Model output discussion - mid January

[ArHu3]

14 minutes ago, blizzard81 said:

Another cold, snowy ecm control run for debilt. I wonder when one of these will verify? I also wonder how close it is to the op?

the last time it verified it looked like this (and nope, we havent seen plumes like this since)

 

Edited January 23, 2018 by ArHu3

[lorenzo]

When MJO experts are quoting eastward movement in the MJO then one tends to take notice.

When MJO experts are citing CFS analogs within other variables, given the credence of CFS on here then one really does take notice, lots of noise in the Wheeler and Hendon plots, this looks legit.

The Matthews site shows solid progression, and many other tweets tease the 7-8-1 progression in the offing.. blocks manifest very, very quickly in this regime. We get hints from the modelling, then they are dropped, GFS has a fight with the ramplified ECM and UKMO steadies the ship. ECM to my eye is 1.5 - 2 days quicker with MJO passage than GFS and subesquent transference to NWP, think this is to do with not the GFS bias but ECM parameterization ( may be wrong) think they were using drones a couple of years back to get into the guts of the MJO and improve performance.

Point being we have the vortex heading into a potentially 'vulnerable' period if the lagged MJO p2/3 manifests vs MJO now active and seeking to mix it up across the pacific = much model interest for month end. My watch is not only for the strat precursors, but the solid MJO activity circa week one Jan and it's downwelling artefact / imposition on upper echelons of the vortex. If we can be lucky and benefit from 781 then great doubles the chances of vortex perturbation, If not it may be weakened enough to see MJO manifest more readily. Time will tell, just a week or so away now to test the p2/3 MJO eventual downwelling vortex impacts theory.

The Italian site with the Nina / Nada / Nino analogs favour the limpet MA block, Nino esque favours the NNE, classical for the NNW by way of blocks. Too early to tell yet, based on today and wishing some further coherence vs CFS and the slant that the US experts are telgraphing their arctic hammer set up, we need to wait a little longer and see the nuanced play out of blocking in our locale. 

[Duane S.]

3 hours ago, igloo said:

Yes it has been the pattern all season this type of setup just one of these years i guess but the usual suspects have done well from these myself included nothing long lasting on these setups of course it just topples over after a 2-3 days but better than nothing the days of greenland and scandi HP Are all but over nowadays but some people will not accept reality unfortunately 

Ian?

[Snowman.]

1 hour ago, ICE COLD said:

Ok fair enough SNOWM4N . I've only been model watching since December 2013 and I have never seen a proper national cold spell count down to T0 it always seems to get watered down it's so frustrating. And yes would rather not see zonal in the models much prefer easterlies and northerlys . But I would prefer it more if it got down to t0 with -12 850s over us and a blizzard ?

With the track record of the past 2 years I see why but things can go right and when they do it's amazing!

[Snowman.]

1 hour ago, ArHu3 said:

From the easterlies I have looked up re-analysis and if possible model history they seem to come into existence from pretty much zonal conditions but the highs in the Atlantic are usually more pronounced and might have some green depressions/"bubbles"  near tropic of cancer, oh and a big huge high pressure of the pacific coast  of the US

 

https://www.meteociel.com/modeles/archives/archives.php?day=1&month=2&year=1985&hour=0&type=ncep&map=5&type=ncep&region=&mode=0

 

We see this pattern many times during winter btw, it usually fails but most successful easterlies saw similar patterns 

Many here who have done this for much longer than I have will tell you that these things can appear in the D7 - D10 range. They are rare and hard to predict and every "failed" easterly can still be an easterly but it fails to live up to the expectation of a beast from the east. Lots of moving gears some are big like your -PNA but some are small like a trigger shortwave on the chart you showed. All part of a big machine which can fall apart if one gear doesn't fit.

But my point stands i'd rather see attempts at easterlies in FI rather than a flat mess gives you a little bit more confidence that something could lurking in the shadows rather than just make belief.

 

 

[bluearmy]

6 clusters post T240 eps (all below 20%) tells you all you need to know re week 2 evolution 

[feb1991blizzard]

4 minutes ago, bluearmy said:

6 clusters post T240 eps (all below 20%) tells you all you need to know re week 2 evolution 

some of them clusters are so similar though that I think there should be less tbh, although a mute point because I get the point your making.

