[Model Output Discussion - Spring Has Sprung]

It’s like Groundhog Day .

The same old zonal pattern with strong Iberian high repeated ad nauseam.

The GEFS show a few better solutions post day ten .

The ECM op does finally split up the PV day ten but still leaves a lobe over Greenland .

The wait continues ......

[Model Output Discussion - Cold spell ending - what next?]

Not much to report today in terms of hope for coldies barring the last frame of the ECM at day ten which shows the PV finally weakening to the north.

We’ll have to see whether that survives into tonight ! 

We certainly need the MJO to move out of phase 5 and into 6 , the speed of that shows some divergence across the models .

 

[Model Output Discussion - Cold spell ending - what next?]

The GFS more interested in the Scandi high earlier .

The models all sing from the same hymn sheet in terms of overall pattern . Pressure rises to the ne and still an angry looking PV . We await to see which one wins out .

The ECM may just be a timing difference v the GFS and we are seeing the pull back of low heights from the  ne and Svalbard region although the ECM does keep the more rounded PV at day ten .

You generally want to see the more sausage shaped PV orientating ne sw initially.

 

[Model Output Discussion - Cold spell ending - what next?]

The overall pattern has good agreement after the weekends wet and windy weather .

So the upstream troughing will dig south and there will be several attempts to cut shortwave energy se to the east or ne.

Pressure rises to the ne but the question is can that troughing sharpen up enough and will we see a westwards correction. 

We certainly need the MJO to move out of phase 5 and into 6 as quickly as possible and preferably into 7 but the models seem less interested in the latter happening . There’s also a question mark over the amplitude of the signal.

 

[Model Output Discussion - Cold spell ending - what next?]

Back in the UK and enjoying the sunny frosty weather which sadly is going to be replaced by a spell of horrible extremely windy and wet conditions .

Some damaging winds on the way unfortunately.

After this spell of bad weather some suggestions we’re going to see an attempt to build pressure towards Scandi .

So the digging Atlantic troughing results in pressure trying to rise to the ne of that .

The question of course is can you get enough dig south and can you get the jet cutback into the Low Countries with the trigger shortwave .

Still uncertainty there but it’s a lot more interesting than discussing the coming monsoon !

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

I’d ignore those apps . They’re generally useless .

This Atlantic low and its associated precip has been a long winded saga with the models terrified of breaching the southern snow barrier ! 

I would keep low expectations as both the GEM and ICON have now edged the precip further south . 

So just when you think there’s some north momentum another run pops up saying no!

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

The T24 hrs fax chart shows the occlusion further north than the earlier T36 hrs this morning .

T36 hrs to midday tomorrow .

T24 hrs to midday tomorrow .

Puzzling as the models so far look very underwhelming for any snow in the far s and se .

The precip ahead of that occlusion is likely to be further north than any of the models I’ve seen so far .

Very strange .

[Model Output Discussion - Colder but how cold and for how long?]

The GFS 12 hrs run picking up the ECM 00hrs baton from this morning with the digging upstream troughing which tries to send a ridge ne ahead of it .

The more dig south and the sharper troughing the further n the ridge gets ahead of it .

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

1 hour ago, snowray said:

UKMO 06z has the PPN just clipping the south coast again, quite strange since its always shown it way to the south.

 

 

If the others were more interested then that jump north would be more notable . Given where it was on its 00 hrs run it’s a big shift north .

 

[Model Output Discussion - Colder but how cold and for how long?]

Re the Atlantic low , normally once things start correcting south they don’t stop.

That tends to happen though when you have strong blocking , in this instance the block is weakening .

So that’s why  we’ve seen these small north and southwards shifts and even at this stage given the margin for error that could be anything from 50-75 miles further north or south .

It could be a total non-event or bring a decent covering to southern coastal fringes .

Further north there’s that shortwave moving se and then after that further snow showers .

The cold air hangs on to Friday before we sadly see the PV taking its revenge ! 

 

[Model Output Discussion - Colder but how cold and for how long?]

The GFS at T24 hrs is a smidge further north than the earlier 06 hrs run.

[Model Output Discussion - Colder but how cold and for how long?]

6 minutes ago, SussexSnow said:

There is still a bump of 'New Snow' showing for Horsham from the GEFS, but it's shrunk a little since yesterday

 

I think it’s going to be a struggle to get the precip that far north . Frustrating as the set up could have produced some real fireworks .

