Model Output Discussion 26/10 2012 >

[Mark Bayley]

Yes, Phil, - one definitely needs to look at the bigger picture!

Don't just look at the Europe based charts or you could end up disappointed. At T+216 we never see true verification but we do see great trends!

Also that far out I don't look at the 850's (or not seriously) - the pattern is far more important.

Thats a good point, whenever i view a model run i always view it at the hemispheric scale first, never on the European.

The ECM is only one run, the GFS also shows a disrupted PV, and manages to keep us cool for most the run and deliver a northerly at the end. Whats important at the moment is getting a disrupted and disorganised PV, which the models show. What we in the UK get from it remains to be seen, and will vary from run to run

Edited November 1, 2012 by Mark Bayley

[BLAST FROM THE PAST]

The ecm imo is too soon, however, it again demonstrates that we 'could' get the flip to very mild conditions I'm anticipating later in the month. If it does happen it isn't winter death knell, as its very amplified and blocked.

Frosty, re longevity well lets say if it happens I'm expecting it to see Nov out unless the flip does come earlier.....lets see

BFTP

Edited November 1, 2012 by BLAST FROM THE PAST

[Cloud 10]

The 12z ECM looks out of kilter in the later stages of its run compared to its earlier 00z

and ensembles,so maybe one for Nick Sussex's shredder!

The JMA at +192 looks more realistic.

JMA.. ECM..

[EML Network]

It's nice to see both the GFS falling pretty much in line with the NAO forecast.

The High Pressure over Greenland goes away, but quickly re builds , it's no co incidence therefore to see the NAO forecast to go into a brief positive phase, followed by a quick dive back into the negative.

I am in the BFTP camp when it comes to December though, just can't see anything other than a mild month...however If I didn't have access to the CFS charts, then I probably wouldn't even have an opinion about December, so I could well be wrong as it's all I am using to base that assumption on.

[A Winter's Tale]

Good evening. A showery night is on the cards for many places - particulary western Scotland, western parts of Wales, Ireland and England and the southern coast of England - in a cool westerly wind and these showers will fall as snow on the mountains. When there are no showers in sight there should be some clear spells overnight and some good clear spells for a good parts of England away from western, south western and southern parts and clear night skies may extend into southern and eastern Scotland and Ireland may have clear skies for periods too. A pretty chilly night too with typical lows of 4 to 8C and below freezing in a few spots in highland Scotland.

There should be a good deal of sunshine during Friday morning but showers should continue across northern Ireland, western Ireland and into the south western parts of Scotland and showers also continuing across southern and south western parts of England and Wales. Further east and inland things should be drier. Friday afternoon and evening should see more showers across wester areas but Scotland may remain drier and clearer for a period and eastern parts of England should also stay on the dry and clear side with the odd shower make it's way to north eastern England. Maximum temperatures should be 6 to 10C. Friday night should see showers continue in the seas around southern and south western England and Wales and some showers around the north west coast of Scotland but drier further east with some clear spells. Another cold night with lows of -1 to 7C.

There should be further shower activity during Saturday with showers situated across southern areas and western parts of Ireland and Scotland, should be drier north of Cardiff-London and away from western coasts and some sunny breaks across eastern parts of Scotland. Maximum temperatures on the low side with highs of 5 to 10C. Saturday night should see showers and some organised features across much of Scotland aswell as northern England and parts of Ireland and some showers may continue to lurk near the western side of Wales. Drier across a large part of England and Wales - particulary in the south and east with the possibility of clear night skies. Another cold night with lows of -1 to 7C.

Sunday could see the showery theme continuing with many western areas at risk and possibly something more persistent and heavier in the way of precipitation across southern England. Drier away from the west coast across inland areas of Scotland and a good chunk of England. Maximum temperatures possibly 4 to 11C.

Sunday night could see precipitation across large parts of England and Wales but possibly drier in the south west and lighter precipitation in the northern England. And showers should continue around some western coastal parts of Scotland and Ireland. Minimum temperatures of 1 to 8C.