[Nick F]

1 hour ago, chionomaniac said:

Anyone who is a long standing member on this site will remember this tosh being stated in the late noughties time and time again.... However it is not that HLB's favourable for the UK are over, moreso that the conditions haven't aligned to provide them for a while. This year we are battling low GLAAM, and any strat or trop atmospheric response will have to overcome this. With low solar conditions coming for the next few years, there will certainly be chances. Traditionally, La Nina febs don't produce cold for us here, but we still would be foolish to write anything off with the MJO forecasts battling against the low GLAAM and the strat becoming more conducive to a possible SSW. That is the real reality.

 

Been looking at Februaries with a weak La Nina and MJO motoring into colder phases and only a few which match since 1980 as far back as MJO plots go:

Feb 2006 probably the best match, -0.4 on the Nino index, MJO orbit through 7 and into 8 early Feb at decent amplitude, maybe what we could be headed towards.

Feb 2012 was weak La Nina, MJO into 7/8/1 in Feb, a cold and snowy first half, but very anticyclonic

Feb 1993 was neutral ENSO with MJO making it into phase 7 at decent amplitude early Feb before heading to COD, MLB bringing a dry month for the UK.

Feb 1986, early '86 was pulling out of La Nina into neutral, so Feb was -0.2 on the index, MJO through 7 and 8 at low amplitude with some COD in Feb though, extremely cold month.

The models today seem keen to build a ridge N to the west over the N Atlantic next week and by early Feb, in response to the trop PV over Hudson being forced south by the developing -EPO/+PNA upstream. However, it seems the operationals and ensemble means are not hinting at the mid-Atlantic ridge being more than a MLB and morphing into a HLB or Scandi/Greenland high yet, but we may have  to wait until the lagged effect of MJO through 8/1 ... which tend to be more favourable for HLB than 7, so could be a longer wait into February for this.

There is a concern that intense cold vortex shifting back to eastern N America will crank up the jet too much and supress ridging over Atlantic to build north more than just transitory in nature, and this seems to be played out by the operationals this evening, but will have to see if both MJO and also strat-trop interactions over Altantic/Europe can provide some help, particularly as the strat PV looks like being displaced off the pole again via wave 1 induced by MJO wave.

Certainly not overly concerned by the underwhelming model guidance for now, as they may not have the best handle how the likely pattern change into early Feb will affect the upper wave patterns over Atlantic and Europe, despite better confidence of guidance over N America.

Edited January 23, 2018 by Nick F

[Daniel*]

That is a highly encouraging MJO update shared by Nick S I was fearful La Niña would act as destructive interference if the experts are right this doesn’t appear to be the case. Best not to dissect too much from NWP at this stage. Potentially for the first time in the winter, we may be in for a shout of a properly wintry pattern. 

[snowfish1]

20 minutes ago, Daniel* said:

That is a highly encouraging MJO update shared by Nick S I was fearful La Niña would act as destructive interference if the experts are right this doesn’t appear to be the case. Best not to dissect too much from NWP at this stage. Potentially for the first time in the winter, we may be in for a shout of a properly wintry pattern. 

Let's hope so Daniel. To be fair anything modelled has been very transient to my eyes in terms of what we have actually seen here in  Kent. Yes, there's been a few snow flakes but nothing of any note. I agreeee, something worthwhile now please hoping the experts are onto something. February can be an excellent month to deliver cold. Proper cold

Edited January 24, 2018 by snowfish1

[ICE COLD]

WOW . No comments this morning ?? I thought the ECM was petty good for cold and especially the the T240 . That would be quite a bit of snow would it not ?? 

[That ECM]

4 minutes ago, ICE COLD said:

WOW . No comments this morning ?? I thought the ECM was petty good for cold and especially the the T240 . That would be quite a bit of snow would it not ?? 

Every morning ecm sends us off to work with a nice looking day 10 chart. We are not having it anymore until they start moving to day 9,8,7 etc 

[ICE COLD]

4 minutes ago, That ECM said:

Every morning ecm sends us off to work with a nice looking day 10 chart. We are not having it anymore until they start moving to day 9,8,7 etc 

Yer that is true mate , but the models have been quite bullish about a mid Atlantic ridge . Let's just hope it gets further north and really blocks off the Atlantic . Nick Sussex and Lorenzo's updates on mjo are very encouraging so let's hope we start seeing some proper eye candy and it gets to T0 ?

[Paul_1978]

16 minutes ago, ICE COLD said:

WOW . No comments this morning ?? I thought the ECM was petty good for cold and especially the the T240 . That would be quite a bit of snow would it not ?? 

Because it’s at T+240. It’ll never happen like that. 

