Model Output Discussion 26/10 2012 >

[bluearmy]

Not unexpected i wouldn`t think Nick-based on the fact that NAEF`s and ECM ens mean ht. anoms. have been showing heights around that area for a few runs.

It seems the signal for this development is consistent for later in the month.

When and if it moves west remains to be seen.

take a look through them phil - the 12z is a step change west though whether it repeats is the question.

[itsnowjoke]

What would this mean ? Thanks.

[BLAST FROM THE PAST]

Preliminary winter thoughts from Stewart Rampling (GP):

http://forum.netweat...inter-thoughts/

Can't view it at work, can someone give me a quick overview of it?BFTP

[A Winter's Tale]

Good evening. After a spell of cold, frosty, showery and sunny weather to start November, as shown by the models a few days ago that the centre of the high pressure in the atlantic is now to the south of the British Isles allowing milder westerlies aswell as a depression is just to the west of Iceland whereas Scandinavia should see some colder originating from arctic as a low sits to the north of here. Closer to home, there should be some clear spells across southern and eastern parts of England and eastern Scotland whilst further west across northwest England, Wales, Ireland and much of Scotland, there should be widespread cloud cover with a few patches of light rain and during the night a period of rainfall is expected across north western Scotland. A much milder night with lows of 7 to 10C.

Wednesday morning should continue to have some bright spells across southern and eastern areas with cloud and some light rain/drizzle further west and the light rain across north west Scotland should move southwards into the central belt and Northern Ireland. Sunny spells should continue across southern and eastern parts through the afternoon with areas of light rain spread out across western Scotland, north west England and some patches of light rain breaking up over Ireland too with showers in the north of Scotland and just a few showers in the Irish sea. Through the evening, the patches of light rain should spread into north western parts of Wales as the precipitation breaks up across Ireland and northern England but light rainfall should continue across western Scotland. Maximum temperatures should be 9 to 11C. Through Wednesday night there should be further rainfall for western Scotland and into Northern Ireland with a few patches of light rain across northern England and into southern and western parts of England. Cloud cover may persist across Ireland, southern England and northern areas but Wales and parts of Yorkshire for example could have clearer skies. Minimum values of 4 to 11C.

Thursday should be a drier day other than a few patches of light rain in north western areas. It may be cloudier for Ireland, western Scotland, Wales and northern England but there could be decent spells of sunshine for southern England and north eastern Scotland and maximum temperature 9 to 12C. However, on Thursday night a band of heavy and persistent rain should arrive from the north west and the precipitation could be particulary heavy for Ireland and western Scotland. Possibly a few clear spells for inland parts of southern and central England. Minimum temperatures possibly 3 to 9C.

The band of rainfall should have cleared away from Scotland and Ireland but south western and northern England and Wales should be next to see a spell of persistent rainfall although the intensity of rainfall may have decreased. Behind the front should be a few sunny spells with showers in western areas. Maximum temperature 9 to 12C. Friday night could see the front bringing rainfall to south eastern parts of England before it clears south eastwards but elsewhere there should be some decent clear spells away from north western areas where there'll be plenty of showers. Minimum temperatures 3 to 9C.

Saturday could see further showers across western areas and in some southern areas. Further north and east in England there could be a few sunny intervals but possibly a bit cloudier on the whole for Scotland and Ireland. Maximum temperatures at 6 to 10C. There could be some clear spells on Saturday night with some showers around the western coastline, the north of Scotland and along the channel coast. A colder night too with minimum temperatures possibly 2 to 8C.

The coming days look dominated by westerly winds with some rain for the north west tomorrow, a drier day on Thursday with a frontal system pushing in from the north west later on Thursday and into Friday and cooler few days at the end of the week with some showers. The outlook from the 10th to the 13th seems for the moment seems that low pressure to the north west may continue to bring a brief cooler and showery spell for the weekend before a depression arrives on Monday. My confidence in what could follow this is very low as I'm waiting to see what trend is shown by the models regarding the positioning of high pressure systems and I'm unsure on what sort of a track the low pressure systems may take. The coming days of model watching should see progression in the clarity of more detailed weather events in the near-future and some clarity over the general trends a little beyond the reliable.

[Polar Maritime]

I think he means, that the cold Zonal flow from the N/N/W is hitting High pressure closer to the UK to the east over Russia, and blocking it from going further...Which in turn will disrupt the vortex more so.

