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phil nw.

Model Output Discussions 18z 31/01/2016

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The GFS 06hrs run at least delivers some colder air although its shortlived and that's even with a nuisance shortwave near Greenland.

The ECM ditches yet another FI tease and now pushes low heights associated with the PV further east.

Earlier it has some interesting synoptics if there was any cold to the east to tap into but theres no deep cold there.I still wouldn't rule out any snow though because even without deep cold lower dew points and perhaps some evaporative cooling might see some marginal snow. Again though marginal makes it a case of chasing around in hope rather than being able to just say it will snow!

The UKMO sticks to yesterday evenings trend but the low is far too deep and whether that can clear east quickly enough is uncertain.

At the moment there does seem some disagreements as to the orientation of the PV over ne Canada and how exactly that deep vorticity will spill into the Atlantic and interact with low pressure running east.

NCEP suggest that after this initial period of an amplified eastern USA trough the pattern will flatten out somewhat and the timing is quite important and whether any mid Atlantic trough disruption might occur.

Whether the MJO can move more quickly into a more favourable phase is another issue.

At this point any remaining hopes for a decent wintry spell before the end of winter are carried by the MJO and that's the only reason that I haven't thrown the towel in yet.

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Well my post of about a week ago set out my reasons for throwing in the towel on decent nationwide winter weather this season. I have however continued to keep a watching brief and I just wanted to congratulate the core of regular posters on here for some excellent and informative posting that continues to keep this thread interesting despite conditions (actual and projected) on the ground. The post from singularity above highlights this but there are a number of you. Well done and keep up the good work. I just wish I had your depth of knowledge and experience.

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Can't stress enough the important aspect of the continued vortex dominated winters especially during both west based super El Niño and La Niña over the last few years it's certainly dominated.

for one we know a modki El Niño plus a early on set of a weak vortex and Atlantic ridges early in winter or late autumn normally disruptive enough to allow a real blocked winter.

also key is sustained very low solar activity or nonexistent activity has a number of effects on our atmosphere so looking back at winters including current winter we very much had the negative impacts for cold in place there for we chased and chased the elusive blocked winter pattern very frustrating very disappointed but next winter I strongly feel will have more favourable outcome for colder winter yes months away I know but I'm confident in this outcome.

as for the rest of winter and the models powerful vortex cold air to the east swept away deep lows mostly westerly flow tm air alternating with pm air at times threw large part of Febuary.

winter might bite back briefly into spring but winter or should I say decent wintry weather not likely although ski resort in Scotland will do ok as colder air tends to be more dominant Cumbria north.

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So, is there any hope for cold this winter?

Actually, today's ECM ensembles don't completely kill the dream. Between D10 and D15, I see that the main cluster brings an air frost in a few times:

ensemble-tt6-london.gif

Rainfall charts not particularly flat either

ensemble-rrrcum-london.gif

What does this mean? Possibly more temporary Atlantic ridging? I do have this feeling that an Atlantic ridge is trying to form, and it is simply waiting for a break in the low pressure train coming out of the states (ironically, fuelled by the breakout of cold there aided by the SSW, I believe). So last part of February could be time for this pattern change to hit - or 1st March, just to run it in??

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2 minutes ago, Man With Beard said:

So, is there any hope for cold this winter?

Actually, today's ECM ensembles don't completely kill the dream. Between D10 and D15, I see that the main cluster brings an air frost in a few times:

ensemble-tt6-london.gif

Rainfall charts not particularly flat either

ensemble-rrrcum-london.gif

What does this mean? Possibly more temporary Atlantic ridging? I do have this feeling that an Atlantic ridge is trying to form, and it is simply waiting for a break in the low pressure train coming out of the states (ironically, fuelled by the breakout of cold there aided by the SSW, I believe). So last part of February could be time for this pattern change to hit - or 1st March, just to run it in??

