Model Output Discussion - 17th Oct Onwards

[Cloud 10]

Gem 12z continues with the unsettled theme tonight, with a notable low just north of northern Ireland @ t192

 

ECM 12z says "snap"

 

[Captain Shortwave]

Well the later frames of the ECM do offer some break from the very mild conditions, everything looks to become more westerly based which increases the chances of colder shots from the north west

Some of the depressions later on look particularly vicious.

[BLAST FROM THE PAST]

I have had my eye on last 3rd of oct for some time....I really think MetO will give warnings soon....defo for rain and I expect for wind too.  I think that the one or two that hint of a big hit end of month will show more...and I think shift south too....time will tell.

 

BFTP

[tinybill]

I have had my eye on last 3rd of oct for some time....I really think MetO will give warnings soon....defo for rain and I expect for wind too.  I think that the one or two that hint of a big hit end of month will show more...and I think shift south too....time will tell.

 

BFTP

looking  at this week,and  next  week  next problem could  be  flooding  their looks  like  a  lot  of  rain  to come  if  you look  now  to deep fantasy  world  cant  see much  let  up

[phil nw.]

I thought while it was quieter in here i would maybe set out some information for newer members regarding the Polar Vortex and the effect on our Winter pattern.

For anyone new to the charts the 12z ECM illustrates what i mentioned earlier about the cooling Polar Vortex.

 

The 2 images show the colder 500hPa(dark blues and purples)spreading across the high Arctic.

 

 

this is a normal seasonal occurrence as the polar night begins and the atmosphere at the top of the world receives less and less sun until mid-Winter.

This increases the thermal gradient or steeper temperature difference between the high and low latitudes which of course strengthens the jet stream.Hence the deeper lows as show in tonights modeling.

The pool of cold air can be released to lower latitudes when we get some buckling or blocking of the jet or a more meridonal flow as we call it sometimes.

I refer to one of my favourite blocking situations which commenced Nov.2010

Note the Atlantic jet diverted right over the top of Greenland with a solid Greenland high splitting the vortex-a classic omega block.See all the cold air coming sw off the Scandinavian trough.

That is the real mccoy for cold and is pattern to look for if you are a fan of real Wintry conditions.

There are other's of course such as good easterly from Siberia where the blocking high is further east over the higher latitudes and the vortex pushed across towards Canada/Alaska.

 

At the moment the pattern is looking fairly flat(zonal) but with that cold pool expanding up north we can still get brief incursions of colder conditions in brief ridges or kinks in the flow behind passing depressions as the wind turns more north of west.

 

To get that buckling jet we need a disturbance(warming) to the PV so that it becomes fragmented or moved to one side to see the heights build up north(orange/yellow)colours.

 

The colder stratosphere is a major factor on our Winter weather so any warming of this can help weaken the vortex which sometimes-not always i should add-create those Arctic high's.

A good idea is to follow developments on the Stratosphere thread to get a fuller picture of possible developments in the high atmosphere as we go into Winter.

 

.

 

[Mark Neal.]

looking  at this week,and  next  week  next problem could  be  flooding  their looks  like  a  lot  of  rain  to come  if  you look  now  to deep fantasy  world  cant  see much  let  up

Indeed. All models showing sustained unsettled weather with low pressure systems heading right for the UK. GFS 12z run accumulation to the end of next weekend shows some big rainfall to the West, with many areas experiencing a very wet 7 days. If anything the low pressure systems seem to be packing even more of a punch as we progress through next weekend and next week if ECM/GEM are correct.. 

[Summer Sun]

Latest from Gibby

 

All models show a very unsettled week to come with Low pressure in total control of the UK weather positioned close to Western and later Southern Britain. There will be spells of heavy rain most llikely across the West tomorrow and the South on Thursday. Through the remainder of the time showers are more likely with some very heavy showers with thunder possible at times. Winds will often be fresh to strong from the South with gales in places but all areas will stay mild with temperatures well above average until late in the week when cooler conditions might slip down from the NW.

