Model Output Discussion - Late October Onwards

[SLEETY]

Well it would be nice to see a pattern shift.This Euro-trash High is becoming a bit of a pain now,with endless s/w winds and heavy rain for many places.

At least we are seeing these conditions now rather than mid-dec to mid Jan when we most wouldn't want a euro-junk high seemingly stuck and not wanting to budge.

[Liam J]

GFS 00z run has just demonstrated well how it can be pointless watching FI on each run and hopecasting, it has flipped completely from the cold scenario of the 18z which had cold northerly winds and polar air, GFS is now showing a very mild FI with Southerly winds as a LP stalls out west and later replaced by a cell of HP with 850 temps of +4 to +8c.

Ensembles show a few colder options in FI, these will need to now trend into the reliable time frame and gain other support.

ECM 00z also shows some unsettled and very mild conditons with a southerly or south westerly flow and 850 temps of +8 to +10c at times, LP dominating the scene with periods of rain and strong winds affecting many areas.

Edited October 27, 2011 by Liam J

[Radiating Dendrite]

GFS 00z run has just demonstrated well how it can be pointless watching FI on each run and hopecasting, it has flipped completely from the cold scenario of the 18z which had cold northerly winds and polar air, GFS is now showing a very mild FI with Southerly winds as a LP stalls out west and later replaced by a cell of HP with 850 temps of +4 to +8c.

Ensembles show a few colder options in FI, these will need to now trend into the reliable time frame and gain other support.

This is always the case, it does it on pretty much every run

As you say, it will be interesting to see what the ensembles do in the next few runs. Will more go colder or will the cold ones go milder.

[johnholmes]

GFS 00z run has just demonstrated well how it can be pointless watching FI on each run and hopecasting, it has flipped completely from the cold scenario of the 18z which had cold northerly winds and polar air, GFS is now showing a very mild FI with Southerly winds as a LP stalls out west and later replaced by a cell of HP with 850 temps of +4 to +8c.

my, do I have a convert?

[Gibby]

Good morning. Here's a look at the 00zs from GFS, UKMO and ECM for Thursday October 27th 2011.

GFS continues to show the weather governed by Atlantic depressions for the reliable timeframe. Todays rain in the South should clear tonight as a ridge moves across tomorrow. Over the weekend SW winds freshen with rain at times, at first in the NW extending slowly SE to all areas early next week. Before that though the South and East should have a fairly dry and certainly very mild weekend once more. Longer term the operational shows depressions piling in from the West and stalling near to the UK giving rain and strong winds at times but with Britain staying on the mild side of the systems for the most part temperatures should remain respectable with little fog and frost. High pressure is shown over Scotland at the end of the run and should it verufy all areas would become dry and colder with the chance of a touch of frost in the North and a chilly East wind in the South.

The GFS Ensembles continue to be uneventful other than offering rainfall in frequent measure while temperatures remain close to the long term average for all with little fluctuation, especially in the South.

UKMO brings a ridge of High pressure across Southern Britain tomorrow with todays rain and tonight's possible fog giving way to bright spells through the day. The weekend then shows the NW see freshening winds and rain which gradually extend SE to reach Kent probably on Monday. Beforehand the South and East would see a very mild weekend again with bright conditions prevailing. As we move into next week and the end of the run the weather becomes mild and unsettled for all with fresh to strong SW winds and rain at times.

ECM brings the unsettled weather to the SE a little quicker, probably later on Sunday. From then on to the end of its run the weather remains changeable with rain or showers and strong winds at times. With Britain staying for the most part on the warm side of the deep Atlantic troughs for much of the time the weather would remain on the warm side of average especially in the South and East.

In Summary it's the same Autumn picture painted between the models this morning with rain at times for all in the coming couple of weeks. Temperatures are favoured to stay nothing less than normal for most with conditions mild at times in places towards the South and East. Some drier and brighter conditions are likely between depressions when the slightest touch of frost and mist are just about possible to occur.

[Frosty.]

As already mentioned, the models have changed again overnight with no chance of any cold air reaching the uk before mid november. The Euro trash High looks like having enough strength to the east to stop any atlantic lows making it far enough east to allow any colder NW'ly winds even in the depths of FI! The models show next week being unsettled but mild as the uk is bathed in Tropical maritime air and it does look windy with spells of rain, it may then turn a little cooler but remain rather unsettled further into the outlook with temps returning to average, the Gfs 00z then builds high pressure across northern britain which would lead to some fog and frost but I already get a sense that we may be chasing shadows in terms of any cold snaps throughout november at least.

[johnholmes]

And meanwhile the 500mb anomaly charts continue with their version they showed yesterday and for several days now!

