Model output discussion - 5th December 2016 - Into Winter we go

[Frosty.]

4 minutes ago, Don said:

Likely to deliver diddly squat down here but better than a south westerly I suppose.

You could also say a Northerly would deliver diddly squat to most inland parts of the uk due to the wishbone effect but I would just like to see something cold and resembling winter for a change..fingers crossed for Jan / Feb.

[Guest]

9 hours ago, Summer Sun said:

 

Thanks for posting this chart Summer Sun. I'll try to put a bit more flesh onto the bones:

This is of some interest and quite a swing away from the positive AO chart that appeared in Judah's last Arctic Oscillation report with his full update only issued 2 days ago. I provided links to that and a copy of his summary and expected impacts in my last full report (see page 167) and it is fascinating to make comparisons. A strong word of caution though. Whilst there has been a strengthening trend supporting MLB towards the New Year and "possibly" some hints of some HLB moving into early January, there are still huge uncertainties. Even Judah has stated this. As much as I have huge respect for all of Judah Cohen's excellent research, I have noticed that some of his tweets are perhaps a little more bullish than his well considered reports. I sincerely hope that there are increasingly stronger signals for the pattern change. The MJO is one to watch and some of the models (more especially the GEFS) have hinted that it might come to life in the key phases 7, 8 and 1 which usually (but not always) favours greater HLB. As some of our experts have told us, we need greater model consensus and much stronger amplification of the MJO. This may not be enough on its own. What will happen to the strength and position of the PV? Again we need our specialist regular posters to monitor this to see if there might be some greater agreement on a more favourable pattern change. So it is very much something to watch but let's not set our expectations too high at this stage. Perhaps January will delivery something more exciting. 

EDIT: Today's MJO and AO updates are just out (1600, December 21st):

MJO Ensemble Charts for the Big 4 (updated December 21st):

UKMO (7 day forecast):  

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ukme.shtml

ECM (14 day forecast): 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

NCEP/GEFS (14 day forecast):

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

JMA (9 day forecast):  

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/jman.shtml

There are only small changes from yesterday. The GEFS goes more towards phase 1 now but at less amplification than before. The JMA goes into phase 8 with higher amplification and this looks like position GEFS were at yesterday! 

Arctic Oscillation (AO) 14 Day Ensemble Charts (updated December 21st): 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

Quite a few ensemble members are trending negative around the New Year.  Still a very mixed picture.

So, this was just a short interim update and "almost certainly" my last pre-Christmas post. Once again, have a great Christmas everyone. 

Edited December 22, 2016 by Guest
To add links to today's MJO and AO charts

[Tamara]

A brief-ish (!!?) re-emergence from Sundays festive season closedown, but just to offer a response to the majority cluster ECM chart referenced in that embedded twitter

The advertised pattern there, closely reflects the downside risk scenario as posted at various times in recent weeks, should falling atmospheric angular momentum combine with wQBO induced strengthening of the polar vortex.  As suggested back then, a poleward EPO ridge would be/and now is no good to us, this side of the pole in our sector, under these circumstances. 

An upstream tropical/extra tropical forcing is always an amplification assist, but with ocean/atmosphere co-operation no longer favouring a  +ve AAM  de-couplement (to encourage eastward propagating amplification under such forcing) and the upper stratosphere now closed the lid on early winter hopes of troposphere/lower stratosphere decouplement sustaining, this is going to be hard to achieve for the foreseeable future

I don't have the most recent WDT Futures AAM/GWO plots to most accurately depict the way forward in terms of the very latest AAM tropical and extra tropical budget (data on the site is still stuck on 16th December) but its still clear enough that the remainder of December and into the start of the New Year is going to feature this typical winter Nina-esque pattern.

Meaning by that - dictation of the NH pattern by the North Pacific heights and the downstream sequence of trough and then SE US/Bermuda and Azores/Atlantic ridge. The jet stream focussed through the northern branch and flowing around the perimeter of the mid latitude ridging.

Under supressed AAM, it makes sense that the seasonal wavelength changes (which are marked between December and January) retrogresses the Euro heights westward in this way. Note: under a high AAM state and continued increasing vortex destabilisation, a GWO orbit back through Phases 4,5,6,7 would have ramped up the chances of seeing those heights retrogress at a higher latitude from Scandinavia to Southern Greenland.....

