Model Output Discussion 12hrs. 01/10/13

[Gaz1985]

CFS model looking alright for January, looks like a Bartlett pressure with those uppers. 

 

[draztik]

as a point of interest, here's the ECM 12z snowfall for Europe out to 240 (accumulative total)

 

 

In terms of rainfall for the UK, the east coast could see up to 2 inches. Totals are less than what the GFS indicated from its 12z run. *accumulative total out to 192 hrs

Edited October 7, 2013 by draztik

[smithyweather]

Looking at tonights outputs some good northern blocking shown but theres not enough trough disruption for the timebeing. The ECM does stick to its general earlier trend, its becoming apparent that if the shortwave near Iceland does verify at 168hrs then where that goes will determine whether theres something a bit more interesting in terms of bringing some colder conditions from the ne.You do need the favourable cut back in the jet and this is often a problem, we have seen the difficulties in later timeframe modelling in terms of energy distribution with a bias but theres also another complication as to where the main core of the heights go in the later ECM frames.Anyway its only October and you'd need something exceptional synoptically to bring snow especially this early. A positive for those hoping for a decent winter is the possible big increase in northern Eurasian snow cover.

Well it wouldn't be exceptional to get snow in October. Maybe in London but not here and Scotland. It does happen on occasion, perhaps lying snow but actual wet snow falling. NO.

Edited October 7, 2013 by smithyweather

[Frosty.]

WOW that's some awesome cold building to the Northeast on tonight's Ecm 12z op run, all eyes are drawn NE here, hoping it will eventually envelop the uk with those  blue colours 

 

In the meantime, an opening salvo of increasingly strong Arctic sourced N'ly winds and becoming more and more unsettled and eventually feeling very chilly across the southeastern half of the uk with a trough in control but the north of the uk having high pressure for a change later this week, through the weekend and well into next week with lots of sunshine, light winds and overnight frosts.

Edited October 7, 2013 by Frosty.

[nick sussex]

Well it wouldn't be exceptional to get snow in October. Maybe in London but not here and Scotland. It does happen on occasion, perhaps lying snow but actual wet snow falling. NO.

I know the UK has seen some recent episodes of October snow but generally these are towards the end of the month. My interest is more what happens in Eurasia for the timebeing. There are no guarantees but generally the research has found a link between above average snowfall there in October and negative phases of the AO. If you want to see an early taste of winter then that shortwave at 168hrs is going to have to behave and you'll need the core of the heights over Greenland to not slip too far west. Anyway that's past 168hrs and as we've seen the models can be pretty clueless past that point. Edited October 7, 2013 by nick sussex

[Summer Sun]

Latest from Gibby begin conditions to return next week with temperatures closer to average?

 

Anyway Good evening. Here is tonight's look at the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday October 7th 2013.

 

All models continue to show a marked change in conditions as we go through the week. the current fine and dry weather across the South will be eroded by a band of rain and drizzle across Southern England tomorrow. Further North brighter skies will develop with some showers, heaviest in the far North. Through Wednesday and Thursday colder weather will extend South to all areas with a mixture of sunshine and showers to end the week with some heavy and thundery showers in places later in the week. This theme then continues through to the weekend with the showers becoming more prone to SE and Southern England in a cold NE breeze while the North stays dry, bright and rather chilly with frost and patchy fog likely at night.

 

GFS then shows a very unsettled second half to it's run tonight with Atlantic Low's eventually engaging with cold air flooding out of the Arctic to give rise to some explosive low pressure developments around or over the UK with strong winds approaching gales and heavy rain in very Autumnal and chilly conditions for all late in the run.

 

UKMO tonight shows the SE at risk of showers or rain at times through next weekend while many Northern and Western areas stay dry and bright by day with clear spells at night giving rise to frost and patchy fog in these areas.

 

GEM shows a very showery pattern across the South of the UK with High pressure to the North of the UK keeping Northern parts dry, bright and cool with some night mist, fog and frost. Pressure builds South late in the run with many areas becoming or staying dry with widespread fog problems night and morning and still chilly enough for frost at night where skies stay clear.

 

NAVGEM has Low pressure centres close to the South of England over the weekend and start to next week while the North stays dry and bright under a ridge of High pressure. At the end of the run it looks like the quiet and potentially chilly

pattern remains with some frost and fog at night along with the odd shower especially in the South.

