Model Output Discussion 29th December - Into mid-Winter.

[Seasonality]

9 minutes ago, blizzard81 said:

I agree. I remember GP saying we would probably end up back where we started. There is a chance though that things could be more amplified this time. Like I said last night,  there could well be upgrades in the near future. 

Feels the same to me too. Has anyone else noted a repeating cycle in the model outlook? Feels quite "groundhog day."

Edited January 18, 2017 by Seasonality

[Summer Sun]

Even as far north of Inverness this month looks pretty much over for much in the way of snow

Go to the east coast and it's even worse for Aberdeen peaking at just 2

[TEITS]

Difficult to know the direction we are taking. As we all know the ECM tends to over amplify as already mentioned. However what if the best performing model isn't? This opens up the possibility of even further upgrades.

Looking at the chart below lets suppose the ECM becomes even more amplified. We then have the possibility of an E,ly not only hitting the UK but even earlier!

If this ECM trend continues then UKMO is the one to watch and the GFS to be ignored.

[stodge]

Morning all

I'm afraid all I can offer for fans of snow is patience based on this morning's output. The chances of significant lowland snowfall before February are pretty much nil (higher elevations might get something from a more zonal set up depending on a number of factors).

Fans of cold have the here and now (hovering around freezing in lowland east London) and it's likely there will be a lot more frosts and indeed some fog as the week progresses and some of the milder numbers being posited for early next week have been toned down considerably in the south as well so it might be nearly a week before we see a significant upward move in temperatures.

As for the SSW or near SSW - we all know that when such an event comes from the Eurasian side, the initial response, as Judah Cohen tells us, is for the battered PV to shift back to North America keeping western Europe mild. Given the possibly prolonged nature of the event, it's hard to see it not having an effect at some point. Those suggesting the possibility of colder conditions from say mid February may be on to something and it's perfectly possible for lowland snow (and plenty of it) to fall and stick even as late as then if not later.

It's going to be a waiting game - a minimum of 14 days in my view and perhaps as long as 28 days - but hopefully within a couple of weeks we'll start seeing the eye candy and dismissing it.

Until then (and really for the first time this winter which is remarkable), a period of zonal conditions. For interest, the jet positioning will be crucial - quite possible the jet will come a bit further south and with secondary features there are chances for wind, rain and snow to altitude as alluded to above but we'll see. 

Edited January 18, 2017 by stodge

[Radiating Dendrite]

Personally think the ECM is just over amplifying things again. Look at the ECM and imagine everything 500 miles further south and you probably won't be far off.

Surely the issue with any possible easterly is yet again the lack of low heights over southern Europe. We seem stuck in a pattern of the mid latitude high wandering around near us and I think this will continue for the rest of winter. 

[karyo]

16 minutes ago, Radiating Dendrite said:

Personally think the ECM is just over amplifying things again. Look at the ECM and imagine everything 500 miles further south and you probably won't be far off.

Surely the issue with any possible easterly is yet again the lack of low heights over southern Europe. We seem stuck in a pattern of the mid latitude high wandering around near us and I think this will continue for the rest of winter. 

Actually, there are decent low heights over the Med till early next week. In particular, the low that forms in the western Med in the coming days has been upgraded in the last 24 hours. 

It is next week when the Med low pressure is expected to attenuate.

[TEITS]

06Z GFS moving towards ECM!

[Great Plum]

Is the block putting up more of a fight this run? (Also, temps now below average for most outside the north west until Tuesday at least)

 

Great minds @TEITS

Edited January 18, 2017 by Great Plum

[karyo]

2 minutes ago, TEITS said:

06Z GFS moving towards ECM!

Indeed! The 6z makes more of the Med low that I mentioned and the Atlantic low is more North - South alligned.

[Severe Siberian icy blast]

7 minutes ago, TEITS said:

06Z GFS moving towards ECM!

We need that Russian vortex lobe to drop south ideally like the Atlantic is doing then that will really help suck the high northwards in a prime position. It's actually not far from been a great chart 

[chris55]

We are desperate for some energy to finally undercut any building pressure to our east, that's the only way we are going to get anything cold from the east or north east with the current regime.We have that Italy low in place it just seems the Azores energy just can't break through into Iberia to set up some kind of southerly jet. 

Until we see this, the pattern will most likely just flatten even if pressure does begin to rise to our east. 

