Model output discussion - 20th Feb onwards

[feb1991blizzard]

Just now, karyo said:

Impressive mean for 384 hours!

Yes, still nothing below -10c though. Need to see a swing towards it on the ECM ens though soon.

[fergieweather]

4 hours ago, Man With Beard said:

Yes - most ECM members close to 10C during daytime for the same period - pretty average:

Yes, sounds reasonable. There has been a distinction by weekend between models re potential cloud cover & TMax...this will remain the key day to day forecast challenge across the next few days. Take for example the comparative f'cast profiles for 12z Sunday, London, from UKMO-GM (Red), ECMWF (Black) & GFS (Blue). Note lower temperature and moister ascent (at lower levels) in UKMO model versus drier/milder EC & GFS. Hopefully the continental fetch by then will favour more cloud breaks, but still a rather chilly feel in the SE corner whilst springlike in any sunshine as you head NW'wards.

[knocker]

The GEFS 5-10 is showing signs of increasing height NW from our resident HP cell which from it's orientation will bring cooler temps than was at first anticipated but still obviously remaining dry. And importantly there is a deep cut off upper low in mid Atlantic.

In the ext period this evolution continues with heights building over Greenland with the LP moving east backing the upper flow SW bringing temps briefly above average. Continuing this theme we end up with ridging into Greenland with a trough over the UK connected to the main trough in NE Europe. This will veer the upper flow NW and bring some period of unsettled wintry weather to the UK with temps a little below average although will be a few swings and roundabouts with this.

Edited March 9, 2016 by knocker

[Cloud 10]

Just in case anyone hadn't noticed,the ECM has had an upgrade which went live on Meteociel yesterday.

 

https://software.ecmwf.int/wiki/display/FCST/Detailed+information+of+implementation+of+IFS+cycle+41r2

[nick sussex]

Looks like a pretty dry outlook with high pressure in charge. It could turn colder towards the south and east as the ECM drops some colder 850's into the flow which then get advected west.

I think the issue for those looking for some Arctic air associated with the troughing over Scandi is the lack of higher latitude blocking, a PV lobe still remains to the north and with that there we won't see any high pressure developing over Greenland to help pull that sw.

Too early to rule out some of that colder air to the ne getting into the UK but currently it looks a bit of a stalemate. The set up doesn't look quite right, we'd need to see an Omega block type set up which would pull the jet sw out of Scandi, here the jet is angling away from the UK.

 

[Frosty.]

It's great to see charts like these from the Ecm 12z likely to verify following months of wind and rain and bitter disappointment for the vast majority on here but it's spring now and it looks like a nice settled outlook with high pressure becoming the dominant feature for a change!

[shotski]

4 minutes ago, Frosty. said:

It's great to see charts like these from the Ecm 12z likely to verify following months of wind and rain and bitter disappointment for the vast majority on here but it's spring now and it looks like a nice settled outlook with high pressure becoming the dominant feature for a change!

Hi Frosty

it will be dry for sure but grim under that cloud and probably feeling raw for folk in the south east. 

Cant wait !!!

[David Morse]

Looking at the 12z ECM run over the past three days for midday 17th March it's clear that the cold is progressing both south and west across Europe, so its not so far fetched to think it can't keep going and make its way to southern UK or further.

Edited March 9, 2016 by David Morse

[John Badrick]

11 minutes ago, Frosty. said:

It's great to see charts like these from the Ecm 12z likely to verify following months of wind and rain and bitter disappointment for the vast majority on here but it's spring now and it looks like a nice settled outlook with high pressure becoming the dominant feature for a change!

I'm sorry but I can't look forward to  the most boring weather 10 degrees and cloudy, it may be dry, but that's about it. I would much prefer cold crisp days with a risk of snow, which are more than likely this time of year

[Frosty.]

5 minutes ago, shotski said:

Hi Frosty

it will be dry for sure but grim under that cloud and probably feeling raw for folk in the south east. 

Cant wait !!!

I agree it's going to become dry and it will make a welcome change to have dry weather after all the gales and rain during the last 4 months but I think there will be spells of pleasantly warm sunshine everywhere, at least for a time with the north holding on to the best of it for longest as the core of the high drifts north..I can't wait!

[Timmytour]

6 hours ago, Frosty. said:

I don't think it's rather odd to still be looking for cold weather, especially as there was no winter across England and Wales, warmest since records began in 1659 and for all I know, the warmest winter since dinosaurs ruled the earth..

