Model Output Discussion 18/11/2012 12Z onwards

[bluearmy]

i suspect from the point at which the gfs op develops the small shortwave at the base of the trough (T120) which then takes too much energy ne, this run is unlikely. the fi period isnt a solution i've spotted in the ens recently. the ridge extended from the azores in high res ? just looks wrong at that angle based on all the runs we've been looking at. raising heights over iberia in week two. completely at odds with whats been shown on the ens means and noaa cpc. the best bit is the run manages to create the 'holy grail' feature of cut off greenland/iceland high but it does nothing to bring any cold sypnotic pattern.

[Ice BIast]

looks like the cold spell is looking less likely now .oh how good it feels to be so right just far to much energy in the alantic we will get some cold shots but they will be just short artic blasts.

I wouldn't speak so soon. Anything is possible so lets just wait and see.

Edited November 18, 2012 by lce Blast

[chionomaniac]

If I suspect a post is purely made to troll then it will be removed. Other reasonable posts illustrating any range of options will be welcome.

Thank you

[nick sussex]

well it gets to some sort of easterly at the lower resolution part,but what goes on before that anything could happen.perhaps nick could talk about it before i fall asleep

Lol!

Sorry I nodded off after having to endure the GFS run!

As Chiono mentioned the UKMO is the cleaner run in terms of how we move to a pattern change,the area to keep an eye on is the eastern USA we want those two lows to phase and this would seem likely as that cross polar flow into the USA amplifies the flow ahead this should help sharpen that upstream troughing.

If you follow the UKMO on the NH you can see that cross polar flow developing into the USA and the pattern being pulled west to the north at the same time that more amplified flow kicks out a low which combines with the other low in the west Atlantic.

[weather eater]

Brilliant, plenty of early promise and then a mighty anticlimax. Forget the details it’s the blocking signal that counts, and we are going to see plenty of other evolutions over the next few days.

Edited November 18, 2012 by weather eater

[bluearmy]

fwiw, the run of the morning is followed by a consistent 12z. (gem)

EDIT: until its last frame !

Edited November 18, 2012 by bluearmy

[EML Network]

Well that was fun run, we end up pretty much where we started the GFS.

FI, has over the past week ended on, a Northerly, A North Easterly, An Easterly, a Westerly, a South Westerly, and now a Southerly , so I guess the 18z will show what ??...maybe a South Easterly ..and then we'd just need one run to show a North Westerly and we'd have a full house :-)

[Zakos]

Quite humorous how the cold manages to avoid the UK on the latest GFS, and the UK ends up in a mild airflow.Its a very messy picture, but it does demonstrate that even with northern blocking, it does not guarantee that the UK will experience a cold spell.

Quite an odd run in the low res output. I believe there is a very strong signal for northern blocking and the models are struggling to come to terms with it.

Comparing the 12z and 06z, the UK experiences completely different weather conditions in the low res output. However, the big picture is exactly the same, and in line with the continuing trend.

[Dampdorset82]

Another messy ops chart, Im not sure ive seen such inconsistancy in the mid range (GFS). I think all anyone can say is it will be a mild week with temps cooling on Friday. Any further than that is anyone guess. I look at the PV and believe the split that is currently showing is in the wrong place for any HLB over greenland. The big question is what will happen to the east of the UK and i think thats where we need to focus.Im not convinced a prolonged block will come about in early december but the the split in the PV and the Strat situation is encouraging for late Dec in January

[chionomaniac]

Out of interest, what would be your view on the perfect split - 50/50? I was looking back at 2010, and we ended up with more of the PV on the Euroasian side - which ultimately I think may have led to the block retrogressing too much - at least from a Nimby South Easterner's perspective. The other side of the coin is that having enough PV on the Eurasian side was important in terms of allowing deep cold to come Westwards - so it's obviously a fine balancing act.

Any split is going to need both timings and position of daughter vortices in the correct position at the correct time. It is these that I would put more importance to rather than percentages.

[fergieweather]

As a UKMO colleague says, putting current NWP output in very good perspective: "... Looks like major hemispheric re-configuration after next weekend's disruption. Not surprising then to see a period of comparative chaos in deterministic output. But northern blocking looks a possibility, so we'll have to watch out for extrusion of low GPH out of the eastern Arctic. EC32 firming up on cold signal..."

[bluearmy]

"so we'll have to watch out for extrusion of low GPH out of the eastern Arctic. "

they must have read lorenzo's posts from yesterday !!

EDIT: and before anyone posts it, i have seen that the gefs control develops the same shortwave at T120 that the op did !

Edited November 18, 2012 by bluearmy

[weather eater]

As a UKMO colleague says, putting current NWP output in very good perspective: "... Looks like major hemispheric re-configuration after next weekend's disruption. Not surprising then to see a period of comparative chaos in deterministic output. But northern blocking looks a possibility, so we'll have to watch out for extrusion of low GPH out of the eastern Arctic. EC32 firming up on cold signal..."

Yep so far we have seen everything including the kitchen sink, personally I’m not surprised, I expect to see the cooker and the washing machine in the next few days, it doesn’t matter at this stage.

