Model Output Discussion 12z 18/10/2012

[johnholmes]

if the ukmo keeps this up, the tv forecasters may start dropping subtle hints about the cold plunge but for now, all they are saying is very mild and settled next week with overnight fog.

I am surprised by this, I would have thought that a comment about temperatures falling towards the end of the week should be part of their closing comments. I notice that their 6-15 day is also not making much of the temperature drop. Not sure why this is so it would be great knowing what the senior man is saying in his regular daily breifings to forecasters and presenters for tv? Any offers from our reps in on this?

[linarite]

See October 18 1991 and Oct 17 1992 in GFS Kartenarchiv. Very similar set-ups to what is forecast for later next week. I remember snow to low levels in Cumbria from the 92 event

[Frosty.]

Cheers

I would say that the longivity of the cold may not be as straight forward as you thing- 1/2 days - hum im not so sure- probably longer 5-10

S

All we know for sure is that the weather is going to be turning even milder in the coming days with a very stagnant benign anticyclonic pattern with overnight fog clearing to hazy sunshine, some areas may remain foggy all day and therefore be cooler as the sun is becoming weaker and lower by the day. At least we now have growing support for something colder beyond the mild spell but details are still very sketchy, I noticed JH thinks 2-3 days cold shot but I imagine it would be longer than that in scotland.

[Liam J]

I think once (if) the cold air arrives we can then look at the longevity of it, exciting as the current prospects may be it's quite easy to get ahead oursleves - Nothing especially extreme on the raw output charts regarding temps/snowfall etc but certainly for October the chances of a below/very below average end to the month are looking quite likely at this stage.

Edited October 19, 2012 by Liam J

[johnholmes]

All we know for sure is that the weather is going to be turning even milder in the coming days with a very stagnant benign anticyclonic pattern with overnight fog clearing to hazy sunshine, some areas may remain foggy all day and therefore be cooler as the sun is becoming weaker and lower by the day. At least we now have growing support for something colder beyond the mild spell but details are still very sketchy, I noticed JH thinks 2-3 days cold shot but I imagine it would be longer than that in scotland.

yes reading my post again I should have said 3-5 days for most parts!

[Iceaxecrampon]

See October 18 1991 and Oct 17 1992 in GFS Kartenarchiv. Very similar set-ups to what is forecast for later next week. I remember snow to low levels in Cumbria from the 92 event

Yes seem to recall '92 but remember being "in it" in November not October - nothing in condition (gullies) obviously but a good early trudge nevertheless.

These synoptics as Steve mentions are extremes to say the least.

Ian

[Frosty.]

yes reading my post again I should have said 3-5 days for most parts!

I'm glad you are onboard in thinking a cold spell is more likely, hopefully the ukmo media team will be soon.

[carinthian]

I am surprised by this, I would have thought that a comment about temperatures falling towards the end of the week should be part of their closing comments. I notice that their 6-15 day is also not making much of the temperature drop. Not sure why this is so it would be great knowing what the senior man is saying in his regular daily breifings to forecasters and presenters for tv? Any offers from our reps in on this?

Hello John,

We had a 40 cm snowfall earlier this week. Now temperatures on the rise as forecast. Just watched the Italian Channel Met Forecaster ( Yes, and he wears an Italian Air Force uniform and forecasts with a big stick! ) What I can make out is he is showing is a big drop in temperatures by next weekend and shows a Arctic Front over the Alps with blizzards after a further 6 days milder conditions . The A/C air mass is shown also to invade the UK on his colourful map presentations. A real professional this guy .

PS You still ski-ing in Wengen? Had my first run of the season this week, but a bit of a hike with no lifts working yet. Good fun though .

Paul

[johnholmes]

yep I'll be there the day after the Lauberhorn again for 2 weeks, skiing rather gently these days mind you. Yes IF theEC and GFS are correct then prospects of further snow fairly well down. Wengen village had its first snow a few days ago although 'summer' has arrived again. I envy you being out there for all the seasons. Hope you are well, also fingers crossed some white stuff for this country this winter. Not too much too often though unlike some of the folk and their hopes on here.

Scottish ski resorts may do well by next weekend.

