Model Output Discussion - cold spell to end Autumn

[mpkio2]

WARNING: EPIC POST INCOMING!!!!!

Quoted from last MOD thread: 

"Model Output Discussion 01/09/17"

Link to comment:

(Within this post I will make quotes from my last post from the last MOD thread. Link is above!)

----

Hello all once again!

So around this time last week, I made a post regarding UK COLD weather potential, with some ramping and some strong caution going forward.

Most models were showing a cold pattern emerging.....

This is what ECM/GFS/GEM was showing on the 21st November for today...

12z ECM 21/11 t192:

12z GFS 21/11 t192:

12z GEM 21/11 t192:

And....

12z UKMO 23/11 t144:

And this is where we are currently.....

12z GFS 29/11 t06:

So.....as can be seen, not one model got the current pattern correct. This, as I mentioned last week, was down to the shenanigans going on the atmosphere affecting the models, causing model vioity, swings in output.

Although, I think ECM/UKMO was pretty close, especially if you blended their output into one (Though the troughing to the NE is completely wrong!). The best thing to do in these situations is to find a trend/theme that keeps cropping up. And, what all runs had in common on that day was a Northlyflow for the UK with a trough to out NE and ridge to our west - that was the trend.

Thus, I commented.....

mpkio2 said:
"FL for me anyway, is anything after, seeing how all models develop on to something different in look and what the UK "might" receive, but the theme and trend for a "COLD" snap/spelli very strong within them, as well! 9Look above at my faves of the day! ). All models see the Main lobe of the PV taking a holiday towards East Russia, Centered Arctic high with Atlantic heights ridging up, a trough over Scandi digging down cold N/NW winds with a mixture of Snow/sleet/rain affecting the country. Very, very good! "

And that's exactly what happened and where we currently find ourselves in - lobe of PV went to East Russia, Atlantic ridging up to pole connect with Arctic High in place, trough over Scandy and Northly wind bringing down COLD air with a mixture of Snow/Sleet/Rain affecting the country!!!

Ahem....*cough* *cough*

Snow showers for Eastern coasts tomorrow!

And so, what do they models see now? What's been the trend/theme over that past few days?

12z GFS 29/11 t144:

12z UKMO 29/11 t144:

12z GEM 29/11 t144:

0z ECM 29/11 t144:

Very good agreement between the models!  (Especially the GFS/UKMO!) The THEME is for heights in the Atlantic to further ridge up to Greenland (Look at that WAA!!! ), Trough over Scandy, Arctic High STILL in place, trough over NE America, Low off Newfoundland (Helping with WAA to build GH! - Hopefully! ), high building NW of America (Alaskan High?) and high over Russia slowly building too! @chionomaniac  Is that a 3-Wave Tropospheric pattern emerging? )

Of course, the models don't have the details down yet of what will happen after, seeing how previous runs have built a GH successfully and some haven't, with inter-runs showing different outcomes after the t144 period (Which is around the timeframe (6th - 12 Dec) of @Steve Murr 's potential for Blocking to form around Greenland! ).

Asd many have already said, it's knife-edge stuff for the UK (When isn't it, though, really? ) and a case of "Wait and see".

Adding on, however to @Tamara brilliant and fully detailed post early today, there is still some optimism to have for some cold weather to come our way...

Tamara said:
If La Nina consolidates to any greater extent then attempted rises in atmospheric angular momentum tendency are logically supressed. As a consequence, this implies a dearth of +ve torque forcing c/o poleward rossby wave development from tropics to extra tropics and then to polar stratosphere via +MT to develop the Eurasian cold equation as a means of cold air advection from the NE.

In such circumstances, with the vortex more organised this side of the pole, the outcome would favour the Pacific/Atlantic ridge combination and too much overriding polar jet energy to enable sufficient trough disruption of lows heading downstream and in turn allowing height rises from the NE to ride over and cut off low heights to the south.   If La Nina forcing is too strong then this favours increased strength to the sub tropical Azores ridge which would override too weak any -AO signal.