As it stands though, the maximum "potential" for cold from the advertised set-up is temporary and relatively minor amplification of the Atlantic ridge - hence the suggested NW'erlies tally closely with the latest model indicators as supplied by Ian F.

But I wouldn't be getting too excited about these - hence Sundays intended festive break is resumed to look afresh at things afterwards.

Another "Happy Christmas" to all  - and best wishes to those in the North, but especially furthest north, who have to deal with these horrible storms

Edited December 21, 2016 by Tamara

[Grimers]

After the gales of Christmas Day, things start to settle down as we head towards New Year as an area of high pressure establishes itself across the UK and continent potentially bringing some milder conditions but also some frosty nights especially across inland areas.

       

I have to say, I wouldn't mind what's showing over Scandinavia and W Russia, that would be something else! Us coldies would be in heaven! However, dare I say, this chart is not far off.

Edited December 21, 2016 by Grimers

[booferking]

Quite a difference at just 96hr on the Christmas day storm between UKMO & GFS..

[Geordiesnow]

1 minute ago, stewfox said:

GFs 12z shows more stormy conditions for 23/12 in the far north but those two storms for festive period have retreated from the uk

 

I disagree, I think the GFS in particular has nailed this first storm pretty well in terms of its track and strength, much better than the UKMO and ECM which the former as usual underplays the potential strength after its 96 hours output and getting the track wrong(having the storm centre nearer to Scotland) and the ECM likewise with the position of the centre of the low on one or two runs nearer to Scotland, now it looks like the centre of the storm will be between Iceland and Scotland as the GFS more or less predicted and the central pressure could actually be a 950MB low!

I think the first storm you could say could be a lot worse if it did tracked just that bit further Southwards when you just look at that pressure gradient but don't underestimate it, parts of Scotland will experience severe if not storm force winds.

The 2nd low is a bit more uncertain, GFS is going for a shallower feature now but still packing a punch whereas the UKMO is going for a deeper depression, the 2nd low in my eyes has the potential to produce a squall front if it sets up right so that is something to keep an eye on for sure. I don't think it will be as severe as the first low but theres still a bit of uncertainty surrounding it.

[Summer Sun]

After Christmas day next week settles down quite nicely with a return to frost and fog

[Daniel*]

25 minutes ago, stewfox said:

GFs 12z shows more stormy conditions for 23/12 in the far north but the distruption and ' turkey impact' for the festive period have retreated from the uk in this run

 

No it has not comparing the 12z left and 06z right...GFS has backtracked back to developing the storm, much of Scotland seeing stormy conditions on Xmas day not especially problematic as we've seen modelled, but the detail still remains elusive.

.

 

Edited December 21, 2016 by Changing Skies

[Frosty.]

5 minutes ago, Summer Sun said:

After Christmas day next week settles down quite nicely with a return to frost and fog

That fits with the latest MO outlook for next week with colder conditions than recently, similar to late Nov / early Dec when we had some very cold nights.

[stewfox]

15 minutes ago, Geordiesnow said:

I disagree, I think the GFS in particular has nailed this first storm pretty well in terms of its track and strength, much better than the UKMO and ECM which the former as usual underplays the potential strength after its 96 hours output and getting the track wrong(having the storm centre nearer to Scotland) and the ECM likewise with the position of the centre of the low on one or two runs nearer to Scotland, now it looks like the centre of the storm will be between Iceland and Scotland as the GFS more or less predicted and the central pressure could actually be a 950MB low!

I think the first storm you could say could be a lot worse if it did tracked just that bit further Southwards when you just look at that pressure gradient but don't underestimate it, parts of Scotland will experience severe if not storm force winds.

The 2nd low is a bit more uncertain, GFS is going for a shallower feature now but still packing a punch whereas the UKMO is going for a deeper depression, the 2nd low in my eyes has the potential to produce a squall front if it sets up right so that is something to keep an eye on for sure. I don't think it will be as severe as the first low but theres still a bit of uncertainty surrounding it.

I have removed my post apologies folks. A classic example of let the run complete before comment. turkeys need pinning down

 

[mountain shadow]

4 hours ago, Frosty. said:

I disagree, it's not easy to say for sure the actual weather come the first week of January.

As I said earlier, 12z GFS Op on board with the easy to forecast conditions for early January with Uk block, jet over the top......

Absolutely dreadful run for coldies, the output gets worse and worse.

[Frosty.]