Monday may be another day of showers in places - possibly western areas and some southern areas and possibly some showers across eastern parts of England. But inland it should be fairly dry and a drier day for Scotland with the possibility of sunshine. Maximum temperatures of 10 to 8C. Overnight some showers still lingering near the east coast of England and some showers near the western coasts but a mostly dry night - particulary inland - with some clear spells. A cold night with lows of 0 to 6C.

So an interesting few days coming up with plenty of showers and temperatures on the cold side with little significant frontal activity. Looking at the models, with high pressure to the south west for the British Isles winds could from a northerly on Monday to a westerly on Tuesday with some warmer upper air but where that area of high pressure goes after Tuesday is open for debate but I'd imagine that the possibility of changeable and at times unsettled autumnal weather would continue but as high pressure shifts locations there could be more settled spells with high pressure close to the British Isles or even possibly another shot at a northerly depending on where it's going next.

[Frosty.]

Over the next few weeks, we should see a 10 day periodicity in the waxing and waning of blocking signal (placement further north of the mid Atlantic ridge) tied into mountain torque activity. The next MJO wave entering the western hemisphere will signal a step change in the blocking signal, full Greenland block or more significant amplification expected (late November).

It's worth highlighting a part of GP's post from this morning at this point, more significant amplification with depressions diving southeast across the uk, the latest ens mean today also supports an unsettled and cold further outlook beyond the briefly more settled interval next week, mid atlantic high (ridging north to greenland) which would divert the jet loop south of the uk over northern/central france with the uk very much on the cold side, as we famously had in late nov and throughout december 2010. it's still early days of course but i'm optimistic we will have several more potent cold incursions through mid/late nov into dec and lots of cold zoneality before then too.

Edited November 1, 2012 by Frosty039

[EML Network]

yes, if looking for future cold potential, it is essential to look at the hemispheric pattern, rather than the conditions the UK is in.

you may look at this chart and say this is terrible for cold lovers as their is warm air is being pumped up from the south over the UK.

This is completely irrelevant if your looking for future cold

a look at the H500+SLP shows an area of high pressure in the Atlantic and low pressure to the south of the UK. yes there is a euro high which is causing the UK to be under the influence a mild airflow, but there is good potential for cold down the line.

And finally, a look at the hemispheric pattern is very encouraging. The polar vortex is incredibly week and fragmented,there is clear potential for the UK to experience a cold spell later on.

Of course this chart is 240 hours away, and subject to change,but I am just using it to illustrate a point

I do not see solid evidence of a cold spell anytime soon, but I also cannot see much sign of a strong Polar vortex being sustained, it is going to gain in strength soon but already there are hints it may become weak again. Stratospheric temperatures did take a dive earlier but subsequent warmings have bought it back to average levels.

There is certainly very little sign of the Atlantic having much of an effect on the UK, or a strong jet stream.

I think there is a good chance of a cold spell fairly soon, for now though, all eyes to the pole to see how strong the PV gets and if it can be sustained.

Yes very much agree with that, with High pressure building over Iceland then the chances for cold further down the line a massively increased !

[Uncle_Barty]

ECM 216 = Yuck.

Sure, Greenland High and blocked Atlantic, but its West Based, we end up in mild Southerly winds whilst cold air digs down into the Atlantic

Why "yuck?"

I hope we can get through as much of 2nd half of autumn/early winter and preferably to March as possible without freezing cold weather increasing my heating bills and risking life and limb on my longish commute to work each day. Not to mention wrecking the sporting programme!

Milder the better so far as I'm concerned. Don't assume everyone on this thread wants us in the freezer!

Anyway, enough of that!!

However, I don't get the impression I will get my wish... certainly an unusual pattern exists and I can't remember a year when the PV appears very reluctant to get going at this stage. I think any milder spell will likely be short-lived with the hints of HP over Iceland.

