Model Output Discussion

[karyo]

The 6z gfs is very keen with the cold outlook, first easterly and then northerly! In fact, the ensembles have improved considerably with a much colder mean throughout!

However, yesterday, the 6z was also the most enthusiastic in bringing the easterly, so that's something to consider. The real worry is the ECM really, with all the energy ir gives to the northern arm and the lack of high latitude blocking.

The Met Office further outlook is still looking cold, but they emphasize the uncertainty in the further outlook.

The MJO has entered phase 5 but seems to me, to lack a real drive to progress further east! At least for the time being. http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

It will be an interesting afternoon of model watching, that's for sure!

Karyo

[cooling climate]

Any potential easterly will have nothing to do with a forecasted MMW that depends on negative zonal wind anomalies propagating to the troposphere - and that is unlikely to happen before we get into February (and in turn is then dependant on factors such as GP has recently outlined before there is any guaranteed cold weather for the UK)

An easterly of sorts in the shorter term looks very likely - but its type and duration is still very open to debate. There is no -NAO signal and the presence of low heights to the north west makes prospects less straightforward to any sustained cold regime than earlier in the winter. There has been a backlog of positive zonal wind anomalies from the recently cold stratosphere - these have to pass through the pattern before any renewed cold outlook. On that basis the ECM is not implausible - even if it is showing the return of the atlantic that many of us don't like.

I mentioned the MMW but I certainly did not imply that it was connected to the possible easterly.

However going by the mid to long range outlook on the 06z GFS run then the MMW may well have a lot to do

with height rises that we see in the Arctic that would in turn help any easterly high retrogress into a

Greenland high.

Any MMW over this area would certainly encourage any ridging into the Arctic to form a proper block as

the 06z run shows.However with the 12z run just starting to come out we may well see this disappear

before our eyes, but I can not believe that the 06 run could have been that far up the creek so to speak.

[BLAST FROM THE PAST]

I am not favouring the GFS version of strong easterly, indeed I believe that the strong peak energy signal will override the block 25-31 and we see a deep LP system develop to our NW then cross the UK or just to the north and I think the block will not have a major easterly effect. However, I do favour the longer term hint that Pressure will move and rise to our NW with HP sat over Greenland, Greenland Iceland with a trough set up in Scandi formed as this deep LP moves W to E last days of Jan. I will post my Feb monthly outlook later but a taste is that I now favour a 70/30 cold to very cold month with N to NE'ly flow [HP Greenland, then Iceland] for first half and easterly second half [HP transfers to Scandi HP] but a strong blocked pattern to develop and remain in place for most of Feb. I think we have seen the deepest cold of the winter.

I think the ECM may continue to follow on from its 00z output BUT there for sure is potential for surprises.

BFTP

Edited January 20, 2010 by BLAST FROM THE PAST

[Duane S.]

The 6z gfs is very keen with the cold outlook, first easterly and then northerly! In fact, the ensembles have improved considerably with a much colder mean throughout!

However, yesterday, the 6z was also the most enthusiastic in bringing the easterly, so that's something to consider. The real worry is the ECM really, with all the energy ir gives to the northern arm and the lack of high latitude blocking.

The Met Office further outlook is still looking cold, but they emphasize the uncertainty in the further outlook.

The MJO has entered phase 5 but seems to me, to lack a real drive to progress further east! At least for the time being. http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

It will be an interesting afternoon of model watching, that's for sure!

Karyo

I know MJO forecasts are anything but set in stone and can only normally be trusted a few days ahead, if that! But there does seem some interest to take it into phase 6 and maybe 7 which can only be good for us I would have thought? - perhaps helping to beef up the Siberian block. Not sure how this ties in with the projected PV drop into Scandi later on though?

[mountain shadow]

Not sure why no one is posting on the 12z, as it goes with 6Z and the easterly, with snow for Kentish types.

http://209.197.9.129/c9s4a5k3/cds/gfsimages/gfs.20100120/12/132/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf4d4c19cf1d4c491ed84716cf1d4cbf&dopsig=9e51df6e219555104aa97b7475bf8a43

We will get retrogression again though?

[cooling climate]

The easterly looks in much better shape than it did this time yesterday and I have to say

I really like the look at the higher heights developing to the north at t150.

[nick sussex]

Its hard to believe the differences between the gfs and ukmo at 96hrs! The UKMO eventually gets to the easterly for the se at 120hrs but at 96hrs it looks like the Atlantic trough is going to throw too much energy eastwards, the UKMO looks like quite poor in comparison in terms of the set up and it does seem to be following the ECM. So at the moment FI is definitely 96hrs, I think the deciding vote goes to tonights ECM if it backs the UKMO then I can't see the GFS not backtracking later on. At 144 hrs the UKMO improves but it could all go wrong much earlier and for this reason an easterly is definitely not set in stone.

