Model Output Discussion

[MR EXTREMES]

the only worry would low pressure around greenland thats always been the downfall in winter it could be that the alantic roars in after a brief cold spell.

this was always been my worry at the start of the week.

[Polar Continental]

Saga is exactly the right word this morning mate.

Obviously the UKMO is the best output this morning wrt to the E,ly. However the best model run this morning is the GEM which goes from a E,ly to a N,ly and then a NE,ly which is actually supported by the ECM at this timeframe.

If you were going to base your outlook on model consistency then it would probably be the UKMO/GEM with the GFS definitely in last place. However unfortunately there is little point in looking beyond the E,ly until this is finally sorted. Im afraid the old chestnut of following the fax charts is best at the moment.

Speaking of which a lovely fax chart this morning with snow spreading SW across some parts of the UK.

http://www.wetterzentrale.de/pics/brack2.gif

Followed by snow showers in E areas.

http://www.wetterzentrale.de/pics/brack2a.gif

Exactly Dave,

That’s why I never made any comment on the projected northerly, if the models cannot decide at this short range what is going to happen. Slight model divergence begins, as early as T60, the UKMO has a low over northern France and the GFS has the low over the north sea. Small differences like this can have bigh changes later. The further south the low the better for helping to advect the easterly winds in to the UK.

[Kentish Man]

The GFS is certainly on its own this morning with its uber mild prognosis - every other model including the various smaller ones go for colder solutions. That is not of course to say the GFS is wrong. In fact if it pulls this one out of the hat it will be a small triumph for it even if coldies like myself are left disappointed.

[The Weather Dragon]

To be fair to GFS it was showing the scenario that UKMO & GME is showing for early next week a few days ago - it spotted the trend. Fax charts are confident of an easterly at 120z (I tend to find these reliable). Why has GFS backed down over the last few runs. Someone is going to have to fall back in line today!!

Edited January 22, 2010 by Jonathan Evans

[TEITS]

Fax charts are confident of an easterly at 120z (I tend to find these reliable). today!!

Worth highl;ghting that the +120 fax chart is from last night. This mornings updated fax charts go out to +84. The next +0 to +72 fax charts are updated between 17.00-18.00 and the +96/+120 from 22.00-23.00.

[The Weather Dragon]

Models seem to be catching onto the evolution quite quickly now. Details to change of course but the general idea is looking good and right. I believe that we are heading into a cold to very cold Feb, the jetstream will push south and any FI outlook of strong northern arm will disappear. This projection of retrograde and High pressure in Atlantic then heading north...looks familiar doesn't it?

Interesting to see The arctic is colder than average at the moment and are we looking at a SSW due to the very current activity [flares] from the sun?

BFTP

My thoughts exactly BFTP - This hasn't been a normal winter - and we're only half way through

[Cecil Hogmanay Melchett]

Nice ukmo/GEM this morning.GFS is garbage for us and ecm isn;t brilliant either.

Hopefully ukmo and GEM are on the ball here,if they are,esp GEM,another cold spell is on the cards.

The question is which model is correct.

[Rollo]

The stand-off beteen the main players continues but I have to admit after taking into account this winter so far that things have gone the way of the cold lovers and at some point soon we may well enter a period of cold and snow once again-fun init!!

[nick sussex]

NOAA don't include the GFS in their extended outlook this morning but go for the ECM 00hrs combined with the ECM 12hrs ensemble mean for the period upto Wednesday then switch across to the 00hrs GEM and 12hrs ECM ensemble mean for Thursday and Friday of next week.

I think the GFS is too flat upstream and will back down towards the ECM/UKMO/GEM, unfortunately after sticking with its easterly earlier in the week the GFS has now gone walkabout.

[snowmadchrisuk]

The Met office are backing there own model and saying Snow showers for the Midlands , Monday and Tuesday , mostly light but covering likely . As the GFS and the ECM do not show that I am surprised the Met has given so much confidence to it's own model when it quite often ignores it and goes for the ECM mean.

[Duane S.]

Exactly Dave,

Thats why I never made any comment on the projected northerly, if the models cannot decide at this short range what is going to happen. Slight model divergence begins, as early as T60, the UKMO has a low over northern France and the GFS has the low over the north sea. Small differences like this can have bigh changes later. The further south the low the better for helping to advect the easterly winds in to the UK.

Totally agree with this. The 'butterfly effect' in full effect here.

I spent 20 minutes (I do wonder sometimes if I haven't got better things to do with my time ) comparing the GFS and METO and came to the same conclussion. Up to T+60 there isn't a great deal of difference (although the METO charts don't allow you to see upstream events in the way GFS does). Then ,as you say, that small trough say over NE France seems fairly key to the further evolution (plus less energy over Greenland). As it subsequently meanders around aimlessly on the GFS, the damage is done.

