Model output discussion - 1st December onwards

[Ali1977]

Lets hope for a record breaking cold Feb , even then I think Winters CET will be well above normal. Looks like SSW maybe our only chance, not sure how you forecast these. I mean, could one happen in the next few weeks without warning?

[IDO]

25 minutes ago, John Badrick said:

"The good news is that the current CET of +5.1c above average will remain very close to this"

Genuine question; can I ask why is this good news???

Hi. I am interested in all types of weather and something astonishing as a +5c anomaly in December is a once in a lifetime event. There is no chance of cold for the rest of December apart from two fleeting cold fronts, so it is worth getting another mild plume in Dec W4 to sustain that high?

ECM mean at D10 supportive of the GEFS mean and the ECM op:     

[Tropicallass]

"I still believe there is no MJO signal and that the amplification is from a standing Kelvin Wave, so therefore I am still not expecting the 7-10 days composites of a MJO phase 7 to materialise (Scandi block). "

This is a really interesting thread - I'm enjoying reading all of the updates and I'm learning lots so many thanks to you all. 

I'm interested to know what you think this is a Kelvin wave, rather than an MJO?  I've also been thinking that it looks a little odd and the suppressed signal doesn't seem to propagate past the Maritime continent in velocity potential space but the Wheeler and Hendon indices project onto an eastward propagating signal?  Why do you think phase 7 is key to the European pattern? 

   

[Carl46Wrexham]

1 hour ago, John Badrick said:

"The good news is that the current CET of +5.1c above average will remain very close to this"

Genuine question; can I ask why is this good news???

And for who? 

[booferking]

Iv notice that that low front on Xmas keeps getting pushed further South each run and the North of the country holds onto the cold uppers maybe a chance some might get an odd flake on the big day.   The high seems a bit stronger.

[cheshire snow]

Well i have enjoyed my week of from looking at the models,having a

Look through this mornings models,you have to say it is quite dire

If like me you are looking for cold/snow,however its the weather and

Unfortunately there is nothing we can do about it,i do feel our fortunes 

Will change,but i think at this stage we will be looking to the last third

Of January.i do expect some PM blasts though through the early part

Of January,very similar to last year,on that note back to another weeks

Break from model watching,i would like to take the opportunity to wish

All the moderators,and all the members of this forum a very happy

Christmas,stay safe,and lets hope for a better outlook for us

Coldies in 2016

All the best

C.S

[KyleHenry]

1 hour ago, Ravelin said:

How can you be so sure of that? At 144z the UKMO to my eyes has a similar pattern to the GFS and it's the ECM that's odd one out... 

The strength of the ++NAO, and the low pressure systems it sends our way.

The upcoming WAA has no foundation from the East to allow it traction to hold and as ever it will be steamrolled East wards. 

This is the first true attempt to change the pattern.

 

Indian Ocean forcing to finally dissipate and +PNA emerges at years end. 

Then the hold of El Niño ends and more fluidity to our pattern with assistance from SSW. 

 

[Interitus]

49 minutes ago, KyleHenry said:

 

Indian Ocean forcing to finally dissipate and +PNA emerges at years end. 

Then the hold of El Niño ends and more fluidity to our pattern with assistance from SSW. 

 

When do you think this is going to happen?

I fear the only SSW in the near future will be the wind direction.

[feb1991blizzard]

9 minutes ago, Interitus said:

When do you think this is going to happen?

I fear the only SSW in the near future will be the wind direction.

Probably wrong thread but when (if at all) do you feel we will get an SSW?, I just wondered because I value your opinion on the Strat, FWIW I think we will get one in time for cold in Feb but not absolutely 100% certain one will happen at all.

Edited December 22, 2015 by feb1991blizzard

[Interitus]

41 minutes ago, feb1991blizzard said:

Probably wrong thread but when (if at all) do you feel we will get an SSW?, I just wondered because I value your opinion on the Strat, FWIW I think we will get one in time for cold in Feb but not absolutely 100% certain one will happen at all.

Well looking at analogues in the latest GEOS / MERRA data up to 29/12/15, at the moment I think it would be probably last week of January at the earliest, and more likely early February - if there is one of course.

Although they are called 'sudden', the data going back to 1979 shows that the warming and wind reductions associated with SSW form quite well defined envelopes and the current and forecast wind speeds and temperatures are such that while an SSW in the first half of January cannot be ruled out, it would involve changes more dramatic than any seen in the previous 36 years.