[Model Output Discussion - Colder but how cold and for how long?]

23 minutes ago, Mcconnor8 said:

Arome gives hope for the far South East

The models just refuse to really break through the snow shield with these coastal teases .

At this timeframe there’s still room for changes but we do need the 12 hrs runs to collectively push things north .

 

[Model Output Discussion - Colder but how cold and for how long?]

The Atlantic low drama needs to just make its mind up .

The models keep throwing out the odd scrap to southern coldies and it’s just painful .

After the ICON 06 hrs run I thought that was a good sign only for the GFS to shoot that down in flames .

 

[Model Output Discussion - Colder but how cold and for how long?]

3 minutes ago, northwestsnow said:

Such a shame the south look like JUST missing out

Hopefully some further North into Cumbria NI and Scotland hit the jackpot over the next 48 hours ..

NWP looks awful after Thurs, we need the PV to go and get a life away from Greenland.

There’s still some uncertainty there , also as the front might pivot as the low tracks east so some precip could edge nw into the far se as that happens .

It is very frustrating as the snow could have lasted a while .

I’d give it till the end of today .

 

[Model Output Discussion - Colder but how cold and for how long?]

The ICON and GEM 18 hrs runs are further north with the Atlantic low . 

This whole episode is almost cruelty to southern coldies . The precip is almost waving in the Channel and saying oh see what you could have had!

For the sake of a hundred miles north or south , as is the way with these attention seeking lows. Either total frustration or elation .

I think we really need to find a bit more deepening to help that ne momentum.

 

[Model Output Discussion - Colder but how cold and for how long?]

Just now, Ali1977 said:

Can you see this tracking further north still? That seems to be where the momentum is at the minute!! 

To be honest I wouldn’t like to say ! 

I suspect the UKMO are just as in the dark as to what might happen as we are in here ! 

[Model Output Discussion - Colder but how cold and for how long?]

There’s been a large modification of the raw data for the T84 hrs fax chart , aswell as that the fax chart shows the main band of snow associated with what is looking like a complex low pressure ahead of the second front .

 

[Model Output Discussion - Colder but how cold and for how long?]

The ECM at T72 hrs has a more oval shaped low and slightly further north  than the UKMO which is flatter .

 

[Model Output Discussion - Colder but how cold and for how long?]

Even if the other models jump on board today with the precip going further north that’s not the end of the story .

Theres still 72 hrs where things could still change . 

These set ups are a complete nightmare to forecast !

[Model Output Discussion - Colder but how cold and for how long?]

Utterly nerve-shredding for those in the south and far se with the GFS op and ensemble mean taking the precip further north . 

The UKMO looks totally disinterested judging by the T72 to T96 hr frames .

The ICON still interested . The GEM less interested than yesterday .

A bit frustrating as last nights ECM 18 hrs run still missed but had taken the precip further north so that looked like a more positive trend .

If you’re in the risk area you need the ECM to jump on board this morning and hope the UKMO has got this wrong .

Later the Atlantic looks like moving in around late Friday so make the best of the colder conditions before the mild rainy muck arrIves.

Lets hope this is just a short spell of milder weather .

[Model Output Discussion - Colder but how cold and for how long?]

This Atlantic low has certainly caused a lot of frustration for coldies especially in the south .

It’s determined to wring every last vestige of drama out of the occasion! 

The ICON after the very progressive 00 hrs run seems to have edged the pattern a bit further west during subsequent runs .

 

 

[Model Output Discussion - Colder but how cold and for how long?]

Just now, Penguin16 said:

Understood but we can’t categorically say that’s what caused it this time? 

No but it’s the main suspect at the moment .

[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, Penguin16 said:

Is that an actual fact or just an opinion?

Strat warming’s can effect where the PV goes . So yes it’s a fact . We have had instances before where a warming has shuffled up the NH pattern to the detriment of coldies .

[Model Output Discussion - Colder but how cold and for how long?]

6 minutes ago, sheikhy said:

I think the time has come my peeps for me to take a back seat again!!the runs are getting worse and worse since yesterdays 06zs!!!enjoy the cold spell and whatever snow you get!!!i shall be back to update everyone if i see some snow and if not then maybe see you guys on the next chase if there is one!!luv you guys!!ciao!!!!

See you this evening !  You won’t be able to resist coming on . If not good luck and hope you get to see some snow .