 

GFS then shows very changeable weather through Week 2 with alternating wet and fair weather with temperatures up and down somewhat too day to day.. Winds would be blowing from the West or SW at times but occasionally NW through the colder moments.

 

UKMO tonight concludes it's run next weekend with a filling Low pressure area over Eastern England ahead of a weak ridge approaching Western Britain. Cloud and remaining showers would die away through Saturday with a drier interlude before it looks like further troughs will spill in from the West later on Sunday with further wind and rain in temperatures close to average.

 

GEM tonight shows a stormy end to its run as a very deep Autumn storm winds up to the North of Scotland with gale or severe gale force winds, squally heavy showers and cooler weather than of late with some snow on Scottish mountains in the showers. At the very end of the run a new intense Low looks set to keep the stormy weather going for all of the British Isles.

 

NAVGEM shows a weak ridge crossing East next week too with a drier and cooler interlude ahead of some more rain at times on inward coming Atlantic troughs. With high pressure closer to the South than of late the South would probably see lighter rain than elsewhere.

 

ECM tonight shows a windy and changeable weekend and after a drier interlude further rain and strong wind is ushered in from the West across Britain by Low pressure to the North. Towards the end of the run an increased risk of storminess is shown as some powerful depressions cross the Atlantic to end close to the NW.

 

The GFS Ensembles show mild weather in place this week with rain at times before temperatures fall back towards the seasonal average but with continuing changeable weather with rain at times along with strong winds.

 

The Jet Stream remains well South across the Atlantic and sweeping NE across the UK for the coming week or so with small signs of a drift Northwards somewhat in Week 2 when it becomes notably strong.

 

In Summary there is little change tonight in the overall sequence of events with a mild or very mild week to come with a lot of rain at times especially towards the SW and West. Late in the weekend and next weekend signs of a window of drier and cooler weather are still evident before a return to unsettled and occasionally windy weather returns this time with temperatures much closer to the seasonal average.

 

http://www.norton-ra...is(2859336).htm

[Frosty.]

There are quite a few very settled looking GEFS 12z perturbations this evening for early November, including the control run, so it could be very mild and sunny, mild/cool anticyclonic gloom or cold and foggy with frost early and late, that is the variety of anticyclonic conditions we could expect by late october and throughout november.

Edited October 20, 2013 by Frosty.

[summer blizzard]

A very traditional Autumn Ecwmf tonight. Wild wet and windy but much more zonal and cooler on the back end.

[Jonan92]

Quite windy weather.....

 

[BlueHedgehog074]

The models generally agree with mild and disturbed weather continuing for the next few days or so as Low Pressure sits about to our West pumping up mild South-Westerly winds. The Westerm side of the UK looks to be the worst affected where the Low Pressure systems will be at their most influential, although many areas of the UK are likely to experience rain and showers from time to time. Their seems to be good agreement as well for Low Pressure to gradually transfer Eastwards/North-Eastwards, with a flatter Westerly airflow following on from behind. What happens beyond then is still kinda open for questions, although it looks like some sort of mobile Westerly pattern will continue. I suppose if the Jetstream can become slack enough without the Polar Vortex becoming too powerful, it could help encourage enough amplification in the pattern with chances of cool Polar Maritime airflows (or possibly brief Northerly topplers) occurring - a bit like what is shown on the 00Z GFS in FI. Though having said that, the last few runs on some of the models have been trending in a cooler direction, maybe with a chance for wintry precipitation to invade some hilly areas to our North and over Scotland. This will, however, depend on the potency of the cool/cold airflows from the North-West/North.

Another option that did seem apparent was the possibility of a blocking High Pressure system developing over Scandinavia - whether this will still happen or not I'm not too sure (though it seems like some of the models have made less of a feature of this on their last few runs).

