Model Output Discussion - 1st - 7th January

[SMU]

All I see is the azores high ridging NE towards the UK and then being flattened out by the jet.

Quite baffled by some of the posts TBH and if i was looking for cold,personally i'd be thinking NW,certainly not NE.

that is because its ONE of the things that are on the table-

The azores high has many a time been part of the scandi high formulation process-

heres one example- all be it not a great one-

http://www.wetterzentrale.de/pics/archive/ra/2005/Rrea00120051223.gif

http://www.wetterzentrale.de/pics/archive/ra/2005/Rrea00120051224.gif

http://www.wetterzentrale.de/pics/archive/ra/2005/Rrea00120051225.gif

http://www.wetterzentrale.de/pics/archive/ra/2005/Rrea00120051226.gif

http://www.wetterzentrale.de/pics/archive/ra/2005/Rrea00120051227.gif

An important note is one I post every year- is the models - more especially the 18z & 06z GFS struggle with a low pressure / shortwave digging south through Scandi curving west under the block- the GFS more often than not slides them away SE as the jet over runs to the NW- when in reality that *MAY* not be the case

S

[mountain shadow]

I would say very good agreement between the GFS and ECM . PV remains around Greenland and generally low heights remain to the north. No sign of any strat warming impacting the PV.

GFS

http://hw.nwstatic.c...240/npsh500.png

ECM

http://hw.nwstatic.c...npsh500.240.png

At the very least if we were expecting a pattern change to something colder I would expect a much better northern hemisphere signal than these. You could argue based on these charts that we are moving into a milder pattern change not a colder one.

Edited January 1, 2012 by mountain shadow

[Cecil Hogmanay Melchett]

Well it actually tries to ridge towards Greenland but it does not break the PV up therefore the high starts to topple however I think what the GFS is saying at this range is quite a low possibility because of the ECM/UKMO outputs which are alot flatter and we know the pub run likes to lead us on one.

Suppose we got to start from somewhere though and we might see upgrades but whilst the models are trying to break up the PV with height rises to our North/Azores high, I'm still unsure about any snowy spell.

There is simply not a cat in hells chance of that Azores high hitting Greenland with the jet as intense as progged.

The danger in this set up is perfecly highlighted by the low res 18Z with the high ending up to our South or South East and an even more intense PV to the NW meaning back to square one and probably most of Jan down the tubes.

To me its all or nothing,either the High gets far enough north (similar to the ECM00Z Op)or we end up back in a very unfavourable position.

I know where my money is.

[Jason M]

Glad to see both yourself and Steve M remain positive, however with charts like this at ten days out..

http://hw.nwstatic.c...240/npsh500.png

There is more chance of Pat Butcher's resurrection than a snowy spell.

to be fair to Steve that chart is in the low res part of the run and GFS won't handle any change well past its high res section. I personally think the chart you post is where were headed, but its not a completely done deal yet. The initial part of the run was actually an improvement Lets see what tommorow (and the ensembles) bring.

Jason

[BLAST FROM THE PAST]

Glad to see both yourself and Steve M remain positive, however with charts like this at ten days out..

http://hw.nwstatic.c...240/npsh500.png

There is more chance of Pat Butcher's resurrection than a snowy spell.

Lets see what the models show over next 3/4 days, we may all be pleasantly surprised......but we will need to see more support or the rut remains.

BFTP

[Cecil Hogmanay Melchett]

that is because its ONE of the things that are on the table-

The azores high has many a time been part of the scandi high formulation process-

heres one example- all be it not a great one-

http://www.wetterzen...00120051223.gif

http://www.wetterzen...00120051224.gif

http://www.wetterzen...00120051225.gif

http://www.wetterzen...00120051226.gif

http://www.wetterzen...00120051227.gif

An important note is one I post every year- is the models - more especially the 18z & 06z GFS struggle with a low pressure / shortwave digging south through Scandi curving west under the block- the GFS more often than not slides them away SE as the jet over runs to the NW- when in reality that *MAY* not be the case

S

Yep, i know exactly where you are coming from Steve,trouble is under the circumstances its a long shot.

[mountain shadow]

To me its all or nothing,either the High gets far enough north (similar to the ECM00Z Op)or we end up back in a very unfavourable position.

I know where my money is.

I think that is ultimately the problem, if we miss the opportunity for the Scandi High you have to wait at least another 10-14 days for another bite of the cherry, that would take us to the end of the month.

[Geordiesnow]

There is simply not a cat in hells chance of that Azores high hitting Greenland with the jet as intense as progged.

The danger in this set up is perfecly highlighted by the low res 18Z with the high ending up to our South or South East and an even more intense PV to the NW meaning back to square one and probably most of Jan down the tubes.

