Model output discussions pm 31/12/15

[knocker]

1 hour ago, -Bomber- said:

The Gfs stalls the low over us for days even as the HP in the Atlantic edges east toward us it's static for quite some time.  I'm a novice at reading charts but it seems strange how it lingers for so long as there is no block to the East. Is there any merit to what I said and please enlighten me if I'm missing something. Thanks

Following on from Mucka Just to add some general comment on the movement of depressions which is quite a complex subject.

Essentially the movement of depressions is determined by the upper westerlies and, as a rule of thumb, a depression centre travels at about 70 per cent of the surface geostrophic wind speed in the warm sector. There is a pretty slack upper wind field around our low at the moment  with the main wind band to the south.

Shallow depressions are mainly steered by the direction of the thermal wind in the warm sector and hence their path closely follows that of the upper jet stream. Deep depressions may greatly distort the thermal pattern, however, as a result of the northward transport of warm air and the southward transport of cold air. In such cases the depression becomes slow moving. We have seen this recently with deep depressions hanging around in mid Atlantic.

Edited January 5, 2016 by knocker

[Ali1977]

ECM going the same way as GFS with a very short cold snap, didn't expect this waking up - not a good morning for coldies.

[Great Plum]

4 minutes ago, Ali1977 said:

ECM going the same way as GFS with a very short cold snap, didn't expect this waking up - not a good morning for coldies.

I am always slightly knarked when I see knee jerk comments like this - and I expect to see much despondency in here today...

The models have only recently latched on to any form of cold weather for us - the signs in all the three letter acronyms (mjo, aam) etc are pointing to potentially cooler weather for this island as well as far greater changes for the hemispheric pattern...

looking at the London GFS ensembles, you can see that there is a large cluster of colder ensembles after 13th Jan - the op has either followed these or gone with the others over the last few days - it will continue to bounce around until it will find some consistency...

importantly, whatever will happen, it will be drier (look at the precipitation spikes) and that is probably the most important thing at the moment...

[mountain shadow]

The one time the GFS trumps the ECM has to be to reduce cold.

Now we know why the Met office are top dogs.

[blizzard81]

You have to laugh! The inevitable ecm downgrade. You really cannot trust this model with it's over amplification issues to our north west. It's been doing this for a few years now.

[Mucka]

3 minutes ago, Ali1977 said:

ECM going the same way as GFS with a very short cold snap, didn't expect this waking up - not a good morning for coldies.

ECM is a little better than GFS and with a strong Atlantic block but it is disappointing given last nights ensembles. Either this is one of the less cold runs from day 10 or the ensembles won't look so good this morning. That said temps could be a bit misleading as would stay cold at the surface under any high.

This morning is definitely leaning toward a toppler rather than Greenland high though.

[Abyss]

1 minute ago, mountain shadow said:

The one time the GFS trumps the ECM has to be to reduce cold.

Now we know why the Met office are top dogs.

Bit premature to throw in towel just yet

[chris55]

00z ens still going cool/cold then split with some very chilly runs intensifing the cold. The op takes the mild option!

 

[Ali1977]

1 minute ago, chris55 said:

00z ens still going cool/cold then split with some very chilly runs intensifing the cold. The op takes the mild option!

 

Be interesting to see the next runs ensembles against these, that might give us a better idea of where this is going - I also thought a slight upgrade in the wording on the METO long range, not to be though.

[Cheshire Freeze]

I said I wasn't convinced last night and to me that ECM run is not great. We're looking at scraps. Maybe slightly too soon with the modelling for anything substantial (poss 3rd week of Jan for interest?). 

RE the ensembles: that's exactly why I do not trust them. Given all available ensemble guidance from ECM and GFS there was a strong suggestion of a major Greenland high cluster....this was borne out in the mean. Looks to be on shaky ground this morning! 

I still believe we'll get a decent block this winter but it's proving to be a frustratingly long waiting game thus far. 

Edited January 5, 2016 by CreweCold

[i luv snow]

I think people need to be patient, I have never known a cold spell occur without wobbles in the models. The op clearly a milder option from the ens later on, so I would suggest waiting for today's runs before losing too much heart. I'm not guaranteeing we will see upgrades, but it isn't out of the question so don't fear people.

Edited January 5, 2016 by i luv snow

[bluearmy]

Hi Crewe, the Greenland ridge always looked mobile and continues to do so today. The question thrown up by the ens was how Far East the Atlantic ridging will get before settling into place.  The Arctic high is the unknown here as it could ridge down to join the Atlantic.  Judging by the extended EC 32 and it's new parallel ec46, the Scandi trough will be semi permanent over the next 6 weeks so how far west and south it can exert its influence will depend on the euro heights methinks. 

The meto update must reflect a strong cluster for the high to drift East and South with MOGREPS support for this evolution. 

Edited January 5, 2016 by bluearmy

[Dorsetbred]

This years catch phrase "Wobbles in models..". Interesting to see the general trend however, this will be a year to remember that taunted & kept us on our seats.

