Model Output Discussion

[thegreat316]

Hello

no1 really mentioned the JMA NOGAPS tonight

JMA and NOGAPS seem to keep the cold throughout till +180

JMA FI looks intresting with a lows undercutting the block .

[weather eater]

Forgive me for saying this,but your comments appear flawless.

Kind Regards.

You might want to change this line, I think flawed is the word you are looking for, flawless means the opposite. On a models note, some very consistent output at the moment and it looks as if those who suggested a few days ago that this looked a dry and certainly not severe event were pretty spot on the money. We now have to look to see how retrogression and a subsequent northerly can turn this spell around more towards what most members are looking for, plenty of projections for this over the coming days, and I suspect lots of interesting evolutions to mull over, before the synoptics for next weekend and beyond become clear.

[MAF]

I've got a hunch that we will not see any significant/severe cold spell now. Was talking to a friend who works at METO Exeter. They are not expecting any major disruption with this cold spell. One look at the models tonight would seem to back this up. The colder pool of upper air slides into France this weekend - just brushing the far South East corner of England (hence the METO warnings for Kent). Any real significant cold keeps getting put back in the model runs - Time is running out.

well its a bit contradictory to this from the Met O

http://www.metoffice.gov.uk/weather/uk/uk_forecast_alltext.html

...........Beyond this an unsettled but mostly cold type of weather looks most likely, with a continuing risk of sleet or snow, except perhaps in the southwest where somewhat milder conditions should prevail.

:wacko:

[Lynxus]

I dont see any point in spening too much time worrying what the meto and models say after this week.

We all know that the models are having a hard time showing whats going to happen ( only a week ago, It all looked like it was gonna be warm )

Now its cold.

While i agree that this doesnt look like it will bring much snow ( countrywide ) like the last lot did, There is still time.

NOTHING the models say now about nextweek and beyond should be taken to heart, It can all change quickly.

[Ben_Cambs]

I've got a hunch that we will not see any significant/severe cold spell now. Was talking to a friend who works at METO Exeter. They are not expecting any major disruption with this cold spell. One look at the models tonight would seem to back this up. The colder pool of upper air slides into France this weekend - just brushing the far South East corner of England (hence the METO warnings for Kent). Any real significant cold keeps getting put back in the model runs - Time is running out.

IMO this is a cold spell that could last a while. Lets start with this week. The snow will not be widespread yes but in a few select areas such as which you mention Kent are at risk of significant snowfall. Troughs have appeared in the latest FAX charts which suggest some other areas are at risk from snowfall, but primarily towards the Eastern side of the UK. We need to remember that sometimes troughs and features with organised PPN might only be picked up within 24 hours of the trough actually occuring.

So towards the start of next week, we see the high retrogress north westwards towards Greenland, and that just opens the door to more cold,from the North or North East, and that also offers the oppurtunity of snow to more than just the East and North of the UK, but to the South and West aswell, and we may see low pressure systems track southward from a Northerly which is one possibility.

A quote from Steve Murr the other day was one that we should remember for this kind of set up, he said roughly on the lines of "Slow to start, but slow to end", and this is due to the expected retrogression of the high to be quite a slow one.

Just like to add that the NAO and AO is expected to stay in negative territory for some while yet. Of course this doesnt guarantee cold weather for the UK and a west based NAO isnt helpful, but the west based NAO is still very uncertain and we may see higher heights to the North of Iceland like CC said and the models may show this in the next few days.

So all in all, what I'm saying is that by no way is a severe cold spell defiently going to happen, but its too early to write off one aswell. I will certainly be watching the models with intrest over the next few days.

[PersianPaladin]

While there is good level of moisture and low-thickness air feeding in around the high; there is the perpetual problem of insufficiently low 500hpa temps to maintain decent levels of showery activity except perhaps the far south-east. Dew points are also a problem and remain marginal for much of the week, except for East Anglia and parts of the south-east and perhaps occasionally the East Midlands. The marginal situation could mean a mixture of sleet, wet snow and rain for most places (except for high ground).