Edited November 6, 2012 by Polar Maritime

[Polar Maritime]

Can't view it at work, can someone give me a quick overview of it?BFTP

Below average temp winter, Thoughts are a typical December if not mild. And a below average Jan/Feb. A cold winter.

He seams very confident with his upcoming forecast.

Edited November 6, 2012 by Polar Maritime

[bluearmy]

Can't view it at work, can someone give me a quick overview of it?BFTP

basically Fred - a neg AO winter. where the mean block sits (canada/greenland greenland/iceland) will be crucial. based on all the indicators, if we dont have a neg AO winter, stewart will have a very sore head !!

[Gibby]

Good evening. Here is the evening look at the 12zs from GFS, UKMO and ECM inc GFS 12z Ensembles and Jet Stream Forecast and my own Summary.

All models show a period of quieter weather for the next few days with a Westerly flow blowing over all areas. The air is milder as it is Atlantic based but carries a lot of cloud with some drizzly rain over the hills. A weak front crosses East on Thursday with a narrowing band of light rain followed by a drier period for a while. During Friday an active cold front moves SE over the UK with strong winds and a band of heavy rain reaching the SE by the early hours of Saturday morning followed by clearer and colder conditions with showers later on Saturday. By Sunday a weak ridge moves East over the UK with a cold bright and dry day for many as the showers die away.

GFS then shows the start of next week becomes influenced by a deep Low pressure to the NW of the British Isles. Mild SW winds will carry rain on a warm front quickly NE on Monday with further disturbances running NE through the middle of the week bringing breezy and often wet conditions to all areas at times. FI continues with changeable Westerly based weather until the last few days of the run when High pressure builds with the attendant problems of frost and fog becoming widespread under the static winds of the High over the UK.

The GFS Ensembles show a fairly flat period of weather with regard to temperatures as uppers stay close to the long term mean or a little above over the coming two weeks. There will be quite a bit of rain at times as the pattern remains an unsettled Atlantic based one from nearly all of the members. There are no indications of any colder weather in the offing with not much spread in the pack until the final days of the run.

The Jet Stream shows the main flow in an undulating pattern tonight which ridges and troughs between 50 deg N and 60 deg N latitude over the coming week or so. The Southern arm continues to weaken and disrupt over the coming days as it moves further South.

ECM shows another showery spell developing next week behind a series of fronts that cross the UK early in the week. Once the cold front passes, colder and showery conditions take hold for several days with winds decreasing, perhaps allowing some frost and fog overnight and some wintry showers over Northern higher elevations. At the end of the run a weak ridge moves in to be quickly followed by a warm front bringing a return of SW winds and rain followed by cooler showery conditions in the days to come past Day 10.

In Summary tonight the unsettled weather look continues with a generally Atlantic based Westerly flow remaining uninterrupted over the coming 10-14 days backed up by a static set of GFS Ensembles. There will be some colder interludes with showers but this weather type looks like remaining brief and fleeting with the next warm sector hard on its heels. The incidence of frost, fog and snow look very limited anywhere in the UK over the model period.

[Frosty.]

The Gfs 12z ens mean shows a suckers gap in the bad weather on sunday as one low departs to the northeast with another steaming in from the atlantic, a little bit of flat ridging so a drier brighter day developing following the blustery showers on friday night and saturday, possibly a touch of frost on sunday evening but wet and windy, milder weather for most areas for a time on monday followed by a cooler mixture of sunshine and showers but yet more bouts of wet and windy weather through the midweek period and then clearer showery westerly winds flooding east, temps look mostly just below average and some wintryness cannot be ruled out on northern high hilly areas, temps in the range of 8-10c generally next week, a little milder in the wet and windy spells, nearer 10-11c. The unsettled pattern goes on and on and on with nothing anticyclonic apart from brief ridging in the next 10-14 days.

Edited November 6, 2012 by Frosty039

[cold snap]

sometimes i wish we could see the ecm 32 dayer

[Suburban Streamer]

Below average temp winter, Thoughts are a typical December if not mild. And a below average Jan/Feb. A cold winter.

He seams very confident with his upcoming forecast.

Wasn't it the cfs v2 that gp said was showing a typical, if not mild December? And he thought the model had not quite "got it" with patterns for Dec / Jan?

I will have to watch it again, might be wrong

[Grimsby Snow Lover]

no sign of cold any where next week windy with gales and heavy rain a typical uk winter.

Just remember blackdog that November is an Autumn month. It is very common to see huge variations in temperature as well as large rain totals and gales.