Even if a cold spell during the next 2 weeks doesn't materialise, I guess it's obviously not the end of the world with further chances along the path of Autumn and Winter. I suppose the models aren't always going to be like a 'basket of roses!', in regards to the weather we're after (whether it's mild and unsettled, mild and dry, cold and snowy, cool and windy etc). ;-)

[BLAST FROM THE PAST]

Can't post links on work computer, but two runs stand out to me. Having said that all models seem to be sizing up to bring an impactual storm or two to all UK and Ireland.....correct. The 00z GFS sends the track of the lows more southerly even going into Nov, and GEM at end of month has a southerly tracking LP crashing right over us. For me any model that brings in a big hit or two shifting track south are on the money and I'll call the ECM to shift track soiuth a bit. We have entered a period of weather that is going to put a strain on us with so much rain and then some stormy weather with gales/severe gales to chuck in on top. Interesting for sure but miserable for many I suspect.  I'm surpised there aren't more warnings out yet....cos IMO there should be as the ground is already pretty sodden in many areas.

 

 

 

 

BFTP

Edited October 21, 2013 by BLAST FROM THE PAST

[The PIT]

Unless I'm looking at different runs I can't see any stormy weather in the reliable time frame i.e gusts in up to 60 mph. Most of the winds seem to be 40mph range. Unpleasant but not high enough fort the warning level. Plenty of stuff in deep fI but that's the nearly always the case. Main problem this week will be the rain which warnings may be issued for later according to this mornings forecast.

Edited October 21, 2013 by The PIT

[Summer Sun]

Latest from Gibby

 

All models continue to show a very unsettled period to come. Through this week Low pressure remains close to or over the West and NW of the UK with very mild South or SW winds. There will be spells of rain at times, notably tomorrow as a potentially vigorous trough moves slowly East carrying some heavy and thundery rain as it goes, all this following today's more sporadic but still occasionally heavy rainfall, especially in the West. Behind the old front Wednesday will see more in the way of brightness with rainfall falling in the form of heavy showers perhaps heavy locally with thunder. Later in the week a new Low moves NE from the SW over Britain with further spells of wet weather before at the very end of the week and more likely into the first half of the weekend cooler and fresher NW winds look like sweeping South across Britain and as pressure rises briefly a window of fine weather is possible at some point through the weekend, especially in the South.

 

GFS makes little of this improvement with the weather remaining unsettled and windy throughout the latter part of next week and certainly through the week that follows as very potent storm systems cross the Atlantic on a very strong Jet Stream and wind up to the North of the UK bringing gale or severe gale force winds at times with fast moving spells of rain and heavy, squally showers, all this at it's worst in the North and West but not exclusively so. Temperatures would of fallen back from this week's very mild values with average levels more likely and with colder uppers over the North at times, showers could turn wintry over the hills at times. Very late in the run another brief colder and brighter period looks possible as a temporary ridge collapses SE over the UK with frost likely on at least one night before milder air returns to the NW later.

 

UKMO shows next Sunday shows a broad Westerly flow across the UK with a band of rain and drizzle moving East across the UK. The strong winds will ensure that temperatures remain on the mild side of average into next week, though not as mild as currently.

 

GEM also shows very changeable and often windy weather as we move through next week as Low pressure continue to feed into UK airspace from the Atlantic. Spells of rain and showers would be inevitable for all driven on by a brisk and often strong West or SW wind. Temperatures are also shown somewhat lower than recently across the UK at times with the chance of wintry showers over the Northern hills later next week but in general temperatures would still hold close to average.

 

NAVGEM too shows trough laden Westerly winds as we move into next week with rain and showers at times in temperatures close to average for late October.

 

ECM shows some very windy and wet weather potential next week as very deep Low pressure crosses East North of Britain. Later in the latter stages of it's run improvements do take shape as a ridge crosses East damping down the rain and showers and allowing a short window of dry and bright weather, especially across the South with the chance of a frost and the odd patch of fog midweek.

 

The GFS Ensembles show the general understanding between the members this morning is for unsettled and often windy weather to persist over the UK for some considerable time to come. Temperatures will fall back towards the October average next week but with little sign of any significant dry and cold weather to grace our shores anytime soon.

