Model Output Discussion 18th Nov.2013-12z onwards.

[Ian Brown]

I remember a lot of 'zonal resets' during the 1990s. 1989 had too many to count!

 

I'd have though that there's more likelihood of 'eventually' seeing cold weather from what we currently have, than from full-on zonality; and, fortunately for us, no model is suggestive of it.

Yes, as long as HP is around us or to the West there is always that chance that it could pull back NW, I don't think it will at least for any length of time but if we have a zonal reset that means the High slipping into Europe from our present position and if there is one set-up that can last a helluva while, it's that one !

[Gaz1985]

Certainly a trend colder with the 6z Manchester ensembles today compared with yesterday but uncertainty after 1st December with lots of scatter, some very cold runs especially with the control run, but also some mild so nothing nailed on with proper cold. In the meantime for most of us it looks like turning milder for a bit this week.

 

[Mucka]

All I have seen in today's output is the strengthening of the signal for a pattern change as a deep trough drops into Europe and a mid Atlantic ridge builds behind giving the prospect of at least a taste of something Wintry for the North but with the potential to deliver something much better though we are not really seeing a signal for prolonged cold at the moment - then again we are not seeing a signal for a return to typical zonal conditions so I have no idea where people are seeing that.

 

Over recent days we have seen the pattern moved West and increased amplification when the pattern change comes (the limpet high is sunk by the trough) which are both positives so Wintry prospects have increased for early December if anything (although they were coming from low expectation admittedly)

It may be we initially get a Westerly flow as the pattern sets up a little too far West before dragging in colder air a couple of days later as the trough moves East or we may get lucky and have the trough set up in the right place and forgo a brief wet and windy spell for colder showery conditions or we may get unlucky and have it set up too far East and remain under the influence of high pressure (low probability)

 

ECM is not great but in no way does it signal a dominant Westerly flow as some seem to have commented. To e it looks like scenario one I painted above with a fairly brief spell of Westerly unsettled muck as the trough relocates East with strong amplification likely behind - very probably the UK would be under cold air tow or three days from this chart but it is all academic anyway because no way is that 10 day chart going to verify. 

 

EDIT: Just for accuracy;

What I should add is that we will get an essentially dry Westerly flow as the high sinks but the Westerly flow I am referring to is brought about by low pressure being charge to the N/NW of the UK.

 

To reiterate;

 

What we are looking at is a pattern change through the first week of December with colder more unsettled conditions taking hold though how far South the cold gets, how cold and for how long are still up for grabs but we will get an increasingly good idea through this week. By Wednesday we should have a good idea if we are looking at an amplified pattern in early December which leads to a gradual flattening of the pattern to a Westerly regime or something more blocked and colder. 

In other words all options are on the table but there is a window of opportunity for a cold spell to take hold toward the end of the first week of December, keep watching the models and fingers crossed.

Edited November 25, 2013 by Mucka

[Joe Levy]

The gfs 12z is emerging, all eyes on the charts folks! If it's a good one, don't go over the top, if it's a bad one, remember it's just one run!

[Summer Sun]

Current signals for the NAO suggest it will stay positive till mid December

 

 

The met office favour a negative NAO this winter so thats something to keep an eye on

Edited November 25, 2013 by Summer Sun

[chionomaniac]

Current signals for the NAO suggest it will stay positive till mid December

 

 

The met office favour a negative NAO this winter so thats something to keep an eye on

I would call that neutral Gavin - ie average NAO conditions.

[Tim Bland]

Great GFS ensembles. I expect some epic Op runs will be coming our way soon.

 

Optimistic mid range forecast from the Met Office

 

" Later in this period, there is a chance that colder conditions may return south across the UK, with more wintry weather for some, and a risk of gales, especially towards the north."

[Mucka]

Current signals for the NAO suggest it will stay positive till mid December

 

 

The met office favour a negative NAO this winter so thats something to keep an eye on

 

Worth noting that the projected NAO is only out to Dec 1st and any pattern change is not expected to take hold until a few days later - it is really just reflecting what we already know, that our pesky high will be loitering around the UK through that period

 

Edit. Misread that chart, yes it is out to 1 week December, my mistake but what I said still pretty much applies.

Edited November 25, 2013 by Mucka

[Scorcher]

I must be living in a parallel universe, it is cold and continues to be so. Even with the brief 'warm up' if it can be called that, has temps recovering to where they should be before dropping again, as demonstrated by the beeb last night. I still haven't seen the much vaunted barty or south westerlies, we were promised a while back.

 

The CET would suggest otherwise, it's only slightly below the average at the moment and that could change from midweek with milder conditions coming in. It looks like ending up a very average month overall.

