Model Output Discussion - Deeper into Autumn

[feb1991blizzard]

2 minutes ago, blizzard81 said:

That is a right kick to the gonads. Looks like the complete opposite to last night's if it is the ecm. I wondered why those ecm 360 mean charts hadn't been posted this morning. Now I know why. 

think thats a run to run differential, but can't think its Ecm - the graph and map look ok on meteociel without being spectacular.

[minus10]

This block has the potential to hang around for some time...t300 on z500 anoms gfes

The jet, well , nowhere to be seen in our part of the world..

Unusual position for the jet pattern at this time of the year..

As others have stated a slow pattern development however once the block is in place they often stay longer than initially forecasted...days still getting shorter so assuming no changes to overall pattern ( which of course we cannot assume) potential for home grown cold. ..if conditions are right....

just caught last few posts..here is eps 500 geo anoms for t336...

Doesnt look too bad to me..higher anom over greenland..

Edited November 23, 2022 by minus10

[blizzard81]

6 minutes ago, feb1991blizzard said:

think thats a run to run differential, but can't think its Ecm - the graph and map look ok on meteociel without being spectacular.

Thanks Feb. It isn't very clear what is but I'm sure the ecm op stops at day 10. Some clarity would be nice but I know Blue likes to play these games from time to time

[Rain All Night]

4 minutes ago, blizzard81 said:

Thanks Feb. It isn't very clear what is but I'm sure the ecm op stops at day 10. Some clarity would be nice but I know Blue likes to play these games from time to time

It looked like a Tropical Tidbits plot, this is the EPS mean anomaly for day 15 so it wasn't that...

[northwestsnow]

9 minutes ago, blizzard81 said:

Thanks Feb. It isn't very clear what is but I'm sure the ecm op stops at day 10. Some clarity would be nice but I know Blue likes to play these games from time to time

Hasn't helped my doubts !

[markw2680]

2 hours ago, Eagle Eye said:

Exact modeling aside

Look at it on the face of it;

MJO constantly recycling through phases 6 and 7, therefore a Nino-esque AAM regime, that way the westerly jet is slowed down. 

What happens when the westerly jet is weakened?

1) The amplification of oscillating waves gets stronger.

2)Warm Air Advection pushed up the waves

3)Blocking

4)If it gets close enough to the Arctic or even just to Greenland then...

5) -NAO due to pattern flip.

Of course this doesn't happen every time

But with more chances the risk of a -NAO from at least one of them increases.

Of course a -NAO doesn't always bring cold but it increases the chances significantly.

Not only that but WAA near the Arctic increases vertical Eddy Heat Flux. So the SSW chance increases.

Without the current modelling flips and changes. There is a signal of some sort of blocking, mainly focused to the North of us, perhaps to the North West.

Take it on the face of it and it’s very good as an initial setup.

What’s mad is we are not even into December yet and looking at decent charts and not just the odd rogue one in fi!

I have a pretty good feeling about this coming winter especially earlier on in the winter.

I tell you what’s even madder (how the hell are you only 15?)

very knowledgeable and obviously very interested in the weather, keep it up you will go a long way I’m sure 

[Metwatch]

Wanted to point out the current Sea Surface temperatures, They are looking quite mild relative to average, and if we manage to get colder air like what the end of the operational GFS 06z shows, the lake effect machine could be quite something, delivering a lot of snow. Still a big IF though.

 

 

Edited November 23, 2022 by Metwatch

[Methuselah]

1 minute ago, Metwatch said:

Wanted to point out the current Sea Surface temperatures, They are looking quite mild relative to average, and if we manage to get colder air like what the end of The operational GFS 06z shows, the lake effect machine could be quite something, delivering a lot of snow. Still a big IF though.

 

 

If conditions are just right, as in Goldilocks weather, some places could see some massive snowfalls. And, now for the 12Z forecasting 22C!

[TSNWK]

I went on the tropical tidbits site. Checked all 4 ensemble means for day 12 onwards.

