Model Output Discussion - 28th November

[TEITS]

Models are all over the place with the GFS and UKMO disagreeing at 144hrs.

The UKMO is full of potential at 144hrs but the sub tropical low could still yet cause problems, where will it go?

I hope this feature isn't going to turn into a nuisance.

You can be sure this low will be a nuisance because it already is based on the differences in the model runs. What would be interesting is if this sub tropical low could engage some of the cold air that the low tracking SE could potentially bring to the UK.

Most certainly a time to sit on the fence and just wait until the models sort this period out before I make anymore predictions.

[Iceberg]

GFS later in the run (which shouldnt be bothered with too much due to much uncertainty far before then), goes on develop an easterly into the med (-12 850) rather than our shores as it pushes too much energy northwards.

[bluearmy]

where the ex sup trop depression meets the colder air we will get quite a deepening. the way ukmo deals with it, most of the warmer air will be mixed out by the time it phases into the euro trough. it would certainly help to bloster the low heights to our south. as much as the ukmo at T144 look good wrt a noreaster to follow, i suspect its a bit progressive with this.

[Hammer]

That low in the Central Atlantic with some tropical character to it, seems to first deepen and then neither progress or further deepen.

[london-snow]

I think the UKMO & GFS offers signs of a shot from the east - north east. The UKMO being the more quicker to offer that shot 144+ and the GFS possibly but dependent on the track of that low and at a more non reliable time frame.

[Cheshire Freeze]

You can be sure this low will be a nuisance because it already is based on the differences in the model runs. What would be interesting is if this sub tropical low could engage some of the cold air that the low tracking SE could potentially bring to the UK.

Most certainly a time to sit on the fence and just wait until the models sort this period out before I make anymore predictions.

Yes I think the 12z GFS & UKMO highlight the 2 possibilities on offer. If we can clear that sub tropical low east as per UKMO, the Azores high can move westwards and allow a sharper digging in of the trough & more amplification to the pattern. If the low remains disengaged as per GFS,we run the risk of having the high displaced eastwards and then, as the 12z GFS shows, we run the risk of lowering pressure to the NW and a mid latitude high scenario. We HAVE to hope & pray the UKMO is correct this time!

[MisfitDog3]

Been following closely for the last couple of weeks but have resisted commenting until now. 'nick sussex' comment "models are all over the place" seems to have nicely captured the entire roller coaster ride. From what I have seen over the last few days, there is little cause for the huge disappointment from coldies...or some of the forecasts of 'coldmageddon' that seem to have been put out there by others. There is just so much of a lack of consistent signals at the moment.....and the Atlantic does not want to be shut down!

All very interesting model watching anyway.

[chris55]

GFS looks to slide the Low a little more on the 12z and the very cold surface air to our east just sits there like a stone in a stream deflecting the Low underneath

Edited November 29, 2012 by chris55

[Methuselah]

I'm not absolutely sure why, but I suspect the best place to look, if it's very cold & snowy with north-easterly winds you're after, is way up to the NE...And we may need to wait till after mid-month?

Edited November 29, 2012 by Rybris Ponce
As it's actually cold already!

[phil nw.]

On the GFS12z run it`s frustrating to see all that lovely Arctic blocking across the Pacific/Asian side of the pole in the HR frames.

Those low heights continue to cling to E.Canada and Greenland scuppering any attempts by the Atlantic heights to maintain any ridging.

[Glacier Point]

GEFS might be quite illuminating tonight.. operational doing all sorts of weird and wonderfull things with the polar field in the extended range. I sense another shuffling of the deck coming on.

BTW, Steve - where r you ?

http://www.meteociel.fr/modeles/ukmo2.php?nh=1&carte=1007&ech=60&archive=0

Edited November 29, 2012 by Glacier Point

[Buzzit]

Personally I am treating FI at +48 - anything specifics after that is a guestimate in my opinion, and even then I am sceptical of the extent of the deepening of the low off the coast of Canada in the next 24 hours - and I am certainly sceptical of the strength of the forming atlantic low over the next few days.