[Mucka]

I still feel that if the Scandi high idea gets dropped we will soon see more amplification but this time to our West with an Atlantic ridge, let's say around the end of the first week of Jan

I'm going with this because I see a southerly jet and high pressure finally waning over NW /Central Europe but we all know how many times the death of the Euro slug have been greatly exaggerated.

Met Office don't see that outcome at all but they are suggesting blocking will set up in the second week of Jan with the South coming under a continental influence so that is good news.

It has been an awful winter thus far and nothing left to do now except enjoy the holidays and watch for developments in January - once again I expect the evening model runs to have a little more cheer than this mornings.

When it has all been one way this winter it is easy to imagine it continuing that way and certainly the idea of cold snow never seemed  further away or more unlikely as we bask in weeks of unrelenting unseasonal warmth but things can and do change. I absolutely do not expect January to resemble December and still feel we will see a proper cold/very cold, spell before winter is out. Personally I am surprised so many are writing off January and looking to Feb and a SSW event as our only hope and I still don't feel we have to wait too long before we at least have hope again through the model projections.

 

Edited December 22, 2015 by Mucka

[snow mad]

13 minutes ago, Interitus said:

Well looking at analogues in the latest GEOS / MERRA data up to 29/12/15, at the moment I think it would be probably last week of January at the earliest, and more likely early February - if there is one of course.

Although they are called 'sudden', the data going back to 1979 shows that the warming and wind reductions associated with SSW form quite well defined envelopes and the current and forecast wind speeds and temperatures are such that while an SSW in the first half of January cannot be ruled out, it would involve changes more dramatic than any seen in the previous 36 years.

But are we just as likely to get some cold to our shores from SSW precursor high pressure set ups in favourable places as we are likely to get cold from the after affects of an SSW lottery fallout?

[Froze were the Days]

I'm going to take a break from model watching too over the xmas period and will be back around October 2016 and hopefully we'll see a pattern change!

Just want to wish all NW members a merry Xmas and Happy New Year and enjoy Easter 

[phil nw.]

This pattern is disappointing to say the least for cold lovers and maybe even some neutrals as i think many of us would.t mind a bit of seasonal snow and frost around this time of year.

Unfortunately we have no magic wand to wave away this endless Atlantic driven setup with the Euro slug to the south and the deep Greenland vortex to our north west.

The Day 10 ECM mean and the T384 forecasted neafs ht anomalies tell the story

Moderate wave 2 action is going on in the background into the lower vortex as seen with the EP and Scand/Siberian +ve ht anomlies but not enough yet to land any meaninful blows on a very solid and cold Stratospheric vortex.

The latest temperature graph shows how cold it is at mid-level,especially over the pole.

so we need further wavebreaking and that is why we look to the engine room of the Earth's weather in the Tropical Pacific which is the main driver.

A look at an image from the 006z GFS run at T120hrs.

http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=global&pkg=z500_mslp&runtime=2015122206&fh=120&xpos=0&ypos=286

shows convection spread right across the warm Pacific-a typical EN pattern.We can also see in this image the moisture conveyor from the Pacific spreading ne over the sub tropical high over the SE of the USA and then ne towards the UK and this has been the picture so far this season.

Current forecasts from all the agencies have seen an MJO signal recently in phase 4 and now going into phase 5- still west of the dateline.

Composites for high amplitude signal for these phases match current nwp quite well

 

so we expect those Scandi hts to gradually give way to a more zonal westerly pattern come the new year.

That setup would see at least temperatures somewhat closer to normal with more chances of some colder polar maritime incursions from the north west from time to time.

Scant compensastion i know but probably the best we  can squeeze out of this setup whilst we wait in hope for something better down the line.

 

 

 

Edited December 22, 2015 by phil nw.

[MR EXTREMES]

Pretty much following the script of  the last few years by the time the vortex established itself and coupled with El Niño of this magnitude it was asking a lot for decent cold spell.

lets hope 2016 see the return of a spotless sun as there was no question in my mind that this really did show the bench marks for true wintry blocks and weather patterns after the sun had awoke we see a gradual return to the default pattern.

of course this is a major player in our weather patterns but not the only factor of coarse.

anyway all models suggest continued mild south but at times cold enough for wintry weather in the north but into fi we have southerly winds pumping mild air into the north to.

i think I'd be inclined to say the euro heights are just as bad as the dreaded Bartlett high.

if we could see a weak Atlantic I'd be happy to except a cold shot would be likely but from all the models we have euro heights and vortex Nino party going on.

i admit anything can change dramatically but as it stands now background signals are very favourite to continue what we have had weather wise for a awhile now.

