model discussion Model output discussion 11th July onwards

[LRD]

3 minutes ago, northwestsnow said:

Flat is one word...

Really hate these synoptic in November

+NAO setting up ...

Agreed

As Crewe Cold said, better now than Dec/Jan but it is utterly tedious. This autumn and pretty much the last 15-20 autumns (with the odd exception) is producing/have produced the weather equivalent of a powerful sedative. Total yawn-fest

Thin gruel, admittedly, but the GEM at least shows something lively at 240 with the high pulled Westwards and pressure slightly lower over Europe compared to what is depicted on GFS and ECM op runs:

[Cambrian]

From the 12z GFS and GEM operational runs, it looks like a spell of westerlies is likely following the 2 day northerly between 120h and 168h, but big differences between the two models on the duration of the west-east aligned jet stream before it realigns NW-SE.

At 240h, 12z GFS op / 12z GEM op

 

1030mb in the southwest approaches or 990mb?

 

The key difference leading up to this is the lack of mid-Atlantic amplification with the GFS at 144h compared with GEM

At 144h, 12z GFS op / 12z GEM op

 

 

UKMO at 144h is more similar to GEM, ECM is a halfway house between GFS and GEM, as is its alignment of the jet stream at 240h.

At 144h, UKMO / ECM ops

  

ECM op at 240h

[Ali1977]

I think what happens 2nd week of Nov is still very much up for grabs, although being only the second week of Nov it’s not going to be anything overly cold either way.
There’s plenty pointing towards a cold Nov, so hopefully that’s what happens - I’m sure the pub run will improve the mood again in here - for 6 hours or so

There are plenty of the latest GEFS ENS still looking good for coldies. Some belters in fact. 

[Mike Poole]

When a quite abrupt change in the outlook appears in FI, I like to compare the output at T144, the semi-reliable or better:

There is plenty of potential at this point, maybe a cause concern at this point is losing the heights over the pole on the GFS and GEM but not on the UKMO and ECM.  This would explain the latter frames of GFS where the vortex seems to properly form.  I’d hold with UKMO and ECM at this point, we’ll know more tomorrow.  

[Frosty.]

I’ve mentioned a few times today about heights to the south becoming more influential longer term?….and tonight’s ECMWF 12z ensemble mean shows this too, so perhaps beyond next weeks generally unsettled / cyclonic and rather cool spell, we may see more of a north-south split developing with the south becoming largely fine with light winds inducing a risk of overnight & early morning fog whereas the n / nw has more Atlantic weather.

[damianslaw]

GFS and ECM are showing less amplification in the mid atlantic ridge, and this has the knock on effect of a flatter pattern, but this is predicated on the position of the PV.. which looks uncertain.. I would not be surprised to see future runs revert back to a more amplified flow again.. the jet will be elongating on a NW-SE trajectory beforehand, and the azores high will be pulled back quite far westwards. Need to let this play out for a couple of days I feel. I said yesterday the forcing is from the NW, and I'll hold firm on that for now.. which should maintain the jet on a predominantly NW-SE trajectory though not exclusively, i.e. may be temporary shift to a west-east path but shortlived..

[Ali1977]

The ECM Op was a big mild outlier by day 9!! 

[Griff]

Got to love the pub run, doing its best to be a bit more amplified. It's got spirit, you must admit... 

(Edit... Am I really looking at FI charts in October?) 

Edited October 27, 2021 by Griff

[damianslaw]

14 minutes ago, Griff said:

Got to love the pub run, doing its best to be a bit more amplified. It's got spirit, you must admit... 

(Edit... Am I really looking at FI charts in October?) 

Only 5 days away the chart above, within the reliable. 

[ICE COLD]

Better FI this morning on the GFS 00z . 

[Ali1977]

32 minutes ago, ICE COLD said:

Better FI this morning on the GFS 00z . 

Yep, and by day 15 lots of ENS are starting to show more and more northern blocking/heights. A small reset after the initial Northerly then maybe things starting to build for a mid Nov freeze

[sheikhy]

3 minutes ago, Ali1977 said:

Yep, and by day 15 lots of ENS are starting to show more and more northern blocking/heights. A small reset after the initial Northerly then maybe things starting to build for a mid Nov freeze

Any more added amplification in the atlantic between days 5 and 7?!

[ICE COLD]

13 minutes ago, sheikhy said:

Any more added amplification in the atlantic between days 5 and 7?!

ECM is a bit better this morning no rounded low like yesterday’s run . Brings in lower uppers . 

[swfc]

11 hours ago, northwestsnow said:

Flat is one word...

Really hate these synoptic in November

+NAO setting up ...

Not sure a + NAO is forecast northwest. Neutral by mid November app

 

[jules216]

So much for when UKMO was forecasting settled and frosty weather for the second week of November onward. Now we see a flat westerly and Euro high, typical of the recent years. I have wrote this exact outcome on the 15.10, so much for early Canadian warming and hundreds of heavily week vortex bias tweets of CFS zonal winds showing weak vortex, yet vortex is now going all guns blazing and MJO will hardly be going to desired phases for cold 4-7 anytime soon. Again and again all the analog talks of years prior to 2015 are obsolete.

[TSNWK]

On 28/10/2021 at 08:22, jules216 said:

So much for when UKMO was forecasting settled and frosty weather for the second week of November onward. Now we see a flat westerly and Euro high, typical of the recent years. I have wrote this exact outcome on the 15.10, so much for early Canadian warming and hundreds of heavily week vortex bias tweets of CFS zonal winds showing weak vortex, yet vortex is now going all guns blazing and MJO will hardly be going to desired phases for cold 4-7 anytime soon. Again and again all the analog talks of years prior to 2015 are obsolete.

