Model output discussion - 20th Feb onwards

[Essex snowman]

26 minutes ago, bobbydog said:

whats that about? i assume you have unintentionally quoted me there, as it makes it look like its me who is having a go at frosty!

it should be noted- i haven't!

Sorry bobbydog don't no what happened but in no way meant it to sound like u were having a go at Karl my apologies Esnowman 

[bobbydog]

16 minutes ago, Essex snowman said:

Sorry bobbydog don't no what happened but in no way meant it to sound like u were having a go at Karl my apologies Esnowman 

no problem. probably the 'previous quote' glitch happening there.

anyway, GFS still wants to throw some 'chillyness' our way in the later stages-

funnily enough, my post you accidentally quoted still stands- i would rather it didnt happen as it would be mostly horrible sleety stuff. i'm enjoying the dry weather and a warm up now would be much more pleasant!

[knocker]

1 hour ago, SLEETY said:

looks like heading towards something similar to late march 1975 with snow even in South,if gfs is correct lol 

 

Snow in the south if the gfs is correct? am I receiving different charts to other people as I can see absolutely no justification for saying that.

Edited March 14, 2016 by knocker

[bobbydog]

10 minutes ago, knocker said:

Snow in the south if the gfs is correct? am I receiving different charts to other people as I can see absolutely no justification for saying that.

well, technically, you cant say NO justification....

[SLEETY]

lol that was 06 z run the 12z run not at all so good

12 minutes ago, knocker said:

Snow in the south if the gfs is correct? am I receiving different charts to other people as I can see absolutely no justification for saying that.

lol that was 06 z run the 12z run not at all so good

 

[Nick L]

1 minute ago, bobbydog said:

well, technically, you cant say NO justification....

Those charts exaggerate snow probabilities in my opinion, especially light stuff like that...and over 2 weeks out. I don't see any meaningful snow for the south on the 12z. 

[John Badrick]

1 hour ago, bobbydog said:

whats that about? i assume you have unintentionally quoted me there, as it makes it look like its me who is having a go at frosty!

it should be noted- i haven't!

No, I believe it was my post and I wasn't having a go, was just pointing out that yesterday it was quoted that it is ridiculous to look out for cold at the end of march but today not so, because charts are showing somthing different. 

[bobbydog]

2 minutes ago, Nick L said:

Those charts exaggerate snow probabilities in my opinion, especially light stuff like that...and over 2 weeks out. I don't see any meaningful snow for the south on the 12z. 

of course they do nick, its about as likely as me being the next US president but strictly speaking, the GFS is showing snow in the south which was the point in question.

[knocker]

11 minutes ago, bobbydog said:

well, technically, you cant say NO justification....

Oh you are a wag bobbydog. twelve hours later

[bobbydog]

3 minutes ago, knocker said:

Oh you are a wag bobbydog. twelve hours later

thats a shame, all those hurriedly built snowmen would melt....

[feb1991blizzard]

The 240 could be a special.

[feb1991blizzard]

 

BULLSEYE!

[Frosty.]

6 minutes ago, feb1991blizzard said:

The 240 could be a special.

You are right, what a BEAUTY

Sensational end to the Ecm 12z..for coldies

[feb1991blizzard]

Just now, Frosty. said:

You are right, what a BEAUTY

Sensational end to the Ecm 12z..for coldies

I would like to see some sort of developing wave, a la 8th Dec 1990 with a positive tilt on it but that's just being picky, plenty of time for that, plus with surface heating, there would be convection developing inland, the main thing though, we need to see it garnish support from elsewhere.

[Frosty.]

1 minute ago, feb1991blizzard said:

I would like to see some sort of developing wave, a la 8th Dec 1990 with a positive tilt on it but that's just being picky, plenty of time for that, plus with surface heating, there would be convection developing inland, the main thing though, we need to see it garnish support from elsewhere.

Agreed but it's great to see the very good continuity from the Ecm with this trend since the 12z last evening, hopefully this will firm up!

[TomDav]

About a quarter of the GEFS members support a solution similar to the ecm at D10

[feb1991blizzard]

2 minutes ago, TomDav said:

About a quarter of the GEFS members support a solution similar to the ecm at D10

A similar evolution but without the depth of uppers, not that many are really potent, if that ECM went another frame, although possibly a toppler, it would have the -8c isotherm clipping the Eastern side with snow showers down to low levels as far south as Kent first.

[feb1991blizzard]

Just now, Greenland1080 said:

We've hacked out the rough, been in the bunkers...Were about to hit the Easter snow green mate....I want a cold snowy Easter

To me it does look possible although not the favourite in my opinion.