 

[nick sussex]

Another day another batch of underwhelming operational runs.

The will it won't it shortwave is still causing some model divergence but the upstream troughing looks to be flattening out somewhat which is disappointing.

The GEFS ensembles however aren't anywhere near as bad as I expected and I think they're beginning to respond to the MJO movement. Its noticeable that we're seeing these better ones trying to carve the jet further se.

The debate surrounding the MJO is I think confusing for some newer members with talk of Kelvin waves versus a real MJO signal. They are both connected, the Kelvin wave is part of the MJO process.

To quote from an expert in the field:

Kelvin waves travel through the MJO, and nearly every MJO event has a Kelvin wave at some point in its life. Most of the rainfall and PV generation within the MJO occurs within Kelvin waves that are moving through.

In relation to Phil's post now heres another way of looking at that, if the composites are currently matching the NWP why should we assume that if the MJO reaches phases 7 and 8 that those composites won't match. Will there suddenly be a disconnect?

In terms of any full blown Scandi high I think I agree with recent posts this is unlikely however we might see a ridge hold to the ne which could help to force the jet at a more favourable angle into the UK and western Europe.

For the timebeing I think all we can do is sit patiently and see exactly what the NWP response will be if and when the MJO reaches a more favourable phase.

Edited December 22, 2015 by nick sussex

[gottolovethisweather]

On 18/12/2015 at 7:13 PM, gottolovethisweather said:

My bets for the big day (Christmas Day) now would be for a wet out West, drier towards the East type scenario with mostly average Temperatures, always warmest towards the South and West. As for snow, only on those ole Christmas movies I reckon , Boxing Day might offer more hope for those at elevation.

Well, with only three days to go now until the big day, I guess my prediction wasn't so far out after all, especially given this was at D7 range. Now D7 (29th December) was previously judged by me and few others as the date when things start ramping up again in the Atlantic, after a brief spell of calmer weather. Unfortunately, this latter aspect looks rather unlikely now which proves how we can't look too far into the future when either chasing cold or mild weather. For now, the milder weather continues and Christmas Day and Boxing Day is looking rather unseasonal down South in particular but also for most of the UK. The change to something colder has to come eventually and I live in hope that I'll see at least an Air Frost before the year turns.

[Mucka]

Oh dear,

This morning MetO forecast sounded quite promising around mid month with mention of drier and cold, especially for the South but that has changed now to,  "The chance of a prolonged cold spell taking hold is currently considered to be low. "

So they may have been going for some form of UK high but now that looks to be further South.

We will just have to hope it is totally wrong and we can lower pressure to our South instead although it is certainly fair to say that chances of cold spell are low based on all current output.

Edited December 22, 2015 by Mucka

[MPG]

Lol, it hard to predict mate! 

14 minutes ago, gottolovethisweather said:

Well, with only three days to go now until the big day, I guess my prediction wasn't so far out after all, especially given this was at D7 range. Now D7 (29th December) was previously judged by me and few others as the date when things start ramping up again in the Atlantic, after a brief spell of calmer weather. Unfortunately, this latter aspect looks rather unlikely now which proves how we can't look too far into the future when either chasing cold or mild weather. For now, the milder weather continues and Christmas Day and Boxing Day is looking rather unseasonal down South in particular but also for most of the UK. The change to something colder has to come eventually and I live in hope that I'll see at least an Air Frost before the year turns.

Give yourself a pat on the back, it wasn't that hard to get right was it!:)

[phil nw.]

50 minutes ago, nick sussex said:

Another day another batch of underwhelming operational runs.

The will it won't it shortwave is still causing some model divergence but the upstream troughing looks to be flattening out somewhat which is disappointing.

The GEFS ensembles however aren't anywhere near as bad as I expected and I think they're beginning to respond to the MJO movement. Its noticeable that we're seeing these better ones trying to carve the jet further se.

The debate surrounding the MJO is I think confusing for some newer members with talk of Kelvin waves versus a real MJO signal. They are both connected, the Kelvin wave is part of the MJO process.

To quote from an expert in the field:

Kelvin waves travel through the MJO, and nearly every MJO event has a Kelvin wave at some point in its life. Most of the rainfall and PV generation within the MJO occurs within Kelvin waves that are moving through.