Edited January 20, 2010 by nick sussex

[Rollo]

Not sure why no one is posting on the 12z, as it goes with 6Z and the easterly, with snow for Kentish types.

http://209.197.9.129/c9s4a5k3/cds/gfsimages/gfs.20100120/12/132/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf4d4c19cf1d4c491ed84716cf1d4cbf&dopsig=9e51df6e219555104aa97b7475bf8a43

We will get retrogression again though?

I think the reason there are so few posters Mountain Shadow is that there is so much uncertainty currently,it is so difficult to come to any judgement as to where we are heading. It would help a lot of the ECM came on board but until one or T'other backs down we are in a sort of no mans land.

Edited January 20, 2010 by Rollo

[mountain shadow]

Uk MET isn't to far off it's 0z output and similar to GFS 12Z. Would be amazed if ECM didn't at least move a little towards them a little more.

The models still cannot agree on the jet energy and strength of lows around Iceland/Greenland.

Looking further ahead and the PV is still looking to drop into Scandi with all the potential that offers.

http://209.197.11.165/c9s4a5k3/cds/gfsimages/gfs.20100120/12/180/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf4d5032cf1d50621ed85b3dcf1d5054&dopsig=0512fff32fdc38723c6d9718dcfee7ae

Good inter run consistency on the GFS up to T+180 within the High Res.

[karyo]

Uk MET isn't to far off it's 0z output and similar to GFS 12Z. Would be amazed if ECM didn't at least move a little towards them a little more.

The models still cannot agree on the jet energy and strength of lows around Iceland/Greenland.

Looking further ahead and the PV is still looking to drop into Scandi with all the potential that offers.

http://209.197.11.165/c9s4a5k3/cds/gfsimages/gfs.20100120/12/180/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf4d5032cf1d50621ed85b3dcf1d5054&dopsig=0512fff32fdc38723c6d9718dcfee7ae

Good inter run consistency on the GFS up to T+180 within the High Res.

The 12z gfs is sticking to its guns but I think the UKMO has made a small step towards the ECM.

The gfs ensembles should be interesting before we see the ECM.

Karyo

[nick sussex]

Uk MET isn't to far off it's 0z output and similar to GFS 12Z. Would be amazed if ECM didn't at least move a little towards them a little more.

The models still cannot agree on the jet energy and strength of lows around Iceland/Greenland.

Looking further ahead and the PV is still looking to drop into Scandi with all the potential that offers.

http://209.197.11.165/c9s4a5k3/cds/gfsimages/gfs.20100120/12/180/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf4d5032cf1d50621ed85b3dcf1d5054&dopsig=0512fff32fdc38723c6d9718dcfee7ae

Good inter run consistency on the GFS up to T+180 within the High Res.

The UKMO might look similar at 144hrs but at 96hrs its on dodgy ground and given what the ECM has been showing its too early to say if an easterly will happen. At 96hrs that energy off the trough could easily scupper the whole thing, the ECM will be key this evening.

[Frosty.]

No sign yet of the GFS dumping the Easterly and it also gives us a NW / SE tilted jet profile in FI with a chance of N'ly or NW'ly reloads which would probably offer more wintry potential than the lame looking E'ly the gfs is showing for next week! When the block collapses we will probably see some type of polar airmass as the azores high ridges northwards and a trough moves across the north and sets up home in scandinavia.

Edited January 20, 2010 by Frosty039

[Thundery wintry showers]

The T+96 chart at UKMO could easily support an easterly. The main cause for debate and concern is the T+120 chart, as it has a large dartboard low out to the west which tracks north-eastwards. The further east this low gets, the more likely it is that we'll get a SW flow with HP stuck away to the NE, instead of an easterly flow.

As is so often the case cold/snow lovers are relying upon the northern arm of the jet not being too strong.

[The Weather Dragon]

The Scandi high trend will be backed by ECM tonight - We are seeing the building blocks for the next cold spell - Next week will be cold with snow about. I have a feeling that we will see retrogression of this Scandi high into the Atlantic and towards Greenland. The big question is that will conditions be condusive to maintain this block and prolong our cold spell.

[Polar Continental]

An interesting 12z GFS evolution, this follows the 06z and the 0z Gem. The easterly starts to trickle in on Sunday with –6c to –10c uppers getting in to the east with a few snow showers hitting eastern counties overnight.

There after the cold gets more potent, all be it, mostly surface cold, as less cold uppers get in to the mix from time to time.

With pressure projected to be mostly high, this would mean mostly dry and cold for the majority of the country, but if an easterly does get established, then any lows undercutting the high could easily change this.

ECM next.

[Duane S.]