Long-term the models show an uncertain orientation for the northerly. Secondary cyclogenesis south of Greenland could push mobility sufficiently to mix-out the circulation and keep the cold sub 30 uppers to the north of the UK.

[john mac]

Its possible that the models are being a little too progressiveand tomorrow everyone could well ramping up again.

All still up for grabs imo, its not as if the atalantic is blasting through

[BarnetBlizzard]

Although the high is in a very similar place on the 18z, the low to the south-east is further north-west, therefore squeezing the cold air westwards quicker and i would expect the isobars to be a little tighter later in the run. I would also expect the PPN to be a little further north on this run.

[damianslaw]

Odd looking ECM today, with heights rapidly transferring far to the west preventing any real cold arctic shot making headway, however, at the same time the scandi trough looks ready to pounce, It doesn't look right to me.. expect it to downgrade the progressive nature of the high and instead put us in a pronounced northerly flow by the end of the weekend into next week.

All signs are that for retrogression of the high and a arctic blast as we head into next week.

Short term - my eyes are on this trough feature coming down from the north as shown on the FAX charts, could deliver some surprise snowfalls to northern parts on Thursday. The BBC just seem interested in the SE as always, and hardly mentioned this feature whilst showing snowfall over much of E Scotland and NE Scotland, I guess its because they do not expect much snow from it.. watch this feature it could easily develop further even though it is crashing into high pressure..

[Freezing-Point]

The HP is going nowhere and the cold air is gradually warmed as the air circulates. There is no real cold left in most of Europe by T+120. LOOK NORTH.

At T+144 the Northern Ice Train is heading directly for us. This is the pattern to watch in the coming days as there is a far greater chance of it delivering to goods to most of the UK than the ever watered down NEly.

SE seems to to better on this run into Saturday.

A tumbleweed has just bounced across my screen. Where is everyone?

Edited February 8, 2010 by Freezing-Point

[Snowyowl9]

This is cold.

http://www.wzkarten.de/pics/Rtavn1201.png

http://www.wzkarten.de/pics/Rtavn1202.png

http://www.wzkarten.de/pics/Rtavn12017.png

[Tim Bland]

I know it's FI but plenty to keep the dreams alive on this run!

http://www.wetterzentrale.de/pics/Rtavn2521.png

http://www.wetterzentrale.de/pics/Rtavn2522.png

http://www.wetterzentrale.de/pics/Rtavn2524.png

http://www.wetterzentrale.de/pics/Rtavn25217.png

[Snowyowl9]

At 240 hrs its obvious where all the cold is heading.so close.

Torwards us,a very interesting setup.

http://www.wzkarten.de/pics/Rtavn2402.png

http://www.wzkarten.de/pics/Rtavn2642.png

[damianslaw]

I know it's FI but plenty to keep the dreams alive on this run!

http://www.wetterzentrale.de/pics/Rtavn2521.png

http://www.wetterzentrale.de/pics/Rtavn2522.png

http://www.wetterzentrale.de/pics/Rtavn2524.png

http://www.wetterzentrale.de/pics/Rtavn25217.png

If this transpired, many of us could rival the snow in Washington at the moment.

Pity its way beyond the reliable timeframe, it would be perfect timing just before the weekend at the end of the half term hols, I'd be booking the Friday off work now..

I firmly expect next week to deliver a much greater chance of severe wintry conditions than this one which is looking a preety weak cold spell, maxes of 4-5 degrees are hardly cold and passing light showers depositing a couple of cms at best are nothing to right home about. Bring on the cold northerly and let the troughs and low heights from the north descend upon us.

[chionomaniac]

The HP is going nowhere and the cold air is gradually warmed as the air circulates. There is no real cold left in most of Europe by T+120. LOOK NORTH.

At T+144 the Northern Ice Train is heading directly for us. This is the pattern to watch in the coming days as there is a far greater chance of it delivering to goods to most of the UK than the ever watered down NEly.

