Model Output Discussion October 2012

[AWD]

Perhaps some more knowledgable kind soul could help me out a little here on the ECM T168 chart as it's not the sort of chart i've seen a lot of in the relatively short time i have been model watching.

A few things:

- Is that the PV that is in the East Atlantic?

- In winter, would this sort of chart bring widespread cold & snowfall?

- Is it a locked in pattern or is it a temporary thing?

I know its an unsettled outlook, much of the ECM run is, but taking this chart solely, and with the upcoming winter, would this be the type of chart/pattern that would deliver wintery conditions over the UK?

Sorry for the questions, I always try and post with my opinions & ideas, and the default seasonal patterns over the UK I can handle and read now. This sort of chart, especially in October, I become a little confused about.

[MR EXTREMES]

Northern blocking galour and very much in a good time scale early but promising if u like the fresher feel.

[MR EXTREMES]

And heights pushing lower pressure south.

[Geordiesnow]

Yep some interesting charts again showing by the models with height rises being predicted by every model with the UKMO/ECM looking the most similar whilst the GFS wants to develop a block over Russia instead.

As I said earlier, an interesting Northern Hemisphere pattern developing and whilst it unlikely it will result in any snowfall in the future, it does certainly provide some interest thats for sure.

[Summer Sun]

The one plus is it wouldn't be overly cold, even if it was wet and cloudy

[ICETAB]

The one plus is it wouldn't be overly cold, even if it was wet and cloudy

It wouldn't be cold for the UK but I think it's a good sign to see cold pools hiting europe so early in the season. Could be a sign of things to come I think.

Edited October 7, 2012 by ICETAB

[tcc]

Perhaps some more knowledgable kind soul could help me out a little here on the ECM T168 chart as it's not the sort of chart i've seen a lot of in the relatively short time i have been model watching.

A few things:

- Is that the PV that is in the East Atlantic?

- In winter, would this sort of chart bring widespread cold & snowfall?

- Is it a locked in pattern or is it a temporary thing?

I know its an unsettled outlook, much of the ECM run is, but taking this chart solely, and with the upcoming winter, would this be the type of chart/pattern that would deliver wintery conditions over the UK?

Sorry for the questions, I always try and post with my opinions & ideas, and the default seasonal patterns over the UK I can handle and read now. This sort of chart, especially in October, I become a little confused about.

I'll try and help with my limited knowledge!

- No that's not the Vortex, what PV there is over Alaska at the moment.

- Not necessarily, we would need embedded cold first and for it to be cold in the east for the LP to pick up.

- It could be either, need to keep an eye on forecasts as the HP could well drift SE and settle over Scandi.

- If we are seeing this type of chart alot during winter, then we will end up with a below average temp wise winter! Fact!

[Summer Sun]

ECM ends unsettled and cooler with high pressure setting over Scandinavia

Edited October 7, 2012 by Summer Sun

[cooling climate]

I really hope the pattern that the UKMO/ECMWF models are programming

materialize for I think it is very important for our coming winter

prospects that long lasting cold digs in early over Scandinavia and

western Russia.

[Gibby]

Good evening. Here is my take on the 12zs from the big three for this evening Sunday October 7th.

All models show a weak frontal zone over Southern Britain over the next few days delivering rain at times in light winds. Northern areas are shown to remain in a weak area of High pressure with very light winds and overnight frost and fog patches. On Thursday a cold front moves East over the UK with squally winds and a band of rain followed by a veer of winds to the NW and clearer, fresher conditions likely for Friday.

GFS then moves forward then throughout the rest of its run with a mobile Westerly pattern with fresh to strong SW or West winds and spells of rain or showers in never desperately cold conditions.

The GFS Ensembles show a typically Autumnal changeable conditions with trough, ridge trough pattern throughout once we lose the influence of the high pressure in the North over the next few days. 850's remain close to average across the run.

The Jet Stream ridges North on its Northern arm while the Southern portion weakens and disrupts. The flow runs to the North of the UK for a while before in the seas around the UK the flow is very weak, though it looks like ploughing a line straight for the UK near to 180hrs.

UKMO for midday on Saturday shows a weak ridge moving East away from the UK late in the day ahead of a Low pressure trough and freshening SW winds developing later.