[chionomaniac]

I am surprised by this, I would have thought that a comment about temperatures falling towards the end of the week should be part of their closing comments. I notice that their 6-15 day is also not making much of the temperature drop. Not sure why this is so it would be great knowing what the senior man is saying in his regular daily breifings to forecasters and presenters for tv? Any offers from our reps in on this?

Perhaps, they haven't had a SM banging on at them about the splitting of energy at the tip of Greenland!!!

[Severe Siberian icy blast]

Perhaps, they haven't had a SM banging on at them about the splitting of energy at the tip of Greenland!!!

Lol very true chiono but it is his words that really opened my eyes and he is very knowledgeable and although he obviously loves the cold like most do on hear , he was on to something right at the beginning which he deserves full credit for. The blocking signal has been there for a while for us all to see and I thank yourself , glazier point , Steve , and BFTP for helping us all to see the bigger picture , along with others of course such as John .

Very good times on hear and it becomes more fascinating every year.

[Frosty.]

The Gfs 06z op run does not hold back with the Northerly blast, for this time of year it would be noteworthy. I'm not sure whether it could upgrade much further for so early in the season but it would produce a lot of snow for the scottish hills and mountains together with the hills of northern england (pennines and north yorkshire moors) and sharp frosts becoming more widespread as the arctic air digs further south, the 6z shows a very mild anticyclonic spell with overnight fog which may linger in places making it cold and dull but outside the fog it should be sunny and warm with little in the way of cloud before winds increase as high pressure is pulled northwest from scandi and a trough replaces the high in scandinavia, the mildness is drained away with colder and colder air sweeping south and wintry showers for exposed coasts and hills, maybe even some troughs becoming embedded within the arctic aiflow with more widespread wintry showers if the northerly can be sustained.

Edited October 19, 2012 by Frosty039

[Chris W]

A real yo-yo of temperatures in the next week or so it seems! A bit like earlier this year (March? I cannot remember exactly) when we had a warm/very cold transition in a matter of days (from t-shirts to scarves in a week). It does look to me that the remnants of Rafael merged with the low off the southern tip of Greenland will drag some pretty toasty air (for October!) up for a nice weekend/early week across England at least to start with. I have been mostly looking at the GFS on Netweather's free charts tool (many thanks for this guys) but have glanced at the ECM and UKMO, and it looks to me that there will be a north-easterly next Wed/Thurs through to Sat/Sun toppled briefly early the following week before a colder northerly plunges down later that week from slightly further west. Interestingly the latter is looking timed (though in FI of course) for my trip to Sunderland to see family, so perhaps I will see snow there? During that period the GFS also has the 528 dam line reaching to south-east England by my reading of the chart.

Regardless of the chances of snow it is looking pretty good to me for a pretty cold end of the month/start of November, that is, after a pretty nice weekend first up.

[Gavin P]

Hi all,

Here's todays model based video - Firming Up On The Greenland Blocking;

http://www.gavsweathervids.com/

Some very good agreement now on a change to much colder weather at the end of next week, with all the main models going for a classic blocking feature around Greenland and Iceland. Though its still just about too far away to have good confidence, despite seemingly excellent agreement.

Next week does looks very, very interesting though as we go from one extreme to 'tuhter.

[shedhead]

It's certainly looking like tickets for this years terror ride on the Winter weather rollercoaster are going in sale early, with the models predicting marked changes more akin to Spring across the next 6 or 7 days. Some of us could see a 10c+ drop in temps between Tues and Friday next week, with shorts and t-shirts giving way to overcoats and wooly hats....IF everything goes to plan that is!

Edited October 19, 2012 by shedhead

[johnholmes]

Perhaps, they haven't had a SM banging on at them about the splitting of energy at the tip of Greenland!!!

hey did you see who one of the 'likes' was?

UK Met!

[SMU]

Really ^^ Whos on here from them then?

S

[Liam J]

hey did you see who one of the 'likes' was?

UK Met!

LOL - not actually the UKMET, just a member using that as a username, You knew that..... Right??

Edited October 19, 2012 by Liam J

[Methuselah]

The interesting thing for me is not the cold shot, but more the fact that it looks like we start November with a very weak polar vortex!

Thanks for that, RD. I was hoping someone would say that. The fact that all of the models are showing such a situation must put us in with a better than even chance of a great start to winter??