The Meto has it helping to prop up the Eastern HP initially then dropping down to the Med to help form a stronger trough at the same time as the ridge from the Azores is linking with the original block to the east. Timing certainly is a factor here and it works in our favour on the METO. The question is, are we seeing a new trend of retrogerssion into Greenland, something I was expecting but maybe not quite this quickly. The window of opportunity will be there though I reckon, as the PV is being progged to firmly split into two, the main section to head to Northern Svalbard before maybe then dropping south, the other way over to the West.

The NAO forecasts from yesterday were very encouraging and showed more members going for a -NAO signal. MJO also continues its hinting that we could be heading into phase 7, maybe even 8.

Edited January 22, 2010 by s4lancia

[Eugene]

TBH i would take the worst case scenario anyday.

http://www.wetterzen...s/Rtavn1321.png

No sign of relentless deep lows crossing the UK from the southwest as some were predicting.

Edited January 22, 2010 by Eugene

[TEITS]

The NAO forecasts from yesterday were very encouraging and showed more members going for a -NAO signal. MJO also continues its hinting that we could be heading into phase 7, maybe even 8.

The NAO ensembles from yesterday suggest a range from +1 to -1 with the rogue ensemble of -2. Now if the ensembles are between +1 and -1 this suggests the NAO around Neutral. A - NAO signal would be when a majority of the ensembles are at least -2 or below.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

Back to the models and looking at the 06Z GFS/ECM at +120 I have to admit this is more likely than the UKMO. Would love to be wrong but its hard to go against the ECM/GFS when they are both very similiar to each other at +120/+144.

[Frosty.]

WOW just seen the GEM 00z, can we have that please

I think the gem 00z has to be the pick of models this morning with a truly awesome N'ly which would be every bit as potent as we had during the recent wintry spell but no doubt it's too good to be true.

[Guest North Sea Snow Convection]

WOW just seen the GEM 00z, can we have that please

I think the gem 00z has to be the pick of models this morning with a truly awesome N'ly which would be every bit as potent as we had during the recent wintry spell but no doubt it's too good to be true.

Morning Karl,

It is the UKMO,GEM,NOGAPS AND GME vs GFS and ECM

Basic retrogression pattern similar in all models but the energy amounts are different on both sides of the divide which make the difference between both an easterly and then a northerly for many parts of the UK.

Although the ECM does get there in the end for the northerly.

[TEITS]

Despite the differences between the models I have this feeling the ECM/GFS are right on this. One word to sum up the E,ly and N,ly is weak!

I reckon over the next 24hrs we shall see the UKMO/GEM backtrack towards the ECM/GFS and the fax charts will change accordingly. This will mean the BBC/Met O forecasts are less wintry tomorrow morning.

I know BFTP is suggesting blocking developing to our NW with the aid of the SSW. However a SSW could weaken the PV but I doubt this will occur within the timeframe that we're currently looking at.

Really hope that I have this completely wrong though.

[Kentish Man]

Subtly better 06z GFS run (compared to the dire 00z run) for those hoping for a low January CET with TM air kept away further west and the UK away from the far NW remaining largely cold for the next 6 days or so after todays mild interlude.

Edited January 22, 2010 by Kentish Man

[Polar Continental]

Totally agree with this. The 'butterfly effect' in full effect here.

I spent 20 minutes (I do wonder sometimes if I haven't got better things to do with my time

Hi lancia, lol, it is sad really, I suppose we should find better things to do, but I fully admit to being a complete anorak now.

The GFS, still not budging on this, how many more runs can it produce before it falls in line, or have the other 3 major models got to fall in line with the GFS?

Though looking very closely there are very subtle changes on 06z, where as the colder uppers get a little further west on this run, almost in to Wales.

[Guest North Sea Snow Convection]

Despite the differences between the models I have this feeling the ECM/GFS are right on this. One word to sum up the E,ly and N,ly is weak!

I reckon over the next 24hrs we shall see the UKMO/GEM backtrack towards the ECM/GFS and the fax charts will change accordingly. This will mean the BBC/Met O forecasts are less wintry tomorrow morning.

I know BFTP is suggesting blocking developing to our NW with the aid of the SSW. However a SSW could weaken the PV but I doubt this will occur within the timeframe that we're currently looking at.

Really hope that I have this completely wrong though.

You could well be right Dave. There is no sign of the GFS moving enough to support the current fax charts. Other than a last minute change on the 12z GFS (which is still possible!) then the changes you suggest do look quite likely. If the GFS is still the same then The UKMO will probably change this evening along with the GEM

The current warming of the stratosphere if it is to have any effect in the outlook then this won't be for some time yet - could be up to another three or probably four weeks at least.

[Frosty.]

Morning Karl,

It is the UKMO,GEM,NOGAPS AND GME vs GFS and ECM

Basic retrogression pattern similar in all models but the energy amounts are different on both sides of the divide which make the difference between both an easterly and then a northerly for many parts of the UK.

Although the ECM does get there in the end for the northerly.