In relation to Phil's post now heres another way of looking at that, if the composites are currently matching the NWP why should we assume that if the MJO reaches phases 7 and 8 that those composites won't match. Will there suddenly be a disconnect?

In terms of any full blown Scandi high I think I agree with recent posts this is unlikely however we might see a ridge hold to the ne which could help to force the jet at a more favourable angle into the UK and western Europe.

For the timebeing I think all we can do is sit patiently and see exactly what the NWP response will be if and when the MJO reaches a more favourable phase.

Hi Nick,

Re,The underlined bit of your quote  and a good question.

I would think the stronger the MJO amplitude,away from the circle of death,the more relevant the historical composite would be?Of course i am only assuming but a strong signal in 7 or 8 would represent effective wavebreaking into the vortex where we then expect strong +ve cross polar heights ie.High latitude blocking.

A weak signal would see less effective northern heights and a watered down pattern.

I am sure there are other factors such as angular momentum and the influences  through mountain and frictional torques but i would have thought those composites are built from historical occurences and all those factors are interlinked.

 

Edited December 22, 2015 by phil nw.

[gottolovethisweather]

39 minutes ago, MPG said:

Lol, it hard to predict mate! 

Give yourself a pat on the back, it wasn't that hard to get right was it!:)

Thanks for your insights too MPG . Yes, less predictable though is the widespread mildness, in fact it's looking increasingly likely that nowhere will be cold over the festive period, at least by what's currently forecast.

Edited December 22, 2015 by gottolovethisweather

[nick sussex]

1 minute ago, phil nw. said:

Hi Nick,

A good question.I would think the stronger the MJO amplitude,away from the circle of death,the more relevant the historical composite would be?Of course i am only assuming but a strong signal in 7 or 8 would represent effective wavebreaking into the vortex where we then expect strong +ve cross polar heights ie.High latitude blocking.

A weak signal would less effective northern heights and a watered down pattern.

I am sure there are other factors such as angular momentum and the influences  through mountain and frictional torques but i would have thought those composites are built from historical occurences and all those factors are interlinked.

 

I've spent the last few hours reading up on research re the MJO, its very complicated!

In terms of NWP and the MJO how good is that at anticipating the response in FI. If the current MJO composites weren't matching the near time outputs then one could suggest a disconnect caused by El Nino interference.

Yes I agree in terms of the amplitude because you'd think that the logical conclusion would be that you need more amplitude to make any dent on the PV and the entrenched Euro high.

From past memory of the response to the MJO this is initially a splitting of the Euro high slug with the jet angling se as the Azores high displaces further west and the Euro high lobe forced eastwards. Theres around 8 GEFS now doing that.

However it seems as if the UKMO aren't figuring on much impact from the MJO but again with this type of variable how good is the NWP at anticipating how this will impact things.

We'll see over the next week if of course the MJO continues to go through the phases.

 

[nick sussex]

My MJO obsession has reached new levels of sadness! Apparently NCEP do a live briefing with their thoughts and then a release on to their site.

One thing to take from last weeks release:

 The potential MJO development needs to be monitored quite closely over the next few weeks because if organized, robust, long lived it could modify the circulation across the PNA sector .

That would impact the pattern in Europe. Lets hope for more news on that front later on.

PS the live briefing is only available via webinar but the overview should be out in about an hour.

Edited December 22, 2015 by nick sussex

[No Balls Like Snow Balls]

From Twitter

Michael Ventrice ‏@MJVentrice  2 hrs2 hours ago

We are running out of time for any impactful changes to the Winter pattern by the stratosphere.

 

 

 

 

 

 

 

[Interitus]

1 hour ago, snow mad said:

But are we just as likely to get some cold to our shores from SSW precursor high pressure set ups in favourable places as we are likely to get cold from the after affects of an SSW lottery fallout?

You tell me lol!

To be serious, it's not totally unusual for it to be colder before an SSW than afterwards, and the precursor set ups are quite vague - though the forcing may be Atlantic or Pacific side or whatever they are large areas. From the data for example it appears there might be a signal for lower AO, NAO and CET roughly between 35 and 25 days prior to SSW give or take a couple of days here and there. There doesn't appear to be much sign of this at the moment and in any case this pretty much amounts to looking for a cold spell with the models regardless of if it is a precursor or not. I will have to look closer at the precursor set ups and include minor warmings to get a better picture.