[EML Network]

It will be interesting to see how the ECM handles that Sub Tropical Low, where as the UKMO wants to sink it South, the GFS wants to keep it in the Atlantic, and then we have the 3rd option.. A La overnight ECM which is a direct hit into the UK.

Of the 3 options available, I'd take the UKMO for snow potential, ECM for a decent ''weather event'' ..all be it a wind related one, the GFS is about as bad a run as I have seen from it for cold and snow potential, with the UK being ohh so close, but ohh so very far away.

[weather eater]

The 06z and the 12z have really show why making predictions beyond 120hrs is so difficult, just when you thought the models had got it pretty much nailed, along come these two runs to shake things up again, my advice is the same as TEITS and that’s wait and see before making predictions . I like the UKMO, the GFS is not far off backing it.

[Iceberg]

Looking at the phase diagrams for the sub tropical low, its a low level, warm core with marginal sub-tropical formation with the ssts when it starts life, but maintains the sub tropical low level circulation and structure as it moves north and is isolated with the upper high over top. models are struggling to understand how the two co-exist and how sub tropical the charecteristics are maintained.

[Cheshire Freeze]

Just to add, if the high does get shunted east just as the GFS 12z portrays, it's going to be a hard slog to get out of that pattern of heights to the south with low heights to the NW & it can potentially eat up weeks of winter. That's why I'm hoping the GFS FI is wide of the mark and the UKMO closer!

[Gowon]

I'm not absolutely sure why, but I suspect the best place to look, if it's cold & snow you're after, is way up to the NE...And we may need to wait till after mid-month?

It's cold already Pete

[chris55]

We need to watch out for the possibility of some wintry ppn to the southwest as the fronts come in on Sunday, positioning looks interesting to me,

Edited November 29, 2012 by chris55

[Methuselah]

It's cold already Pete

My bad! I guess it is...Perhaps I ought to have clarified: very cold, snowy weather with north-east winds!

[phil nw.]

GEFS might be quite illuminating tonight.. operational doing all sorts of weird and wonderfull things with the polar field in the extended range. I sense another shuffling of the deck coming on.

BTW, Steve - where r you ?

http://www.meteociel...ch=60&archive=0

I note extensive warming at mid-levels of the Strato.in the later frames of the GFS Stewart.

This looks like a transfer of the main vortex towards Siberia.

Possible Greenland Heights with a North/North Easterly incursion down the line-if it verified.

[bluearmy]

I note extensive warming at mid-levels of the Strato.in the later frames of the GFS Stewart.

This looks like a transfer of the main vortex towards Siberia.

Possible Greenland Heights with a North/North Easterly incursion down the line-if it verified.

which continues the disconnect between the trop and strat phil. at this point, we are expecting a large canadian trop vortex near hudsons.

[Iceberg]

gem sits as a half way house between the meto and gfs at T144, not bad really and the hint that it will remain cold, but not probably very cold.

Re longer term re-organisation of the N.Hemisphere, very much agree as the models at extended range are playing lego with the major players, but they dont seem to have a clue whether its star wars or ninjargo atm.

[No Balls Like Snow Balls]

Being relaistic here but there will be no raging Easterly / Neasterly for at least next 7-10 days. Look at the 500mb charts.

We will have rather cold NW/W flow for forseeable future, not ruling ouT chance of snow as these fronts crossing the country have the ability to give surprise snowfalls in right conditions. These 500mb charts are normally not wrong.

I HOPE I AM AND THEY ARE WRONG :-)

Edited November 29, 2012 by No balls like Snow Balls

[Jupiters Winter]

Is that a 527 DAM Line I see on the UKMO T144 over most of the UK? With the 522 just off the east coast?

[phil nw.]

which continues the disconnect between the trop and strat phil. at this point, we are expecting a large canadian trop vortex near hudsons.

I know what you mean Nick - compare the 500 and 100hPa levels at the same time.

going by them the disconnect is quite low down.Look at the last 500hPa frame in the run

A build of NA heights into the Arctic-a response perhaps delayed and signs of a wavelength change across our side of the pole?

Just something to mull over whilst we get through the up and coming Atlantic phase.