The Scandi high trend will be backed by ECM tonight - We are seeing the building blocks for the next cold spell - Next week will be cold with snow about. I have a feeling that we will see retrogression of this Scandi high into the Atlantic and towards Greenland. The big question is that will conditions be condusive to maintain this block and prolong our cold spell.

Wow! I wish I shared your optimism. There are hurdles to jump before the evolution you suggest can be attained. Although... it is plausable if nothing else so fingers crossed the Northern Arm doesn't fire up too much.

You may

[Frosty.]

As is so often the case cold/snow lovers are relying upon the northern arm of the jet not being too strong.

We better pray the ecm changes then as it has shown that for the last couple of runs.

Edited January 20, 2010 by Frosty039

[Eugene]

http://91.121.94.83/modeles/gem/run/gem-0-144.png

http://91.121.94.83/modeles/nogaps/run/nogaps-0-144.png?20-18

Very nice GEM and Nogaps tonight.

We may have an atlantic front sneak through on sunday before the block asserts itselt

[SP1986]

I fine the GEM and NGP tends to just follow like sheep to be honest, it's probably showing what was being shown by the GFS yesterday, they are certainly not trend setter models.

With the UKMO going one way ad GFS going the other, todays outputs are going to be reliant on the ECM to suggest the way - and knowing our luck it'll probably make another scenario all of it's own!

[The PIT]

Another run another solution. I think we're very unlikely to get a full blown easterly from the High pressure. Looking like a period of dull quiet cool weather coming up after a kilt raiser further up north tomorrow. The attempt at real cold stays out in FI land without moving any closer.

The high is impressive for three things. The pressure the ability to stay stuck in one place and the ability not too do a lot.

[snowmadchrisuk]

The Scandi high trend will be backed by ECM tonight - We are seeing the building blocks for the next cold spell - Next week will be cold with snow about. I have a feeling that we will see retrogression of this Scandi high into the Atlantic and towards Greenland. The big question is that will conditions be condusive to maintain this block and prolong our cold spell.

Well I think you was right about something you said yesterday , But I would prefer to see last night's UKMO +144 chart at todays +120 ... When UKMO keeps charts at +144 and doesn't bring them forwards it get's worrying . GFS was right about the last Cold spell so let's hope it is right this time.

[Eugene]

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Pretty good ensembles notice the lack of much precipitation, hardly indicative of atlantic dominating, probably no mega cold spell on the horizon just yet but below average and dry in southern UK at least looks likely, alot better than some were predicting not too long ago with atlantic wet and windy weather dominating.

Fronts will probably skim far northwestern reaches of the UK though but for the vast majority looking great for some nice seasonal dry weather.

[swilliam]

http://91.121.94.83/...n/gem-0-144.png

http://91.121.94.83/...0-144.png?20-18

Very nice GEM and Nogaps tonight.

We may have an atlantic front sneak through on sunday before the block asserts itselt

Not so nice GME and shows what could happen if things do not go our way.

[bluearmy]

I fine the GEM and NGP tends to just follow like sheep to be honest, it's probably showing what was being shown by the GFS yesterday, they are certainly not trend setter models.

With the UKMO going one way ad GFS going the other, todays outputs are going to be reliant on the ECM to suggest the way - and knowing our luck it'll probably make another scenario all of it's own!

dont agree Stephen - GEM was quite progressive last year and often the first of the models to show the strange evolution which then verified below T180. recently, it has been performing badly. NOGAPS has verified quite well on a few occasions over the past couple of months. it normally had last place to itself. i wonder if it has been upgraded. incidentally, i'm sure the new GEFS is due soon.

anyway - are we any the wiser what will happen to this block? i have a feeling that if i look at ecm history, i'll see a fair few runs showing the block to the east ridging down around the euro trough to the AH. it does have the knack of picking the correct mid range solution much of the time.

[LomondSnowstorm]

http://www.wetterzen..._London_ens.png

Pretty good ensembles notice the lack of much precipitation, hardly indicative of atlantic dominating, probably no mega cold spell on the horizon just yet but below average and dry in southern UK at least looks likely, alot better than some were predicting not too long ago with atlantic wet and windy weather dominating.

Fronts will probably skim far northwestern reaches of the UK though but for the vast majority looking great for some nice seasonal dry weather.

Not sure about that. I've been told 'cold and dry' many times before only to find snow events popping out of nowhere - it's still a bit too soon to look at precipitation amounts really, but as long as the uppers are below -5 for most of the time, snow events are likely to crop up at times without too much warning. Still, we're not even sure if there will be much of a cold feed yet!

All eyes on another ECM 12Z

LS

edit: http://www.meteogroup.co.uk/meteo/ecmwf/NSea/2010012012/NSea_2010012012_thgt850_96.png http://www.wetterzentrale.de/pics/Recm961.gif

Edited January 20, 2010 by LomondSnowstorm