Model Output Discussion - Into Winter

[Downburst]

9 minutes ago, Mike Poole said:

Polar vortex lobe anyone?

GFS 12z T294, it’s getting closer.

The GFS op has been very consistent with particularly this evolution even though it is so far in the future, that’s compared to the range of evolutions on the EPS clusters at this time.  We will find out in time whether it is on to something…

Corresponding temps around that time for this run, a lot of people to finish work that day, if it happens nice and seasonal. 

 

850 anomalies, not temps, tell a good story.

 

 

Snow showers?

Edited December 8, 2023 by Downburst

[Big Gally]

6 minutes ago, Cold Winter Night said:

GFS 12z Op seems to go nicely along with GEFS/EPS anomalies in the days leading up to Christmas, posted earlier this afternoon.

Excellent run in deep FI.

Forget this week terrible weather! The 20th looks like the time for change.

[alexisj9]

1 hour ago, Snowboy111 said:

Imagine if the Met released that statement. The meltdown in the tabloids would be incredible! They’d cause huge panic.  And then if it didn’t happen they’d be hammered by the same tabloids. Not worth the hassle. 

Itlltbe in the tabloids anyway, they'll jump on today's Christmas charts tomorrow , saying met says as usual.

[TSNWK]

toppler..

 

[BLAST FROM THE PAST]

Just to show a type of chart I always look for…..this is CLASSIC retrogression trigger scenario for northerly plunge 

 

BFTP

 

 

[LRD]

1 minute ago, TSNWK said:

toppler..

 

Amplifying again... 

[Downburst]

Full of Northerly promise. I wonder if a low could get cut off in the med and the high then move to Scandi. Even at the end it is 1040mb and has some stopping power, even if not moving north enough. Perhaps Scandi is the ultimate destination.

[BLAST FROM THE PAST]

3 minutes ago, TSNWK said:

toppler..

 

In that note….I’m sitting in the camp that Xmas week can be very interesting but no real locked in Northern blocking (not an issue imo and potential pretty stormy conditions)….but comfortable with further stronger shots as we go through Jan and Feb.  
 

BFTP

Edited December 8, 2023 by BLAST FROM THE PAST

[bluearmy]

3 hours ago, Jacob said:

I found this weather model I've never used before and the mean on Christmas Eve looks confident in a cold spell at this time 

Naefs is a combination of gefs and geps. It’s used by NOAA cpc and it’s probably the best ens tool after the eps 

56 minutes ago, snowking said:

Very much worth bearing in mind, particularly those with tendency to follow the trials and tribulations of each individual operational run, that whilst we have an evolving Arctic High in play (such as can already be seen relatively clearly in ensemble means by day 9) then the modelling across the northern hemisphere is likely to be chaotic for many days to come. We will see swings back and forth. The best advice I can possibly give if you want to follow NWP religiously is stick to the ensemble means for the foreseeable:

 

Exciting watching ahead.

Was thinking about this Arctic high earlier Kris - over the years, the favoured evolution for this fella is to head into the Alaskan ridge or the Siberian ridge. Whilst we see model runs that bring it towards our side of the pole, it rarely happens without an ssw reversal wave. If we could get it to time this side of the pole with a greeny ridge then it’s jackpot time 

[Rob 79812010]

58 minutes ago, Met4Cast said:

Because, and this is going to sound rather ridiculoius; we have access to data that they don't. 

Putting aside the fact businesses change operations etc depending on the weather, the Met Office don't have access to the GSDM framework, I've spoken to a number of senior mets and it's simply not used, the AAM is occasionally used for seasonal forecasting but never sub-seasonal forecasting, i.e the 10-30 day period. 

To quote an anonymous source after asking if the AAM/GSDM is used internally;

With that in mind, the Met Office will be looking at the MJO in a more isolated state without factoring in the rest of the GSDM, GWO etc. That alone reduces confidence. The other thing being that despite the MJO/GSDM suggesting blocked patterns being likely during the late Dec period, that doesn't necessarily = the UK being on the cold side of things, we could end up with unfavourable blocking for UK cold. 

So.. all in all, the Met being cautious and vague in the longer term makes sense, they have far more to lose. Us on here? If we go for cold and then it doesn't happen, does anyone really care? Not really.