Actually 1868/69 was a warmer winter Karl.  And although this winter has made it as the second warmest since records began, it's strange to think, in this era, we had to wait over 145 years for a winter warm enough to break into the top two warmest winters ever and move 1833/34 down to 3rd place

Interestingly the CET for March 1869 ended up being sub 4C  and nearly 3C lower than the average for the winter months just prior!  Looking at some recent ensemble runs it's not out of the question that we could end up with something similar for this March

[Frosty.]

2 minutes ago, Timmytour said:

Actually 1868/69 was a warmer

Was it really, in that case BBC weather gave out duff information then because they said it was the warmest winter  across England and Wales since records began in 1659...not my mistake

As for models, great to see High pressure coming, can't wait! 

[I remember Atlantic 252]

1 minute ago, Frosty. said:

Was it really, in that case BBC weather gave out duff information then because they said it was the warmest winter  across England and Wales since records began in 1659...not my mistake

As for models, great to see High pressure coming, can't wait! 

Yes, for you, and north could be sunshine records broken, week maybe of clear blue skies, my area though and rest of the south, sunless days coming up

[Guest]

The Model Uncertainty Continues:

Well after another 24 hours of big model swings for the 10 day + outlook (and, to a lesser extent, for the 5 to 10 day  period) there seems to be slightly more indication that they might be starting to get to grips with the SSW and the possible impacts. Judging by what I have seen posted on here today and some of the 7 to 16 day charts that I looked at, some (like GFS and GEM) are trending to rather colder conditions and a few of the perturbations are closer to showing the outcome predicted by Judah Cohen. I note that 12z UKMO for T+144 for the northern hemisphere is starting to hint at moving the Arctic cold towards our part of the Arctic. They could well develop the lobes into Europe and Siberia. Just go through the 4 charts in the link to view the progress.

UKMO T=144 Northern Hemisphere Pressure Chart:

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

Still a long way to go and we are likely to see considerable run to run swings until there is some greater certainty as to how the SSW manifests itself (extent and timing). It looks like GFS and GEM have colder runs but will the ECM 12z follow suit?

Update: while writing this, I have seen the GFS 12z T384. Perhaps Judah Cohen has bribed them to produce this chart, as it really captures what he expects to see! If it’s going to happen like that, I wonder if we might get there rather sooner. I would still be looking for Judahs’ March 17th to 20th timing (now T+192 to T+264) although he may adjust this in his next report due on Monday, March 14th.

Now on to some of todays’ charts that I have covered in recent reports and there is more to interest the coldies.

AO Ensemble Charts: 

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

Only 2 ensemble members remain positive. All the others go back into negative territory quite sharply around March 15th to 17th and look set to go more deeply negative. This is a marked improvement on yesterday’s “blip". So with, NOAA favouring greater HLB within a week I would expect that this will be reflected in this evening’s anomaly output. Not just the “mean” 8-14 day  chart which should show it more strongly but with the 5-10 day “mean” charts just starting to edge towards greater HLB.

MJO Ensemble charts:

Here are todays MJO ensemble charts for the big 3 and Kyle MacRitchie’s for March 9th. 

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

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

UKMO has changed slightly. They entered phase 2 today but at significantly higher amplitude compared to yesterday’s forecast. They move steadily on to phase 3 at lower amplitude with a few ensemble members entering the circle of death and some going for higher amplitude as they move into phase 4.

ECM is yet again similar to UKMO until it reaches phase 4 at low amplitude but with about half the members going for much higher amplitude and far few entering the circle of death. Then they go through phases 5 and 6 but with a much wider ensemble spread. That is 2 weeks out (March 23rd) but there are now indications they might manage to get back to phase 7 within a few more days. In the unreliable period but a significant change from the last few days’ forecasts.

NCEP/GEFS continue to take quite a different view which is similar to yesterday’s forecast. changed somewhat from yesterday. All the ensemble members have entered phase 2 today but mostly nudging the circle of death.Then most of them go not to phase 3 within 2 to 3 days and then dive into the circle of death but the stalling there is even briefer than shown yesterday. There is then a wide spread of outcomes with one ensemble members entering phase 5, another to phase 6 but the rest rejoining in phase 7 or, more especially, phase 8 mostly within 14 days but at quite low amplitude. Overall, this model’s outcome is still remains pretty confused and probably reflects considerably uncertainty.

