Model Output Discussion - cold spell to end Autumn

[Man With Beard]

46 minutes ago, Danny* said:

Solid set of EC ensembles this morning.

Obviously the usual scatter in the extended but a very large cluster for a continuation of cold, the ECM OP clearly in the warmer few by the end of it's run and interestingly the GFS hardly the coldest of the bunch, either.

ECM op was actually within the largest cluster on the ensembles (20/51) - though I guess on the warmer side even within its cluster.

However, the GFS outcome was also represented in one of the secondary clusters.

[summer blizzard]

GFS6z is a thing of beauty. GFS keeps wanting to flatten the heights over Greenland later in the run but we know that it more normally come in more amplified closer to the time. 

Also observe the Siberian/Arctic Heights/Aleutian Low combination that GP talks of. 

[Met4Cast]

Just now, Man With Beard said:

ECM op was actually within the largest cluster on the ensembles (20/51) - though I guess on the warmer side even within its cluster.

However, the GFS outcome was also represented in one of the secondary clusters.

Yeah, weird how it's so warm given it's in the biggest cluster despite the biggest clusters (at least from the graph above) show mostly cold.. Not quite sure how that correlates. 

Fair support in the clusters for the high to topple/sink to be fair, but a wide range of solutions.

[Frosty.]

5 minutes ago, Mokidugway said:

 

Certainly, the 6z operational has dangled a carrot for all netweather coldies this morning..hopefully much more to come today onwards!

[Guest]

A CLOSER UKMO ANALYSIS

Just a "shorter" (by my standards!) interim post from me prior to my next long report later this weekend. I've noticed a number of posts speculating on the UKMO's evolution, so I thought a comparison of the latter ends of their 12z and 0z runs would be useful at this stage.

First of all the last 2 MetO fax charts from yesterday (next update is later this afternoon/early evening today):

             T+96 for 12z Tuesday, December 5th                    T+120 for 12z Wednesday, Dec 6th

                                         

Having been brought up on the fax charts and studied them since the early 1960s (including 1962/63), I always feel that they can give a few extra clues to future developments or at least one can see what the MetO forecaster has in mind. In particular, the direction of the fronts for the medium term with these as well as the troughs for the shorter term period (like the "Pembrokeshire Dangler" over the last couple of days). At T+96 we can see the HP over Biscay to the south of the UK sinking southward but starting to give way to the building heights to our north-west and the next Arctic outbreak pushing down from close to the North Pole, through Svalbard and Iceland and further south with various throughs also pushing southwards. The cold front stretching from western Norway a long way south-westwards is trying to push further south and south-east but is coming out against the LP to the north-west of the Azores between 40 and 50 degrees north. At that stage, it looks like much will depend on how much the HP over Biscay sinks.  By T+120 the Biscay HP has sunk much further south-east making way for the LPs to push north-eastwards towards the UK. The long cold front has pushed further south-eastwards, quite cleanly on its western flank but appears to be stalling slightly over NW Scotland with a small LP forming just to the north-west between Scotland and Iceland. One (or at least me!) can sense that this LP as well as the LP centred at 50 N and 20 W will push through and assist the Arctic air stream to sweep south and south-east during thefollowing 24 to 48 hours.

Next the UKMO model output at the same 12z time for the same period plus the later charts:

      T+96 for 1300 Tuesday, December 5th      T+120 for 1300 Wednesday, Dec 6th         T+144 for 1300 Thursday, Dec 7th                   T+168 for 1200 Friday, Dec 8th

                                                   

I have used the Meteoceil "Europe 2" view as this version is a rather closer match to the area covered by fax charts (in between Europe 1 and the Northern Hemisphere views).  The model charts and the fax charts are broadly similar but not completely identical for the same periods. Picking up from the fax charts, the LP to the south-west of Ireland is indeed modelled to cross the UK. Not as intense as shown on several recent GFS runs but with the broad northerly quickly being dragged in behind it. Then we are left with the T+168 chart with the western Atlantic view teasing us with the likely synoptic pattern over the UK. It certainly looks like the broad northerly is right over the UK.