And a good day to you too!

[carinthian]

22 hours ago, carinthian said:

Morning all, its that time of year when I can engage with the forecasting portal team over here. Snow cannons are in place and the primary question asked in resort is when can we use them ? Certainly looking at the latest UKMO at 144h , its going to turn colder into NW Europe , especially in to the British Isles . Its the longlivity of any colder weather that interests me. So I will give an insight of the professional views over here in respect to the chart below.  The problem highlighted appears the behavior of the developing low over Northern Labrador and its eventual position and movement . The expectation is to be just south of Greenland post 168h. Here lies the problem for the models as very cold air off the Greenland ice cap engages the very mild flow heading north in the west Atlantic. The result likely for a zone of high baroclinicity to form . So looking longer term with specifics to the British Isles the view is for a mostly NW flow of colder origins likely to prevail across much of the British Isles but with the positioning of the North Atlantic high open to much doubt at this time. Could be Southern England may return back to milder temperatures but with a lot of uncertainty at 168h and beyond. Hope this helps.

Morning all, ok a bit of an update from over here following on from yesterdays posted report above. Certainly a change to lower temperatures going into next week for a few days at least , especially affecting the British Isles and more generally into Western Europe. How transient is this likely to be is the question. The main models this morning show a 3 to 4 day colder spell before less colder flow takes over generally. However, there is a fundamental difference going forward between ECM and GFS regarding the strength of the Euro -high development. The European model shows a weakening of heights in the Western Med by day 10 . The team over here think this is quite conceivably , especially after a few days of colder uppers associated with the trough next week.  So a split in the high cell could entice the North Atlantic one to retrogress and may allow a quicker return to some form of polar maritime air, especially for Northern Britain ( as shown on the chart below from ECM ). Meanwhile back on the ranch some snowfall is expected in the Alps next week as colder source of maritime moves down.

C

[damianslaw]

8 minutes ago, carinthian said:

Morning all, ok a bit of an update from over here following on from yesterdays posted report above. Certainly a change to lower temperatures going into next week for a few days at least , especially affecting the British Isles and more generally into Western Europe. How transient is this likely to be is the question. The main models this morning show a 3 to 4 day colder spell before less colder flow takes over generally. However, there is a fundamental difference going forward between ECM and GFS regarding the strength of the Euro -high development. The European model shows a weakening of heights in the Western Med by day 10 . The team over here think this is quite conceivably , especially after a few days of colder uppers associated with the trough next week.  So a split in the high cell could entice the North Atlantic one to retrogress and may allow a quicker return to some form of polar maritime air, especially for Northern Britain ( as shown on the chart below from ECM ). Meanwhile back on the ranch some snowfall is expected in the Alps next week as colder source of maritime moves down.

C

Backs up my statement the forcing is from the NW.. i.e. increasingly colder air digging down from the NW will have the effect of creating greater temp gradient on the flank of ridge.. greater the contrast the greater the amplification..  a splitting high very probable.. jet still looks meridional.. a temporary west-east trajectory possibly before back to NW-SE. In long long range GFS showing strong heights over Greenland as well.

[johnholmes]

Not time to post charts (sorry) but the latest 500 mb anomaly charts do suggest that a more westerly flow with the meridional pattern being replaced, looks like about day 8-10 for it to start. Neither really show much indication of heights building in Europe.

 

( remember this comment is for the 6-14 day period, not beyond)

Edited October 28, 2021 by johnholmes

[damianslaw]

20 minutes ago, johnholmes said:

Not time to post charts (sorry) but the latest 500 mb anomaly charts do suggest that a more westerly flow with the meridional pattern being replaced, looks like about day 8-10 for it to start. Neither really show much indication of heights building in Europe.

 

( remember this comment is for the 6-14 day period, not beyond)

Suspect we will see a see-saw pattern..  1-4 Nov day 5 to 9 NW-SE aligned jet... 5 - 9 Nov W-E jet then back to a more concerted NW-SE alignment..

[knocker]

52 minutes ago, johnholmes said:

Not time to post charts (sorry) but the latest 500 mb anomaly charts do suggest that a more westerly flow with the meridional pattern being replaced, looks like about day 8-10 for it to start. Neither really show much indication of heights building in Europe.

 

( remember this comment is for the 6-14 day period, not beyond)

Two pennies worth John

The ext mean anomalies this morning are pretty much on the same page. An amplified Pacific; relatively weak tpv; Fairly flat westerly upper flow across the Atlantic with the gefs/NOAA giving a tad more influence to the subtropical high pushing north; This in turn results in temps being a tad below average rather than the ercm average

[Ali1977]

Much more amplified the 06z with much better heights around Greenland , which may help keep that NW/SE flow .

00z

06z

 

This difference by bonfire night is easy to see compared to the last run!! Let’s see what the GEFS do!!  

Edited October 28, 2021 by Ali1977

[swfc]

17 minutes ago, Ali1977 said:

Much more amplified the 06z with much better heights around Greenland , which may help keep that NW/SE flow .

00z

06z

Yes the specifics are the main varient in the riding position. The waxing and waininng will continue but the PV isn't strengthening or taking hold. Hopefully if it does it will be more east based. Unsettled and turning cool

Edited October 28, 2021 by swfc

[ICE COLD]

GFS 6z in FI is trying it’s best to avoid bringing in the cold uppers from the N NE . Need the high further west

[Methuselah]

Well, what an exciting GFS 06Z. Even if the weather is as dull as ditchwater, the models will keep us on our toes:

    

    

    

But I don't think I'll be arranging a snow chase to Yarmouth pier just yet!