[phil nw.]

Looking at the mean heights day 8-10 there`s no sign of any pattern change in the medium term.

The Atlantic trough close by to the West and the Euro.block away to the East.

The upper flow continuing from a West or South Westerly quarter with occasional brief ridging between rain bands.

Upstream the pattern looks rather flat so little prospect of any real cold incursions from North of West at the moment.

MJO in Phase 2 at present and the composite heading into November supports the 10 day outlook at 500hpa level.

Edited October 27, 2011 by phil n.warks.

[johnholmes]

the only thing I would add to my cryptic post above and that well illustrated post from phil above is this

The two models have over the past 2 days begun to show some sign of that upper ridge and +ve heights edging NW. It needs at least a couple more days before, and assuming the NOAA version follows them, to perhaps see something different developing.

Too early to say yet.

[Liam J]

my, do I have a convert?

LOL John, I take it you mean having a more realistic view on the outputs in FI?

[cyclonic happiness]

the only thing I would add to my cryptic post above and that well illustrated post from phil above is this

The two models have over the past 2 days begun to show some sign of that upper ridge and +ve heights edging NW. It needs at least a couple more days before, and assuming the NOAA version follows them, to perhaps see something different developing.

Too early to say yet.

I like the sound of where that may be going

[chionomaniac]

And meanwhile the 500mb anomaly charts continue with their version they showed yesterday and for several days now!

Looking at the mean heights day 8-10 there`s no sign of any pattern change in the medium term.

The Atlantic trough close by to the West and the Euro.block away to the East.

The upper flow continuing from a West or South Westerly quarter with occasional brief ridging between rain bands.

Upstream the pattern looks rather flat so little prospect of any real cold incursions from North of West at the moment.

MJO in Phase 2 at present and the composite heading into November supports the 10 day outlook at 500hpa level.

I have to say this pattern has been foreseen for some time now. I know that this pattern may be the 'form horse' for this time of year but I can't ever remember being so confident that a pattern (Atlantic/Iceland trough) will prevail for some time before it does, and then watching it happen. It helps when the majority of teleconnective factors pointed to the same solution and continue to do so. For those that still doubt in the usefulness of teleconnections do take note and don't ignore this just because the pattern isn't cold!

[No Balls Like Snow Balls]

Looking at the mean heights day 8-10 there`s no sign of any pattern change in the medium term.

The Atlantic trough close by to the West and the Euro.block away to the East.

The upper flow continuing from a West or South Westerly quarter with occasional brief ridging between rain bands.

Upstream the pattern looks rather flat so little prospect of any real cold incursions from North of West at the moment.

MJO in Phase 2 at present and the composite heading into November supports the 10 day outlook at 500hpa level.

I have a question! To my untrained eys the GFS 500MB chart shows heights much further North and not as intense as the ECM chart, would this indicate a change in pattern maybe within the 7-10 day time frame and a transfer of heights further North?. I am trying to understand how these 500MB thingy charts work.

[shedhead]

Looking at the mean heights day 8-10 there`s no sign of any pattern change in the medium term.

The Atlantic trough close by to the West and the Euro.block away to the East.

The upper flow continuing from a West or South Westerly quarter with occasional brief ridging between rain bands.

Upstream the pattern looks rather flat so little prospect of any real cold incursions from North of West at the moment.

MJO in Phase 2 at present and the composite heading into November supports the 10 day outlook at 500hpa level.

Do you have a link to those charts plz Phil?

[Radiating Dendrite]

I have a question! To my untrained eys the GFS 500MB chart shows heights much further North and not as intense as the ECM chart, would this indicate a change in pattern maybe within the 7-10 day time frame and a transfer of heights further North?. I am trying to understand how these 500MB thingy charts work.

There may be some weak development of heights, but this would not stop the current pattern with the trough still out west.

The ECM has been more accurate with this development I believe, so I would place greater emphasis on what that is showing.

[No Balls Like Snow Balls]

There may be some weak development of heights, but this would not stop the current pattern with the trough still out west.

The ECM has been more accurate with this development I believe, so I would place greater emphasis on what that is showing.

Ok cool. Thanks for that. I just want this Euro high out the way so we can get some more transient weather moving across the whole country rather than the South West gggrrr.

[Frosty.]

I like the sound of where that may be going

A cold snap before christmas would be nice but there is currently no sign of any cold weather reaching the uk until mid nov at the earliest unless the op runs change again soon. I was looking forward to a Northerly blast in around a week but that is looking extremely unlikely now.

[nick sussex]

The smallest hint this morning that those positive anomalies might begin to edge nw and allow the troughing to dig a little more into southern Europe which could eventually lead to something a little colder or at least average.