Edited November 1, 2012 by Jim_AFCB

[damianslaw]

Models continue to suggest the trough will continue to have the upper hand for the foreseeable future with any ridging being very weak and temporary, with the jet forecast to stay on a rather southerly course - as it has done since April. Reliable timeframe more of the same, cold and unsettled, temperatures at the moment are on a par with what we normally see in early December - this is a 'cold set up' full of proper polar air no denying the fact, snow is falling to quite low levels in these parts, around 1,000 ft as evaporative cooling kicks in and in clearer breaks many places will always be exposed to the risk of frost.

Strong agreement from ECM and GFS that once the trough finally moves away to the east - what a slow process! we will see a shortlived spell of ridging mid week and milder conditions with a westerly flow, but nothing particularly mild for the time of year. Beyond the reliable timeframe, strong signals that we will maintain stronger than normal heights to our NW forcing the jet loop on a NW-SE trajectory once again with a significant chance thereafter of opening up the arctic floodgates.. this looks a locked in pattern, and a cold pattern for the time of year, its been a long time since we have seen a predominantly cold unsettled November with polar maritime air dominating.. Nov 96 probably the last time.

[stewfox]

It's worth highlighting a part of GP's post from this morning at this point, more significant amplification with depressions diving southeast across the uk, the latest ens mean today also supports an unsettled and cold further outlook beyond the briefly more settled interval next week, mid atlantic high (ridging north to greenland) which would divert the jet loop south of the uk over northern/central france with the uk very much on the cold side, as we famously had in late nov and throughout december 2010. it's still early days of course but i'm optimistic we will have several more potent cold incursions through mid/late nov into dec and lots of cold zoneality before then too.

BFTP is suggesting a potential flip to milder conditions post mid month, your suggesting the jet could stay further south ? and/ or colder conditions.

Does it relate to where the Greenland block sets itself up ?

[BLAST FROM THE PAST]

BFTP is suggesting a potential flip to milder conditions post mid month, your suggesting the jet could stay further south ? and/ or colder conditions.

Does it relate to where the Greenland block sets itself up ?

Yes, my thoughts are 'unusually' mild spell which is likely to be achieved in very amplified pattern, so position of blocking the key.

BFTP

[Frosty.]

BFTP is suggesting a potential flip to milder conditions post mid month, your suggesting the jet could stay further south ? and/ or colder conditions.

Does it relate to where the Greenland block sets itself up ?

A lot depends on the persistence of the mid atlantic high/ridge and whether it can extend north and link up with the greenland high, the result would be the the jet being much further south, I got the impression from GP's post this morning that we have a good shot at some wintry spells mid to late november but BFTP is going for something a lot milder after the next few weeks of potentially cold zonal weather, given the way the ens mean looks today, a colder second half of the month is possible as things stand but the weather models can make a mockery out of predictions as we all know.

[ITSY]

much better arctic ridging and blocking in GFS 18Z FI

[SnowObsessor90]

much better arctic ridging and blocking in GFS 18Z FI

Indeed plus where in the world is the Vortex lol

[damianslaw]

Low pressure systems tend to be at their deepest in late November and early December as the thermal temperature gradient difference between the arctic and atlantic is at its most marked, so if we maintain the current NW-SE tracking jet with stronger than normal heights to the NW, expect the low pressure systems to be much deeper as the month wears on and therefore more capable of pulling down bitter cold from the north with a very notable amplified jetstream profile which would be more conducive to stronger heights to the NW. What I'm saying is if the current pattern holds the chances of a potent arctic blast verifying will increase more and more as the month wears on..

[Tim Bland]

My understanding is that BFTP is suggesting the ridge in the Atlantic shifts over the UK or to the East of us, sucking up warm air from the south. If the ridge stays to our West it gives us cold to our East it gives us warm. Allot more complicated than that but that's it in a nutshell. Personally I think it will stay to our west as the heights around Greenland just won't give into the PV and are supporting it.