Finally, last night's UKMO 0z model output for the same times (forecasts for 12 hours later):

 T+96 for 0100 Wednesday, Dec 6th                  T+120 for 0100 Thursday, Dec 7th               T+144 for 0100 Friday, Dec 8th                    T+168 for 0000 Saturday, Dec 9th

                                                                         

Please note that the runs are 12 hours apart and the charts are 24 hours apart. So, for example, the 12z T+120 is halfway between the 0z T+96 and T+120 charts. Interestingly, the UKMO has moved slightly more towards some of the GFS output by T+144 although this is the first opportunity to see a full view of this chart. The LP crossing the UK has intensified further and appears to be pretty slow moving over the north North Sea south-west of Norway. The HP and ridge to our west has also been sharpened up. The purpose of this particular post was to demonstrate how useful the fax charts can be and to compare them to the model output. Of course, many other factors such as the strength and direction of the Jet Stream are crucial.

Overall, even at this D5/6 range it is still far too early to nail down the precise track and depth of the LP crossing the UK and this will be the deciding factor in how much precipitation we get, where it will occur, whether there is sufficient cold air in place ahead of it and whether it falls as rain or snow. I believe that there is all to play for but it may turn out to be a marginal event initially especially with some of the less cold air from the south mixing into the circulation. With the LP seemingly likely to set itself up for several days more or less in situ before it fills and/or moves away (probably eastwards) there should be increasing snow opportunities with the cold air being dragged into the system steadily deepening and undercutting from the north-west. This is a wonderful and exciting period for model watching but we should all be patient - this may well work out in our favour.

I have a personal dilemma. Like most of you on here, I want deep cold and heavy snow but I have an important business 3 day trip next week at the seemingly critical period. I shall be driving up the M5 from Exmouth to Warwick on Thursday, staying over on Friday and returning on Saturday!  I had better take precautions - at least a shovel, blanket and some food and drink. Perhaps, an ice axe, a snow plough or helicopter would be more appropriate!!! I have driven in many snowstorms before but if things do verify a la GFS then I may need to cancel my trip! 

 

 

 

Edited December 2, 2017 by Guest
Correct typos and check charts

[bluearmy]

Seriously BB63, even the gfs isn’t that disruptive  - take a look at the snow depths on the 0.25 charts by day 8/9.

good to see the op with more amplification to our west.

 

[sparky1972]

good afternoon all, i have no clue in understanding charts etc but i do love reading peoples views and the hunt for snow, and things by the sound of it are looking possible come the back end of next week, i am off for a 3 night trip to Lapland tomorrow morning with the wife and our son, i will have a word with the big man himself and see if he will give us a fab xmas present and deliver lots of snow on xmas day and beyond.

[knocker]

3 minutes ago, sparky1972 said:

good afternoon all, i have no clue in understanding charts etc but i do love reading peoples views and the hunt for snow, and things by the sound of it are looking possible come the back end of next week, i am off for a 3 night trip to Lapland tomorrow morning with the wife and our son, i will have a word with the big man himself and see if he will give us a fab xmas present and deliver lots of snow on xmas day and beyond.

Well I can confirm you are in the correct thread

[I remember Atlantic 252]

Another amazing GFS, but the key is the 12Z's tonight, nervy switch on for me, around 6pm, too see if GFS 12Z is still showing snow, and a key EC, let's hope it stops being spoil sport

[feb1991blizzard]

7 minutes ago, knocker said:

Well I can confirm you are in the correct thread

Whilst I understand that us snowchasers get on your wick, I think that's a little disrespectful to other professionals who give a balanced summary of the models like yourself.

Edited December 2, 2017 by feb1991blizzard

[Northern Sky]

11 minutes ago, feb1991blizzard said:

Whilst I understand that us snowchasers get on your wick, I think that's a little disrespectful to other professionals who give a balanced summary of the models like yourself.

It was a joke feb. I know, to quote Family Guy "we are living in a post joke world" but...

[Frosty.]

At least we won't see much of the red crayon with the models showing a cold outlook..plenty of different shades of blue and purple will do nicely ta

[bobbydog]

12 minutes ago, feb1991blizzard said:

Whilst I understand that us snowchasers get on your wick, I think that's a little disrespectful to other professionals who give a balanced summary of the models like yourself.

chill out mate, it was a joke. knocker is entitled to make jokes like anyone else. or is that only reserved for 'us snowchasers'?

[Met4Cast]

15 minutes ago, feb1991blizzard said:

Whilst I understand that us snowchasers get on your wick, I think that's a little disrespectful to other professionals who give a balanced summary of the models like yourself.