[Weather Boy]

2 hours ago, TEITS said:

06Z GFS moving towards ECM!

Well, to those saying that watching the models is like groundhog day, that is not all that different from today's chart is it?

http://www.netweather.tv/index.cgi?action=nwdc;sess=

[snowray]

1 hour ago, chris55 said:

 

Problem is that in spite of having LP over the Med and Italy in particular, we simply have not seen an undercut. You can see the low move up through Morocco, Spain, and almost becomes a classic Genoa Low, but then moved back SE in the end and HP builds over central Europe. It seems to me that the spoiler as usual in our Winters is the Azores High.

[bluearmy]

A few more gefs members showing what might be considered a quick trop response to the potential SSW

you need to take a NH view and probably a good exercise to see that they don't necessarily lead to a snowy solution for nw Europe 

[nick sussex]

Not such a good ECM today, it was on track upto T168hrs but the issue is upstream with the troughing over the USA. Any troughing has to be amplified which downstream will help dig some energy se'wards and stop so much energy spilling ne.

 

 

[swfc]

Just now, nick sussex said:

Not such a good ECM today, it was on track upto T168hrs but the issue is upstream with the troughing over the USA. Any troughing has to be amplified which downstream will help dig some energy se'wards and stop so much energy spilling ne.

 

 

Its been the same all winter across the board Nick tho hasnt it!!! It would seem yet again this winter "up to now" nothing seems to fall into place.Talk of an ssw coming into play but im not sure on the lag times ete but like most things for our small island may or may not give something wintry.Imo looking at the nhp on all models i cant see a sharpish route to cold and has things stand may its up to feb to bring some joy.If god forbid we end up with a cold unsettled spring and rank summer i think i may have to sell up and move south to warmer climes.That said spain has snow today so ive no idea!!!

[Dennis]

UK get colder air at sunday ; frost with an ESE pattern

Edited January 18, 2017 by Dennis

[Guest]

Further to my post yesterday (the one on page 276), I feel that my comments do need to be put into context. I was looking at the short term period up until early next week.  I showed why I felt that the models were being a little too progressive in dislodging the European cold block so quickly by this weekend (now D4/D5). I note from the recent model output that this has been delayed by several days until towards mid-week next week (now around D7/D8).  I did not look beyond this period and I suggested that there were various outcomes, including the transition to a more zonal spell, which is still by far the most “probable” evolution.

I did not expect to see another easterly appearing at D10 on yesterday’s ECM 12z, although this was downgraded somewhat on their 0z run. Despite there being a variety of outcomes (including several colder ones) as we move through week 2, let’s “go with the flow” for now and assume a milder interlude.  The questions are how quickly might we get there, could the European cold block put up even more of a fight, what might the transition be like, how strong might the Atlantic flow become, will it be a direct flow or one largely deflected away from our shores and how long will a zonal spell last until the next breakdown and changes. I am not going to attempt to answer this and it will, as always, be the subject of much debate on this thread with the models likely to continue to swing quite considerably beyond D7 as they explore the outcomes and the timing of possible changes.  I will consider several factors which might be significant.

The models still show slightly different routes to a more zonal flow but with most showing HP still very close to us.  Let’s take a look at the current cross model output for D7. I show the charts adjusted for their exact times to give the same position for Tuesday, January 24th at 0100 (+ the Met Office fax chart for 1200 next Sunday - the furthest out available + 850s + surface temps):

Please note that I am still struggling to get all these charts to freeze at the run and time shown - I do hope that they do not update automatically to show the next run's output

                   GFS 6z T+138                                            UKMO 0z T+144                                      ECM 0z T+144                                       GEM 0z T+144                                   NAVGEM  12z T+156

           

                      JMA 12z T+156                          GEFS  6z ensemble mean T+138                MetO 12z Fax Chart T+120                 

           

                 GFS 6z T+138 850s                              ECM 0z T+144     850s                     GFS 6z T+138 surface temps      CURRENT SURFACE TEMPS (auto update)      

          

The link for viewing 24 hours animations:   http://www.meteociel.fr/observations-meteo/temperatures.php  (for those new to this - I gave instructions for using the chart in my page 276 post)

So, a delay is suggested with the surface cold retained until D7. I feel that the timing of this breakdown might be important and any further delay might well shorten the anticipated more zonal spell.