Edited November 1, 2012 by Tim Bland

[Severe Siberian icy blast]

Yes, my thoughts are 'unusually' mild spell which is likely to be achieved in very amplified pattern, so position of blocking the key.

BFTP

As you keep on telling us every single post for the last 3 days or so, lets just wait and see its a long way off yet, but you seem very certain of this forecast , you obviously feel we will have a very west based -NAO , not saying your wrong, but we don't no yet, even the most experienced of forecasters comment on general trends but are very vague with detail but you seem to know the exact position of the block , I for one hope your wrong, but I appreciate your inputs on hear there very good, but when it comes to forecasting for me il only ever have faith with two professionals . . . .and yes they are both on hear.

[ITSY]

in fact if you want to see a massive cold spell in mid november look at CFS daily on meteociel. unreal run in early FI

[stewfox]

in fact if you want to see a massive cold spell in mid november look at CFS daily on meteociel. unreal run in early FI

I wish people would post the links. Summary with links as JH and others have said and if you can add a black pen mark with your proposed postioning of where the highs and lows are going to go even better.

[karlosvandango]

ITSY, could you post a link, I don't know how to get there and would love to take a look.

[BLAST FROM THE PAST]

As you keep on telling us every single post for the last 3 days or so, lets just wait and see its a long way off yet, but you seem very certain of this forecast , you obviously feel we will have a very west based -NAO , not saying your wrong, but we don't no yet, even the most experienced of forecasters comment on general trends but are very vague with detail but you seem to know the exact position of the block , I for one hope your wrong, but I appreciate your inputs on hear there very good, but when it comes to forecasting for me il only ever have faith with two professionals . . . .and yes they are both on hear.

I am only answering questions. And if you have read my posts its clear I'm suggesting it may and not saying it will happen as I indeed hope GP gets it spot on...I'm a coldie. Nice you have faith in two forecasters, I don't and that includes myself

[stewfox]

ITSY, could you post a link, I don't know how to get there and would love to take a look.

Some cold intrusions post T320 ? Trying to assist, I wouldn't post charts so far out

http://www.meteociel...&carte=0&run=10

Edited November 1, 2012 by stewfox

[BLAST FROM THE PAST]

My understanding is that BFTP is suggesting the ridge in the Atlantic shifts over the UK or to the East of us, sucking up warm air from the south. If the ridge stays to our West it gives us cold to our East it gives us warm. Allot more complicated than that but that's it in a nutshell. Personally I think it will stay to our west as the heights around Greenland just won't give into the PV and are supporting it.

Or west based -ve NAO as per 06z deep FI, anyway more interesting weather patterns to get through, I'm liking the runs...very chilly autumnal weather

BFTP

Edited November 1, 2012 by BLAST FROM THE PAST

[Frosty.]

I am only answering questions. And if you have read my posts its clear I'm suggesting it may and not saying it will happen as I indeed hope GP gets it spot on...I'm a coldie. Nice you have faith in two forecasters, I don't and that includes myself

Hi fred, thanks for answering my question earlier.

I have high respect for your methods as much as I do for GP's so it's a difficult call beyond mid month and as you said, the position of the block will be crucial, just hope we are on the right side of it. I have been impressed by the weather patterns so far as we go further into autumn compared to the nightmare 12 months ago when there was no sign of cold at the end of the tunnel, things look a lot better as we move forward into the rest of november.

[BLAST FROM THE PAST]

Hi fred, thanks for answering my question earlier.

I have high respect for your methods as much as I do for GP's so it's a difficult call beyond mid month and as you said, the position of the block will be crucial, just hope we are on the right side of it. I have been impressed by the weather patterns so far as we go further into autumn compared to the nightmare 12 months ago when there was no sign of cold at the end of the tunnel, things look a lot better as we move forward into the rest of november.

Actually its making early winter a difficult call IMO, and very interesting hemispheric response to a cooling stratos...blocking and no organised PV, it so reminds me of 85/6. I'm eagerly awaiting his {GP} LRF

BFTP