Edited November 18, 2012 by weather eater

[bobbydog]

well, yet another run following the trend of a blocking scenario. nothing particularly cold on the horizon yet but as we know, the GFS horizon is littered with mirages, so we ignore the details and go with the trends. - blocking

still a lot of negativity towards the models' output, no-one can guarantee the outcome and it is still very undecided but there are many positives in place. so lets look at the evidence-

- the models are all trending towards blocking of some description.

- GP has constantly stood his ground on a developing block to the north west.

- john holmes has done the same, based on reliable anomaly charts.

- as per ian ferguson's earlier post, the met office are entertaining the idea of greenland blocking, with a meridional pattern.

- the troposphere is defying the cold stratosphere and we are now seeing signs of a strat vortex split being modelled.

repeat of 2009 or 2010? i doubt it- has any particular winter been a repeat of any other winter? i'll bet not....

obviously no guarantees of cold- nature decides the outcome. however, there are definite signs of a pattern change, a seemingly unusual one as well.

either just for meteorological interest or for an epic winter, this winter could be one to remember....

[Jonan92]

Hi all, I am writing from Spain, we are also expecting what shows up from this new configuration (excuse me if any language misunderstanding is made)

GFS seemed to be promising, but after entering the second panel it starts to show the issues it has always, the lows are always overestimated, you can easily see that in east USA, three time high pressures are shown there and those three times a deep low makes it disappear. In conclusion, a promising start and a horrible evolution, it seems that the GFS is really struggling in order to catch the pattern change, it has no clue of what's going to happen.

[IDO]

Hi all, I am writing from Spain, we are also expecting what shows up from this new configuration (excuse me if any language misunderstanding is made)

GFS seemed to be promising, but after entering the second panel it starts to show the issues it has always, the lows are always overestimated, you can easily see that in east USA, three time high pressures are shown there and those three times a deep low makes it disappear. In conclusion, a promising start and a horrible evolution, it seems that the GFS is really struggling in order to catch the pattern change, it has no clue of what's going to happen.

Hi and yes, I think you have summed up the frustration many of us are suffering from. We know there is something on the horizon but the days tick by and we are no nearer that evolution. And what is worse, we probably have another 3-5 days of mixed signals to fret over.

[bluearmy]

the story of the 12z gefs is the increase in energy around greenland as we head post T192 (from the vortex chunk ne canada) and subsequently the atlantic ridge is pushed even further towards the uk. we should see this reflected in the 12z naefs pushing the high anomoly closer to the uk in the early T200's. the slow retreat of the canadian chunk away from nw greenland as head into the T300 period should allow for the anomoly to retrogress.

[weather eater]

Hi and yes, I think you have summed up the frustration many of us are suffering from. We know there is something on the horizon but the days tick by and we are no nearer that evolution. And what is worse, we probably have another 3-5 days of mixed signals to fret over.

There's a simple answer to that, don’t fret, I don't, weather is just not that important in the grand scheme of things. Rather I just try to enjoy the banter of the model thread and the fascination of evolving synoptics.

Edited November 18, 2012 by weather eater

[Ian Brown]

Where the GFS is trying to initially build the heights is a difficult struggle for the models and you never see that sort of development pinned down until it is within T144, probably within T120.

But if we are looking for cold I would prefer to see the sort of evolution shown by the 06z or a northerly, as a E/SE feed off the continent is not going to much use in early season and with the continent above average.

[Mark Neal.]

Ecm about to roll out shortly. Enjoy guys. And look at the bigger picture. Encouraging to see no signs of a real strengthening vortex recently and also good signs of potential blocking. FI is FI and any charts there need to be taken with a pinch of salt, but trends are good to look at. Lastly, enjoy what the weather throws at us

[cold snap]

r GFS in totally different world operational and ensembles vs other models in longer term. Trust ECMWF,as usual Joe b on twitter

Edited November 18, 2012 by cold snap

[cold snap]

Up next ECM 12z should be fun this

[Frosty.]

Where the GFS is trying to initially build the heights is a difficult struggle for the models and you never see that sort of development pinned down until it is within T144, probably within T120.

But if we are looking for cold I would prefer to see the sort of evolution shown by the 06z or a northerly, as a E/SE feed off the continent is not going to much use in early season and with the continent above average.

I agree terry, I found the gfs 00z op run quite a messy confused affair from next weekend although on that occasion it found the correct combination to unlock the cold, not terribly cold but 3-4c with a strong easterly and wintry flurries would be a bonus for the end of the month, i'm not surprised the gfs 12z op run crashed and burned, just slight tinkering and it would be so different. I'm glad the longer term signal from ukmetoffice is firming up on a cold outlook, but we have a mild week to endure first, especially mild on tuesday but then tailing off a bit, cooler by the weekend by the look of it.

[Jonan92]

Interesting charts of the ECM at 120h compared to the same one in the yesterday's run. Highs building much norther

Yesterday

Today

[cold snap]

ECM at 120 not very convincing to much energy in the jet

Same at 140 ,I fear another poor run here

Edited November 18, 2012 by cold snap