To me its all or nothing,either the High gets far enough north (similar to the ECM00Z Op)or we end up back in a very unfavourable position.

I know where my money is.

On the other hand, the output is not as simple as that because we were talking about Arctic/russian highs trying but failing to influncing our weather in a cold way, now its the Azores high, there is signs we might break the PV to some extent but at this range, its all speculative and subject to change.

One thing to note is that even after that quite deep low leaves us on Tuesday, it looks like it could be quite a wet and windy week so a fairly interesting outlook in that respect.

[BLAST FROM THE PAST]

Yep, i know exactly where you are coming from Steve,trouble is under the circumstances its a long shot.

Not really if one has looked at a certain forecast/method, which has been darn close thus far and now models hint at pattern change at .......the forecast time? [Not me] :-)

BFTP

Edited January 1, 2012 by BLAST FROM THE PAST

[SMU]

I think my optimism has come from the last few winters where evry time there was an opportunity like this we would default to cold-

So then to summarise- in the last 10 years we probably get these sorts a runs at an Easterly with Scandi high maybe once or twice a season-

we would have the GFS & ECM throwing a ridge NW in the atlantic - Destination Scandi?? possibly?

in the early 00's up to say 2008 it never seemed to happen, although the last 3 years it has & the over running pattern produced by the models like todays ECM12z turned out to be to far SE-

So there you have it- because of the nature of this POSSIBLE set up things are difficult to draw a conclusion at this stage & only ever so slowley would the models evolve to a Cold one if its going to happen at all-

eSome nice developments though in the 18z suite

the Ensemble mean at T90 has that scandi low further WEST so the UK will be under lower heights & colder air-

the ensemble mean at T144 digs the scandi trough harder SW

& finally the mean at 192 has TENTATIVE heights heigher over scandi- but the model bias is always trying to force the atlantic through on an easterly trajectory..............

S

For people wondering what im referring to & how this ridge transfers to scandi & develops the UK cold follow PTB 7

http://www.meteociel.fr/modeles/gefs_cartes.php?code=7&ech=6&carte=1&mode=0

Edited January 1, 2012 by Steve Murr

[SP1986]

The currently models remind me very much of those when cold spells occurred between 2005 and 2007, northerlies bringing 24-48 hours of wintry type weather followed by a toppler high (and frost), and then an Atlantic resurgence for a short time, and often a reload of a polar northerly, a very mobile, but less flat pattern than what we have seen for the past 2 weeks or so.

These type of situations can be very interesting weather-wise, as they are quite unpredictable bringing thunder, hail, rain and sometimes even snow to low levels. The only issue is how quickly topplers tend to move in though, so it's down to chance how wintry the period in question gets. I am looking forward to a spell of potentially unstable weather though (aka sunshine and showers/wintry showers scenario).

I don't really want to start delving into details of potential freezes, as they are not showing on models yet and are not necessarily going to occur at all, but next week looks fairly decent start to something more synoptically interesting.

[kumquat]

Folks are falling over themselves to show that a pattern change is showing in the models. The professionals are hedging their bets as to what this pattern change will lead to. But it is a pattern change nonetheless.

[Thundery wintry showers]

I think the snow potential for most of lowland Britain isn't great during this coming week. Tomorrow is perhaps the day of peak potential with likelihood of some wintry showers at low levels from the Midlands northwards and on southern hills, and lying snow on northern hills. After that, wintry showers look like being largely confined to northern hills. However, it shouldn't be too boring on the weather front with a substantial mixture of weather on offer, and temperatures generally near rather than well above average.

[Jason M]

Some very strange charts amongst the ensembles deep in FI, so clearly some uncertainty.

Overall, 18Z suite looks a bit better in the 120 - 180 hour range, so were in the game still.

Jason

[bluearmy]

I think that is ultimately the problem, if we miss the opportunity for the Scandi High you have to wait at least another 10-14 days for another bite of the cherry, that would take us to the end of the month.

i rather doubt that and anyway, 10/14 days from the 10th takes us to the 24th. MS, events over the pole appear to accelerate around the middle of the month. many have talked up the 20th jan for the start of a cold spell. i see no reason to question that timescale, looking at current modelling.

some amazing gefs FI's on offer. there arent many of the T384 charts that i wouldnt snap off your hand for mid jan. even the ones that dont deliver anything to nw europe ooze potential for the seven days that follow.

if the second half of jan doesnt dleiver a below av CET, i'll be very surprised.

