Model Output Discussion

[TEITS]

It's more likely a mobile atlantic driven pattern will win out next week IMO.

Where have I heard that before!

Whilst im not keen on the trend in the medium term, i've also learn't not to make too many assumptions. The chance of the E,ly remains IMO but how cold is uncertain and the pattern afterwards is even more uncertain.

Due to the model uncertainity I feel we should go with the flow instead of making predictions.

[Frosty.]

Where have I heard that before!

Whilst im not keen on the trend in the medium term, i've also learn't not to make too many assumptions. The chance of the E,ly remains IMO but how cold is uncertain and the pattern afterwards is even more uncertain.

Due to the model uncertainity I feel we should go with the flow instead of making predictions.

All i'm saying Dave is that the models seem to be veering away from an E'ly, I had hoped the ecm 12z yesterday would just be a blip but it's not and even the gfs 00z is nowhere near as wintry as the 12z yesterday, the gem 00z takes most of the really wintry weather into mainland europe instead.

[Weather-history]

Given the mixed output and disappointing ecm I would think the meto update today will be much more sober in tone as the big models jump overboard. It's more likely a mobile atlantic driven pattern will win out next week IMO.

As I said before, it really all depends on that track and intensity of low in the Icelandic region. You can see what the difference can make by the GFS 0z and GFS 06z op runs. And that is just down to the track.

ECM has it further east then most of the other models and it could be very well overegging the intensity of the low.

Edited January 20, 2010 by Mr_Data

[TEITS]

All i'm saying Dave is that the models seem to be veering away from an E'ly, I had hoped the ecm 12z yesterday would just be a blip but it's not and even the gfs 00z is nowhere near as wintry as the 12z yesterday, the gem 00z takes most of the really wintry weather into mainland europe instead.

I don't think they are veering away from an E,ly with the exception of the ECM. The uncertainity is in regards to how cold the E,ly will be. Just the smallest synoptic change in the LP near Iceland and the positioning of the block can make huge differences to what we experience on the surface.

I really wouldn't want to call this at the moment. The block will eventually sink but what happens after is even more uncertain!

The difference between the 0Z/06Z at +162 is incredible with regards to what happens to the PV!

Edited January 20, 2010 by THE EYE IN THE SKY

[weather eater]

Where have I heard that before!

Whilst im not keen on the trend in the medium term, i've also learn't not to make too many assumptions. The chance of the E,ly remains IMO but how cold is uncertain and the pattern afterwards is even more uncertain.

Due to the model uncertainity I feel we should go with the flow instead of making predictions.

Come off it Dave, its really only out past the 120hr mark that we start to see major changes in the overall pattern and that's mainly with the orientation of the high. I would say that's pretty much the range for uncertainty 90% of the year and its never stopped you from making predictions based on charts from the mid-range. For what its worth I don't believe the Atlantic will win-out without a fight, however I rather feel the high will not deliver the expectations of many on NW, it looks cold at times but mainly dry.

Edited January 20, 2010 by weather eater

[cooling climate]

Remembering once again that this is the 06z run but there are massive differences between this

and the 0z run in regards to the vortex over Greenland at the t 144 plus range,and as such am

very dubious of anything it is currently showing.

The ensembles will hopefully give a better insight to what is happening.

The differences are so large that you would tend to think there has to be some substance to

what it is showing.

Edited January 20, 2010 by cooling climate

[snowmadchrisuk]

The 6z is quite nice , It would bring some Snow for Eastern and Central areas next Monday . The changes that we have seen IMO is that the Azores High will be the main driver in bringing the Easterly in as it joins up with the Scandi Block . 6z is also showing sign's of a little undercutting trying to develop .

[TEITS]

Come off it Dave, its really only out past the 120hr mark that we start to see major changes in the overall pattern and that's mainly with the orientation of the high.

Sorry mate your wrong.

Its the track and intensity of the LP which is within +120 that makes all the difference. Until the models figure out the track and intensity of this LP the positioning and orientation of the block is uncertain.