ECM shows a very unsettled end to it's output with rain or showers for all in fresh West or Southwest winds in association with Low pressure over Northern Britain by day 10.

In Summary the weather looks typically Autumnal tonight. After a few dry and settled days for Northern Britain in the next 72 hours the weather thereafter looks like changeable with showers or longer spells of rain for all with just brief drier interludes as ridges pass by.

[BLAST FROM THE PAST]

I've touted a cold end of month, last 3rd. Let battle commence

BFTP

[shotski]

Could be a repeat of winter 2011-12 where we miss the cold by a nats paprika and instead get a westerly flow.

Lets hope not.

[Met4Cast]

I've touted a cold end of month, last 3rd. Let battle commence

BFTP

That chart just goes to show how quickly the continent can cool down and how High Pressure situated in the right place, even in October could potentially bring cold weather to the UK, should of course it stay in position long enough.

Great charts tonight, not that they can be taken too seriously but definitely a trend emerging here

[BLAST FROM THE PAST]

That chart just goes to show how quickly the continent can cool down and how High Pressure situated in the right place, even in October could potentially bring cold weather to the UK, should of course it stay in position long enough.

Great charts tonight, not that they can be taken too seriously but definitely a trend emerging here

The models have not got the atlantic going at all for sometime so are very realistic in 'overall' signal. My method hints strongly at cold period as we go into latter part of Oct, from northern blocking. My chart is cherry picked BUT its enering the right timescale for the cold to make its way towards us.

BFTP

[gottolovethisweather]

http://www.meteociel...1-168.GIF?07-06

The best model in town suddenly not feeling the love for the atlantic..... ( as expected )

S

And when you sit back and think about these charts, now almost into a realistic timescale, they are stunning for the time of year. It will most probably not come to fruition as per shown but if it even went close, from my understanding, it would result in low single digit maximums and hard frosts by night. Again, that could not be maintained thereafter, but nevertheless, these are most interesting synoptics.

*sorry mods, I thought this was the winter thread, please remove if deemed irrelevant.

Edited October 7, 2012 by gottolovethisweather

[IDO]

Headline this week is lots of rain in the West/SW:

http://www.weatherweb.net/tvweather/gfsopuktotpcp144.gif

GFS 0z is Jet dominated with the a very Autumnal feel. LP centric with transient ridges.

FI still about T144. The GFS 0z op run is an outlier from around there:

http://cdn.nwstatic.co.uk/ensimages/ens.20121008/00/prmslLondon.png

Plenty of scatter from the 13th. Lets see if ECMW keeps to its guns.

[Gibby]

Good morning. Here is my look at the 00zs from GFS, UKMO and ECM for today Monday October 8th 2012.

All models show a weak flow of winds over the UK for the next 2-3 days. Embedded fronts over SW England will carry cloud and some mostly light rain at times while Northern areas close to a ridge of High pressure stay fine and sunny by day but misty or foggy by night. By Thursday winds freshen from the South sweeping away any fog from the North and bringing an area of organised rain West to East over Britain as a trough swings East. On Friday this trough is shown to lie down eastern areas with further rain while Western areas come under a clearer and fresher NW flow with just scattered showers.

GFS then shows the remainder of its run as a very changeable one with periods of rain and showers alternating with some brief drier and brighter interludes. Temperatures at the surface will be close to or a little below average though a strong rise of temperature would occur in the SW flow shown in the far reaches of FI in the SE.

The GFS Ensembles show a changeable pattern too with plenty of options day to day from member to member of the pack. The overall outcome though shows that we end up with temperatures and uppers nor far from average and rainfall not quite as much as what the operational shows in the South.

The Jet Stream continues to diverge into two flows over the UK. The Northern arm continues while the Southern arm weakens and moves South. Later in the week the Northern arm continues to ridge North in the Eastern Atlantic and disrupts around the UK.

UKMO at midnight on Sunday shows a slack Low pressure cell over NE England with a trough South over England so rain at times for Sunday in light winds from the West or NW.

ECM shows a complex if shallow area of Low pressure over Britain with some rain on Sunday before a ridge extends SW from Scandinavia with some dry if rather cloudy weather with areas of mist and fog possible should skies clear at night. The NW would probable see a return to cloud, wind and rain later towards the end of the run with fine weather holding on in the South.