[TomDav]

2 minutes ago, feb1991blizzard said:

A similar evolution but without the depth of uppers, not that many are really potent, if that ECM went another frame, although possibly a toppler, it would have the -8c isotherm clipping the Eastern side with snow showers down to low levels as far south as Kent first.

tbh I haven't actually looked at the individual members yet but there's still room for improvement wrt uppers

[Guest]

MY LATEST REPORT UPDATED WITH MARCH 14TH 2016 INPUT

Please note that most of the charts that I refer to in this post are through “live” links which update periodically. So, if you are reading this a few hours after I publication, the charts may already have updated. My comments relate to what the charts showed at the time of this posting.

More for the coldies and what an ECM 12z run!

Are We Seeing the First Signs of the Stratospheric Warming reaching the Surface?

In yesterday’s report (see page 76 of this thread) I said that I would be posting news and comments on Dr Judah Cohen's latest Arctic Oscillation Report this evening. Some of you may not have noticed that his weekly update came out a day earlier than usual and I made a second post last night (also on page 76) on this. For those of you that missed it, here is the link again:

http://www.aer.com/science-research/climate-weather/arctic-oscillation

Firstly, a word of caution. Although I am a coldie, I am not a ramper and I will continue to try to provide a balanced analysis and approach. Yes, I am looking for colder patterns and will usually come from that angle but I will only state what I see and will attempt to avoid blatant exaggeration. With this in mind, it would be easy to get carried away about some much stronger signals that the current stratospheric warming event is about to propagate through the troposphere and reach the surface around this weekend. There is still considerable doubt over “if” there will be strong surface impacts and also “when” they will occur. I remain in the “Judah Cohen” camp and believe that we will see strong impacts and wholesale pattern changes but I will maintain a healthy degree of scepticism.

I will continue to look for the signals and assess the progress (if any) over the next few days. It does seem that we may see an Arctic outbreak about a week from now (give or take a couple of days). Although this could be the first significant SSW surface impact that we might see in this country, it could just as easily be a typical Spring cold snap. If the northerly turns out to be transient, then it could well be evidence of the latter. On the other hand, if the more recent meridional pattern we have seen become established during the last week, goes on evolving, then the Arctic airstream could be much longer lasting. I will focus on these evolutions, using the measures that I have developed in these reports, as part of the checking process.

The Models Today:

Most of the runs continue to be completely inconsistent. For example, the GFS 6z run showed rather more HLB, particularly in the second half of the run but the 12z reverted to a much flatter pattern with very little HLB. These are clear signs that they cannot decide whether we shall see any surface impacts from the SSW in a week to 10 days’ time.

I continue to post all the T+144 Northern Hemisphere pressure charts (now showing for next Sunday, March 20th. This is so that I can include all the main models, as UKMO end their run at 6 days out. March 20th is getting to within several days of when some of the analysts (like Judah Cohen) feel that the current SSW should finally impact at the surface (this may change of course). So, let us see over the next few days how these charts progress. 6 days out should be in the more reliable period but the uncertainties of the SSW surface impacts and how the models assess the possible pattern changes may show even greater confusion and wild swings in the next 2 to 3 days!

I will update these at T+144 for the next couple of days. If the impact signs are starting to show and the timing remains similar, I shall start to home in on that date with increasingly shorter term charts until (if/when) it arrives.

The main changes that I will be looking at over the next few days is to see if (any of) the models are showing whether there is any movement of low heights out of NE Canada and transferring across to Europe and Siberia and also signs of HLB. This would reflect part of the possible pattern changes which might have a greater impact on the UK later this month and into April. Of course, the changes might move the other way. It is another, perhaps rather crude way, of monitoring these possible impacts. I note that the strat thread has remained extremely quiet in the last few days. Will this major SSW with its strong stratospheric reverse propagate down to the surface?

Here are the charts. Once you have used any of the links and have located a model, you can look at earlier and later charts. I hope that the T+144s show properly. If anyone can suggest a better way of making this comparison (which I shall update daily for the next few days) please feel free to say so.

Northern Hemisphere Pressure Charts for T+144 on Sunday, March 20th:

GFS:  http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=144&mode=0&carte=1

UKMO:  http://www.meteociel.fr/modeles/ukmo2.php?nh=1&ech=144&carte=1021

ECM:  http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=1&type=0&archive=0

NAVGEM:  http://www.meteociel.fr/modeles/navgeme_cartes.php?&ech=144&mode=0&carte=1

GEM:   http://www.meteociel.fr/modeles/geme_cartes.php?&ech=144&mode=0&carte=1

JMA:  http://www.meteociel.fr/modeles/jma.php?ech=168&mode=1

Please note that the JMA update their T+84 12z charts overnight and their T+144 was published at 12z yesterday. So I show the T+168 chart for the correct time comparison.