[bluearmy]

16 minutes ago, ICE COLD said:

WOW . No comments this morning ?? I thought the ECM was petty good for cold and especially the the T240 . That would be quite a bit of snow would it not ?? 

But it’s at day 9/10 !

Spreads on the eps uppers and heights by day 10 show that there really isn’t much point trying to make a strong prediction for week 2 at the moment. Give it a day or two to settle down. 

[Nick F]

Looks like quite a defined SW-NE ridge axis from Azores to Scandi (over UK) looking at the day 12-13 EPS H500 mean, that pattern would be indicative of WAA north across the GIN corridor ahead of PV over Canada and cold into Europe + S and E UK as suggested by EPS T850 mean.

However, given recent ensemble spread from day 10, difficult to assume too much from the ensemble means unfortunately.

[SLEETY]

Because ecm never verifies when it shows cold in fl.the model is a complete waste of time after t+144 if your looking for cold trends from it,in the winter months

Not that any other model is much better,looking forward to end of feb,when we usually see northern blocking more likely to actually verify ,when we are not in the winter months anymore

when was the last we saw one of the really cold gfs ensemble members verify ,like this one from today.like never ever

 

Edited January 24, 2018 by SLEETY

[nick sussex]

1 minute ago, SLEETY said:

Because ecm never verifies when it shows cold in fl.the model is a complete waste of time after t+144 if your looking for cold trends from it,in the winter months

Not that any other model is much better,looking forward to end of feb,when we usually see northern blocking more likely to actually verify ,when we are not in the winter months anymore

I can understand your frustration but you know sometimes colder synoptics do verify. 

I know at times it seems that everything that can go wrong does but occasionally even the UKs forcefield against cold can’t hold out!

 

[jvenge]

GEFS from the 0z continue to play with a ridge in the vicinity of the UK. A few of these go onto heights over Scandinavia in the furthest reaches of FI. Most maintain varying degrees of ridging.

If one felt compelled to look for trends in the ensembles, it would need to be stated that the ridge position appears to be shunting a little further west.

Just a general note, but people shouldn't really be expecting the impacts of an MJO forecast for 7 days away to be seen in model output. You will only notice recent observed impacts from MJO/GWO reflect in the day 10 to 15 range, meaning that if you are looking for influence which in itself is forecast 7 days out, you aren't even going to be seeing that in the furthest reaches of model output. Just something to keep in mind. Differences between models in time under that is just general and usual differences of opinion. There are plenty of other more skilled posters to talk about GWO, though.

 

Edited January 24, 2018 by jvenge

[winterof79]

Not one of the colder runs ECM at day ten

[stodge]

Morning all

Another day, another named storm it would appear but it did look as though we were heading into a more settled spell with the change in the month so where are we this morning ?

ECM 00Z at T+240 (February 3rd):

A cracking chart for cold and snow fans to start the day. Rain and snow in abundance to the east and south east and the Azores HP trying to ridge north into Greenland. I expect the T+264 chart wouldn't show that but it's a fine chart for fans of winter.

GEM 00Z OP at the same time:

Very different as might be expected. In comparison to yesterday's GEM, a shade more amplified but with a 960MB LP off the Norwegian coast, a strong cold NW'ly flow across the British Isles with the best of any dry weather to the south west and possibly blizzard conditions in any snow showers to Scottish hills and mountains. GEM has a much stronger Atlantic profile than ECM so no prospect of any HLB but note the small LP in mid-Atlantic and the sense each new HP cell coming off the CONUS is angled further north than its predecessor. It's not a chart without interest or the "p" word.

GFS 00Z OP at the same time:

Strong HP just to the SW of the British Isles and fairly benign conditions for most on a mild W or WSW'ly airflow. The Atlantic profile, while not as vigorous as GEM, means there is enough strength in the northern arm of the jet to prevent the HP ridging N or NE at this time. Further into FI, the PV becomes very powerful trapping a very large pool of very cold air and creating cyclogenesis in the north Atlantic keeping a strong WSW'ly airflow going and the British Isles in mild and fairly benign conditions.

GFS 00Z Control at the same time:

Not too dissimilar to the OP at this stage but further into FI the HP staggers across the meridian and ends up over or just to the east of the British Isles with another attempt to ridge into Greenland under way at T+384.

Looking at the GEFS at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

I'd say the OP and Control are fairly representative. The theme is MLB but the exact location and orientation are far from resolved. A position to the west or SW of the British Isles looks favoured this morning but other options are on the table.

Further on, as you'd expect, the spread becomes considerable but that's not to say there aren't a lot of cold options on the table and, I'd argue, more cold than mild at this stage.