Not sure, was there any update from Fergieweather recently saying what the other models favour? I remember him saying there was a general favour of colder conditions in the latter part of Feb, but other than in FI and some ensembles, can't see anything to suggest that yet.

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No downgrades for me, latest gfs ensembles still showing 10-12th feb as our best chance of snow. 

Quite a few showing coldish uppers making their way down the country: 

 

 

control.png

run 4.png

run 5.png

run 7.png

run 8.png

run 13.png

run 14.png

run 17.png

run 19.png

run 20.png

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Day 6 an actual cold day with a NE'ly a 'rare beast' quite short-lived, reasonable chance of snow showers for eastern/southern counties.

I'm quite astounded by the lack of cold air to tap into this god forsaken mild winter is really taking the proverbial, it really would be very interesting if it was just that bit colder, alas most of the time 850's are in the region of 0 to -4C not entirely suggesting endless rain. I have known there to be widespread snow events with 850's of -2C supporting millwall & taking interest in model watching during the winter time, there are parallels.:bomb:

image.thumb.png.d1b43f465e25ec09854850b0image.thumb.png.47bc494c421ce9710beec631

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Whilst I fully accept all the models are not showing any cold spell in the next 10-14 days history tells me that between now and say mid-march there is a very strong likely hood  that the UK will have 2 or 3 cold snaps in this period where snow could fall anywhere in the UK.( I know that not what most on here want but beggars cant be choosers!!)

When you reflect on this winter so far as others have alluded many factors have been against the UK having a colder than normal winter and so it has proved. Even a SSW that is occurring(however minor) has worked against  us when I think from memory 2/3rds of the time they help the UK have cold(I think I have read that correctly somewhere on that thread) it looks likely we are in the unlucky 1/3rd!!

I will continue to monitor the models and "pray" for a miracle but I am realistic enough to know it is very unlikely to happen for the UK this winter in terms of snow.

Hopefully winter 2016/17 will have more factors in favour of cold and snow and the very early signs look more favourable.:):)     

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I think some folk miss out on these tiny details...

This low will need to be monitored closely I've seen some sort of low crossing over or within close proximity to the UK again and again over this time period. On the basis of this particular chart below, it would need to nudge north so the precip is not wasted in the channel, I do not think you can could rule out wet snowfall it is a slack flow off the N/E, mainland = cold dew points & not super cold uppers are required. 

image.thumb.png.0b1e2d411ccf9154f0df1c8dimage.thumb.png.542932a15968ee6863fa2d46

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The ens. have been pretty steady over the last few days in showing the colder trend for next week and the latest are similar.The London temps.

56b493d29fb8d_ensemble-tt6-london(1).thu

probably a couple of degrees colder further north with the pm air more involved.

With the strong Greenland vortex continuing to call the tune though it does become increasingly frustrating seeing all that Arctic cold locked in so close to the north.We are just not seeing the deeper cold getting far enough south for any length of time under this regime.

We do have the jet trending further south but it remains too flat and with the Atlantic trough disruption extending west into the Atlantic we cant get the more direct northerly cold feed and we get modification of the polar air that does ease south in this cyclonic picture.

A look at the mean charts for a week today

56b496157e714_viewimage(6).thumb.png.afe56b496207df24_viewimage(7).thumb.png.43c

shows the setup.

Again any snowfall looks confined to the usual elevated northern areas but we can't rule out a marginal event further south if we get a small wave running east at the base of the trough.Any ridging upstream would make a difference too but currently this doesn't look likely.

 

 

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1 hour ago, Man With Beard said:

So, is there any hope for cold this winter?

Actually, today's ECM ensembles don't completely kill the dream. Between D10 and D15, I see that the main cluster brings an air frost in a few times:

ensemble-tt6-london.gif

Rainfall charts not particularly flat either

ensemble-rrrcum-london.gif

What does this mean? Possibly more temporary Atlantic ridging? I do have this feeling that an Atlantic ridge is trying to form, and it is simply waiting for a break in the low pressure train coming out of the states (ironically, fuelled by the breakout of cold there aided by the SSW, I believe). So last part of February could be time for this pattern change to hit - or 1st March, just to run it in??

