Model Output Discussion - Colder spell ending, what's to follow?

[Ice Day]

4 minutes ago, Kentish Snowman said:

Hi do you have a link to the charts in this format?  TIA

Hi KS - they're on Meteociel.   https://www.meteociel.fr/modeles/gefs_cartes.php

Select 'Paintings' then just click on your location.  Simples!

 

[feb1991blizzard]

9 minutes ago, Sheldon Cooper said:

Wow what a run. 

 

It is a stonker if you like Hurricane force winds.

[LRD]

Last frame is a bit flabby and underwhelming but ECM is heading in the right direction tonight. It did look like Iberian Heights were going to drain away by the end but didn't

We are in a far, far better place than on Friday though so not bad

[Mike Poole]

ECM T240 - amplified, but I much prefer the GEM at same time, better angle of WAA into Greenland:

[Froze were the Days]

Just now, northwestsnow said:

850 profile by day 9 suggest 12z det is significantly colder than the 00z det...

Been the way for a few days...12z has consistently being showing more promise.

[TSNWK]

3 minutes ago, Scott Ingham said:

Don't be too despondent. I'll explain why.

Current State?

We have a northern latitude set up and ongoing weakening of polar winds that are absolutely wipe for northern blocking to take hold due to ongoing weakening of the vortex caused by wave 1 and wave 2 activity the past 4 weeks.

What do we need to take advantage?

Amplification

How do we create amplification?

By creating a rise in angular momentum (AAM)

What can increase angular momentum?

MJO - Tropical convection that moves east into areas of the globe known as the western pacific and central pacific (these are phases 6 7 and 8. Initial forecasts were for a move into 6 and 7 low amp 8 then dieing. Current forecasts show this struggling to get going into 6 which affects its move into 7. Since November this has been under forecast until nearer to time. So no need to worry just yet. Its the NINA we are currently in thats counter acting this. We obviously have cooler waters in the pacific at the minute.

Torque events - This is the current wild card. We have a moderate event an East Asian Mountain Torque (+EAMT) happening right now peaking next Monday or Tuesday as high pressure moves over the Himalayas pushing east into Asia. We also have a forecasted MUCH stronger event due around Christmas time.

What happens if both the convective rain moved east (MJO phases 5 6 and 7) at the same time as the forcing from the torque events? 

We get a rise in AAM (angular momentum) from a base state that isn't that low to start with its just a little above neutral.

What happens if AAM rises?

We get our amplification. Remember the polar field is susceptible right now. Zonal winds are dropping like stones and we have an arctic high waiting for a ridge to come join it from the south to create a winter dance. 

I know the MJO is showing signs of dieing before it gets going but this isn't a certainty the models keep getting it wrong and underestimating it and we have 2 moderate and another strong event almost in the bag.

This year if might not even matter if the MJO runs out or poof and we just have the torque events as the polar atmosphere is so susceptible from the polar high and strat weakening from novembers wave attacks.

Hope this is in enough layman's terms for everyone to understand 

 

Thank you... Really useful.. reading charts is one thing but of course the next bit is understanding what cause and effect is...

[Scott Ingham]

Just now, TSNWK said:

Thank you... Really useful.. reading charts is one thing but of course the next bit is understanding what cause and effect is...

Youre welcome. I hope you've taken something from it.

[northwestsnow]

Day 10 is incredibley finely balanced.

Which is the kind of time Steve's thoughts are really missed by myself.

Anyway  , a step forward this evening..would imagine EC quite chilly by Christmas Eve ....

[Snowman.]

2 minutes ago, Mike Poole said:

ECM T240 - amplified, but I much prefer the GEM at same time, better angle of WAA into Greenland:

ECM making much more of that Russian high and refuses to try and budge the low north of the UK. Without any significant focing on that low we end up no mans land. 

[BARRY]

3 minutes ago, Froze were the Days said:

Been the way for a few days...12z has consistently being showing more promise.