Beyond +168 and we can clearly see what I mean't by the PV in my previous post.

Fasintating model watching at the moment.

[weather eater]

Sorry mate your wrong.

Its the track and intensity of the LP which is within +120 that makes all the difference. Until the models figure out the track and intensity of this LP the positioning and orientation of the block is uncertain.

Beyond +168 and we can clearly see what I mean't by the PV in my previous post.

Fasintating model watching at the moment.

Past 168hrs I certainly agree with you, pre 120hrs the details you speak of are changes that go on practically every run of ever day on all models, however the overall pattern out to the 120 mark is as consistent as its likely to be. Of course the changes in track and intensity of the LP will make big changes by the mid-range, what's new. As I say it happens all the time and these types of factors have never stopped you nailing your colours to the mast before. Mind you caution is never a bad thing and should IMO be exercised more often in the model thread.

[cooling climate]

Referring back to my post 199 with regard to the AO and whether we see a flip back from

the positve mode the models have been showing to a much more blocked and very - AO.

No sooner do I mention this and hey presto, but one run and that being the 06z leaves me

wanting far more proof than this.

This could very well be the first real signs of the models picking up on the MMW with 30mb

temperatures over the pole and Spitsbergen likely to rise by some 40 degrees over the coming

days if the ECM model is to be believed.

Something to watch and as I said earlier to have such a large change from the 0z run leads me

to think there is more to this than a dodgy 06z run.

Link showing temperatures expected over the Arctic in the coming days at 30mb.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

[Polar Continental]

Well, well, the GFS 06z brings the easterly back with vengeance, even with snow in the east and south east. Those –8c to –10c uppers shown at T120 would be quite sufficient for that.

The 06z GFS, really does go for it this time, even after the high eventually settles over the UK, producing very low minimums, it then goes on a trip to Greenland, thus a very potent northerly is thrown in for good measure. A sub zero mean would be a certainty if this came off.

Great model watching.

[Thundery wintry showers]

Some OTT posts from both sides of the mild-cold debate this morning- it remains as much up in the air as it ever was. GFS and UKMO go for an easterly at around 5-6 days' time, giving mostly cold dry weather but snow showers are certainly possible in eastern and southern areas in either case. ECMWF in contrast goes for a mild SW'ly. The ECM may on average be the most accurate but when it's up against both GFS and UKMO it shouldn't be taken as the definitive scenario. There is still all to play for regardless of whether your preference is for cold or mild.

[phil nw.]

Most certainly the track and intensity of the LP thats causing the differences in the modelling of the E,ly.

I have to say im not very happy with the models in the medium range. A trend towards a +AO/NAO is currently being suggested.

Yes the energy showing it`s hand more and more towards our North West which is always a worry with a Scandi. High.

Looking at the overnight output i reckon we will still get some surface cold from a South Easterly into next week but the block looks as if it will become under increasing pressure from the vortex.

,

[Southender]

Well, well, the GFS 06z brings the easterly back with vengeance, even with snow in the east and south east. Those –8c to –10c uppers shown at T120 would be quite sufficient for that.

The 06z GFS, really does go for it this time, even after the high eventually settles over the UK, producing very low minimums, it then goes on a trip to Greenland, thus a very potent northerly is thrown in for good measure. A sub zero mean would be a certainty if this came off.

Great model watching.

I'm glad someone likes the 06z. But to me it looks more of an SE flow coming from N.Africa, through the Med onto the UK. Bringing in highly modified upper air. Not as cold as it could be and not ideal for snow countrywide at all. Still plenty of time for the HP to change its orientation though, with any luck.

Edited January 20, 2010 by LeighShrimper

[shuggee]

The evolution after the block moves away is interesting. Been a few hints on here and in the models (e.g. last night's JMA) that one of the arms of the PV is likely to move into Scandinavia, bringing a period of disturbed northerlys and proper cold. Much better than some half hearted easterly that will have taken ten days to send a bit of cloud over eastern England :winky:

[Frosty.]