SE seems to to better on this run into Saturday.

A tumbleweed has just bounced across my screen. Where is everyone?

I think everyone is probably watching - it's a bit like watching a football match where the commentator is refreshingly quiet!

For those who think that the ridge is going to drop this isn't going to be the case with eventual slow retrogression to the west of Greenland the likely outcome. How much ridging remains over the Atlantic will be important in holding back any intrusion from the south west, whilst allowing the Scandi trough to drop. The pattern is there long term but in the mean time the ridging is always going to keep closer to the north and west, which will keep these areas drier until a northerly kicks in. The orientation of the UK has changed slightly over the last few days, but in reality the modeling hasn't changed much and in these situations we can all be aware that a small change can have a big implication on whether there is snow or not.

[NorthantsSnow]

Small short term upgrades on this run. Later on Thursday we see an area of snow feed into the East Midlands region:

http://charts.netweather.tv/gfsimages/gfs.20100208/18/75/ukprec.png

Which sticks around into the early hours:

http://charts.netweather.tv/gfsimages/gfs.20100208/18/78/ukprec.png

OK so it's not going to be a massive snow event but potential for a covering away from the favoured SE corner.

Also the 850s are a lot colder come the weekend compared to the 12z run:

http://charts.netweather.tv/gfsimages/gfs.20100208/18/111/h850t850eu.png

FI meanwhile is very snowy with a cold plunge from the north and then a deep LP crossing the UK bringing the potential for blizzards and drifting snow:

http://charts.netweather.tv/gfsimages/gfs.20100208/18/240/h850t850eu.png

So overall a much better run compared to what we have been seeing recently. I still maintain that the northerly is our best chance of seeing widespread UK snow, and not the current easterly; as the uppers are not especially cold, the flow is slack and pressure is a little on the high side, especially over northern Britain.

[J10]

I think everyone is probably watching - it's a bit like watching a football match where the commentator is refreshingly quiet!

For those who think that the ridge is going to drop this isn't going to be the case with eventual slow retrogression to the west of Greenland the likely outcome. How much ridging remains over the Atlantic will be important in holding back any intrusion from the south west, whilst allowing the Scandi trough to drop. The pattern is there long term but in the mean time the ridging is always going to keep closer to the north and west, which will keep these areas drier until a northerly kicks in. The orientation of the UK has changed slightly over the last few days, but in reality the modeling hasn't changed much and in these situations we can all be aware that a small change can have a big implication on whether there is snow or not.

Going from the teleconnections, is such a fast retrogression and a switch to a west based -NAO likely, or are the models overdoing this slightly.

[Lewis]

Anyone seen the latest UKMO fax charts ?

http://www.wzkarten3.de/pics/brack0a.gif - T 36

http://www.wzkarten3.de/pics/brack1.gif - T 48

http://www.wzkarten3.de/pics/brack2.gif - T 72

http://www.wzkarten3.de/pics/brack2a.gif T - 84

http://www.wzkarten3.de/pics/brack3.gif T - 96

http://www.wzkarten3.de/pics/brack4.gif T - 12

[January Snowstorm]

The orientation of the UK has changed slightly over the last few days, but in reality the modeling hasn't changed much

Not too sure about that, all the majors were showing a potent Easterly a few days ago for late this week. The Easterly has vanished totally, and now it's North we look as we head for FI. To me this high looks weak and flimsy as it heads for Greenland and is nothing special. As JH said earlier temps of 3-6 by day is barely below average

[chionomaniac]

Going from the teleconnections, is such a fast retrogression and a switch to a west based -NAO likely, or are the models overdoing this slightly.

Reading GP's latest update he seems to think so. The stratospheric 100 hPa vortex positioning also tends to suggest that this retrogression may be a little too quick also. I think that the modeling around 70ºN to the North Pole from 7 days plus could show a lot of volatility and uncertainty due to stronger downwellings from the stratosphere forecast for around this time, and this will have a knock on effect to any retrogression.