In summary. the three main models at T+240 all have their own evolutions which suggests huge buckets of uncertainty. ECM is dramatic for cold fans and perhaps less lonely than it was yesterday. GEM has amplified slightly while GFS loves its HP cells in the SW approaches. I suspect after the short colder blip on Thursday we'll see a return of milder conditions for a few days but the evolution from early next week remains far from clear.

[Singularity]

According to this analysis we finally have an observed point (the one before the 'day zero' starred one) within P4 of the GWO phase space.

We even have the GEFS mean visiting P5 for a day, which is a new development but we do need the trend to continue and bring about more than such a short visit in order to start confidently shifting expectations toward HLB scenarios for early Feb. Obviously some caveats here anyway given the uncertain polar vortex behaviour; if it displaced cleanly to Greenland that'd not be very handy unless we could set up a strong enough block near-NE/ENE of us.

 GFS 00z capitulates the vortex strength right at the end, a sign that the potential knock-on effects are being picked up on. Much to  be resolved over the next 3-5 days...

[Nick F]

1 hour ago, jvenge said:

Just a general note, but people shouldn't really be expecting the impacts of an MJO forecast for 7 days away to be seen in model output. You will only notice recent observed impacts from MJO/GWO reflect in the day 10 to 15 range, meaning that if you are looking for influence which in itself is forecast 7 days out, you aren't even going to be seeing that in the furthest reaches of model output. Just something to keep in mind. Differences between models in time under that is just general and usual differences of opinion. There are plenty of other more skilled posters to talk about GWO, though.

 

Indeed, we may not see any impacts from the amplification of the MJO wave on the tropospheric wave patterns as it moves into the Western Pacific until well into February, given the lag, the wave seems to be slowing on recent EC forecasts and we only get into phase 7 as February starts, 7 more of a transitions too to phase to 8/1 which tend to produce blocking and HLBs.

The models still agreeing on amplification over the Atlantic days 8-10, but this is likely a result of greater amplitude in the upper wave  patterns upstream created by the -EPO block that has formed from anti-cyclonic wave-breaking  downstream of the Siberian Low and possibly downwelling form the strat too. So the Atlantic ridge building N signal around the start of Feb is not likely a manifestation of the 'colder' phases of the  MJO moving into the western Pacific, so unlikely to form a high lat block from there, but if we can squeeze some cold and wintry weather out of the this amplification later next week, before the pattern possibly flattens out from the NW again, the that would be a bonus!

But there are nagging doubts over how much the MJO will have an impact for NW Europe as it moves towards and into the more favourable P8, if it makes it at decent amplitude, and possibly 1. As Chino mentioned recently, the low GLAAM and GWO orbit may act against ridging building sufficiently north to build HLB to bring us a worthwhile more protracted and deep cold spell nationwide. There also the matter of strat-trop interactions too to bear in mind that can influence the trop patterns, as although we are seeing decent wave 1 hits over the coming days, which will help dislodge and weaken the SPV again, probably towards Europe, wave 2 amplification is appearing rather  elusive this winter, which doesn't bode well for a SSW and may mean the SPV bounces back again to the pole and re-strengthens. 

Anyway, in the meantime, lets hope we can pull off a half decent cold snap to start February from the possible Atlantic amplification the models are keen on showing for later next week.

Edited January 24, 2018 by Nick F

[jvenge]

7 minutes ago, Singularity said:

According to this analysis we finally have an observed point (the one before the 'day zero' starred one) within P4 of the GWO phase space.

We even have the GEFS mean visiting P5 for a day, which is a new development but we do need the trend to continue and bring about more than such a short visit in order to start confidently shifting expectations toward HLB scenarios for early Feb. Obviously some caveats here anyway given the uncertain polar vortex behaviour; if it displaced cleanly to Greenland that'd not be very handy unless we could set up a strong enough block near-NE/ENE of us.

 GFS 00z capitulates the vortex strength right at the end, a sign that the potential knock-on effects are being picked up on. Much to  be resolved over the next 3-5 days...

Worth adding that it has been wrong for the last 5 days about that forecast position into P4. It has repeatedly been keen for a strong move into P4, only to stall in 3. Therefore, sincerely, considering it is consistently wrong at T24, I'm gonna say that forecast is fairly useless.

[Nick F]

Steve Murr sausage a la 06z, the SE that's missed out on the cold recently gets a turn late next week with -10C T850s, pity it's unlikely to verify at t+216!

Edited January 24, 2018 by Nick F