 

ECM tonight shows Low pressure to the South filling up at the start of next week with occasional rain or showers and rather cloudy skies slow to recover with slack winds across the UK. Late in the run the model shows Low pressure closing in towards the UK from the West with South and West Britain becoming more unsettled from the SW with rain at times.

 

The GFS Ensembles look distinctly unsettled tonight particularly through the second half of the run with plenty of rain opportunities highlighted. Temperatures depressed at first will recover to closer to average values soon after the coming weekend.

 

The Jet Stream tonight shows the flow to the North diving South over the UK around a depression close to SE England by the weekend. This weak but significant portion of the flow then dissolves away but the new flow passing over the Atlantic is then diverted South of Britain by High pressure over the Arctic through Week 2.

 

In Summary the weather will remain much cooler than currently after the inception of the colder weather on Wed/Thurs. However, despite this it will never be desperately cold but be particularly noticeable due to the duration of temperatures of current values and the strength of the northerly winds. As we move through next week it looks like the cold winds in the SE will subside and a period of slack pressure will ensue with a lot of dry and benign conditions with temperatures close to average. In the outer edges of reality there are some interesting dynamics shown from GFS with gales and heavy rain likely with ECM too showing an attempt at Low pressure feeding in off the Atlantic at the end of the run but as we all know 2 weeks is an age in model terms.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[london-snow]

CFS model looking alright for January, looks like a Bartlett pressure with those uppers.

My god you really are going to struggle if you are pinning your hopes on a cfs chart which changes its mind almost everyday.

[Frosty.]

I'm happy with the latest output, a welcome burst of proper autumn weather blowing the mild and benign weather well away from the uk, the outlook shows more variety with chilly, wet and windy spells and calmer but cooler weather with a risk of frosts... about flippin time :- )

[Yarmy]

CFS model looking alright for January, looks like a Bartlett pressure with those uppers. 

 

And the 18z shows a 3000 mile long fetch Easterly on the 23rd Jan. Honestly, can't all this CFS nonsense be confined to its own thread?

[Cloud 10]

And the 18z shows a 3000 mile long fetch Easterly on the 23rd Jan. Honestly, can't all this CFS nonsense be confined to its own thread?

 

 http://modeles.meteociel.fr/modeles/cfs/run4/cfs-2-2622.png?18

[Timmytour]

 

 http://modeles.meteociel.fr/modeles/cfs/run4/cfs-2-2622.png?18

Love the Purple Eastern Finger pointing towards the UK as if to say, "over there lads!"

[Zenarcher]

My outlook for the next 5 days,

 

Tuesday - High pressure sits to our West, meanwhile low pressure is to our North giving off mostly cloudy conditions with showers over Scotland.

 

 

For most a cloudy day, with showers in the morning over Scotland but they will move away in the afternoon. Wales, Southern and Eastern England look to get a good amount of sunshine tomorrow and also any Eastern coastal parts may get a few hours of clear conditions with sunshine. Breezy for most but across Scotland a strong breeze and later gales. Lowest temperatures 7c to 10c and maximum temperatures 12c to 20c. 

 

Wednesday - High pressure to our West gets stronger but low pressure moves down to our East giving us a cloudy start with showers and snow showers over the Scottish Highlands as strong North Westerly winds rip through the country making it colder overall. Some sunshine is likely in some parts towards the end of the day.

 

 

During the morning and afternoon it will be cloudy with showers across Scotland although the South of Scotland and Northern England may see some sunshine. Some snow showers are possible in the Scottish Highlands. Into the late afternoon and evening the cloud will break away across most of England and Wales giving clear sunshine as the day ends, elsewhere will remain cloudy with a risk of showers. Gale force winds across the entire country with severe gales in the North, the wind will bring in much colder temperatures ranging from 2c to 8c and maximum temperatures 10c to 16c.

 

Thursday - High pressure starts to move into most of the UK giving mostly clear and sunny weather but low pressure sits to the South East giving cloudy weather with showers. The wind will be very strong across the Eastern coasts.

 

 

Every part of the UK at some point is looking very likely to get clear sunshine for a good few hours hours apart for the far South Eastern England that may still stay cloudy with a chance of showers. Severe gales will be along all the Eastern coasts and elsewhere the wind eases down. Minimum temperatures 1c to 7c and maximum temperatures 9c to 11c.