[johnholmes]

Current signals for the NAO suggest it will stay positive till mid December

 

 

The met office favour a negative NAO this winter so thats something to keep an eye on

 

 

which simply goes to show how unreliable NAO and AO predictions are beyond about 7 maybe 10 days as I often say. I think it was the last one SS that showed -ve as being the most likely idea towards the middle-end of the run.

[snowice]

well it looks like the 12gfs is more off the same, another high approaching in FI from the west. could it be a repeat pattern?

 

Edited November 25, 2013 by snowice

[Ali1977]

This looks better to me, the incoming Low at T218 looks like it may bring a better, more sustained Northerly.  Could be totally wrong though.

 

Much better...........Finally some V good eye candy, Snow by 240 over much of the UK. And not at t384

Edited November 25, 2013 by Ali1977

[Joe Levy]

This is exactly the sort of chart us coldies are looking for! It does go well with numerous ensembles from the 6z set. Let's see how this fits with the other models

And if we have a look at the NH view, the PV is very much reduced in strength and a large high cuts right across the Arctic

Edited November 25, 2013 by Joe Levy

[Yarmy]

This run intensifies the Alaska block:

 

 

Proper omega that splits the PV later on.

 

Edit: The vortex is wrecked in FI. The details will of course be miles out, but is it a pattern? It's hard to reconcile such developments with the Strat profile and the GFS FI has a propensity for PV destruction that rarely seems to come off.

Edited November 25, 2013 by Yarmy

[Mucka]

This looks better to me, the incoming Low at T218 looks like it may bring a better, more sustained Northerly.  Could be totally wrong though.

 

Much better...........Finally some V good eye candy, Snow by 240 over much of the UK. And not at t384

 

Far FI would be quite snowy for the North, marginal further South way from high ground - being in the NW I would bank that right now but many more runs needed.

[Summer Sun]

Many more runs of course needed to bring it into a reliable time-frame but some interesting developments in FI for coldies

 

[EML Network]

Far FI would be quite snowy for the North, marginal further South way from high ground - being in the NW I would bank that right now but many more runs needed.

 

Yup for us in the South this might as well be zonal especially IMBY , I have NEVER seen snow here from a North Westerly , still at least the charts are offering something of interest from a cold perspective. 

[MR EXTREMES]

well the ukmo has data missing 0 to t36 so that's a no go.

as for the gfs nothing really to exciting couple more days and were know more.

 

nao and ao will only respond to the models so not taking the forecast by summersun seriously infact im taking anything seriously right now.

[Joe Levy]

Far FI would be quite snowy for the North, marginal further South way from high ground - being in the NW I would bank that right now but many more runs needed.

Not sure it would be that marginal in the south. I've seen snow in the south in uppers much higher than are being shown there. These charts are for early December, so it's not like the time of year is against us in this case. Besides, let's get the pattern in first before we start deciding where is going to get snow The synoptics on the 12z are pretty great for the whole country if you like cold and snow

[Summer Sun]

UKMO between t06 to t36 is updating once more after 11 days of data problems

[Cold Winter]

Seems to be some clustering from the 6z GFS ensembles for colder weather from Day 8 onwards. Nothing major yet with still a wide spread in ensembles but a definite trend compared to a few days ago.

 

Edited November 25, 2013 by Cold Winter

[legritter]

Certainly some good looking frames  on GFS lets hope it continues ,steady as she goes rather than Mega one day, gone the next .Just need a good ECM run and i would like to see that Vortex being smashed up a bit ,all eyes on the ECM and looking forward to FROSTYS thoughts ,perhaps the Models  are getting in the Winter mood .

[Summer Sun]

UKMO delivers a north westerly at t96

 

 

before the high edges east again

 

Edited November 25, 2013 by Summer Sun

[MR EXTREMES]

then the ukmo delivers a reload nw at t144

[gottolovethisweather]

Seems to be some clustering from the 6z GFS ensembles for colder weather from Day 8 onwards. Nothing major yet with still a wide spread in ensembles but a definite trend compared to a few days ago.

 

 

Yep, day 8 being 3rd December, some consistency there, I do hope the GEFS 12z reflects the same developing scenario and the ECM 12z ensembles continue to join the colder brigade. That's not to say this Friday isn't of interest for some (not so sure about this though) but those at elevation might get some brief wintriness before it turns to rain. Then it's back to HP domination for a further couple of days thereafter before we reach the 3rd of December. Clearly December is where its at.  Damn, I sound like a broken record.

 

A consistent theme, so maybe something's up - http://forum.netweather.tv/topic/78508-model-output-discussion-18th-nov2013-12z-onwards/?p=2845028 This COULD be when the coldies can start believing once again, not that it's not cold now but maybe the S... what might get a mention in more of the forecasts.

Edited November 25, 2013 by gottolovethisweather