[Methuselah]

GFS06 Z coming more towards the UKMO pattern-

Now we are at 132 the overall chance of significant change is beginning to receed & now we are homing in on angle of attack etc-

http://modeles.meteo...snh-0-132.png?6

any further west & Im sure someone will trawl out the Dec 62 charts....

S

Wouldn't the late October/early November charts be more apropos, Steve?

[AWD]

Thanks for that, RD. I was hoping someone would say that. The fact that all of the models are showing such a situation must put us in with a better than even chance of a great start to winter??

Depends, we could be unlucky and be stuck in a west based -NAO pattern!

[Summer Sun]

The met office are now on board for a cold November

Saturday 3rd November 2012 to Saturday 17th November 2012:

As is usual, there are uncertainties in the forecast for this period, however there is a signal for temperatures to be below average for November across much of the UK. Scotland is more likely to see near normal temperatures. Rainfall amounts are likely to be around average with periods rain or showers at times and the chance of wintry showers for upland parts of Scotland. There are likely to be clear and dry spells too, leading to an overnight frost risk at times across the UK.

So I think we can start to gain more confidence in the models of a cold spell during November, how much if any snow there would be is another question for low level parts

[snowfall09]

If we were to have -5 uppers over the whole county for example during December then it would be highly likely that any precipitation would fall as snow/sleet. At this moment in time -5 uppers are shown to affect parts of the country in the next week or so, therefore I don't understand why people are doubting that any precipitation could well fall as snow and affect a large part of the UK??.... That's if what we are seeing at the moment on a range of forecasting models actually materializes.

Can anyone shine any light as to why this may be?? I'm still learning so be nice

[A Winter's Tale]

Good afternoon everyone.

So far conditions in the north have been grey and overcast with a little precipitation, overcast and wet across parts of the south east, sunny spells over a good part of inland and western England and Wales and some sunny spells in the north west of Scotland. And conditions should remain cloudy and little damp over Scotland, overcast for much of Ireland, wet and cloudy for the south east and clear skies for western and central areas through the rest of the day. Tonight, the rain should disapear over the south east and overcast skies should be less widespread there, some clear skies may develop over parts of Ireland but Scotland should remain cloudy with some light drizzle over the highlands and cloud cover may be present down the west coast of England and Wales. Mist and fog patches are also likely to develop over some inland and central areas of England. Minimum values in cities should be 8 to 12C.

Saturday morning should have some early sunshine over eastern and central parts of England and few breaks in the cloud cover should occur across parts of Scotland and Ireland. There may be one or two showers in western areas and highland Scotland where here skies are most likely to be overcast. Through the afternoon sunshine should become a lot more widespread over many parts of England and Wales away from the west, and across eastern parts of Ireland and Scotland, western areas (north west Scotland in particular) should stay mostly cloudy with one or two showers. Maximum temperatures should be 10 to 15C. Possibly later in the evening cloud cover may spread and rain may fall over south eastern parts of England for a time. Overnight large parts of England and Wales and into southern Scotland should remain under clear night skies. Ireland, northern Scotland and perhaps some coastal regions could have some cloud cover at times. Minimum temperatures of 7 to 10C.

A similar story for Sunday with England, Wales and southern and eastern Scotland enjoying sunny spells with northern and western Scotland and Ireland remaining mostly overcast and the threat of rain for extreme western parts of Ireland and the outer hebrides. Maximum temperatures could be 12 to 15C. And a similar story for the night-time with clear spells over England, Wales and more widespread this time over Scotland away from the west coast; Ireland looks likely to remain overcast overnight with the close proximity of a rain band out to the west. Minimum temperatures of 7 to 12C.

On Monday, at the moment some areas may have wall to wall blue skies and some areas could have under totally grey skies but there at this stage there is a lot uncertainty as to where, it seems likely that Ireland, northern Scotland and possibly some southern and south western parts of England and Wales could end up having a cloudy day with the threat of some precipitation. Maximum temperatures could be 12 to 16C. Monday night looks like being mostly overcast in northern and western areas, the south east of England may have some clear spells. There could be some rainfall across western areas of the British isles overnight. Minimum temperatures of 10 to 14C.