 

Friday and Saturday

 

Friday starting off clear and sunny but cloud with showers may cover England and Wales later. On Saturday southern parts staying cloudy with showers meanwhile the North stays clear and sunny.

[Mark Neal.]

Got to love the consistent inconsistency of the individual CFS runs

Interesting model runs again today with Strong Northern Blocking showing up. That cold to the Ne will aid Eurasian Snowcover which is already doing well! Foggy and chilly days with a fresh feeling after this weekend. Though cold rain as cold and unsettled weather moves in from the east to end the week. Something a bit more seasonal I suppose!

[damianslaw]

 

And just to balance things out the North East seeing the lowest uppers at -4, which sadly for you is near to your neck of the woods. 

 

Last winter we saw the cold take a big bite out of the first couple of months of spring. I just wonder after seeing today's output that it could be that this winter takes a big bite out of the last couple of months of Autumn??

Certainly seems at present that the coldies amongst us (not you gavin, obviously) are having to wait less and less time in between each winter.

I also seem to remember that a few isolated places in the UK saw snow last October? Although i'm not 100% sure about that. I'm sure someone will correct me if i'm wrong 

Maybe some snow again for this October? ...I certainly wouldn't rule that out at present after the developments over the last few days.

Whatever happens this winter, the anticipation and expectation is certainly building.

 

 

 

Last October delivered localised snowfalls in eastern parts in the early hours of Saturday 27th, it was quite a surprise for many. Uppers and dewpoints were just on the right side of marginal as the trough moved through in the arctic air - just at the right time in the coldest part of the night. I remember being very surprised to see snow lying a cm thick on the other side of the A66 close to Barnard Castle, leaving a green scene on this side of the Pennines. The snow stuck around well into late morning and never melted in sheltered spots despite temperatures getting up to 7/8 degrees in strong sunshine. It shows how weak the sun is by late October.

 

I think October 2010 delivered localised snowfalls in places.

 

 

October 2008 saw widespread snowfall during the last week, even London from memory saw some.

 

Back to the models, all in strong agreement this evening at least in the reliable timeframe. After another very mild albeit quite cloudy day for many with a band of increasingly patchy rain travelling south, a marked change to cooler conditions will occur on Wednesday as the high pressure ridges out to the NW and forces down a trough and chilly northerly airstream thereafter. Thursday morning could deliver the first widespread ground frost for NW parts, and the day itself looks a chilly showery affair, eastern parts will feel quite raw under the strong N wind. Friday sees the high pressure toppling back SE but it will stay chilly with further showers in the southeast and east, drier in the NW after a widespread frost I imagine. The weekend at this stage doesn't look too bad, alot of dry weather about especially in the north, but compared to recent ones it will feel decidely chillier and much more autumnal.

 

So after a lengthy very benign spell of weather with only one shortlived blip last Wed-Friday, much more cooler more typical conditions for this time of year are about to move in.. and we can probably now safely say goodbye to any return of the conditions of late at this in terms of similiar duration.

[Richard Lake]

I also seem to remember that a few isolated places snow last October? Although i'm not 100% sure about that. I'm sure someone will correct me if i'm wrong

I recall travelling home last October at around 1am in an intense hail storm that suddenly turned into heavy snow a minute late back to hail again. Very early in the season especially here less than 3 miles from the coast.

[Iceni]

Well it wouldn't be exceptional to get snow in October. Maybe in London but not here and Scotland. It does happen on occasion, perhaps lying snow but actual wet snow falling. NO.

 

 

We had a couple of cms of snow in late October last year here in East Anglia (there's no high ground, although my location is about as high as it gets East, and can't be called the North) and the year before that and everyone remembers 2010. I'm getting quite used to it.

Edited October 8, 2013 by Iceni

[Captain Shortwave]

It won't

Remember back to mid-September with Hurricane Humberto, you have a similar pattern killer here moving up the East coast of the states.

That low shown with the circle will phase with the Atlantic low and will move north east, this will force the Azores high North East and allow it to cling onto the high to our North. It's a sinker and that low is on both the UKMO/GFS and NAVGEM those the result on the latter still looks cold with the high sinking slower.

If you want retrogression, you want that low to disappear from the output pretty quickly.

