a North/South split over the outlook period today with cold weather still shown to be outside of the current timeframes covered by the models.

Edited October 21, 2014 by Gibby

[johnholmes]

Using the 500mb anomaly charts it will be interesting to see which of them is closer to reality come the month end

NOAA has slowly moved at 6-10 day time frames to what is shown below. This would suggest surface high pressure will develop beneath the upper ridge and +ve height anomaly.

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

If you move to its 8-14 day outlook then this idea is persisted with. Indeed it was the 8-14 that showed a ridge and +ve heights before it got into the 6-10 day time frame.

Below is the latest from EC-GFS, neither really support the NOAA version

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

When there is this divergence it is rare in the years I have been using these that they give a better handle on things than the NOAA outputs. This is especially so when both the 6-10 and 8-14 show similar patterns.

So by month end do we have a mobile westerly with some decrease in that effect for the SE 1/4 of the UK or is the NOAA idea more likely giving more settled conditions over a larger part of the UK?

Interesting to see how this plays out. My money is on the NOAA version.

No sign of any major cold plunge in the next 2-3 weeks either in my estimation.

[NorthYorksWeather]

last night ecm model 

 

gfs

 

gem

 

 

gefs

 

jma

 

 

southern tip of greenland looks a interesting area atm,

 

and possibly into november, the tracking of low pressure systems could well take a more south east route as heights although weak from the models so far build in around southern greenland.

 

 

Certainly marked differences between GFS and ECM this morning in the area you have highlighted

 

ECM

GFS 

 

ECM much keener to build heights towards the southwest of Greenland.

Edited October 21, 2014 by vizzy2004