1 minute ago, mountain shadow said:

As I said earlier, 12z GFS Op on board with the easy to forecast conditions for early January with Uk block, jet over the top......

Absolutely dreadful run for coldies, the output gets worse and worse.

Good for a return of surface cold, frosty nights and freezing fog.

[Summer Sun]

4 minutes ago, mountain shadow said:

As I said earlier, 12z GFS Op on board with the easy to forecast conditions for early January with Uk block, jet over the top......

Absolutely dreadful run for coldies, the output gets worse and worse.

 

 

 

Temps stuck in single figures some frost and fog likely

It could be worse we could have flooding and gales

Whilst it's not good for snow it's certainly not dreadful for cold

Edited December 21, 2016 by Summer Sun

[Whether Idle]

It will be cold under high pressure. Cold at the surface is cold.  Frost is part of winter, or at least it used to be.

[mountain shadow]

4 minutes ago, Summer Sun said:

 

Whilst it's not good for snow it's certainly not dreadful for cold

True, I should have caveated my post as proper cold which includes the white stuff.

[northwestsnow]

8 minutes ago, mountain shadow said:

True, I should have caveated my post as proper cold which includes the white stuff.

You are kind of right MS, esp the further north and west you are.But with the atmosphere as it is faux cold is the very best we can hope for.In so far as high lat blocking is concerned its another 1988 in my book...

Ariston....

Edited December 21, 2016 by northwestsnow

[minus 9]

How about the cfs daily. What a beaut of a chart shame it's at 552 hrs.

[Johnp]

21 minutes ago, mountain shadow said:

As I said earlier, 12z GFS Op on board with the easy to forecast conditions for early January with Uk block, jet over the top......

Absolutely dreadful run for coldies, the output gets worse and worse.

It's good for coldies but not for snowies.

[Frosty.]

12 minutes ago, northwestsnow said:

You are kind of right MS, esp the further north and west you are.But with the atmosphere as it is faux cold is the very best we can hope for.In so far as high lat blocking is concerned its another 1988 in my book...

Ariston....

And on..and on

[booferking]

This is what you want to see.. Frost is overrated when your a colder searching for snow in the Winter

There are a few ens that deliver a Northerly or North Westerly and one that produces an easterly but we have been here so many times already this winter so take what you see with a pinch of salt..

Edited December 21, 2016 by booferking

[northwestsnow]

1 minute ago, Frosty. said:

And on..and on

Mate it got worse lol.

Anyway, like you say, it will get colder next week..But for snow, we are in an absolute weeble of a pattern, one of the worst to get out of, gutted!

[Geordiesnow]

29 minutes ago, mountain shadow said:

As I said earlier, 12z GFS Op on board with the easy to forecast conditions for early January with Uk block, jet over the top......

Absolutely dreadful run for coldies, the output gets worse and worse.

Be interesting too see if this is near reality or not, by the 4th January we could have the Atlantic steam rolling in with no UK blocking high at all so I don't think the forecast is "easy" at all. Since when is weather forecasting long range ever classed as "easy"?

The trend does seem to be for high pressure to nose in after this stormy period but what happens after that is open to doubt as some forecasts hints we may have high pressure to the West and a NW'ly flow for the UK so nothing is ever cut and dry.

[Frosty.]

3 minutes ago, northwestsnow said:

Mate it got worse lol.

Anyway, like you say, it will get colder next week..But for snow, we are in an absolute weeble of a pattern, one of the worst to get out of, gutted!

It's good we can laugh about it, and let's hope for height rises to the west during Jan as is being hinted at by the seasonal models.

 

[northwestsnow]

1 minute ago, Frosty. said:

It's good we can laugh about it, and let's hope for height rises to the west during Jan as is being hinted at by the seasonal models.

 

Aye, you are right Karl.I am gutted but its pointless getting hung up about it.Im not buying into any of the signals of height rises/north westers if i were being honest.Obviously i would like to see it as a coldie but im feeling very despodent about winter now.:(

[Frosty.]

1 minute ago, northwestsnow said:

Aye, you are right Karl.I am gutted but its pointless getting hung up about it.Im not buying into any of the signals of height rises/north westers if i were being honest.Obviously i would like to see it as a coldie but im feeling very despodent about winter now.:(

Chin up, enjoy christmas and keep an open mind about January, at least it looks colder and more settled next week with frosts returning and then it's all about where the high goes..hopefully west / northwest or even..to scandi