All 4 haf heights to out northwest and lower  pressure to out south at varying intensity  

I'm not sure where @bluearmy got that plot from / so keen to understand if i missing something 

[Dangerous55019]

Hello everyone. 

Well, it's been a while since I've done one of these; so here's a look at the CFS V2 four weekly anomalies... Hopefully they'll help out some of our more knowledgeable members...

Week 1: 23rd to the 29th November - The Azores high appears to be centered over southern Spain/north Africa, with a very large trough of low pressure sat out in the Atlantic. This would leave us in a mild(ish) south westerly airflow, with more bands of wind and rain coming at us from off the Atlantic. All in all... Typical November fayre. 

Week 2: 30th November to the 6th December - All Change! A giant area of high pressure (Scandinavian High) stretching out over us here in the UK and also Iceland, and Greenland as well. This would leave us in a chilly/quite possibly cold north easterly airflow! I'm guessing that most nights would be frosty and I dare say foggy in the usual places as well! Plus with the sun being weak at this time of year, the fog could well linger all day! Could this give us our first frost days of 2022.

Week 3: 7th to the 13th of December - The high pressure is now stretching out over the north Atlantic, and covering Iceland, Greenland, Canada and the eastern seaboard of north America. Low pressure over mainland Europe would again leave us in a potentially cold north easterly airflow!

Week 4: 14th to the 20th December - High pressure over the North Pole, and stretching down over Greenland, Iceland and us here in the UK!! Again, I'm going to say that it'll give us more cold, frosty and foggy weather.


So there you go! The current spell of unsettled weather looks like it's going to be taking a break for a while. Will it verify? Only time will tell, so lets see what happens. 

[johncam]

40 minutes ago, Metwatch said:

Wanted to point out the current Sea Surface temperatures, They are looking quite mild relative to average, and if we manage to get colder air like what the end of the operational GFS 06z shows, the lake effect machine could be quite something, delivering a lot of snow. Still a big IF though.

 

 

Going to take a lot of cooling to our north to get sea ice growing around Svalbard and Barents which will modify any northerly we get 

[Cold Winter Night]

I don't think enough people here appreciate the meaning of the different ensembles moving in tandem right now.

Operationals jump between runs, but stepping backward for a wider view, the EPS, GEFS, GEPS are consistently showing more and more NE height rises across the board.
Confidence of an influential blocking episode in early is growing by the day.

Getting the cold here is always a step-by-step process though.
Don't worry about cold T850's that are not immediately here, or cold that does not seem to be available.

If it appears indeed, a powerful Scandi High, especially in December, will both generate and attract cold by itself.
The dense, subsiding (=sinking), relatively dry air will lead to clear skies during the long December nights over an already snow-covered surface in Northwest Russia and Scandinavia. This tips the radiative balance towards cooling nearer to the surface.
A large High in that location will, because of the clockwise rotation around it, also pull in cold air from the East and Northeast (Cold Air Advection). The stronger the High is, and rounder or more oval its shape, the faster this process can go.

Step 1 for now is building heights NE, moving towards a Positive Blocking regime.
The EPS regime chart shows exactly that, out to day 8:

What we would like to see, is retrogression.
First a move into Positive blocking (upper half of the chart), and then a anti-clockwise move towards a Negative NAO (Greenland Block, left hand side of the chart), a classic winter process that almost guarantees an extension of a cold spell.

There's a lot for coldies to be excited about, as long as they stay level headed for a good 1-2 weeks more (good luck with that, folks!) and realise that the ensembles still show less favourable options as well.
Nothing is in the pocket yet, but the above is all within the realm of possibilities right now.

[Kirkcaldy Weather]

Just seeing the overnight and morning runs now.

Continuing on the expected theme and some excellent outputs creeping in from a view of chances that a quite substantial (for so early in the season) cold flow will develop in a good position and could be inclined to move in our direction at some point.

 

 

 

check these 2 beauts

 

[bluearmy]

2 hours ago, feb1991blizzard said:

is that the Gefs mean?