The path and the strength of the Jet Stream will be important.  Although there are various factors that dictate this (especially from the upper flow), I shall pick up on one of them (which I mentioned about a week or so ago). This is the thermal contrast between the USA eastern states and the adjacent western Atlantic. A strong contrast with a cold land mass usually fires up the Jet Stream or intensifies it further, often for a sustained period – eg: for weeks on end during last winter. This winter the USA was unusually mild until early December before a brutally cold spell that lasted for about 7 to 10 days from mid-December through to Christmas.  We saw a brief zonal spell during the latter part of this period. There was another briefer and less intense cold plunge after that which was more confined to the western states. Since then much of the USA has been predominantly mild and exceptionally mild just recently.The current position is still very mild in the eastern USA but with a much colder wedge over eastern Canada. If anything, the position at D7 shows even milder conditions in eastern USA but further cold in eastern Canada. There are further colder plunges predicted in the longer term. This is illustrated by comparing surface temperature and jet stream charts.  Let’s look at the charts for D1, D6 (as before), plus D8 and D12:

           GFS 6z T+6 surface temps                   GFS 6z T+138 surface temps             GFS 6z T+192 surface temps                GFS 6z  T+276 surface temps  

         

            GFS 6z T+6 Jet Stream                          GFS 6z T+138 Jet Stream                     GFS 6z T+192 Jet Stream                         GFS 6 T+ 276 Jet Stream  

       

It is not really until after D10 that the USA eastern seaboard gets its next cold plunge and then the jet does start to head more directly at us. Of course the models will change and the pattern and timings might be different but keeping an eye on the USA cold (or lack of it) is one consideration. IMHO the zonal spell may not get going until much later in week 2 or in the final days of January. If this happens, just how long will it extend into February? If we do get the SSW, will it kick in properly and perhaps (after the initial warm up in Europe) give us a decent cold spell during February? 

 

Edited January 19, 2017 by Guest
Correcting typos and to ensure that all the links and charts work properly.

[Seasonality]

Similarities between 06z GFS control run and yesterday's 12z ECM. Perhaps not an entirely outlandish solution? *edit, also P1

 

 

Edited January 18, 2017 by Seasonality

[bluearmy]

6 minutes ago, Seasonality said:

Similarities between 06z GFS control run and yesterday's 12z ECM. Perhaps not an entirely outlandish solution? 

deleted - no idea what I was looking at!. 

Edited January 18, 2017 by bluearmy

[Troubleatmill]

37 minutes ago, bluearmy said:

deleted - no idea what I was looking at!. 

It's in settings to delete search history

Edited January 18, 2017 by Nicholas B

[Summer Sun]

 

[nick sussex]

Looking at todays Velocity Potential 200 signal, for those not following the thread last night this over the last few weeks has been better at discerning the correct MJO signal. That shows the MJO now in phase 1:

Although this has now come into more agreement with the normal Wheeler Hendon index it could be because of the lag effect that the models are still trying to incorporate too much of the phase 8.

We really need to lose that phase 8 effect!

In terms of the trend, this has been in recent days to have the high near the UK hanging on for longer. The ECM in particular although now given some support from the GFS 06hrs run tries admittedly without vain to bring high pressure to the ne into the equation but too much energy spills over that and we see as we have done for much of the winter the deep cold heading towards the eastern Med.

Trying to resolve whether this green shoot can turn into a plant depends greatly on the behaviour of troughing in the eastern USA. Last nights ECM had more amplification at a key timeframe which means theres less easterly push to low pressure to the nw, todays has less amplitude and that's the reason that the ECM 00hrs doesn't have the same interest towards days 9 and 10.

Overall the ECM ensembles and GEFS aren't really interested in another easterly drama, whether that changes over the next few runs we'll have to wait and see but we do need a favour from that upstream troughing if the trend is to gather any pace.

 

Edited January 18, 2017 by nick sussex

[Seasonality]

5 minutes ago, Summer Sun said:

 

Suggestive of a return to cold where exactly? I like Judah Cohen's work but his tweets can be quite opaque at times. I assume this means cold over the US?

[swfc]

9 minutes ago, Seasonality said:

Suggestive of a return to cold where exactly? I like Judah Cohen's work but his tweets can be quite opaque at times. I assume this means cold over the US?

think it says europe on the said tweet