 

3 minutes ago, Froze were the Days said:

Been the way for a few days...12z has consistently being showing more promise.

nice to have you back for the duration 

[feb1991blizzard]

2 minutes ago, Scott Ingham said:

 

 

 

Torque events - This is the current wild card. We have a moderate event an East Asian Mountain Torque (+EAMT) happening right now peaking next Monday or Tuesday as high pressure moves over the Himalayas pushing east into Asia. We also have a forecasted MUCH stronger event due around Christmas time.

 

 

 

Is this what is driving the strat warming in GFS 12 FI?  feel that it will fall short of an SSW this time but ripe for the taking around 20th to 30th Jan.

[chris55]

7 minutes ago, LRD said:

Good trends on the ECM. This morning's run:

This evening's:

Everything much further south. Atlantic looking far more amplified

This caught my eye when looking at the 12z ECM!

This mornings run compared to the this evenings shows the fine line we are walking. A few slight changes and we move from mild southwesterly to cold northerly airmass. (Although longer term it looks like we may get the colder airmass regardless) 

GEFS highlighting this

 

Lots still to play for into and beyond Xmas

 

[Day 10]

5 minutes ago, Mike Poole said:

ECM T240 - amplified, but I much prefer the GEM at same time, better angle of WAA into Greenland:

Much better ECM this eve, good job it's day 10 and time for more improvements. I agree GEM is nice!

Onto the 18z for Mucka's Snowmageddon

[Froze were the Days]

3 minutes ago, BARRY said:

nice to have you back for the duration 

Never went away...just packed in doing my daily winter recordings. Always follow the ecm...

[markw2680]

11 minutes ago, Scott Ingham said:

Don't be too despondent. I'll explain why.

Current State?

We have a northern latitude set up and ongoing weakening of polar winds that are absolutely wipe for northern blocking to take hold due to ongoing weakening of the vortex caused by wave 1 and wave 2 activity the past 4 weeks.

What do we need to take advantage?

Amplification

How do we create amplification?

By creating a rise in angular momentum (AAM)

What can increase angular momentum?

MJO - Tropical convection that moves east into areas of the globe known as the western pacific and central pacific (these are phases 6 7 and 8. Initial forecasts were for a move into 6 and 7 low amp 8 then dieing. Current forecasts show this struggling to get going into 6 which affects its move into 7. Since November this has been under forecast until nearer to time. So no need to worry just yet. Its the NINA we are currently in thats counter acting this. We obviously have cooler waters in the pacific at the minute.

Torque events - This is the current wild card. We have a moderate event an East Asian Mountain Torque (+EAMT) happening right now peaking next Monday or Tuesday as high pressure moves over the Himalayas pushing east into Asia. We also have a forecasted MUCH stronger event due around Christmas time.

What happens if both the convective rain moved east (MJO phases 5 6 and 7) at the same time as the forcing from the torque events? 

We get a rise in AAM (angular momentum) from a base state that isn't that low to start with its just a little above neutral.

What happens if AAM rises?

We get our amplification. Remember the polar field is susceptible right now. Zonal winds are dropping like stones and we have an arctic high waiting for a ridge to come join it from the south to create a winter dance. 

I know the MJO is showing signs of dieing before it gets going but this isn't a certainty the models keep getting it wrong and underestimating it and we have 2 moderate and another strong event almost in the bag.

This year if might not even matter if the MJO runs out or poof and we just have the torque events as the polar atmosphere is so susceptible from the polar high and strat weakening from novembers wave attacks.

Hope this is in enough layman's terms for everyone to understand 

 

You know your stuff don’t you mate, keep it up always good to get good information on here from knowledge folk, dare I say things are starting to look up again, let’s hope that Monday morning feeling is a good one

[Eagle Eye]

Signifacnt advances tonight on the Eastern front certainly a good pub run, even the models have been drinking. 

I never drink though

Maybe I have a tad, even better on the Eastern front now. 

