Model Output Discussions 06z 04/11/16

[ArHu3]

1 hour ago, Mucka said:

Good morning all.

Looking at the output so far this morning  it seems we are firming up on that Northerly outbreak with UKMO primed at 144 for the trough to dig South with decent upstream amplification which should accentuate any ensuing Northerly flow.

Beside it the slightly faster and flatter GFS 00z

 

And that is encouraging given this GFS 00z at 192

So we could be seeing the very quick development of a cold spell here and a better insight into recent MetO thinking re  early Dec cold,

It will be hard to predict how cold uppers will be as it will depend on exactly how the trough develops and if we get any spoiler shortwaves develop on its Western flank cutting off the Northerly flow or developing a West based -NAO.

That said, if we stay on the cold side of any embedded troughs it could also be  potentially quite snowy. Caveat being there is a fine line between cold rain and heavy snow in such situations - all that is for 72 hours and less if we actually get the Northerly to verify though really - getting ahead of myself again.

Very exciting output so far so let's hope ECM comes on board. 

 

Edit.

Stunning GEM with a direct hit and WAA into the heart of Greenland, hope this is our ultimate destination.

That would be very cold indeed. Remember GEM massively under-does negative 850's

 

GFS FI looks primed to give us a Scandi high and Easterly

But instead drives a trough down from the Arctic and ends very blocked which while not to be taken seriously is much more encouraging than seeing deepest FI return to climatology.

 

 

I can tell it is not going to happen, ec is still at 96h but it looks very different from gfs at that point in time

 

Edited November 24, 2016 by ArHu3

[knocker]

Today

Very much a two way split between Scotland and the rest..The former will start with clear skies and quite a severe frost and the clarity will continue during the day with temps picking up but remaining on the cool side. Elsewhere the temps much higher, particularly in the south, but the price for this is remaining cloudy virtually everywhere. The significant factor here may well be the wind with a squeeze between the HP and LP. and the north easterlies will be quite strong down south and particularly in the channel.

This morning's GFS

Saturday sees energy tracking NE from the eastern seaboard and SE from N. Canada phasing to form a new low SE of the tip of Greenland that tracks NE pushing the HP east and forming a weak trough mid Atlantic. At 1200z Monday the high cell is over the UK

 

Continued upstream forcing doesn't allow any meaningful development of the Atlantic trough but it  does invigorate the energy running east from Greenland and another surge from the Azores HP which is quickly flattened by the former leading to a very tight thermal gradient and a strong jet running west to east over Scotland by 12z Wednesday. On the surface this translates to strong westerly winds, particularly over Scotland, which will also suffer some very wet weather

From here the main trough to the NW drops SE and deconstructs leaving one arm running N/S to the west of the UK. An action that amplifies the Azores HP into Greenland with strong WAA between Greenland and Canada and CAA into the mid Atlantic. Best left here this is still wide open to various interpretations.

So a quick summation of the weather in general. Remaining dry if rather cool until the beginning of next week when the situation becomes quickly unsettled with strong winds, very wet interludes and the UK and the eastern Atlantic under large, complex low pressure area. The temps during all of this very variable running from quite cool to just above average and then just below.

 

 

Edited November 24, 2016 by knocker

[Mucka]

17 minutes ago, ArHu3 said:

I can tell it is not going to happen, ec is still at 96h but it looks very different from gfs at that point in time

 

We never seem to get cross model support just when we think cold is within our grasp do we?

That said it is somewhat on its own (Op output) and even then it ha s corrected the trough West a long way from yesterday morning so I'm hopeful GFS is leading the way.

Definitely not a done deal though and I guess it will help keep expectations low should it be another let down

 

Edited November 24, 2016 by Mucka

[snowbunting]

Not often you see the pub run agreeing with the 0z GFS charts.  upto time 240 ish, the ECM is also beginning to toy nicely with a Northerly outbreak 4th to 7th of december ... roughly. as that depression from the south bangs into that colder air.. potential for more snow for those in higher parts of NE england, south scotland. the GFS is also picking up zonal weather and a very positive NAO by the end of the run... way out I know but I feel that will continue to get pushed further back into december. 

[knocker]

One of the options I mentioned above is adopted by the ecm. Instead of dropping the trough south it has a resurgence of the Azores HP NE to be over the UK by T216. An infinitely preferable option as it would virtually remove the descent into very windy and wet weather.

Edited November 24, 2016 by knocker

[Frosty.]

48 minutes ago, Steve Murr said:

Morning-

upgrades all around today - GEM /UKMO in the ballpark for the 30th now- GFS still solid !

S

Here's hoping Steve, an infinitely preferable option on the cusp of winter!

[BLAST FROM THE PAST]

7 hours ago, Geordiesnow said:

Definately a brilliant forecaster and I always enjoyed watching his forecasts but I just have to question why they mentioning about the AO and prospects of cold during December where its beyond the 6-10 day period. Also it looks like too me the AO will go positive with quite a strong PV over the Arctic, whether this will change again or not then who knows.

Agreed re John Hammond. Re the PV that has been my point. It will be a player but displaced.  This at times will bring very volatile weather (2nd week and Xmas week of particular interest) to our shores with wild jetsream swings and I believe and have for sometime that we will be  below normal this Dec And Jan.  

00z GFS again I'm liking the overall theme.

 

BFTP

 

 

[Swave Snow]

7 hours ago, Summer Sun said:

Maybe things will click into place for the UK 

Lol that's my twitter feed 

[bluearmy]

A łot of fuss over JH's broadcast. We are under a low anomoly in early December. Most of the uk is under mean sub zero uppers. Of course that delivers a snow/ice risk. The neg AO representation is setting the background for December as per Ian's info and most long range predictions worth taking note of. 