GFS have trended decidedly colder during their last few runs. They weaken and then re-build the north-east Canada low heights.They develop the Siberian low heights moving them more into north-west Russia and then they have a lobe extending down into central Europe. They move secondary or smaller cut-off low pressures around the main lobe. They back the pattern at times with brief periods of milder incursions before they show renewed cold returning from the north or north-east. Although GFS show many colder patterns, I feel that their charts are still far too progressive to truly reflect any significant SSW surface impacts. They build a strong polar high but manage to eject it. Even for more normal Spring patterns with brief northerly incursions, their charts do not look right. I expect more substantial swings from them.

UKMO develop the European lobe through to T+120 but then weaken it slightly. Nearer the UK, they back the Atlantic flow somewhat by T+144. They have now built a strong polar high which looks like it will send a ridge southwards towards Iceland. So a chance of a true Arctic high to our north-west within a week or so with a proper Arctic incursion. Need to see next couple of runs and whether they change their mid-term (6 to 15 day) outlook to a generally colder set-up. Even if their charts start to show a pattern change, they often tend to change their public forecasts rather more slowly – quite understandably awaiting greater confirmation of any change and not wishing to mislead the public and play into the hands of the tabloids. Of course, I might be wrong!

ECM have just finished their output for their 12z run and what a run it is. Again they have the coldest patterns, which they have developed over their last few runs. They also transfer the north-east Canada low heights across to north-west Siberia and north-east Europe by T+96. All the time they strongly build heights right across the pole and towards Greenland. By T+144 they have the main lobe over Siberia but with a very cold north-easterly flow running down into Scandinavia and northern Europe. At T+216 they re-build low heights in north-east Canada and maintain the Siberian lobe but strongly develop the European lobe much closer to the UK. This is looking very “Cohenesque” with a huge wedge of high pressure now extending right across the Arctic and well beyond, both on the opposite side and on our side, probably for over 2,000 miles north to south!  By T+240 we have a very long fetch north-north-easterly flow originating from the high Arctic heading down right across us with -8c uppers moving in and -16c to -20c uppers approaching Iceland and upstream from us. If ECM are anywhere near right, this is definitely not a “transient northerly”, in fact it looks like it will deepen further. This is timed for around March 24th and looks very potent indeed! If it verifies, it looks extremely wintry under it!

This has not come out of the blue. ECM have been working towards this for several days and must surely be picking up strong SSW surface impact signals. We still need to see consistency from them over the next few runs and with other models joining the party?

Here are the links to theT+240 Northern Hemisphere pressure and 850s charts:

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=1&type=0&archive=0

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=0&map=1&type=0&archive=0

Although some will agrue “not the dreaded ECM T240 promise again” but this time they get there gradually step by step and it would be consistent with the suggested timing (by Cohen and some others) of the SSW surface impacts.

GEM have rather more mixed charts again. They move the lobe and low heights across from north-east Canada to north-east Europe and north-west Russia by T+72 (more quickly than yesterday). Then they move it eastward to Siberia, weaken the European lobe and redevelop lower heights again in north-east Canada all by T+144.. Then they build strong heights right through the Arctic, across the pole and extend a ridge down towards eastern Greenland and on further to another high in the mid-Atlantic by T+216. This block does have a look of permanence about it but no! By T+240 they swing lower heights into Grenland and try to redevelop lower heights in Europe. Like GFS, this does look too progressive to me.

NAVGEM move the low heights from northern Canada across to northern Siberia and north-west Russia by T+84 and develop the lobe in north-east Europe (rather too far to our east to influence the UK directly). Later they re-build the Canadian low heights All the time, they have built a strongly polar high. Towards the end of their run, they show lower pressure over Greenland and a mostly north-westerly flow of the UK. Little real sign of them taking account of any SSW surface impacts.

JMA move low heights into northern Siberia early on but always maintain some low heights in north-east Canada. They too develop strong heights near the pole. After a benign period over the UK, they swing a low pressure area down from Greenland, right across us and out into the North Sea by T+264. An interesting way of introducing an Arctic flow but perhaps not particularly plausible although the final pattern does look much more meridional.

AO Ensemble Charts: 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

As yesterday, all 10 of the ensemble members move back from being temporarily positive to neutral around March 17th. From there, 3 members flirt between neutral and slightly positive until March 23rd (far less positive than yesterday) and 2 of these then go negative right at the end of the 10 day period. Only 1 remains slightly positive.at the end. The other 7 members trend increasingly negative between March 17th and March 24th.A few go strongly negative. At the end 7 of the 10 members are still trending down with every indication that the AO will go more deeply negative beyond this period.