Morning Tamara,

Fully agree with you, must admit the GFS 06z is another poor run in my opinion and fuels the doubts regarding the E'ly and then the N'ly, we may get neither at this rate but there are some excellent charts still to be found so all is not lost yet.

[Methuselah]

I must admit, I am getting a little confused... :lol:

Before the Sun re-awoke from its slumbers, its relative quietness was a signal for Northern blocking (I think?). Now, however, it's re-awakening is also a signal for Northern blocking - only this time, via SSWs??

Meanwhile, the models look as confused as ever, today? :lol:

[snowmadchrisuk]

Despite the differences between the models I have this feeling the ECM/GFS are right on this. One word to sum up the E,ly and N,ly is weak!

I reckon over the next 24hrs we shall see the UKMO/GEM backtrack towards the ECM/GFS and the fax charts will change accordingly. This will mean the BBC/Met O forecasts are less wintry tomorrow morning.

I know BFTP is suggesting blocking developing to our NW with the aid of the SSW. However a SSW could weaken the PV but I doubt this will occur within the timeframe that we're currently looking at.

Really hope that I have this completely wrong though.

You got the Easterly wrong so fingers crossed hee hee , I Think the truth is the way the models have been this week then nobody can call next week. In some cases we are only talking about Monday and it is Friday Today. Time out is required I think and let nature take it's course. This reminds me of when I was little and only new it was going to Snow when I seen it fall from the Sky ... arh the good old days.

[BLAST FROM THE PAST]

I must admit, I am getting a little confused... :lol:

Before the Sun re-awoke from its slumbers, its relative quietness was a signal for Northern blocking (I think?). Now, however, it's re-awakening is also a signal for Northern blocking - only this time, via SSWs??

Meanwhile, the models look as confused as ever, today? :lol:

Pete

Its not just about sunspots. the magnetic field is weakening, the longer term cycle is driving the jetstream south and the magnetic particle interference with the atmosphere affects ozone build up etc etc not suitable for this thread indepth. The main thrust of all this is the jetstream moving south [for me perturbation cycle equates to -ve NAO phase equates to jet forced south.

Dave, re timescale, what one are you referring to for clarity. I am aiming for beginning of Feb,

BFTP

Edited January 22, 2010 by BLAST FROM THE PAST

[Duane S.]

Time out is required I think and let nature take it's course. This reminds me of when I was little and only new it was going to Snow when I seen it fall from the Sky ... arh the good old days.

As my girlfriend said to me the other day, one day you are going to be sat on the damn computer working out if/when/how/where it will be snowing and outside it will be dumping down the biggest load of snow we have seen for years! She's probably got a point (although of course I didn't admit it )

06z, a slight improvement but not enough to show it budging from its trend set the other day unfortunately. Still, I would rather it was the GFS not showing what we want and the METO doing so, rather than the other way way. The ECM is being sided with the GFS but I think it is in a bit of a halfway house camp (although, yes, it is closer to the GFS than the METO). The ECMWF and METO 12z will be very interesting this evening.

I think primarily, mid-term, the key here is that the secondary, lesser, peice of the PV doesn't linger too long (which it may) around the Labrador area to allow pressure to build over Greenland. If this stays too far East then we have no chance of retrogression and subsequently no chance of a sustained Easterly followed by a potent Northerly. In this respect, the NAO forecasts are going to be interesting in the next 5 days or so because, whilst I agree they are not really indicating one thing or the other ATM, in the same way as we view the ensebemles for trends so should we should also be viewing the NAO forecasts for trends. Yesterday it 'trended' more negative, albeit very slightly.

[snowmadchrisuk]

As my girlfriend said to me the other day, one day you are going to be sat on the damn computer working out if/when/how/where it will be snowing and outside it will be dumping down the biggest load of snow we have seen for years! She's probably got a point (although of course I didn't admit it )

06z, a slight improvement but not enough to show it budging from its trend set the other day unfortunately. Still, I would rather it was the GFS not showing what we want and the METO doing so, rather than the other way way. The ECM is being sided with the GFS but I think it is in a bit of a halfway house camp (although, yes, it is closer to the GFS than the METO). The ECMWF and METO 12z will be very interesting this evening.

I think primarily, mid-term, the key here is that the secondary, lesser, peice of the PV doesn't linger too long (which it may) around the Labrador area to allow pressure to build over Greenland. If this stays too far East then we have no chance of retrogression and subsequently no chance of a sustained Easterly followed by a potent Northerly. In this respect, the NAO forecasts are going to be interesting in the next 5 days or so because, whilst I agree they are not really indicating one thing or the other ATM, in the same way as we view the ensebemles for trends so should we should also be viewing the NAO forecasts for trends. Yesterday it 'trended' more negative, albeit very slightly.

The GFS though , I don't know if anybody has noticed but it dumps a heck of alot of Heavy Snow on Northern England during Sunday/Monday. If this trough can come a little further South we may have a notable Snow Event there. It doesn't even look marginal with the 528 dam line well inland. This is at 48 hours so it's all or nothing on the 12z's.