The GEFS does suggest this and the GFS operational run also within 240hrs, the ECM is much more reluctant to do this so its a case of waiting to see which model is right. Theres no way out of the current pattern if this ridge remains to the east and southeast.

Personally I'm hoping the GFS is right to allow for some decent mountain snows as the skiing season is fast approaching.

Edited October 27, 2011 by nick sussex

[phil nw.]

I have a question! To my untrained eys the GFS 500MB chart shows heights much further North and not as intense as the ECM chart, would this indicate a change in pattern maybe within the 7-10 day time frame and a transfer of heights further North?. I am trying to understand how these 500MB thingy charts work.

There are minor differences for sure but the overall global pattern of ridge,trough around the hemisphere are pretty similar-remember these are mean charts for days 8-10 from both runs so to get a mirror image for both would be unusual.

Upstream signals as i illustrated show no promise of any major change to this in the next 7-10days.

Do you have a link to those charts plz Phil?

Here you go

http://www.cpc.ncep....k/MJO/mjo.shtml

http://raleighwx.ame...wx.com/MJO.html

http://www.cpc.ncep....day/fxus06.html

Hope this helps.

Edited October 27, 2011 by phil n.warks.

[shedhead]

There are minor differences for sure but the overall global pattern of ridge,trough around the hemisphere are pretty similar-remember these are mean charts for days 8-10 from both runs so to get a mirror image for both would be unusual.

Upstream signals as i illustrated show no promise of any major change to this in the next 7-10days.

Here you go

http://www.cpc.ncep....k/MJO/mjo.shtml

http://raleighwx.ame...wx.com/MJO.html

http://www.cpc.ncep....day/fxus06.html

Hope this helps.

Thanx Phil, much appreciated.

[memories of 63]

Well FI 500mB charts are starting to repeat, run to run and may indicate a move towards cooler weather. It all depends on where the jet goes from mid Nov onwards. A dive into Africa would be nice :-)

[johnholmes]

LOL John, I take it you mean having a more realistic view on the outputs in FI?

true

I have to say this pattern has been foreseen for some time now. I know that this pattern may be the 'form horse' for this time of year but I can't ever remember being so confident that a pattern (Atlantic/Iceland trough) will prevail for some time before it does, and then watching it happen. It helps when the majority of teleconnective factors pointed to the same solution and continue to do so. For those that still doubt in the usefulness of teleconnections do take note and don't ignore this just because the pattern isn't cold!

well said ch

[ribster]

well said ch

I don't think anyone doubts the usefulness of teleconnections as a tool, but they also indicated did they not, that summer would be rather blistering, but it wasn't. That's not to say that we won't be stuck in the current pattern for some time, but lets not get ahead of ourselves, as the situation can and does change, as it clearly did late spring/early summer.

my, do I have a convert?

A convert? Is it not you John that says it is pointless comparing consecutive runs, i.e. in this case, the 18z and 0z, but to use the same run or couple of runs each day and compare those. There are often wild swings between consecutive runs, but less so when comparing the same run.

Edited October 27, 2011 by ribster

[Frosty.]

The Gfs 06z is a little more progressive and pushes the main trough into scandinavia eventually but it's a bit like pulling teeth without anasthetic, a painful process to watch. It doesn't really bring much of a cold surge to the uk, if the uk was 500 miles further west then the 6z has an early arctic plunge but as it is, the 6z does bring a cool down beyond the mild and unsettled spell next week followed by a mid latitude high settling down over the uk for several days later so the 6z does offer more hope of something colder but the odds still favour the main low to not move eastwards enough to drag the cold air south sadly.

[Thundery wintry showers]

A dry, sunny and warm interlude for the 28th/29th October previously looked likely across England, but the 28th October now looks like having a weak front produce some residual cloud, especially across south-east England. Some places will nonetheless have some hazy sunshine. The 29th looks set to be notably warm across the south-eastern half of England with a fair amount of sunshine, but cloud will be increasing across the north-western half. Meanwhile, Scotland, Ireland and Wales look set to remain cloudy with rain at times.

After that, it continues warm, but not particularly sunny- a lot of cloud and some rain can be expected due to the generally tropical maritime flow and low pressure, with the west again seeing most of the rain, rather than the parched parts of central and eastern England. There is a chance that we could start to see a returning polar maritime influence return in about a week's time associated with deep lows to the west, giving sunshine and showers and temperatures nearer average, but this is a long way off and prone to change as the blocking high to the east could easily keep us locked in tropical maritime air for a while longer.

Nothing unusual for the time of year, but the south-westerlies and Tm air will help to keep temperatures a good few degrees up on the long-term seasonal average.