[MATTWOLVES 3]

As Scott says... KEEP THE FAITH!! ECM not to bad, at least looking pretty chilly and seasonal, the real dramatics may occur a few weeks later as the Vortex finally falls over from excessive alcohol over the Xmas Holidays.. That was me putting it into layman's terms. GFS deep FI precipitation graphic says we have the possibility of something wintry in places... Hey if its cold enough, just about anywhere could get a sprinkling. 

Rudolph is on suspension currently, due to Covid restrictions.. But he's gerrin excited... Bit like me... Know throwing toys out the pram from me this Xmas, I would much rather play with em..

Edited December 13, 2020 by MATT☀️

[nick sussex]

A much improved ECM op run .

An important point is to keep the shortwave which is shown in the mid Atlantic at day 6 separate from any low pressure near the UK.

The reason here is if you get phasing and then renewed upstream amplification you’ll force a ridge ahead of that ne and the cold air ends up to the west of the UK.

So you want that shortwave to remain separate and edge east any phasing needs to be avoided until the pattern is sufficiently east.

[Eagle Eye]

15 minutes ago, Scott Ingham said:

Don't be too despondent. I'll explain why.

Current State?

We have a northern latitude set up and ongoing weakening of polar winds that are absolutely wipe for northern blocking to take hold due to ongoing weakening of the vortex caused by wave 1 and wave 2 activity the past 4 weeks.

What do we need to take advantage?

Amplification

How do we create amplification?

By creating a rise in angular momentum (AAM)

What can increase angular momentum?

MJO - Tropical convection that moves east into areas of the globe known as the western pacific and central pacific (these are phases 6 7 and 8. Initial forecasts were for a move into 6 and 7 low amp 8 then dieing. Current forecasts show this struggling to get going into 6 which affects its move into 7. Since November this has been under forecast until nearer to time. So no need to worry just yet. Its the NINA we are currently in thats counter acting this. We obviously have cooler waters in the pacific at the minute.

Torque events - This is the current wild card. We have a moderate event an East Asian Mountain Torque (+EAMT) happening right now peaking next Monday or Tuesday as high pressure moves over the Himalayas pushing east into Asia. We also have a forecasted MUCH stronger event due around Christmas time.

What happens if both the convective rain moved east (MJO phases 5 6 and 7) at the same time as the forcing from the torque events? 

We get a rise in AAM (angular momentum) from a base state that isn't that low to start with its just a little above neutral.

What happens if AAM rises?

We get our amplification. Remember the polar field is susceptible right now. Zonal winds are dropping like stones and we have an arctic high waiting for a ridge to come join it from the south to create a winter dance. 

I know the MJO is showing signs of dieing before it gets going but this isn't a certainty the models keep getting it wrong and underestimating it and we have 2 moderate and another strong event almost in the bag.

This year if might not even matter if the MJO runs out or poof and we just have the torque events as the polar atmosphere is so susceptible from the polar high and strat weakening from novembers wave attacks.

Hope this is in enough layman's terms for everyone to understand 

 

Well I could understand it so you're sorted

[Anthony Burden]

Beginning to show more promise from ecm low tracking further south and 

showing colder set up earlier.Pressure rise further north,fingers crossed 

continuity is what’s needed now.

[BARRY]

1 minute ago, Sheldon Cooper said:

Signifacnt advances tonight on the Eastern front certainly a good pub run, even the models have been drinking. 

I never drink though

Maybe I have a tad, even better on the Eastern front now. 

well i for one would drink more if it showed those synoptics more often

[Scott Ingham]

1 minute ago, markw2680 said:

You know your stuff don’t you mate, keep it up always good to get good information on here from knowledge folk, dare I say things are starting to look up again, let’s hope that Monday morning feeling is a good one

I could always know more mate always looking to learn and develop and this place is perfect for it. The models are flipping because they are trying to work out just how much angular momentum and consequently amplification and high level blocking and where it should be. All 14+ days away. This is why we shouldn't react in a good or bad way past day 6 in my opinion. All we know for certain is we have a ticket. There is a train to momentum avenue but how far away is the destination how fast will we get there and will there be plenty to see when we get off the train 

[Matt H]

4 minutes ago, Sheldon Cooper said:

Signifacnt advances tonight on the Eastern front certainly a good pub run, even the models have been drinking. 