In Summary the changeable weather remains in place for the coming few weeks with many options on offer ranging from dry Autumnal misty conditions and wind and rain. Nowhere is immune from any of these conditions but it looks unlikely that anything other than normal values with regard to temperature and rainfall for the UK look likely in the next few weeks.

[Thundery wintry showers]

Looking at the model outputs it seems that the quiet spell for central and northern areas will move away eastwards on Thursday as the next set of low pressure systems move in from the west, although initially they will be quite weak. Late on Thursday and into Friday it could well become very wet for a time with a slow-moving frontal system progressing north-eastwards (I don't think the rain will be all that heavy, but it may be very persistent). Something to watch out for, perhaps, in the areas that are currently at risk of flooding following the deluge around 23-25 September.

Pressure does look like rising over Scandinavia, but as so often happens in the winter, it is unclear whether the cold continental air will make it this far west- we may well stay under the influence of the Atlantic. If we do get an easterly incursion, daytime temperatures will fall below average but overnight minima will probably rise in the east due to cloud cover off the North Sea, so the average may not be especially cold, with 850hPa temperatures close to the 0C mark. Although there have been very rare instances of "easterly" October snowfalls, generally in October the vast majority of snowfalls come from the north, with "easterly" snowfalls not becoming relatively common until late-November when the continent often cools down significantly.

[Glacier Point]

Both GFS and ECM ensemble forecasts for the MJO suggesting a high amplitude phase 7-8 to develop in the next 10-14 days as westerly wind bursts in the Indian Ocean and western Pacific extend eastwards.

With the GWO slightly disconnected in phase 1-2-3 (and likely to orbit around phase 1-2-3-4 in the foreseable), expect to see some chopping and changing around day 7 forecast period. I would favour a stronger ridge in the Arctic extending towards Scandinavia and lower pressure over Europe as a mean solution (see MJO phase 4 composite for best fit).

The real story evolving looks like being the complete lack of an organised jet over the western hemisphere, a southward depressed Asian jet, and the spilling out of Arctic air through a main trough axis over eastern Russia and China (lots of snowfall to come here weeks 2-3).

With upper level zonal flow very weak, the increasing pressure put on the system through wavelength changes will bring about increased meridionality and these type of Arctic outbreaks in the weeks to come. Just starting to pencil in some chance for our first taste of winter in December.

Before that, if the westerly wind burst keeps the centre of convection and MJO activity in phase 8 (GWO more likely tilted phase 4) into November, then something like this (which would be interesting in seeing that trough axis drop closer to our east setting up the cold in that locale).

Edited October 8, 2012 by Glacier Point

[chionomaniac]

Big, big change in the MJO forecast since last week. I expect to see that correlation between MJO phase 7/8 and negative NAO to really show itself, then.

[Summer Sun]

Big, big change in the MJO forecast since last week. I expect to see that correlation between MJO phase 7/8 and negative NAO to really show itself, then.

What does this mean for our weather? (MJO phase 7/8)

[BLAST FROM THE PAST]

Interesting seeing GPs thoughts.

Watch for the southerly position of the jetstream and I anticipate cold from N/NE last 3rd of month. ECM suggesting large HP cell developing to out NNE at t144/168. It goes on to shunt it away, I don't think that will happen.

BFTP

[The Northern Ramper]

Charts and sypnotics being discussed are wasted in October, come back in December/January please.

[chionomaniac]

What does this mean for our weather? (MJO phase 7/8)

As I said it correlates to a negative NAO - normally associated with a southern jet, Greenland blocking and high amplitude wave patterns.

In October that may mean cool and wet but turning increasingly cold as the autumn progresses if the pattern was to lock in.

[gottolovethisweather]

What does this mean for our weather? (MJO phase 7/8)

http://en.wikipedia.org/wiki/Madden%E2%80%93Julian_oscillation

For you and me both Gavin, Tony H and anybody else for that matter.

My understanding now, is that GP and Chiono were referring to the correlation between these two climatic processes on opposite sides of the globe. Thereby, one pattern having a knock-on effect on the other in the days and weeks to come. These chaps are too clever by half.