In the meantime, the ens drift slowly towards winter hemispherically and opportunities exist prior to that for low temps and surprise events. 

[Ali1977]

PV looks like staying quiet 

[Frosty.]

5 minutes ago, BLAST FROM THE PAST said:

Agreed re John Hammond. Re the PV that has been my point. It will be a player but displaced.  This at times will bring very volatile weather (2nd week and Xmas week of particular interest) to our shores with wild jetsream swings and I believe and have for sometime that we will be  below normal this Dec And Jan.  

00z GFS again I'm liking the overall theme.

 

BFTP

 

 

Ditto, hopefully the Azores high won't spoil the party, it seems the majority of the 00z output wants to bring winter on time.

P.S..Great reading all the positive posts about wintry potential from the likes of SM etc!

Edited November 24, 2016 by Frosty.

[Seasonality]

Still divergence between the ECM and the GFS. Here at 192h. Leading to a very different outcome for the UK in terms of uppers and resultant surface conditions.  Until the big two show more consistency caution is needed.

 

[Nick F]

Wow ... stark differences between EC and GFS operationals this morning in the 8-10 day range across the Atlantic.

EC has a southerly tracking jet across the Atlantic which pushes a trough east towards Iberia - which looks unlikely given there's a ridge extending NE from the Azores days 6-7. And it would pump warm N across Europe too.

GFS sticking to its guns with the amplifying ridge across NW Atlantic into Greenland while a 500mb cold pool drops south from the arctic further east across N Europe - but doesn't quite manage a clean northerly.

Some volatility from EC over recent runs at the 500mb level while GFS seems more stable though with surface differences.

[karlos1983]

New ECM clearly needs AVG installing !! What is it playing at,  bore fest.  We could really do with having it onside though. 

 

Edited November 24, 2016 by karlos1983

[knocker]

Quite a pleasant way to start December. Now if this was Xmas week................................

[Severe Siberian icy blast]

5 minutes ago, Nick F said:

Wow ... stark differences between EC and GFS operationals this morning in the 8-10 day range across the Atlantic.

EC has a southerly tracking jet across the Atlantic which pushes a trough east towards Iberia - which looks unlikely given there's a ridge extending NE from the Azores days 6-7. And it would pump warm N across Europe too.

GFS sticking to its guns with the amplifying ridge across NW Atlantic into Greenland while a 500mb cold pool drops south from the arctic further east across N Europe - but doesn't quite manage a clean northerly.

Some volatility from EC over recent runs at the 500mb level while GFS seems more stable though with surface differences.

Yes very different modeling over the Atlantic and the way jet behaves.

Even with the gfs though it's all very messy and seems intent on keeping cold air away from the UK. Not sure we're gonna get a cold spell from this because even when we actually get the colder air filtering down on some runs it's full of shortwaves and troughs so my guess will be cool not cold with wintry showers to high ground and cold rain for the majority. Really hope I'm wrong . . . 

[Seasonality]

1 minute ago, knocker said:

Quite a pleasant way to start December. Now if this was Xmas week................................

Good Morning @knocker Thank you as usual for these charts. A good illustration of why nothing is certain quite yet. Do you happen to have any t2m charts for the same period that you can post please?

[Frosty.]

The Gem 00z is how December should start! It's what coldies deserve

Edited November 24, 2016 by Frosty.

[knocker]

6 minutes ago, Seasonality said:

Good Morning @knocker Thank you as usual for these charts. A good illustration of why nothing is certain quite yet. Do you happen to have any t2m charts for the same period that you can post please?

Not with the ecm I'm afraid.

[blizzard81]

8 minutes ago, Severe Siberian icy blast said:

Yes very different modeling over the Atlantic and the way jet behaves.

Even with the gfs though it's all very messy and seems intent on keeping cold air away from the UK. Not sure we're gonna get a cold spell from this because even when we actually get the colder air filtering down on some runs it's full of shortwaves and troughs so my guess will be cool not cold with wintry showers to high ground and cold rain for the majority. Really hope I'm wrong . . . 

Yep. Quite ironically, the ecm run holds far greater potential for a worthy cold spell as we approach mid Dec. Atlantic lows diving towards Iberia on a north west/south east (negatively tilted) axis and the amplification over the pacific.

[Frosty.]

3 minutes ago, knocker said:

Not with the ecm I'm afraid.

I think the Ecm 00z ensemble mean will look rather different

[tight isobar]

The ecm continues to be stagnant looking in any evolution I.e' waa upstream and having little/no influence on major displacement of hp cell around our shores.

The gfs 'however' remains steadfast in evolving at least as far sticking to its continued fixation of forming a block to the north west of sorts.

I have to say "and some won't agree here"!..but due to comparable evolutionary' for me the ec' is alittle off key atm and may well be playing catch up to the slowest' of degrees! ..

We shall certainly know more by end of all 12zthis evening. 

Edited November 24, 2016 by tight isobar

[jvenge]

9 minutes ago, Seasonality said:

Good Morning @knocker Thank you as usual for these charts. A good illustration of why nothing is certain quite yet. Do you happen to have any t2m charts for the same period that you can post please?

The 2m ones are in F and only in snapshots, rather than average mean. I can post them if you wish, but they generally show the UK a little above average at those times, before going to at average or a little below further into the run.

[mulzy]

16 minutes ago, knocker said:

Quite a pleasant way to start December. Now if this was Xmas week................................

That's a just for fun chart - rather meaningless at that range.  Disagrees with many of the other operational runs this morning.  Let's see what the ensembles say...

[knocker]

1 minute ago, jvenge said:

The 2m ones are in F and only in snapshots, rather than average mean. I can post them if you wish, but they generally show the UK a little above average at those times, before going to at average or a little below further into the run.

jvenge if you are looking at the charts from the Regional Surface run posting them is a definite no no.