Kyle MacRitchie continues to take a much more positive view. He shows the MJO still in mid phase 8 today and on into phase 1 around March 11th/12th (slightly faster progression than yesterday) and then on to phase 2 around March 16th/17th (2 days slower than yesterday = so staying in phase 1 for slightly longer). All 4 of his ensemble members progress all the way though phases 3, 4, 5 and 6 between about March 21st/22nd to April 2nd. Then they re-enter the important phase 7 around April 3rd/4th. They retain good or very good amplitude throughout the whole period.

All 4 charts again show some changes from yesterday. I wonder if GloSea5 has changed from its movement and stalling in the circle of death. So, we really have 4 (or 5 including GloSea5) rather different model predictions. I still wonder if Kyle MacRitchie is on to something or is he completely wrong, continuing to defy the big 3 and GloSea5? I have spent some time trying to find good verification statistics for the big 3 and, especially for Kyle but this search has proved fruitless so far. Please can a fellow poster point me in the right direction. 

Svalbard Temperature Forecast:

Having updated my Svalbard post from last week only yesterday, I was intending to leave the next update for several more days but with much colder conditions forecast for later next week I decided to include these again now. Here are the links.

Central Svalbard – Longyearbyen 28 m asl:   

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

March 11th  -3c;   March 15th  -6c;    March 18th  -12c.

West Svalbard – Ny-Alesund:                                                            

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

March 11th  0c;   March 15th  -7c;    March 18th  -16c.

South Svalbard – Sveagruva:                                          

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

March 11th  -8c;   March 15th  -6c;    March 18th  -17c.

The overall trend is strongly downwards.

These links will update automatically several times a 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 temperatures falling to average and then below if the trend continues, for the first time since Winter 2014/15. I note that some of the latest March 18th (currently T+216) model charts for the northern hemisphere show the Arctic cold shifting towards our side of the North Pole.  So the Norwegian met office is singing from the same hymn sheet and getting much closer to Judah Cohen’s predictions. This is very exciting times for model watchers, whether warmies or coldies, surely anyone with an interest in this wonderful subject will enjoy seeing how all the uncertainties are resolved over the next few days. Expect some very exciting looking charts.

Before I sign off this evening, I noticed that someone was asking about the June 2nd, 1975 snow event. Here’s one useful link:

http://www.metoffice.gov.uk/media/pdf/i/1/Snow_in_June_-_2_June_1975.pdf

I’ll leave it up to other posters to provide the archive charts. From memory (I was age 22 at the time, living in Hertfordshire) the Arctic airstream and the trough bringing the unseasonable wintriness only lasted a couple of days. Less than 5 days later we had temperatures over 25c and then a hot dry summer (not quite as hot as 1976 but the best since at least 1959 or even 1947).

 

Edited March 9, 2016 by Guest
spelling, grammar, missing words

[Frosty.]

14 minutes ago, I remember Atlantic 252 said:

Yes, for you, and north could be sunshine records broken, week maybe of clear blue skies, my area though and rest of the south, sunless days coming up

Yes it would make a pleasant change for the north to have the sunniest weather would'nt it?...the north usually suffers while the south has the sunniest and warmest weather but I don't think we can say for sure which the most favoured areas will be, it's a bit negative in here this evening!

Edited March 9, 2016 by Frosty.

[ANYWEATHER]

Good Evening All..! The signal for some drier weather looks pretty strong for at least a while, after a months worth of rain fell in some parts in the last 24 hours! Spring ,still looks on hold as a continental feed of colder air effects the British Isles into next week with southern Britain getting the lions share of this. Into next week the northwestern  half of the uk is likely to benefit from any early Spring warmth. The big Question is.....How much cloud will there be, Answer= Probably the cloudiest conditions in southern Britain, the northwest perhaps seeing more sun?  The charts Im showing tonight are for Monday, and feeling raw especially if theres no sunshine for southern Britain.

[Singularity]

As relaxed as ECM is with the pattern, we still see that seemingly inevitable retrogressing theme which increasingly looks to capture the Siberian vortex lobe as well as the Atlantic one. 