[NorthantsSnow]

Anyone seen the latest UKMO fax charts ?

http://www.wzkarten3.de/pics/brack2a.gif T - 84

http://www.wzkarten3.de/pics/brack3.gif T - 96

Is that the trough that's going to provide me and my fellow East Midlanders with a snow event?

Looks very similar to the GFS.

[chionomaniac]

Not too sure about that, all the majors were showing a potent Easterly a few days ago for late this week. The Easterly has vanished totally, and now it's North we look as we head for FI. To me this high looks weak and flimsy as it heads for Greenland and is nothing special. As JH said earlier temps of 3-6 by day is barely below average

The average daytime temperature as far as I am aware is around 7ºC for Feb JS. After tomorrow a lot of the country will struggle to reach 3-4ºC for the next 5 days going by the latest GFS run. That is not barely below average. We are yet to see how strong any Greenland block will be and we should only be looking at trends. I still maintain that small differences in the orientation and positioning of the high to the west and North of us has significant impacts on the ground with the flow of cold - that's all it takes.

[swilliam]

Looking through the GEFS ensembles at +192 is quite interesting with most showing a weak ridge from the NW UK to Greenland with a very far South jet. The lows then undercut potentially giving some very interesting weather for next week. This is shown by the mean pressure.

The mean temp shows the cold pool to the East.

The result of the undercutting lows is to produce a more even, rather unusual looking (at this range) mean temp towards the end - the -5 line is flat across the Atlantic the UK and Europe.

So there should be some interesting developments for next week over the next few days runs. Just as well because the models for this week do look a bit uninteresting. I think this weeks weather looks like being a bit disappointing. This is especially considering that not too long ago the models were consistently showing some possible quite interesting weather. A strong Easterly with a cold pool moving over us and potentially some significant snow.Whilst the pattern has not changed much we look like having quite a watered down version of this. Pleasant enough weather but just not very interesting, not particularly cold or snowy.

As I say next week could be quite interesting - ashe UK METO say - cold and unsettled. This is seen in the esemble fot London. The mean is still quite low at around -5 but much more precipitation.

A.s Ian Brown said earlier I think we need to start looking for some snow events now rather than prolonged cold. Let's hope the pattern does not take one of the less interesting options such as the lows not undercutting but linking up with PV moving down from the North

Edited February 8, 2010 by swilliam

[TEITS]

Have to say im becoming increasingly fasinated by the model output for next week. I know this is a long way away but something is brewing in the output I feel.

Take a look at the ECM ensembles.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

In recent days the trend in the extended ensembles has been a warm up with very few cold runs. However note on the 12Z a few very cold runs are beginning to appear. This to me indicates a LP bringing SW,lys isn't so certain now.

I am also spotting a similair trend in the GEFS mean.

http://91.121.94.83/modeles/gens/run/gens-21-1-240.png?18

http://91.121.94.83/modeles/gens/run/gens-21-1-300.png?18

Manchester ensembles show the mean no higher than -5C but far more cold runs appearing.

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

Aberdeen is -7C.

http://www.wetterzentrale.de/pics/MT8_Aberdeen_ens.png

Obviously I cannot put any details into this because im only looking at the mean. However I said this morning the trend looks better in the GEFS ensembles and thats continued on the 18Z. What im saying is im not convinced next week will only bring snow to N Britain and assume a mild SW,ly afterwards is a cert.

A very interesting week ahead I feel.

Edited February 8, 2010 by THE EYE IN THE SKY

[FENDER.]

Trouble it seems Dave the interesting stuff is always NEXT week lol The Easterley is a bit of a flop and we need to see the back of it, The best chance of snowfall for most of the country will come from the north. At the moment its not that cold and certainly not snowy, but perhaps NEXT week it will be

The high remains a concern too close now, but may be not close enough come next week

Edited February 9, 2010 by At least it will be mild