Edited January 1, 2012 by bluearmy

[J10]

I think the snow potential for most of lowland Britain isn't great during this coming week. Tomorrow is perhaps the day of peak potential with likelihood of some wintry showers at low levels from the Midlands northwards and on southern hills, and lying snow on northern hills. After that, wintry showers look like being largely confined to northern hills. However, it shouldn't be too boring on the weather front with a substantial mixture of weather on offer, and temperatures generally near rather than well above average.

Recent similar events have been more wintry further south than you describe, largely due to thickness levels being lower than the 850HPA levels would lead you to believe , However if this does not transpire, a bit more sunshine looks likely tomorrow and that should make a nice change. from the mild damp and misty muck of recent weeks.

http://hw.nwstatic.c.../h850t850eu.png

http://hw.nwstatic.c.../h850t850eu.png

http://hw.nwstatic.c.../15/h500slp.png

http://hw.nwstatic.co.uk/gfsimages/gfs.20111227/18/135/h500slp.png

GFS also modeled this pretty well from a decent period out.

[phil nw.]

Just looking at the control run on the GFS18z -this is the evolution that i was talking about earlier this evening--if the PV plays ball.

ifyou run it from there we get a good Northerly-arctic air right down to the Med.

As i said earlier there will be many changes in the later frames on this,but this to me is one of the likely evolutions and at the sort of timeframe talked about so much lately-15th Jan anyone?

[SMU]

Phil- thats as amplified as the jet can get!

Steve

[phil nw.]

Phil- thats as amplified as the jet can get!

Steve

Indeed Steve--I think that much would be an outsider but if the vortex starts to fragment -who knows?

The Canadian troughing much better on that--sucks up the heights from the Azores.

I prefer that way than an Easterly that may sink too quickly..

Edited January 2, 2012 by phil n.warks.

[Tom Montalbano]

Just lost my post!

Steve et al, another couple of examples of a high pressure cell to our south, assisting a favourable pattern change, albeit extreme in respect of all the jigsaw pieces falling together positively for us.

http://www.wetterzentrale.de/pics/archive/ra/1984/Rrea00119841228.gif

http://www.wetterzentrale.de/pics/archive/ra/1984/Rrea00119841230.gif

http://www.wetterzentrale.de/pics/archive/ra/1984/Rrea00119841231.gif

http://www.wetterzentrale.de/pics/archive/ra/1985/Rrea00119850101.gif

Which eventually led to this

http://www.wetterzentrale.de/pics/archive/ra/1985/Rrea00119850105.gif

And of course

http://www.wetterzentrale.de/pics/archive/ra/1986/Rrea00119861230.gif

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870101.gif

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870103.gif

That attempt failed

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870104.gif

Lets have another bite of the cherry

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870106.gif

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870108.gif

Will it, wont it

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870109.gif

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870110.gif

Get these trigger lows out of the way and......

http://www.wetterzentrale.de/pics/archive/ra/1987/Rrea00119870111.gif

Bingo!

Of course these are extreme examples, how many times has it been a case of close but no cigar!

Forgive me mods, just wanted to illustrate the many hurdles we have to cross to hit the jackpot and sometimes it takes a few bites of the cherry.

Crikey, how many metaphors have I used!

As you can see this kind of synoptic can take a week, ten days, maybe longer, to achieve. Lets hope the models start to show these type of scenarios, in the coming week or so.

Regards,

Tom

[MP-R]

Oh dear, a rather... annoying (want of a better word) model run yet again. The GFS certainly gives us plenty of interest and variety as far as wind and rain is concerned but nothing very seasonal either in the reliable timeframe or into FI. It would appear that an Atlantic ridge will quickly move in after a NW-Nly incursion at the end of the week and rapidly get flattened but then not move out of the way! I fear this will be a repeating occurrence over the coming few weeks. On the plus side, there is mainly cool zonality to be had this week with the possibility of strong winds countrywide late Tuesday into Wednesday.

[kumquat]

WAA goes west. Another nail in the coffin for the PFJ. Should slow rapidly, if not, come to a halt around mid-month. Cut-off jet stream to boot.

[Great Plum]

Another day, another mild outlier!

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Some interesting options from some of the ensembles...

[Nick F]

Rather mobile looking ECM this morning, the operationals still not entertaining the idea of the much touted big change, though the ensembles may indicate otherwise. Still some waiting to do before we see if the pundits for a change are correct.

[IDO]

Hi

I am a relative newbie and have been looking at the models and just not seeing what other members have been seeing over the last couple of days. All I see is zonal, brief topplers but with a raging jetstream pushing through west to east. Nominal cold for the south and cool/cold more often in the north. Can anyone show me on GFS where the change to cold is happening mid-Jan? Thanks.