Signs in the tropics that the El Nino may serve to increase the upstream amplification at this time. Watch out for the trough/ridge combination in the Atlantic for later next week trending sharper over the next few days. The main thing that sticks out like a sore thumb for me is the continued 'roundness' of the high by the UK on the ECM run. Essentially I can see the risk that it transforms into more of a sausage shape aligned N-S or perhaps the revered heart-shape that reflects an omega block.

As many will already be thinking, we could do with getting the move of the Siberian vortex in our direction out of the way sooner rather than later. Every week counts at this time of year and the balance tips strongly toward cold rain by mid-April. Though there is a counter-argument if you enjoy thunderstorms - unusually cold air aloft can combine with the strong April sunshine to produce dramatic results. Unless there's high pressure too close by, in which case extensive low cloud makes for a miserable heart of spring. On balance, a snowier outcome in late March is preferred!

 

Really we can see the major ingredients on display here;

- a fairly weak vortex remnant in thew eastern Atlantic that's responding to amplification driven by the tropical Pacific

- a strong high in the vicinity of the UK that's looking to move poleward

- a deep trough over Siberia, associated with the stronger, more persistent vortex remnant in that area.
   The depth of cold within is pretty good for the time of year (-15 to -25*C at the 850 hPa level).

- a strong high in the Central-Northern Pacific. Also linked to the El Nino forcing, it raises the possibility of a cross-polar linkup with the high near the UK. Then    you have the long-fetch easterly that Cohen anticipates, aligning well with the stratospheric profile despite the difficulties that looks to have propagating      
   down. It's kind of like the tropical forcing patches up a damaged machine (one designed to achieve extensive high latitude blocking that directs cold toward    the UK and NW Europe).

However it pans out, it should be a fascinating period of model watching from a scientific perspective  Just a shame that extensive low cloud will be likely to feature in our weather on at least a few occasions, it always ends up that way!

[Singularity]

Expanding on the above - the GEFS outlook for the GWO has been adjusting upward and upward in recent days as it responds to the tropical forcing from the El Nino. So we see a modestly positive AAM orbit followed by the usual slow decline which may be largely a manifestation of the usual -ve AAM bias that plagues the model. This corresponds to the added westerly momentum that the model keeps finding in the 10-16 day range or even a couple of days sooner in some cases. GEM seems to behave in a similar way.

Long story short, IF we do see the currently anticipated forcing from El Nino play out without a hitch (basically it's fighting back a bit against the seasonal decline), then I expect to see the idea of a gradual shift east in the pattern flipped around to one of gradual retrogression west. This would be a bold prediction of it wasn't for me sticking that massive caveat in as usual - we forecasters have to be sly in that way 

[John Badrick]

48 minutes ago, Frosty. said:

Yes it would make a pleasant change for the north to have the sunniest weather would'nt it?...the north usually suffers while the south has the sunniest and warmest weather but I don't think we can say for sure which the most favoured areas will be, it's a bit negative in here this evening!

 You keep banging on about warm spring weather, but like shotski said it ain't gonna be that pleasant this time of year especially under cloud cover it will feel quite raw.

[Frosty.]

1 minute ago, John Badrick said:

 You keep banging on about warm spring weather

LOL no I don't, I was just being positive about a DRY spell on the way that the models are showing but I can do without being criticized for being positive! Don't think I will bother posting if this is the attitude I'm going to get...thanks a lot!

[Redwood]

Calm John Calm

 

[Methuselah]

Aye, I think it's time you all stopped bickering...But I'll spare you my cliché!

[knocker]

Taking much of the next ten days as read except the orientation of the HP cell the ecm T240 anomaly is very similar to the GEFS with the HP diminishing and stretching towards Iceland with the Atlantic trough edging east and the main trough locked in NE Europe. The ext EPS is also not greatly different to the GEFS with the Atlantic trough continuing to edge east and heights building over Greenland. Ultimately this leads to ridging mid Atlantic and a weak trough over the UK linking to the weakening trough in NE Europe. Ergo a NW upper flow with temps a little below average and periods of unsettled weather but nothing sinister in the woodshed.

[mcweather]

Having seen my first falling snow this morning since Feb 2015, I can't help but notice that todays 12z gefs ensemble  members seem to be showing an increasing number of cold or very cold options late in the run. Only one model I know but these very cold runs seem to be to be gradually increasing in number with time. Possibly a trend to keep an eye on.

Edited March 9, 2016 by mcweather

[bluearmy]

The gefs much more amplified than eps to the west with a strong greeny anomoly in two weeks time.