I never drink though

Maybe I have a tad, even better on the Eastern front now. 

Sorry but what do you mean by this?

[stodge]

Evening all

One or two crumbs of comfort last evening for those hoping for a break from unremitting mildness and almost unremitting wetness in the next 14-21 days but let's see where tonight leaves us:

12Z GEM: by T+120 (next Friday), a complex LP sits out to the west of the British Isles with a mild SW'ly flow for all areas. Heights over Europe with the main centre way to the south-east. By T+180, the mild theme continues with a secondary LP from the Atlantic developing and running NE to be off the North-West coast of Scotland bringing a further spell of rain for all. A defined HP cell is moving across Iberia while the Eurasian HP is off to the far east but the strength of the northern arm of the jet is enough to keep it at lower latitudes. A new HP is in the Atlantic with a small LP just to the west of the Azores. Now, this small LP is interesting as it sends the HP into mid-Atlantic where it ridges SE to join with the HP over Iberia and to the north where it links with heights over Greenland to produce a new elongated HP ridge running NW-SE from Greenland to Iberia. There's an evolution to something much more interesting from here and there's some colder air over the British Isles by this time.

12Z GFS OP - well, for the second evening, GEM teases and tantalises in FI. GFS OP certainly didn't do that with a T+384 of absolute horror for cold weather fans. T+120 has a few interesting differences in the position and orientation of the Atlantic LP which may be of significance (or may not). By T+180, the initial LP has moved through to the north and north-east of the British Isles while the new LP has passed between the HP systems and has deepened markedly so I suspect this evolution will look very different from the GEM. Well, perhaps not - by T+240, GFS OP and GEM have some significant similarities with both showing mid-Atlantic ridging. GFS has sent the trough into Scandinavia with a PM airflow now over much of the British Isles and heights over eastern Greenland and Iberia. By T+300, it's getting messy - the trough is now over Scandinavia with weak heights over and to the west of the British Isles and heights over Greenland but wr have a new trough coming out of Canada and heading into the Atlantic. Unfortunately, from there, it all goes very wrong for cold fans - the energy in the Atlantic and Scandinavia link as heights rise over central Europe and we end up with a very mild SSW'ly by T+378 despite Greenland heights. Could this be down to the second strong 10 HPA warming now being forecast in FI? I'm not sure but while superficially it looks poor for coldies there's a lot going on behind the scenes.

12Z ECM - not as bad last night as seemed possible but we'll see. No huge surprises at T+120 though the trough perhaps a fraction more accentuated to the south than on GEM or GFS.  On to T+192 and the LP from lower latitudes is developing to the south west between the two HP cells though it's not as vigorous as GFS at this time. Yet the evolution to T+240 is much different to the other models as the LP ends up filling as it approaches Biscay and the rig=dge builds behind it in mid-Atlantic while a new LP seems to be heading off the eastern seaboard. Chilly if not cold over Scotland and the north in a slack PM airflow but milder further south.

Looking elsewhere, 12Z Control ends with a strong mid-latitude block while the 00Z Parallel is a Christmas present for every coldie with a complex LP moving south through the British Isles and with 850s of -4 to -8, we'd probably not be asking "will it be snow". 

Conclusion - the question for tonight is will be throw two sizes or will it be, as usual snake-eyes? The amplification forecast across the models at T+240 "could" give us a nice cold outbreak for the immediate post-Christmas period but it's all very tenuous and on a knife edge. The GFS OP shows how it could be a disaster while the morning Parallel shows how it could work so well. I have no clue at this time - I'm also noting the second strong 10 HPA warming suggesting the PV coming under renewed pressure at month end. It all looks very interesting.

[Allseasons-Si]

3 minutes ago, Sheldon Cooper said:

Signifacnt advances tonight on the Eastern front certainly a good pub run, even the models have been drinking. 

I never drink though

Maybe I have a tad, even better on the Eastern front now. 

i think you mean the 12z runs