Model Output Discussion October 2012

[BLAST FROM THE PAST]

No question about it, its certainly looking very unsettled for the foreseeable future. All models show a strong jet crashing into Britian, bringing low pressure sytems with it.

GFS

UKMO

ECM

There seems to be some mega depression over the Eastern Seaboard in the coming days, is it an ex hurricane or something?

That ECM follows the Steve Murr thoughts, as it hits the southern tip of Greenland it seems to disintegrate?

BFTP

[johnholmes]

re the weather on Sunday. As per the TV forecasts UK Met are unsure how far north the rain will get and how much.

Once again a system predicted to move in from the south or south west and the models are having major problems dealing with it-why I wonder?

[Zenarcher]

There seems to be some mega depression over the Eastern Seaboard in the coming days, is it an ex hurricane or something?

Yes it's tropical depression 16 http://www.nhc.noaa....8.shtml?5-daynl

Assuming you mean this,

Edited October 11, 2012 by weathermaster

[johnholmes]

re my post at 272

you only have to look at the two versions available on their Fax charts for 12z Sunday to see the trouble they are having, one issued this morning and the later one recently.

[AWD]

Looking at the ensembles, the operational and control run were both pretty consitent and well supported throughout most of the run, only become a outlier in deep FI, when the effects of the WAA up into Greenland are felt on the UK.

Edited October 11, 2012 by AWD

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2012101112/ECH1-192.GIF?11-0

BOOM- headshot to the polar vortex being smashed around 60N backwards-

looks at that record breaking october AO signature with that epic cross polar flow-

The 10 day train is taking shape...

S

[BLAST FROM THE PAST]

re my post at 272

you only have to look at the two versions available on their Fax charts for 12z Sunday to see the trouble they are having, one issued this morning and the later one recently.

John

What would your 'personal thoughts' be on this say if you were duty met man. Could be a very nasty period ahead of us?

BFTP

[Frosty.]

re the weather on Sunday. As per the TV forecasts UK Met are unsure how far north the rain will get and how much.

Once again a system predicted to move in from the south or south west and the models are having major problems dealing with it-why I wonder?

Yes John it's the same situation as last time we had all the widespread floods isn't it, the models seem to really struggle when the systems move up from the south compared to how they handle the usual sw to ne or w to e patterns.

And to BFTP (Fred) I will do my best with the updates when I can mate.

Edited October 11, 2012 by Frosty039

[AWD]

Yes it's tropical depression 16 http://www.nhc.noaa....8.shtml?5-daynl

Assuming you mean this,

Didn't notice that one, I was looking more into the one below.

Although, thinking about it, its probably to far north to be an ex hurricane.

[johnholmes]

Just happy I am not!

Wait and see, take care not to do any knee jerk reactions, play it much as they are doing until they have more corroborating evidence for one way or the other.

[Summer Sun]

Quite an unsettled end to ECM tonight with a deep depression over the UK, the depth of the depression look similar to that of the last storm a few weeks back

Edited October 11, 2012 by Summer Sun

[Gibby]

Good evening. Here is the evening look at the 12zs from GFS, UKMO and ECM.

All models show a showery Westerly flow developing over the coming hours with a trough becoming slow moving over NE Scotland. A showery trough enhances the showers in SW Britain later tomorrow. Saturday shows a similar showery setup, but that's where the similarities between the models ends.

GFS shows Sunday with Low pressure clearing SE Britain leaving a legacy of rain and showers over the UK. A ridge crosses East on Monday offering a drier interlude for many. On Tuesday a new Low pressure move in from the Atlantic with rain bearing troughs crossing the UK once more. The rest of the working week is influenced by this Low pressure anchored over the North with rain and showers swirling around for all. Through FI tonight the trend is for little change for the majority of the run before a mid Atlantic High pushes a ridge across the UK right at the end with drier and brighter weather.

The GFS Ensembles when taken as a whole show a continuation of unsettled conditions with rain at times. 850's remain close to or a little above for a time for all, though with conditions at the surface far from perfect it will feel cool irrespective of this.

The Jet Stream shows the pattern as before. As we lose the split flow the Southern arm once more becomes the dominant driver of our weather for the foreseeable. A powerful flow off the US comes across the Atlantic and steers the close to or South of the UK next week.

UKMO for noon on Wednesday shows deep low pressure just to the West of Britain with a mild Southerly flow for all. Rainfall would be heavy at times, especially in the West while any drier interludes would be restricted to the far east.

ECM too is not too dissimilar with an extensive area of Low pressure near NW Ireland driving rain and showers across all areas at times. Later in the run a deep, intense area of Low pressure slips down close to SW Britain and becomes slow moving over the UK at the end of the run filling slowly. Further heavy rain and showers would no doubt occur for all with strong winds and temperatures close to average.

In Summary the weather from the models point towards a very unsettled spell with copious rain events for all at times in strong winds and near normal temperatures. With little change shown from the ensembles and operationals, which are unison in continuing wet weather in the reliable time scale it looks all systems go for a very wet October for most.