I think it's a displacement rather than a full SSW - which is actually a reversal of winds at 10hPa at 60N. A modest amount of warm air over the Pole is by no means the same as a full reversal at lower latitudes.

Any true SSW is accounted for in the models as soon as it's significant I believe. :)

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You can draw some similarities to March 2013 channel low which hit the Channel Islands v hard, by far the superior synoptic with a block centred just SW of Iceland - although this occurred a month later, so you need that extra 'quality'. It is a shame there is nothing of the sort being modelled currently but it would make a world of difference many attempts, being foiled from an active Atlantic unusual for February. I for one decidedly do not think the latter part of the month into early March is going to be bring the UK bursting into spring.

image.thumb.png.7693584ec38e9b59a9805591image.thumb.png.a2638d439ad951180caa2839

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4 hours ago, snowfish1 said:

I feel compelled to  agree with that. It was a fiasco between ecm,  gfs and ukmo on the January "cold spell" it's always fi and its covering the bases on behalf of the models with this latest display from them 

But if you look at the statistics for 10 day charts, the input from Gibby shows this, they are, in terms of the upper air pattern correct about 40-50% of the time. In other words 1 in 2. Then the hard bit, trying to get the botoom 18,000 feet of the atmosphere predicted correctly. Very difficult, even the 10 day anomaly charts I use which are correct in terms o fthe overall upper air pattern 70% of the time still leaves any forecaster, professional or amatuer, with that problem. Forecast accuracy has improved over the years, substantially in the first decades of computer use but now much more slowly. This will contiue with improvements at all time scales but only very slight.

I confess I am not sure if the statistics that Gibby shows are for the upper air mean charts or for the daily synoptic outputs?

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Some may find this bit I've done interesting, an initial explanation of why some surface lows deepen a lot?

 

jet streans and deepening lows 5 feb 16.png

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another post from me!

Nothing in the anomaly charts suggests that the next 2 weeks is going to be anything other than Atlantic dominated, expect both upper and surface wind flows to vary between about WSW and NW for upper winds and SW-NW for surface winds as depressions form in the entrance to the jet off North America and are carried across the Atlantic, deepening as they do so with more rapid deepening occurring with some as the do the 'right entrance-left exit' move described above. So a mix of Pm possibly briefly Am air with intervals of Tm air. No signal I can see in the next two weeks of any marked cold be that settled or unsettled. Nor any prolonged mild for that matter.

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The GEFS is known for being very poor at forecasting the MJO with it normally very slow to pick up on the transition through phases.

So is todays big change a sign that its finally picking up the signal.

So yesterdays GEFS MJO forecast and todays on the right:

mjogefs1.thumb.gif.033a844f4f826241350acmjogefs2.thumb.gif.163299c7c6d78f54f54b8

 

Still waiting for the other models to update but this is certainly a positive if the MJO can get its skates on.

We should bear in mind that even with the powerful PV the January cold spell was helped because of the MJO transition into more favourable phases. Though we didn't see a proper Greenland block we still saw those positive anomalies to the west and nw of the UK.

I don't see any reason why towards the latter third of February the MJO would have less of an impact, indeed the reverse would be more likely.

Although the UKMO seem unconcerned by the MJO movement they had the same view before the January cold spell. Anyway we'll see over the next week whether the MJO can help to at least bring something more wintry showing up in the outputs.

 

 

 

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10 minutes ago, nick sussex said:

The GEFS is known for being very poor at forecasting the MJO with it normally very slow to pick up on the transition through phases.

So is todays big change a sign that its finally picking up the signal.

So yesterdays GEFS MJO forecast and todays on the right:

mjogefs1.thumb.gif.033a844f4f826241350acmjogefs2.thumb.gif.163299c7c6d78f54f54b8

 

Still waiting for the other models to update but this is certainly a positive if the MJO can get its skates on.