On Tuesday, the southerly winds may replace the clear skies with cloudy skies across southern and eastern areas of England, Wales, western England and few parts of Scotland and Ireland seem more likely to have sunshine. Southern Ireland could stay cloudy with nearby rainfall and highland Scotland could stay cloudy too. There may be one or two showers in eastern England. Maximum temperatures look like being 13 to 16C. Tuesday night seems likely to be an overcast night for almost all of us, especially in the south, there could be one or two clear patches across highland Scotland with the current scenario. Mostly dry but some damp precipitation could be possible across south eastern England and coastal parts of southern Ireland. Minimum temperatures could be 11 to 12C in the cities.

So, in summary the next few days should be mainly dry with some regional damp conditions in the form of showers or drizzle or weak fronts. Central parts of England look good for sunshine, whereas Ireland and northern Scotland may stay largely cloudy for the next few days. As the southerly develops, the skies may alter between cloudy and clear, no persistent rain but some showers may move northwards in the southerly.

The peak of mini-indian summer next week should be between Monday and Wednesday and maximum temperatures could be as high as 19C in very southern parts of England. Temperatures away from the south east during day seem likely to range between 10 to 15C. Parts of Scotland,northern England and northern Ireland may miss out on the temperatures close to or above the mid teens.

You can see that the warmest of the uppers are in the south and east of England, 10C uppers in the easterly wind and by looking at the chart you can see why differences in temperatures seem likely across the British Isles during the beginning of next week. High pressure centred over southern Scandinavia is responsible for bringing in mostly dry and mild conditions from the continent. So a quiet spell of weather is set for the weekend and start of next week with a little bit of daytime sunshine for some and milder weather for the south of England for a time.

However, recent scenarios shown by the models for next week are akin to Spring. If you remember late March earlier this year, there was some very notable early season warmth - and in Scotland in particular where records were broken - a few days later in early April, northerly winds brought a snowfall to the same locations that had record breaking warmth. The scenario for next week is that dry, quite mild, quiet continental weather during the first few days of the week could be replaced by much cooler or colder weather thanks to a northerly airstream with high pressure to our north west and low pressure over northern Scandinavia. In some previous runs it seemed likely that this arctic blast may end to only to our east but some recent runs have shown Scandinavia and western Siberia still getting cold and snowy weather later next week but the northerly looks a lot closer to British shores. The models are showing the start of this northerly to develop to the east of Iceland during Wednesday and reaching the northern isles by Thursday. This is still 5-7 days, so it isn't too far away but far away enough for runs between now and then to adjust subtle changes that could change things so watch this space.

The chart above is quite interesting as there are still 10C uppers present over southern England whereas the Shetland Isles are under -10C uppers. That's quite an impressive gradient in temperatures. And the flow for the Shetland Isles is fairly decent for showers to develop so I'd say that at the moment the Shetland Islands are best for any snowfall from this northerly, the airflow may struggle to move further south or could end up further east but Shetland is currently in the driving seat for the first British lowland snowfall of the season.

High pressure is quite close to the north west of the British Isles here. Sub -5/-6C uppers on this run are able to make it across much of Scotland and northern England. The flow isn't particulary strong but I'd say that the chart above would suggest a possibility of some wintry showers for eastern areas. But regardless of whether there is shower activity in the flow, the cold upper air and high air pressure would suggest low overnight temperatures. My word of guidance regarding following the models is not to look beyond 7 days, focus on the first 3 to 5 days in particular. You'll learn more about hints of what could come futher along the line by looking at what happens first in the reliable timeframes, as I've said before the scenarios beyond next week are all up in the air, take hints at what is shown in the next 7 days. Enjoy the quiet coming days, and enjoy the evolution of what looks like a very interesting week.

[Mapantz]

If we were to have -5 uppers over the whole county for example during December then it would be highly likely that any precipitation would fall as snow/sleet. At this moment in time -5 uppers are shown to affect parts of the country in the next week or so, therefore I don't understand why people are doubting that any precipitation could well fall as snow and affect a large part of the UK??.... That's if what we are seeing at the moment on a range of forecasting models actually materializes.

Can anyone shine any light as to why this may be?? I'm still learning so be nice

Still many factors involved, such as dewpoints and the 0 degree isotherm. You can have the uppers and dewpoints just right, but if the isotherm level is down to say 500m, lower levels can expect rain, possibly sleet at best.

I wouldn't start worrying about that too much, we need to get the pattern fully established first.

Edited October 19, 2012 by Mapantz