Overall, this is a significantly more negative run compared to yesterday. The timing and extent almost mirrors Judah Cohen’s surface negative AO predictions. This should be indicative of much stronger HLB.

As I have mentioned several times recently, NOAA produce, amongst other things,  these AO indices and the 500mb pressure anomaly charts, which are regularly posted on this thread. The latter are “mean” charts. As I said, while these charts are normally extremely valuable in assessing the broader picture and the general trend (smoothing out the more extreme ensemble members) I feel that they can be misleading when we are faced with the possibility of a broad pattern change. If, for example, 30% of the members point to a flatter more zonal pattern and another 30% point to a blocking or more meridional pattern (with the others somewhere in between) then the mean charts will not strongly indicate either outcome but instead more of a halfway house. With the type of scenario we currently face, either the SSW surface impacts will deliver a strong meridional pattern or they will barely impact at all, the compromise or mean would be incorrect in both situations! What would be far more useful right now, would be a chart showing the spread of ensemble members and the recent trend.

A request: Can John Holmes, Knocker or another specialist in handling these charts, please post this data or say whether or not it is available. I feel that it would be incredibly useful.

My hunch is that the “mean” anomaly charts will slowly start to reflect what the AO indices are telling us but they will take 3 or 4 days to adjust. Do correct if I am wrong.

MJO Ensemble charts:

Here are todays MJO ensemble charts for the big 4 and Kyle MacRitchie’s for March 14th. 

UKMO:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ukme.shtml

ECM:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

NCEP/GEFS:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

JMA:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/jman.shtml

Kyle MacRitchie:  http://www.kylemacritchie.com/real-time-maps/realtime-mjo/ 

UKMO: A bit of a change today. They moved into phase 4 today and then on to phase 5 by March 17th/18th  (5 days more quickly than yesterday). In the following 3 days they progress further into phase with some members getting closer to phase 6. All of this is at steadily increasing amplitude (ending considerably higher than yesterday).

ECM:  After a big change yesterday, today’s chart is very similar. They moved into phase 4 at quite low amplitude.Then they progress much quickly than UKMO, to phase 5 by March 16th/17th  and on to phase 6 by March 21st  at steadily increasing amplitude. They reach the important phase 7 by around March 26th and towards phase 8 by March 28th with are wider spread of ensemble members but mostly at reasonable amplitude but still a few members re-entering the circle of death. The ensemble mean stays out of the circle of death

NCEP/GEFS: yet again take quite a different view and their chart seems to reflect the great uncertainty shown across almost all their other output. Little change from yesterday as they generally nudge the circle of death as they progress through phases 3 and 4 and on into phase 5 during the next 5 days at low amplitude by around March 18th. Then they mostly stall with all members returning to the circle of death. Just one member is looking to head towards phase 8 at the end of the run.

JMA: There is very little change with all ensemble members inside the circle of death but they have moved them from the phase3 boundary across to phase 4 with one member entering phase 5. Pretty lifeless.

Kyle MacRitchie:  Continues his consistently bullish approach. He shows the MJO progressing through all the phases from 1 right through to 8 by April 13th. He has maintained high to very high amplitude.

The MJO is not in the important phases 7, 8 and 1 for several weeks and would not contribute to HLB in our part of the Arctic. We would need to rely on the SSW impacts and perhaps less directly from the El Nino or other factors.

What does GloSea5 show now? Please can Fergie provide another update.

Current Surface Arctic Temperatures:

GFS – Northern Hemisphere Current Temperatures:

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=9&carte=1

The link to this chart updates 6 hourly with each GFS run. At the time of writing it is showing a chart for 1900 today (14th March***). As this is T0 to T6 hours, it should be pretty accurate. 

In the Arctic, temperatures close to the North Pole are around -20c to -28c (-28c to -32c yesterday). In “our” part of the high Arctic (around the Barents Sea) temperatures are unchanged at around -8c to -16c. Most of Scandinavia is also unchanged at around 0c to -4c today. Much of northern Siberia remains around -32c to -40c (similar to yesterday). The cold wedge developing through north-west Russia is now around -24c to -28c (-20c yesterday) with -8c  to -12c still  extending over a wider area south of this and into north-east Europe.

So little overall change since yesterday but the trend to greater cold in north-west Russia continues.