Haha Knocker actually managed to make me laugh with that joke, I thought it was funny. 

Northerly next week is nailed on, lets hope we see further support for the snowy low at the end of the week, I wont be excited about it until it starts showing on the Euro4 though.

[I remember Atlantic 252]

1 minute ago, Frosty. said:

At least we won't see much of the red crayon with the models showing a cold outlook..plenty of different shades of blue and purple will do nicely ta

True Frosty, I can only see them if they're quoted though

nervy 12Z's Frosty? GFS amazing for all areas really, classic Cheshire Gap days, next Fri, Sat and Sun

[Frosty.]

16 minutes ago, I remember Atlantic 252 said:

 

nervy 12Z's Frosty? GFS amazing for all areas really, classic Cheshire Gap days, next Fri, Sat and Sun

Nope not nervy at all, (excited more like) think we have a lot of below average / cold temperatures with snow at times to look forward to in the mid to probably longer range with only short-lived milder intrusions..I'm happy

Edited December 2, 2017 by Frosty.

[knocker]

36 minutes ago, feb1991blizzard said:

Whilst I understand that us snowchasers get on your wick, I think that's a little disrespectful to other professionals who give a balanced summary of the models like yourself.

Quite right, and speaking only for myself of course, I've decided to treat the comment with the contempt it deserves.

[lassie23]

First half of December cold, second half not as cold, but not exactly mild either, with more stormy spells? Is that what the models are hinting at? Wanted to do a BBQ next weekend

[Mucka]

I can understand some being cautious, track of the low all important as far as snow to low levels concerned but ppn should be heavy helping with evaporative cooling.

If it comes off anywhere near as programmed by GFS though this should not be confused with a standard toppler where we get some back edge PM air.

This low is set to draw in very cold Arctic air on its Northern flank as things stand. The mean is around -8 for the 850 temps.

NW England 06z ensemble graph

 

The mean ppn spike is at its highest just as the upper air gets to around -5 (quite a plummet from the +5 hours earlier)

That should mean rain turning to sleet then snow before clearing SE.

No way to forecast such a finely balanced set up so far out with such small changes to the depth and track of the low as well as timing meaning the difference between rain/sleet/snow - if you like snow and live on West facing hills you will be doing a jig though.

This may end up one of those head out of window jobs.

[captaincroc]

51 minutes ago, I remember Atlantic 252 said:

True Frosty, I can only see them if they're quoted though

nervy 12Z's Frosty? GFS amazing for all areas really, classic Cheshire Gap days, next Fri, Sat and Sun

You couldn' make it up...i live on a hill in the Cheshire Gap but am away all that weekend for my birthday. ?

[JBMWeatherForever]

Watched my first Christmas film for this year last night - The Polar Express !

If the GFS is correct I will be able to see such scenes replicated outside the house later next week, but without Tom Hanks.   Even if GFS isn't exactly right though, all models are now showing that northerly, and a potent one too. What's more with the Met Office now having changed their forecast for the second half of December to be colder and less mobile (Probably blocked), there seems to be a great deal to look forward to on the run up to Christmas !        

[Fitzwis]

1 hour ago, bobbydog said:

chill out mate, it was a joke. knocker is entitled to make jokes like anyone else. or is that only reserved for 'us snowchasers'?

"chill out mate" ... snow more jokes please - you'll be giving me the cold shoulder next  ... mods, I'll get my coat and see myself out 

Edited December 2, 2017 by Fitzwis

[MattStoke]

1 hour ago, I remember Atlantic 252 said:

True Frosty, I can only see them if they're quoted though

nervy 12Z's Frosty? GFS amazing for all areas really, classic Cheshire Gap days, next Fri, Sat and Sun

I love the Cheshire Gap Streamer as an ex-Londoner now in Stoke 

[ACCOUNT DELETED]

Much more agreement in the colder runs on the GEFS 6z for Porthcawl South Wales. Top photo is yesterday, bottom is today. There's still hopes!! 

Edited December 2, 2017 by Draig Goch

[terrier]

Well not long now till the next instalment of model runs. Will the gfs and ukmo stick to there guns. Or will they move towards the ecm thoughts of a brief northerly later next week. Only concern for me is the verification stats of the gfs which is languishing in 5th place at the moment. Think my eyes will be firmly fixed on the ecm and ukmo which are performing much better. Anyway eyes down for the model rollercoaster.