Well this mornings output is of no surprise given the warning signs were there and flagged up. Interesting to see by day 8 that there is good agreement on mild southerly winds to be pushing eastwards from the low in the Atlantic. Still time for change but that pattern killing low I marked is on all the model output now which is not a good sign for those wanting the north/north easterly winds to continue. Last nights ECM did not have this low which hence gave the cleanest retrogression signal. Today it has it and now heights collapse into Scandinavia.

Edited October 8, 2013 by Captain shortwave

[snowking]

Well this mornings output is of no surprise given the warning signs were there and flagged up. Interesting to see by day 8 that there is good agreement on mild southerly winds to be pushing eastwards from the low in the Atlantic. Still time for change but that pattern killing low I marked is on all the model output now which is not a good sign for those wanting the north/north easterly winds to continue. Last nights ECM did not have this low which hence gave the cleanest retrogression signal. Today it has it and now heights collapse into Scandinavia.

Whilst I agree with the idea of the low from the atlantic is likely to be influencing our weather in around 10 days time or so, I wouldn't be making that call right now based upon NWP, which actually shows a clear split this morning.

 

GFS is most keen on that idea:

 

 

Where as the ECM isn't too interested just yet:

 

 

With the low stalling and pushing Northwards though days 8-10 this morning.

 

So NWP actually looks more split at present. GFS det. is backed up rather well by the ensemble mean:

 

 

But as we saw a few days ago, the GEFS suite is really rather prone to swings, so this is far from clear cut just yet.

 

The current MJO forecast based upon OLR plots has changed somewhat in the last day or so away from the idea of a low amplitude phase 1/2 orbit to something really too weak to read. I would stick to the previous idea this had before which was indeed something such as the GEFS is showing this morning in terms of <1 amplitude composites, but the support for the GFS idea is far from universal.

 

SK

Edited October 8, 2013 by snowking

[johnholmes]

All 4 of the anomaly charts show a similar idea to what you see below on ECMWF-GFS, that is a marked upper trough only edging very slowly east from about 30 west with the upper ridge holding over and to the north of the UK.

On the latest forecasts from the NOAA hurricane centre they show some activity but it is not yet at all clear whether either of these two storms will get into the North Atlantic. Also I agree with SK about the MJO having little effect in the near future at least with northern hemisphere weather.

 

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

[Summer Sun]

Looking at ECM the low which comes over the Atlantic is going to get forced northwards in Iceland and Greenland

 

[draztik]

Taking into consideration what SK said regarding the GEFS swings and roundabouts, the ECM evolution cant be disregarded. Tho, its 12z ens supported the idea of the Atlantic moving close to the UK - which is also supported by NAEFS. Lets see where this mornings ECM ens take us.

[chionomaniac]

Well this mornings output is of no surprise given the warning signs were there and flagged up. Interesting to see by day 8 that there is good agreement on mild southerly winds to be pushing eastwards from the low in the Atlantic. Still time for change but that pattern killing low I marked is on all the model output now which is not a good sign for those wanting the north/north easterly winds to continue. Last nights ECM did not have this low which hence gave the cleanest retrogression signal. Today it has it and now heights collapse into Scandinavia.

Looking at the charts between T+120 and T+144 which was yesterdays T+144 - T+168 that Steve was highlighting we see neither a true retrogressing high - but neither do we see a sinker as you suggest. Rather we see the halfway house solution where heights start to build north of the Atlantic low before fading - but so does the Atlantic trough fade at that time frame. The anomaly charts that John posted show that the heights are likely to be strong in the Greenland region keeping the Atlantic trough detached from the main core of vorticity from T=144 onwards - so as SK says it is probably best to watch what happens from here on in.

Edited October 8, 2013 by chionomaniac

[Summer Sun]

Latest from Gibby

 

Good morning. Here is the report on the 12 midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday October 8th 2013.All models show the same pattern that's been shown for some time now. After a sustained period of above average temperatures across the UK things are set to change as a couple of cold fronts move South through Britain today and tomorrow. Pressure then rises to the West and NW of Britain with a chilly and strong Northerly flow developing, especially in the East where showers will be heavy and prolonged in places on Thursday before the risk of these becomes restricted towards more Southern and SE areas by the weekend as High pressure builds back NE over the North. Away from the South and East the weather will become dry and bright with clear or sunny spells and temperatures on the low side with frost and patchy fog possibilities at night.

 

GFS then shows next week as becoming more changeable and sometimes windy after a short spell of higher pressure has collapsed over the UK by midweek. Thereafter rain at times moves in off the Atlantic in association with Low pressure areas moving NE across the UK. Temperatures would be close to average though rather chilly in the wake of cold fronts having passed through.