Basically, whats she saying is that a "cause and effect" needs to occur for ample opportunities ala cold weather prospects for the UK. If La Nina gets stronger then atmospheric working can't take place (angular momentum, +ve torque forcing ,rossby wave development, etc), which we need to allow for a cold pattern to become established.

TO BE CONTINUED.......

[Summer Sun]

t216 sees it turning milder and more westerly just as parts of the USA go into the freezer

[Frosty.]

Mild mush incoming at T+216...help

 

Edited November 29, 2017 by Frosty.

[weirpig]

It's a good job the ecm isn't the king of models and has the highest verification stats. Sorry what was that  oh. In all seriousness in its early frames it was certainly a move towards the gfs. However was scuppered  around t 144 with that shortwave.  As we were chaps . Eyes down for the pub run 

[radiohead]

 

[northwestsnow]

Think we have all seen enough to realise if EC is correct the metoffice will be hastily re writing their update tomorrow.

 

 

[Methuselah]

2 minutes ago, Frosty. said:

Mild mush incoming at T+216...help

Now where's that 'reverse zonality' gone when we need it?

[Moorlandman]

Euro High and a cold snap for Eastern America. It doesn’t look well for us

[Summer Sun]

Eastern USA gets colder Jet stream fires up and sends milder air to the UK

[Snowman.]

1 minute ago, northwestsnow said:

Think we have all seen enough to realise if EC is correct the metoffice will be hastily re writing their update tomorrow.

 

 

The most knee jerk reaction in this thread. Not needed take it somewhere else.

[mountain shadow]

19 minutes ago, frosty ground said:

It could easily be wrong just as it could easily be right...... only time will tell 

The ECM would have to be monumentally wrong to give any chance of a Northerly next week, i have been model watching for over a decade and I can't hardly remember a time where a T+120 ECM chart has been that monumentally wrong. Remember, we are a small island, if the jet pushes everything 200 miles East, we miss out and the cold goes East.

Time will of course tell, but it's looking increasingly likely that our ship has sailed as the jet fires up due to the bitter cold sweeping into the US and Canada over the weekend.

[nick sussex]

The difference between the ECM 12hrs run and 00 hrs in the later stages is unbelievable . 

Upstream it’s all over the place. 

Then it ejects the main trough from the eastern USA which means it’s completely lost the plot .

Stick it’s later output in the cat litter tray. 

[weirpig]

1 minute ago, ShortWaveHell said:

Well the ECM put a double or nothing knife edge bet on at 168 and cleared its bank account .. now into days 8-9 it’s re mortgaged the house and now the bailiffs have arrived in a daffodil filled garden ! 

Absolute quality. Cheers for that 

[Snowman.]

Just now, mountain shadow said:

The ECM would have to be monumentally wrong to give any chance of a Northerly next week, i have been model watching for over a decade and I can't hardly remember a time where a T+120 ECM chart has been that monumentally wrong. Remember, we are a small island, if the jet pushes everything 200 miles East, we miss out and the cold goes East.

Time will of course tell, but it's looking increasingly likely that our ship has sailed as the jet fires up due to the bitter cold sweeping into the US and Canada over the weekend.

It was wrong enough for me to wake up one morning and easterly at 96 completely vanished

[tight isobar]

12 minutes ago, weirpig said:

It's a good job the ecm isn't the king of models and has the highest verification stats. Sorry what was that  oh. In all seriousness in its early frames it was certainly a move towards the gfs. However was scuppered  around t 144 with that shortwave.  As we were chaps . Eyes down for the pub run 

Yes certainly no-done deal...

However! 

The atlantic ridge is fast becoming-via output, an atlantic mobility conveyor! 

And relaxing via shortwaving, to the west of iberia/atlantic.

And certainly cannot be ignored now!