 

[Cheshire Freeze]

Just now, bluearmy said:

Hi Crewe, the Greenland ridge always looked mobile and continues to do so today. The question thrown up by the ens was how Far East the Atlantic ridging will get before settling into place.  The Arctic high is the unknown here as it could ridge down to join the Atlantic.  Judging by the extended EC 32 and it's new parallel ec46, the Scandi trough will be semi permanent over the next 6 weeks so how far west and south it can exert its influence will depend on the euro heights methinks. 

Well signalled in GLOSEA seasonal for months- 2nd half of winter= Scandi trough. Common theme has been for euro heights to pose limitations initially before receding somewhat and allowing a backing of heights into Atlantic then Greenland. Impressively, that looks to be the script thus far (given it signalled the wet December/beginning to winter very well).

[i luv snow]

48 minutes ago, Dorsetbred said:

This years catch phrase "Wobbles in models..". Interesting to see the general trend however, this will be a year to remember that taunted & kept us on our seats.

 

haha, I wouldn't say it's just this year. Wobbles happen every single year, ever since I have began using this site 13 years ago, and they happen with every single cold spell. Doesn't mean this is just a wobble, it might be a trend, but it might not be!

Edited January 5, 2016 by i luv snow

[winterof79]

Yes a disaster isn't it..may as well stay in the pattern we're in......come on people there is nothing to be despondent about

[terrier]

Well it seems once again the ecm moves towards the gfs outcome how many times have we seen this over the last few winters. Looks like the ecm over amplifies everything again. Seems like the meto are following the gfs over the ukmo which shows a brief cold shot. Which ties in with there update overnight. Let's hope we may see a better output in maybe a weeks time when we should start to see signs in the models of what glacier point has been alluding too. 

[Radiating Dendrite]

I did mention yesterday that the ECM can often be too clean with its synoptics and prone to over amplification especially towards Greenland.

Let's hope this is just a blip and it shows a better long term pattern on the 12z. Given the timescale though there is still plenty of time for things to change 

[cyclonic happiness]

How can people be getting so upset about a great amount of shortwaves, that have popped up overnight 7-10 days away?

Do you really think these will be there on the next run?

 

The trend is still the same, cold from the north spilling out of the Arctic at the end of the week.

Things will change, as others have said, this might be the traditional 'pre cold spell wobble' which all the models are liable to, but especially the ECM

[wolvesfan]

Morning all

Cold still on the way,uncertainty on how long it will last but that is always the case.

GFS op run a mild outlier in the later stages,majority ensembles showing cold.

We've seen the models deviate run to run when there is a major pattern change afoot in the past.

ECM looks to me like it couild deliver a true scandi high.the high doesn't to me look like toppling.-10 upper air temps on its last frame.

The trend is still for a much colder pattern.

 

[BLAST FROM THE PAST]

8 hours ago, BLAST FROM THE PAST said:

And the difference between 12 and 18z....although one must toy with the idea that it may take more than one hit/BITE to really flip the set up

 

BFTP

I suggest that this might be the case.  00z ECM backing off and for me even the t144 UKMO shows that the block won't hold if we move on.  You can see LP south west of Greenland moving in to split the block

As they say the ECM is one run but having watched the models for many years like many, folk know nothing is in the bag....well only once was it and that was Dec 2010.  Remain cautious in both directions

 

BFTP

Edited January 5, 2016 by BLAST FROM THE PAST

[blizzard81]

Also, it is a real concern to me that the meto are not forecasting anything notable in terms of prolonged cold. I don't know about anyone else but I get a feel for winters as they progress. Unfortunately I am just not getting that feeling about this winter in terms of producing anything substantially cold. It is a gut feeling. A transient northerly just doesn't do it for me, especially after the dross we have suffered thus far.

[i luv snow]

2 minutes ago, blizzard81 said:

Also, it is a real concern to me that the meto are not forecasting anything notable in terms of prolonged cold. I don't know about anyone else but I get a feel for winters as they progress. Unfortunately I am just not getting that feeling about this winter in terms of producing anything substantially cold. It is a gut feeling. A transient northerly just doesn't do it for me, especially after the dross we have suffered thus far.

I would imagine the metoffice update today will be a little more positive, but let's wait and see. If you saw the weather for the week ahead with John Hammond last night then the bbc/ met office clearly think something is afoot. Also, after December a 3 day transient northerly will do me for starters! With this sort of change in the NH, then the rest of Winter is certainly going to be more interesting.

[Day 10]

The ECM isn't great this morning, the GFS is doing it's damned hardest to push heights up into Greenland from 144 to 192 but doesn't quite succeed and the UKMO at 144 doesn't look too bad to me. Maybe I'm wrong but I still think it could turn out ok. We may not get a prolonged freeze but at least a shot at snow for the UK will do for me after this quite crappy winter so far AGAIN!

[winterof79]

6 minutes ago, blizzard81 said:

Also, it is a real concern to me that the meto are not forecasting anything notable in terms of prolonged cold. I don't know about anyone else but I get a feel for winters as they progress. Unfortunately I am just not getting that feeling about this winter in terms of producing anything substantially cold. It is a gut feeling. A transient northerly just doesn't do it for me, especially after the dross we have suffered thus far.

Do I detect a moan

Major scatter late on with the OP milder.

Transient Northerly mabe on GFS 06z but a generally colder theme is touted by all models.It will not take much fluctuation for snow to fall