Edited November 6, 2012 by Grimsby Snow Lover

[Paul]

Can we keep it to the models in this thread please

^^^^^^^^^^^

[legritter]

looking at tonights modell runs i just see plenty of typical Autumnal weather . im just waiting the same as most posters to see a big change come along . but as we all know IF there is one around the next corner its going to be a painfull wait .but very very early days yet , some action to come possibly late fri /sat and again next week so plenty to keep us occupied .And who knows what tomorrows modells will bring .

[chionomaniac]

I have just been looking at the MJO forecasts and we are seeing some differences in the forecasts.

The GFS (NCEP) forecasts are suggesting a return to phase 1:

Now this translates as a signal for northern blocking and I believe is very much what the ECM 32 suggests for the 10-20 day time frame. That long wave trough over the UK slowly becoming detached from the main vortex by heights building inbetween.

The ECM ensemble MJO forecast still head towards phase 6 - anomlay chart below - but another blocking pattern:

and the UKMO ensemble MJO forecasts head towards phase 7 - less blocking with this one but no enhanced polar vortex to our NW either!

In the absence of the cool stratosphere downwelling just yet, these forecasts may be our best guide to the forthcoming pattern. And not a bad one at that!

Edited November 6, 2012 by chionomaniac

[Snowman.]

"Settled" as in resolved, I think.

Yeh models don't seem to be fun atm just the same up to 240

[chionomaniac]

Spot which ensemble member I want to happen.

Otherwise very much average ECM ensembles.

[Fozfoster]

Spot which ensemble member I want to happen.

Otherwise very much average ECM ensembles.

Yeah that's Steve Murr ;-)

[Cloud 10]

Spot which ensemble member I want to happen.

Otherwise very much average ECM ensembles.

The gefs has it's own lonesome coldie member as well.

http://modeles.meteo...-9-1-384.png?12

[chionomaniac]

day 10 GEFS develop blocking just east and north of us on 65% of the runs. expect steve m to be back shortly !! the ens are 'getting it' (or are they a bit progressive?)

Latest GFS run is 'getting it', ba.

[Cloud 10]

Height rises over Svalbard on Fi 18z...

http://modeles.meteo...0-276.png?18?18

oooof!

Edited November 6, 2012 by Cloud 10

[Ice BIast]

In FI, but nice to see nonetheless:

[BLAST FROM THE PAST]

PM and BA

Thanks for reply guys, so a potential 'descending' winter then.

BFTP

[andymusic]

GFS 18z's way of easing us into a cold cold winter step by arduous step tonight! - maybe enabling us to put on more and more layers and "not" feel the cold - mmmmm!

[SMU]

evening All-

Yes im here- Always here in fact-...

Its been a frustrating 24/36 hours for many a coldie.

In the interest of honesty I expected the Scandi block to be another 5 / 10 degrees West after the overnight runs - hence the post- expect an overnight change.

whats developed today is that the first Scandi ridge ISNT retrograding back far enough west to halt the westerly flow over the UK, so fair play to John on the assessment around the UK remaining in some form of westerly flow out to day 10- that appears to be correct.

What we see in the 18z which is supported by the ECM 16 day ensembles is at day 7 & 8 a low amplitude high east of Scandi thats just starting to back the pattern up, however its not enough for the UK, however with Scandi blocks they can work their way back retrograding west over 2 / 3 cycles as they wain & rebuild eventually seeing some form of undercutting -

This is what the GFS has done on the 18z, 3 retrogrades with the final one at day 16 sends the cold all the way to the UK-

The trouble we have at the moment is to expect large varience in the outputs - WHY?

* Downward propergation from the stra cooling is now beginning to filter to 30 HPA & that is effecting the zonal Mean- so the modality & mode of the teleconnections are changing sharply-

EG- + PNA to a strong - PNA ridge-

NAO negative to positive...

* Interseasonal model variability increased due to strong phase changes in the teleconnects as mentioned above-

* Quasi stationary Scandi High oscillating South & east then back North & west- this then drives the model accuracy down for the UK as the models will ALWAYS pitch to far south & east with the jet in these flows...

In Summary, I was slightly premature with the scandi assessment, however its there, nowts changed- the models always want to push it away south but as we edge along to reality it will bounce back & rebound towards us-

The thinking would hopefully be west west then MAYBE NW towards greenland- however that process may span 10-18 days..

thanks for the comments- the usual rollercoaster is full steam ahead!

S

Edited November 6, 2012 by Steve Murr