[Cloud 10]

http://www.meteociel...H1-192.GIF?11-0

BOOM- headshot to the polar vortex being smashed around 60N backwards-

looks at that record breaking october AO signature with that epic cross polar flow-

The 10 day train is taking shape...

S

Couple of days later its a # epic cross polar flow!

[tinybill]

some parts could in the north of the uk could see their first snow at the end on the month

[Grimsby Snow Lover]

some parts could in the north of the uk could see their first snow at the end on the month

A bit of a daft question but how do I know what snow is on those charts? I struggle with this every year

Edited October 11, 2012 by Grimsby Snow Lover

[Met4Cast]

A bit of a daft question but how do I know what snow is on those charts? I struggle with this every year

The colours with white lines through it represent snowfall

[liam79]

A bit of a daft question but how do I know what snow is on those charts? I struggle with this every year

The Hatched areas are snow Not that it is accurate at this range

[Paul]

Latest look at the models and the forecast for the week ahead with Michael Fish - he even mentions snow in amongst the wet and windy weather..

[Chris W]

I'm a little concerned about Tuesday-Thursday with that strong-looking secondary low rounding the main area of low pressure to our west and approaching from the south with more apparent energy/moisture than a standard westerly and then becoming stuck for most of the week. All in all from what I've had a chance to look at it's going to be a bit of a battering next week, though of course things could change.

Edited October 11, 2012 by Chris W

[legritter]

evening all ,looking at tonights data and charts puts a buzz into modell watching . at present im convinced that mother nature is putting or about to put a few things right .high presure over northern latitudes , to address the ice loss ,whether man made or weather related . i will stop there as im drifting off topic ,but we do have i think a fair possibility that the end of october early nov according to present charts and data could see some cold air to our north . if this does work out it will be an interesting time in n/west europe ,but modell watching will become frustrating at times with the cold air playing havoc with some of the computer modells .but we already have some cold air about ,so for those worried Dont ,we are not at present in the period of MILD mush [1987 /2006 ish ].getting back to modells whilst in canada back in may and june i spoke to a retired meteorologist who explained how some of the modells get very inacurate compared to normal when arctic air comes south early in the season .these charts could look totally different in 10 days time but im getting a hunch .thanks for the more technical posters for keeping us others informed . PS Dust off the PROZACK BOTTLE ,cheers gang

[BLAST FROM THE PAST]

I have to say that this weekend starts a week to ten days of a whole lot of trouble for the UK and Ireland. I think we have some stormy weather and particularly exceptional wet weather. I anticipate upgrades to warnings this weekend and beyond. Jetstream way south, trough close to or over us.....wet wet wet and windy.....concerning....then cold.

BFTP

Edited October 11, 2012 by BLAST FROM THE PAST

[OldMetMan]

I just wanted to add a few thoughts on the upcoming winter as I am seeing some intriguing signs.

At present, there is nothing much in the model output to suggest the current unsettled spell will stop any time soon. Indeed, with a powerful looking jet heading out across the Atlantic in a few days, it could become quite stormy at times.

What has caught my eye in recent days is the HP developing over the Norwiegan Sea and pushing towards Greenland and, as legritter points out, in spite of the much-hyped loss of sea ice from the Arctic and from Greenland this summer, there seems to be a quite rapid cooling occuring with some 498dm thickness values appearing over Greenland at times this week - quite unusual for this early in the season. The Canadian cold pool is also getting quite pronounced already - another innteresting sign.

Overall, the models are showing a much more meridional flow in the short- to medium term, so, as others have suggested, there seems potential for an early taste of winter within the next few weeks, if the block to the north of us persists. That, together with some late season tropical storm activity currently going on, and the push of very warm air over the W Atlantic that is likely to accompany it, could certainly favour a cold pool over the UK and near continent quite soon.

I've said it before, but this has been a peculiar year in many ways, with many extremes. I think it reasonable to expect there to be some longer spells of drier conditions than we have had for some months in the months to come, as there has been such a lack of prolonged HP anywhere near us for a while.

I shall watch the block to the N with great interest in the next week or two - might be a sign of things to come!

[bluearmy]

omm - not sure how old you are but how often do you recall the polar pattern in the last third of october reflecting that currently shown on the models ?

[Glacier Point]

Funny, was just looking at that Nick.

It now seems verly likely that the existing and programmed anomalies will leave us with a solid anomalous ridge over large parts of the Arctic, centred over Svalbard.

There were periodic phases where this type of anomaly persisted in October, notably none in the 1990s and few in the 1980s.

Roll these forward into November, little change. I'll leave others to take these into the winter thread but note the development of a set wave pattern across the NH with well defined ridges and troughs.

[johnholmes]

Younger than me and I do not recall this in October, but then in the 90's when I was forecasting NONE of this was ever discussed other than in very isolated cases within the R Met Soc quarterly journal.

I did ask if anyone could post charts of 5 days or more duration from the web that might show charts that are similar to this predicted pattern which I think is pretty certain to be what we see at 500mb in the run up to the end of October/start of November.