 

The Jet Stream remains the focal point for all this unsettled weather as it continues to cross the Atlantic and then over the vicinity of the British Isles for the next 10 days at least.

 

In Summary it's more of the same from the models this morning as the next two weeks look more than likely to continue unsettled, windy and wet at times. Some windows of drier and brighter weather are shown but they look unlikely to last more than 24-48hrs in any one place before the Low pressure conveyor belt returns. Temperatures, while mild or even rather warm at times this week look certain to fall back to more average levels next week and in any of the drier spells a grass frost is just about possible but with the winds often strong with gales at times only areas with good shelter, even under clear skies would experience this. Once again this morning there is little sign of this pattern being removed soon as the Jet stream continues to be strong and positioned at a latitude that puts the UK in the firing line of further Lows and fronts.

 

http://www.norton-ra...is(2859336).htm

 

Now available is a 7 day farmers forecast - http://www.norton-radstockweather.co.uk/NEW-FARMERS-7-DAY-FORECAST%282913973%29.htm

[Mapantz]

Unless I'm looking at different runs I can't see any stormy weather in the reliable time frame i.e gusts in up to 60 mph. Most of the winds seem to be 40mph range. Unpleasant but not high enough fort the warning level. Plenty of stuff in deep fI but that's the nearly always the case. Main problem this week will be the rain which warnings may be issued for later according to this mornings forecast.

 

The GEM has been modelling a fairly potent low quite a few times now, as has the GFS, at about T+160 or so. I can understand why some of these models are doing it, they're taking in to account the colder air and the fact that the PV has gone on the move. We all know that the GFS tends to over do it, even up to around T+72 - I think a few ECM PB's last week were showing something a bit lively?  

If the low that the GFS is modelling actually came off like that, i would imagine it would be quite nasty, it seems to hang around  in the West for quite some time. I just get this feeling, something could be lurking around the corner. 

Edited October 21, 2013 by Mapantz

[BLAST FROM THE PAST]

Unless I'm looking at different runs I can't see any stormy weather in the reliable time frame i.e gusts in up to 60 mph. Most of the winds seem to be 40mph range. Unpleasant but not high enough fort the warning level. Plenty of stuff in deep fI but that's the nearly always the case. Main problem this week will be the rain which warnings may be issued for later according to this mornings forecast.

And if you read it properly pit you'll see I'm talking about the rain re warnings as the ground is sodden with the stormy weather to come later on top of it.BFTP Edited October 21, 2013 by BLAST FROM THE PAST

[Bobby]

More of the same from the models today, looking unsettled for the rest of the month with a strong Atlantic flow with abundant rainfall, especially in the N/W as usual. Could be a deep stormy low or two at some point as well. GFS 06z looking especially unsettled out to +384.

NAEFS supports the unsettled theme to the end of the month, then a slight lifting of the low pressure anomalies for a few days then they restablish at the end of the run. ECM ensembles similar at day 10. Probably turning cooler compared to what we've seen recently but nothing wintry unless you live on Cairngorm.

 

NAEFS

 

ECM ensembles

[bluearmy]

Naefs trending away from the week 2 height rise just to our east. Ecm, whilst not going as far out hasnt looked keen on its day 10 output re following suit.

Of course, the pendulum could swing back again come tomorrow!

[Frosty.]

Totally agree with Fred (BFTP) Flooding is going to occur this week in the most vulnerable areas and localised flooding elsewhere because there is going to be a full months worth of rain during the next week which is going to swell the river system to critical levels, the models are looking extremely unsettled, take care all. : - )

[Bobby]

Totally agree with Fred (BFTP) Flooding is going to occur this week in the most vulnerable areas and localised flooding elsewhere because there is going to be a full months worth of rain during the next week which is going to swell the river system to critical levels, the models are looking extremely unsettled, take care all. : - )

 

Looks likely, warnings for rainfall out from the Met Office for today and tomorrow across the SW/Wales, can see why with the NAE/NMM suggesting 50-75mm of rain to come by the end of tomorrow

 

 

Over 100, maybe 150mm in places over the next week or so on the GFS

 