 

 

 

the link for 6 and 5 in Feb for 500mb anomalies

not sure why it is not showing the actual link for both 5 and 6?

FebENMJOphase5gt1500mb.gif

 

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1 minute ago, johnholmes said:

the link for 6 and 5 in Feb for 500mb anomalies

FebENMJOphase6gt1500mb.gif

That still looks more wintry than whats been on offer for most of the winter! And of course those anomalies are just a guide. Movement into phase 6 will add more amplitude into the pattern.  We'll just have to see how things unfold but I'd rather have the MJO moving through the phases than stuck in the COD.

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Multitude of comments. 

UKMO is showing weak height rises from Iceland extending to southern tip of Greenland. 

Comparing that to GFS at 144hr different! 

image.thumb.gif.a154dbfb37c803c156abc8f7image.thumb.png.baa4e673766ff2323632429d

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One comment over a GFS run, that says it all.

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10 minutes ago, Ali1977 said:

One comment over a GFS run, that says it all.

Think people have started to call it a day. To be honest it is pointless commenting on the GFS when it shows a completely different outlook 6hrs later. 

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Until that massive block to the east dissipates somewhat, there isn't anywhere for all these low pressures to go....so we rinse and repeat. The fat lady is clearing her throat as we speak...

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The GEFS towards day ten and further on now seem to be showing an MJO response. The Azores high displaced in the majority. The GEFS mean has a strong signal at that range:

gensnh-21-1-240.thumb.png.26b7c9544f8934

Theres a mix of solutions in terms of low pressure running nw/se through the UK, some with high pressure to the n/ne aswell.

Whether we can tap into any cold is of course the big question. I'm willing to give it to next week before finally admitting defeat, until then hopefully we can see some improved outputs.

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2 hours ago, nick sussex said:

The GEFS is known for being very poor at forecasting the MJO with it normally very slow to pick up on the transition through phases.

So is todays big change a sign that its finally picking up the signal.

So yesterdays GEFS MJO forecast and todays on the right:

mjogefs1.thumb.gif.033a844f4f826241350acmjogefs2.thumb.gif.163299c7c6d78f54f54b8

 

Still waiting for the other models to update but this is certainly a positive if the MJO can get its skates on.

We should bear in mind that even with the powerful PV the January cold spell was helped because of the MJO transition into more favourable phases. Though we didn't see a proper Greenland block we still saw those positive anomalies to the west and nw of the UK.

I don't see any reason why towards the latter third of February the MJO would have less of an impact, indeed the reverse would be more likely.

Although the UKMO seem unconcerned by the MJO movement they had the same view before the January cold spell. Anyway we'll see over the next week whether the MJO can help to at least bring something more wintry showing up in the outputs.

 

 

 

Yes, but EC Monthly MJO forecast yesterday was for a shallow orbit around to 7, but with many ENS inside the COD across a pretty broad scatter. There's currently little major influence for us currently seen by UKMO in the MJO output from either EC or GloSea; whilst 2nd half Feb still looks essentially changeable, there still remain signs of a more settled trend for at least the south and east into early March. Here's hoping...

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3 minutes ago, fergieweather said:

Yes, but EC Monthly MJO forecast yesterday was for a shallow orbit around to 7, but with many ENS inside the COD across a pretty broad scatter. There's currently little major influence for us currently seen by UKMO in the MJO output from either EC or GloSea; whilst 2nd half Feb still looks essentially changeable, there still remain signs of a more settled trend for at least the south and east into early March. Here's hoping...

Thanks for the update Ian. In terms of the MJO the last major movement in December/January did indeed show less bullishness initially but the amplitude of the signal was under estimated.

The MJO is difficult to forecast with accuracy especially when you have the El Nino interference aswell as Kelvin waves especially in the early stages.

I think its a case of watching and seeing what exactly does transpire. I'm keeping an open mind.

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