 

2 hours ago, blizzard81 said:

That is a right kick to the gonads. Looks like the complete opposite to last night's if it is the ecm. I wondered why those ecm 360 mean charts hadn't been posted this morning. Now I know why. 

 

2 hours ago, feb1991blizzard said:

think thats a run to run differential, but can't think its Ecm - the graph and map look ok on meteociel without being spectacular.

It was the run to run variation from gefs 00z to gefs 06z at T378. Blues are where mean heights have dropped wrt the 00z etc etc 

an illustration of where we don’t want the runs to trend to where the Atlantic height high anomoly drops away and the euro height low anomoly does the same. we can cope with this trend occasionally from run to run but not if it continues. 

here are the two runs at the same timescale 06z and 00z. You can see where height anoms have changed which is what the original chart I posted reflects 

     

Edited November 23, 2022 by bluearmy

[Ali1977]

Icon is on board for the easterly by day 7, much cleaner in the making compared to its last run.

A good start to the 12z’s

I expected a better METO long range update today to be fair, I’m hoping they are just sitting on the fence not to spark any panic for those not wanting cold  - obviously nothing is certain at this stage, and they may well see this potential cold spell not really materialising to much!! 

Edited November 23, 2022 by Ali1977

[TSNWK]

17 minutes ago, bluearmy said:

 

 

It was the run to run variation from gefs 00z to gefs 06z at T378. Blues are where mean heights have dropped wrt the 00z etc etc 

an illustration of where we don’t want the runs to trend to where the Atlantic height high anomoly drops away and the euro height low anomoly does the same. we can cope with this trend occasionally from run to run but not if it continues. 

here are the two runs at the same timescale 06z and 00z. You can see where height anoms have changed which is what the original chart I posted reflects 

     

Got it.  Trends..... we do like a trend..

[syed2878]

Well, here is the 10 day trend from UK met and they are going for dry start to December

[sheikhy]

12z update!gfs op so far shortwave back north of scotland at 144 hours and the para much flatter to the north west!lets see where this takes us...

[TSNWK]

Gfs going for the messy option at day 6.. not expecting this to bring in any easterly from day 10ish

[Ali1977]

Day 7, and the GFS isn’t as good as earlier   Doesn’t mean to say we won’t get a good day 10 onwards though - let’s see 

Edited November 23, 2022 by Ali1977

[swfc]

I'd suggest like matt said earlier don't be jumping the gun run to run. Many hurdles, shortwave etc to come. Keep your powder dry and give it while the weekend minimum. Uto

[sheikhy]

2 minutes ago, Ali1977 said:

Day 7, and the GFS isn’t as good as earlier

Which is why i say we need favourable developments a lot earlier for us to then benefit down the line!!nao tanking 2 weeks from now and cpc charts looking fantastic for 2 weeks from now is all well and good but we been in this situation plenty of times where everything looks rosey  in the future but then we just chasing and chasing and chasing and before u know it we are halfway through winter!!similar thing happened last winter!!!gota temper expectations!gfs could still salvage it from here!!

[northwestsnow]

That Exeter update is certainly very sobering.

GFS 12Z 168

shouod be ok for a drying out ..

[sheikhy]

1 minute ago, northwestsnow said:

That Exeter update is certainly very sobering.

GFS 12Z 168

shouod be ok for a drying out ..

Yup i reckon that could be that!!ukmo looking flat to the northwest and not as amplified as well at 144 hours!!!could be okay if you like the boring 8 degrees during the day and a slight frost at night!but we all looking for so much more!!

[northwestsnow]

1 minute ago, sheikhy said:

Yup i reckon that could be that!!ukmo looking flat to the northwest and not as amplified as well at 144 hours!!!could be okay if you like the boring 8 degrees during the day and a slight frost at night!but we all looking for so much more!!

Similar to GFS..

The something more has never been in the reliable timeframe.

 

Edited November 23, 2022 by northwestsnow