[Tamara]

The trend continues to suggest that the bulk of the strengthening polar vortex will migrate across the pole and extend more towards the Canadian side of the arctic and as cold air is released from here, this will assist in steepening temperature gradients in the north atlantic and fuelling the jet stream coming off the eastern seaboard of the US/Canadian continental landmass. Hence no surprise to see hints of deep lows crossing the atlantic in the further outlook on much of the present modelling (at 7 days and beyond)

 

The further invigorated atlantic pattern is well adverstised by the ECM ensemble maps

 

On that basis it is understandable that the suggested NAEFS anomaly patten is adjusting accordingly with the pattern flattening zonally and a traditional +AO/NAO scenario evolving.  The exact track of the jet stream will determine the extent and influence of these lows - but all areas look to see unsettled and very windy conditions to start with in at least the 7 to 10 day period.

 

In the shorter term, this week we see a continuation of the more southerly airstreams and well above average temperatures, but as the vortex to the NW becomes more influential we will see low pressure tracking on the more traditional path out of NE Canada. This will turn the wind more definitively south westerly/westerly and mean that temperatures will adjust accordingly a little downwards - but never far from normal/ a little above in the south.

 

It is conceivable with time that the jet stream will re-adjust far enough north for pressure to rise somewhat south as a downstream ridge response signal, and thus areas to the south and east of the UK may see rather less unsettled conditions, but should this occur then it is unlikely until at least the first week of November.

 

There isn't anything to be read into this pattern in terms of anything unpalatable for winter at this stage, and the stratosphere usually is undergoing its seasonal cooling period at this time of year, with associated vortex strengthening. Indeed, there could be an argument to suggest that we would rather see this start now than in 6 weeks time. Lots can happen before then

Edited October 21, 2013 by Tamara תָּמָר

[Frosty.]

 Probably turning cooler compared to what we've seen recently but nothing wintry unless you live on Cairngorm.

 

 

When you consider the temperatures are currently in the 16-18 celsius range, if they can drop to the 10-12c range it will feel wintry, especially in strong to gale force winds which will make 11c feel like 5 celsius, if we can get max temps into single digits celsius I will consider that a major victory when you look at how warm the autumn has been overall.

[egret]

 

Looks likely, warnings for rainfall out from the Met Office for today and tomorrow across the SW/Wales, can see why with the NAE/NMM suggesting 50-75mm of rain to come by the end of tomorrow

 

 

Over 100, maybe 150mm in places over the next week or so on the GFS

 

Meto have issued alerts for Thursday and Friday also (Devon/Cornwall) so that will be heavy rain for 6 out of 7 days.  Nature has its ways of catching up!

[draztik]

 

The total rainfall out to day 8 from this mornings GFS 6z highlights the possibility of flooding for parts of Wales & the SW specially, where 5 inches + could fall. The MetO now has warnings for this problem in these areas.

Edited October 21, 2013 by draztik

[egret]

Mr model rollercoaster, you have posted some good analysis in the past and I know that from personal contact with you, but this post adds nothing to the Model Output discussion part of this thread, so please think again when posting and the same goes for everyone. On your question re: November, I have an open mind as to how things might develop towards the end of this month and I composed a post in the CSE & SW thread yesterday suggesting some thoughts. Not a lot has changed in the meanwhile IMHO but the model output over the coming days may help guide us towards an early trend. November is certainly a long way off yet and is pretty much beyond the realms of FI in terms of what the current models are capable of predicting. In the meanwhile, the overwhelming headline is WET, WET, WET, but "at least it will be mild".

A bit harsh? If I were to make  an observation on the model runs and how future model runs in FI might develop, I would not argue with MR.

 

A week or two back the unsettled spell looked brief indeed, but as so often happens the changes keep getting delayed and allow a continuation of the current pattern. 

Tamara's observation re shift of PV however is also worth watching to see if it triggers the shift in jetstream required to usher in drier, colder weather.

 

A most interesting period for model watching. Time to wind up the old barograph and put a new paper in it!