*** Please note:   At the time of posting this link it was showing 1900 on Monday, March 14th. The charts are automatically updated 4 times a day, so the temperatures shown will be different to those I just mentioned above. We can follow the trends by looking at the latest data at any time from now on. It is vital to note the time of day to take account of daytime/nighttime variations. So for like for like comparisons, for example the 1900 charts for each day should be available to view from the 12z (T+6) updates which are published around 1600 or about 4 hours later. This also applies to some of the other charts I link to in this post.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

Here are the links to the 3 Svalbard stations that I am monitoring.

Central Svalbard – Longyearbyen 28 m asl:   

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/forecast.pdf

March 17th  -14c;   March 20th  -12c;    March 23rd  -10c.

West Svalbard – Ny-Alesund:                                                            

http://www.yr.no/place/Norway/Svalbard/Ny-%C3%85lesund/forecast.pdf

March 17th  -16c;   March 20th  -15c;    March 23rd  -12c.

South Svalbard – Sveagruva:                                          

http://www.yr.no/place/Norway/Svalbard/Sveagruva/forecast.pdf

March 17th  -17c;   March 20th  -20c;    March 23rd  -16c.

The general trend is for the “maximum” temperatures to fall during the next 3 to 4 days, then to level out and stay close to or just above the lowest values after that. So, once the much colder conditions have arrived by later this week, they look like they will continue in the foreseeable future.

These links will update automatically at frequent intervals throughout the day. They are the Norway met office’s predictions. We need to be aware that these are only a forecast that is subject to change and I am told that the Arctic surface temperature forecasts are not completely reliable even at short range. 

To put the above figures into context, here is a link to the main Longyearbyen site:  

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

This shows monthly means, and actual highest/lowest temperatures recorded during this winter and goes back further. Apart from a couple of days in December, Svalbard is likely to see “maximum” temperatures falling to well below average, for the first time since Winter 2014/15

Final Comment:

So, we have a second consecutive day with a colder trend showing on various indicators. The ECM seems to have picked up on this far more than the other models and it really looks like they are picking up on signals of the likely SSW surface impacts. I have a hunch that we might see some very interesting developments for coldies during the rest of this week. Surely this thread will come to life again? More tomorrow.

Edited March 15, 2016 by Guest
check all links are working + grammar & spelling

[knocker]

The ecm ten day chart is a perfect example of what could easily materialise from the day ten anomalies as mentioned in earlier posts. I'm going for a transitional cold N/NE so the the next two or three day charts should be interesting later.

 

Edited March 14, 2016 by knocker

[knocker]

Back to more mundane matters. The GEFS anomaly tonight is on a familiar theme on the 23rd although not so amplified as previously with the trough remaining further east and ridging to the west. Ergo still the NW upper flow which could bring some cooler unsettled weather as system(s) track SE into Scandinavia,Possibly even a transitory northerly.

Within two or three days the pattern becomes less amplified with the flow backing westerly although as the run progresses it does build heights again in the vacinity of the UK with the trough in situ over Scandinavia. Temps in general around average.

[ANYWEATHER]

Good Evening Folks....! Both ecm and gfs show a retrogression of high pressure into the Atlantic towards day 10. Perhaps the last dance of Winter, which given these synoptics below, will give fire and lightning and snow

[shotski]

7 minutes ago, ANYWEATHER said:

Good Evening Folks....! Both ecm and gfs show a retrogression of high pressure into the Atlantic towards day 10. Perhaps the last dance of Winter, which given these synoptics below, will give fire and lightning and snow

Trouble is we had a similar set up for the start of March with uppers of -8 widely and it just didn't deliver. I remember a couple of days with -8 850's and +8 on the ground. 

[knocker]

The EPS 850mb flow and temp chart for T288 has a weak ridge over the UK with winds backed to westerly quadrant and temps average.

The anomaly at day ten has ridging to the west and the trough over Scandinavia with the upper flow NW and..............well you know the rest.

During the ext EPS the amplification is quickly lost. By T300 there is a trough running SE from the Canadian vortex to Mid Atlantic, a weakening Scandinavian trough and very weak ridging just to the west of the UK. Ergo pretty much an unsettled cool zonal flow giving temps just below average.

By T360 the Atlantic trough dominates and has moved east, whilst the Scandinavian trough has gone but heights building over eastern Europe. So continuing with periods of unsettled with temps a tad below average.

Regarding this evening's NOAA the 6-10 has the HP a little closer to the UK but that  may be down to the averaging otherwise not dissimilar the the ecm. The 8-14 going for less amplification and slight retrogressing ogfthe HP and weakening of the Scandinavian trough so weaker flow from the WNW.

Edited March 14, 2016 by knocker