 

UKMO today continues it's approach to more modified influence from Low pressure to the SE at the weekend, filling it up and leaving a spell of slack winds and pressure to start next week with a lot of dry, cloudy and probably misty weather with the risk of a shower almost anywhere.

 

GEM today shows most Southern areas of England and possibly South Wales cool and showery at the weekend before these conditions ease to quiet and rather cool weather at the surface with a lot of cloud and mist around. Later in the run the trend is for Southerly breezes to develop with occasional rain moving in from the West towards or over the South and West later.

 

NAVGEM shows a more meaningful attack from the Low pressure over the South of England at the weekend with most Southern areas seeing rain or showers at times in rather cool conditions while the North stays dry and bright if cool. At the end of the run this drier and benign weather extends South to all as a weak ridge of High pressure ridges down from the North with light winds and mostly cloudy weather but foggy if skies clear by night.

 

ECM this morning shows the showery Low near the SE at the weekend filling up to allow the ridge of High pressure in the North to extend South to all with fine and dry weather for all when there will be a lot of cloud, mist and fog or all three in temperatures just about scraping to average values if conditions brighten. Late in the run fronts approaching the SW could bring a little rain into these parts later before High pressure returns on Day 10 killing any rain and returning the UK into fine and quiet weather with fog looking likely to become a major issue later next week should this pattern evolve.

 

The GFS Ensembles this morning indicate an unsettled spell to come from this weekend with some rainfall for all areas at times for the rest of the run. The operational run was one of the drier members with some members opting for more Low pressure dominance with most members showing average temperatures in the second half of the run once the influence of the cold Northerly has been lost at the weekend.The Jet Stream Ensemble forecast this morning shows the flow to the North diving South over the UK today and tomorrow to the East of which forms the Low pressure near the SE. This circulation draws a new arm of the Jet towards in and begins a spell when the Southern arm of the Jet crosses the Atlantic well South of recent positioning.

 

In Summary today the pattern shown over yesterday is maintained this morning. There are variances on how much influence the Low to the SE affects the weather in the South at the weekend with UKMO showing very little spread while GFS and NAVGEM are more bullish in potential wet weather in the South. Meanwhile the North look more guaranteed to stay dry if rather chilly with some night frost and fog. Next week looks fairly benign as what's left of the Low near the SE fills up leaving a legacy of cloud and mist across the UK in very light winds. In the outer limits the Atlantic does look at least interested in playing a part in our weather later in the month but there looks nothing distinctive about this at the moment with only the South and West likely to see some rain from this scenario. However, GFS does show much more push from this especially within it's ensembles with all areas seeing some rain too later next week. Whatever happens all models share the fact that the unseasonably warm weather of recently will be a thing of the past after today with much more average and at times below average temperatures more likely with some fog and frost issues if skies clear by night. Having said that there seems little sign of anything desperately cold to excite folks as yet.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[Frosty.]

4 inches of snow building up across the Grampians by the end of tomorrow

A strong Northerly blast sweeping the warm benign weather away southwards during tomorrow and thursday, even in the south although numerically the temps will be around 11-12c but add in the high wind chill factor and it will feel like it's 5 or 6 celsius, it's the first of hopefully many increasingly cold incursions as autumn deepens into winter.

 

By thursday, it will look like this across some of the scottish mountain ranges as high pressure begins to build in across the far north.

Edited October 8, 2013 by Frosty.

[Timmytour]

It would be nice if Scotland could have yet another good ski season....it doesn't seem so long ago that it all doom and gloom about their prospects... 

Global warming forces sale of Scottish winter sports resorts

 

Back in Charles Dickens day there was a run of several winters with a White Christmas....so much so that, for charles dickings, it was normal for him to think of being small and seeing snow at Christmas.Perhaps we are entering a similar run of winters now. Perhaps years of disappointment of seeing potential in the models never quite realised will become amazement at the actual development?  PErhaps we can have a cold end to October and yet still have a winter that sustains its impact through to the middle of March?  (but not April again please!)it will be interesting viewing this year to see if the models start to pursue some of the milder solutions we usually expect them to come up with in a winter only to find they are backtracking within days to much colder ones.  One live in (lots of) hope!

Edited October 8, 2013 by Timmytour