The upstream pattern is becoming bad to the eye also.

And with a eastern seaboard trough taking the states into winter 'proper'..

The alarm bells are certainly ringing!!!

But-as again we wait and see!!!???

Edited November 29, 2017 by tight isobar

[northwestsnow]

2 minutes ago, SN0WM4N said:

The most knee jerk reaction in this thread. Not needed take it somewhere else.

Why? If EC is correct dont you think they will be re writing their update? Becasue their update will be massively wrong.

I didnt say EC was correct, did i?

[mountain shadow]

Just now, SN0WM4N said:

It was wrong enough for me to wake up one morning and easterly at 96 completely vanished

Yup, that's one of the times I remember.

:-)

[Snowman.]

1 minute ago, mountain shadow said:

Yup, that's one of the times I remember.

:-)

Still hurts to this day

[blizzard81]

4 minutes ago, nick sussex said:

The difference between the ECM 12hrs run and 00 hrs in the later stages is unbelievable . 

Upstream it’s all over the place. 

Then it ejects the main trough from the eastern USA which means it’s completely lost the plot .

Stick it’s later output in the cat litter tray. 

I hope you are correct Nick. However, it shows an all too familiar tale of the double whammy sucker blow to the UK - US goes frigid, we defrost rapidly! 

[markw2680]

4 minutes ago, SN0WM4N said:

It was wrong enough for me to wake up one morning and easterly at 96 completely vanished

I remember that very well too. There will be so many more changes in the next 24 hours let alone a few days. It’s very much up in the air atm, could go either way.

[Kentish Snowman in Yorks]

10 minutes ago, northwestsnow said:

Think we have all seen enough to realise if EC is correct the metoffice will be hastily re writing their update tomorrow.

 

 

Going against 85% of the GEFS and the Meto outlook as you say so I would be highly sceptical of this run unless it garners support from the 18z and 0z suites tomorrow morning.

I will go out on a limb and say it will be very much at the mild end of the EC ensembles...

[Guest]

 

               Now where have I seen this before?   Oh yes.....

 

         

Sorry MODS, not like me to do that, I must be suffering from model fatigue. One of @nick sussex 's short waves off the Falkland Islands, crossed the Equator and thoroughly disrupted me!

I'll be back with a serious report at the weekend.

Edited November 29, 2017 by Guest

[tight isobar]

1 minute ago, Kentish Snowman said:

Going against 85% of the GEFS and the Meto outlook as you say so I would be highly sceptical of this run unless it garners support from the 18z and 0z suites tomorrow morning.

I will go out on a limb and say it will be very much at the mild end of the EC ensembles...

Should be.

 

[MattTarrant]

This thread has been somewhat hostile at the moment. This is a 'model output' thread, not a thread to display your weather wishes. I think people really need to consider whether what there posting is of any use (Ie contains some scientific knowledge to it, or more importantly some more open minded analysis). 

[knocker]

According to the ecm the twin energy flows from the Canadian lobe and the southern States continue to cause downstream major problems starting quite early in the piece,

At T120 troughs are running around Greenland and sinking south into central Europe between the two high cells whilst energy from the eastern seaboard is putting the high cell to the west of Cornwall under pressure with a W/NW flow over the UK with temps maybe a little above average

The pressure continues and by T144 there is a deep surface low in mid Atlantic and another off the north west coast of Norway with the high cell hanging in there south of the UK and attempting to ridge north west.A little frontal wave associated with the low to the west has sneaked around the high and is impacting Scotland

Over the next 24 hours there appears to be some renewed amplification and the front moves very little giving quite a wet 24 hours for Scotland  But the amplification does briefly reinforce the HP to the west so that by T192 a narrow ridge is orientated N/S over the UK and the front squeezed south the France/Belgium

But, you have guessed it,  the ridge rapidly comes under pressure from the Atlantic driven by 150kt jet out of the eastern seaboard.

Edited November 29, 2017 by knocker