We care 

[Midlands Ice Age]

Reports on the NOAA NCEP Reanalysis show that about the 15 - 16th of December 1961 high pressure moved up from the south, and it stuck around just to the west of Northern Ireland for about 5 days . During this time it kept trying to ridge to the NW towards Greenland, but it never made it beyond Iceland, and eventually towards the 20th it settled towards the East of the Northern Isles.  Here it hung on for a couple of days before  the blast of the colder air to the north pushed it a bit further west.  There was no Greenland high until later on in the run.

During this time the weather over the UK was cold with extensive fog and the temperature gradually fell so Xmas was cold, and frosty with night time lows dropped from -4C to -10C . It was Boxing day onwards that a low from the Atlantic went under, up the Channel,  and the rest was history.

I remember it well....

See the reanalysis of it all in the link below -

1961 December

MIA

Edited December 8, 2023 by Midlands Ice Age

[I remember Atlantic 252]

34 minutes ago, Mike Poole said:

Polar vortex lobe anyone?

GFS 12z T294, it’s getting closer.

The GFS op has been very consistent with particularly this evolution even though it is so far in the future, that’s compared to the range of evolutions on the EPS clusters at this time.  We will find out in time whether it is on to something…

Nightmare 20th Dec 2009 redux! SK4 over 30cms, here not a flake

[swfc]

1 hour ago, That ECM said:

Summer sun post everyday in the met office outlook forum. Everyone knows this and this is where to pick over every word. 
 

I honestly think we should make a real effort to use it and then this forum won’t get bogged down in it. There will not be one of us that doesn’t look at there updates and yes we are interested obviously but if we get in the habit of using it people won’t feel the need to post in here because no one will see it in the outlook forum.

 

lets give it ago eh?

Thanks pal, it's becoming repetitive

[Derecho]

UKMO at day 7 highlights a risk. We wouldn't want the high to settle over France as it could become very mild if it gets stuck there. Also the less ridging north this high does the higher the risk of the high becoming stuck making retrogression more challenging for further down the line.

GFS is better.

[NewEra21]

If the GFS does nail this, you have to say the overall consistency run to run has been incredible. Slight variations of course, but the overall pattern and result is always the same!

Edited December 8, 2023 by NewEra21

[swfc]

The old adage anything over 144 hrs seems not to resinate if its showing a sign of blocking and anything wintry. Its works if were in a position of a westerly flow. Best hang fire see what the next 7 days brings on the mo/nhp. Looks good on the background signals but relax a bit on meto/bbc longe range outlook

[Dennis]

ssw signs after 20th

[BartyHater]

23 minutes ago, Derecho said:

UKMO at day 7 highlights a risk. We wouldn't want the high to settle over France as it could become very mild if it gets stuck there. Also the less ridging north this high does the higher the risk of the high becoming stuck making retrogression more challenging for further down the line.

GFS is better.

ICON is on very much the same page as UKMO at 168hrs....nothing nailed down yet beyond high pressure setting up over or close to the UK later next week. 

[Alexis]

1 hour ago, alexisj9 said:

Itlltbe in the tabloids anyway, they'll jump on today's Christmas charts tomorrow , saying met says as usual.

They play the percentages. At this range, there's always a 60% chance of the high sinking and it going mild, and 40% chance that it won't.

 

[lewis clark]

The snow and cold arrives on the 22nd at 6pm according to gb news lol!

[swfc]

2 minutes ago, lewis clark said:

The snow and cold arrives on the 22nd at 6pm according to gb news lol!

Fantastic we have time travel forecasts

[TSNWK]

4 minutes ago, lewis clark said:

The snow and cold arrives on the 22nd at 6pm according to gb news lol!

Brillant.. save us all a job and can be more relaxed viewing the overnights... 

[Catacol]

US and Canada looking increasingly warm through later December. About time that North Pacific ridge that has been semi permanent for years goes into retreat and stops promoting the Atlantic train…

[johncam]

1 hour ago, Derecho said:

UKMO at day 7 highlights a risk. We wouldn't want the high to settle over France as it could become very mild if it gets stuck there. Also the less ridging north this high does the higher the risk of the high becoming stuck making retrogression more challenging for further down the line.

GFS is better.

Not for us up north 

[Bats32]

2 minutes ago, johncam said:

Not for us up north 

Its a horrible chart for us.