The evolution after the block moves away is interesting. Been a few hints on here and in the models (e.g. last night's JMA) that one of the arms of the PV is likely to move into Scandinavia, bringing a period of disturbed northerlys and proper cold. Much better than some half hearted easterly that will have taken ten days to send a bit of cloud over eastern England :winky:

Agreed, the GFS has recently been showing an FI Northerly at times and I would love it to happen, the first cold blast of winter began on the back of a N'ly which then became an E'ly and the rest is history. There is way too much variabilty in the output again today and we have the last 2 ecm runs having no interest in a wintry outlook, the ecm is powering up the northern arm of the jet with a lot more energy than the other models at the moment.

Edited January 20, 2010 by Frosty039

[karyo]

Could someone please post the 0z ECM ensembles as I am at work and don't have the link here.

It would be interesting to see where the operational was standing!

Karyo

[SP1986]

There is indeed a wide spectrum of outcomes this morning across the board. The ECM is clearly out on it's own, and this was the model that I and a few others had expected to be the stable model, but perhaps this is more confusing that anyone first thought. It could well be that the ECM is right, and if it is then it's ratings will in my mind be higher then the GFS. It's not too often the ECM out-muscles the GFS to shows a new trend so at the moment I'm pretty sceptical of the ECM.

To me the GFS looks more like the kind of outlook I might have expected the other day - a cold easterly but not too cold, and quite modified by milder air pockets in the high zone.

[Osbourne One-Nil]

bringing a period of disturbed northerlys and proper cold.

Are you allowed to talk about northerlies in here?

[Weather-history]

Here's the mean pressure chart based on the GFS 06z ensembles

[Polar Continental]

I'm glad someone likes the 06z. But to me it looks more of an SE flow coming from N.Africa, through the Med onto the UK. Bringing in highly modified upper air. Not as cold as it could be and not ideal for snow countrywide at all. Still plenty of time for the HP to change its orientation though, with any luck.

Some milder upper air would eventually be brought up around T168 if the 06Z verified. Though surface temperatures would still be very cold, because of the still very cold near by continent. Any snow that fell early in the east and south east would not melt a great deal with those maximum surface temperatures.

Yes I love that run, but the 06z is just one of many outcomes, slight changes around T54 with that low near Iceland will make all the difference as Mr Data mentioned.

[derrylynne]

The charts are changing so much from one output to another at the moment that it is my view none of them can be relied on. There is so much uncertaintly that to me forecasting instinct is going to be the only way to come to a conclusion. The lates GFS for instance is so very different to the previous. My instinct is the cold will be back - given the winters style this year and the solar output. Although I prefer mild I cannot for a moment see the Atlantic winning out to an old style raging Atlantic. A case of blowing hot and cold at best - cold at worse with no mild....

[Methuselah]

The evolution after the block moves away is interesting. Been a few hints on here and in the models (e.g. last night's JMA) that one of the arms of the PV is likely to move into Scandinavia, bringing a period of disturbed northerlys and proper cold. Much better than some half hearted easterly that will have taken ten days to send a bit of cloud over eastern England :winky:

I've been noticing that possibility too, Shuggs. I'm keeping my eyes peeled for Arctic Terns???

[Guest North Sea Snow Convection]

Any potential easterly will have nothing to do with a forecasted MMW that depends on negative zonal wind anomalies propagating to the troposphere - and that is unlikely to happen before we get into February (and in turn is then dependant on factors such as GP has recently outlined before there is any guaranteed cold weather for the UK)

An easterly of sorts in the shorter term looks very likely - but its type and duration is still very open to debate. There is no -NAO signal and the presence of low heights to the north west makes prospects less straightforward to any sustained cold regime than earlier in the winter. There has been a backlog of positive zonal wind anomalies from the recently cold stratosphere - these have to pass through the pattern before any renewed cold outlook. On that basis the ECM is not implausible - even if it is showing the return of the atlantic that many of us don't like.

[Duane S.]

Are you allowed to talk about northerlies in here?

Hopefully because I am still convinced that is what we will all be talking about here in about 7 days time.