Model Output Discussion 12z 18/10/2012

[Iceni]

My wife constantly tells me to get off computer and look out the window ,but do it in the kitchen with lights off ,so no one see,s you .oh well todays mod and data still giving us plenty of action over coming weeks ,with pressure still high around greenland and n atlantic .a fair chance at this stage of low pressure moving south over us or near next week .for us coldies its going to be an interesting and frustrating time ,there is also the possibility of an ex hurricane moving into mid atlantic in the far outlook , so if we still have some v cold air to our north and pressure is high enough it could give us some very interesting modell watching im off to dig me veg patch , so the FROST can break it down ,cheers gang .

Just what I've been doing Managed 3 raised beds but the mud defeated me so will crack on tomorrow and finish it off — need to get that garlic in so it gets frosted for bulb forming.

Only problem is it now seems we'll only get a night or two — what's with these models the pv was over western Russia at the weekend, but now it seems to want to set up shop over Greenland again like last year

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121023/06/348/h850t850eu.png

Edited October 23, 2012 by Iceni

[Met4Cast]

Just been in contact with the MetOffice re: getting my hands on some of the charts that are not publicly available. They want to chart £500 + VAT for basic charts with the price increasing from there on in depending on how advanced the charts get. I think I can forget about going for that, then!

Good to the the overnight models continuing the trend of High Pressure being over Greenland into FI, no sign of the PVA setting up shop here or near Iceland yet which is great! 12z will be rolling out in a couple of hours, lets hope the trend continues

[Severe Siberian icy blast]

Just what I've been doing Managed 3 raised beds but the mud defeated me so will crack on tomorrow and finish it off — need to get that garlic in so it gets frosted for bulb forming.

Only problem is it now seems we'll only get a night or two — what's with these models the pv was over western Russia at the weekend, but now it seems to want to set up shop over Greenland again like last year

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121023/06/348/h850t850eu.png

Pls don't take a chart from the gfs for 13 days away seriously. Firstly anything past 144hr is fi , (up for debate) but anything past 160hr maybe much closer is used for nothing other than trends, gfs will revert back to the dominate theme in our climate which is westerly themed weather patterns by default it seems 9-10 times in fi.

[Zenarcher]

Here's a 24 hour comparison between the models,

GFS 00z for the 29th October

Yesterday

Today

Everything is pushed further West.

GFS 06z for the 30th October

Yesterday

Today

Things pushed back West again but looks similar to yesterday.

ECM 00z for the 31st October

Yesterday

Today

Despite today's chart that has a 24 hour advantage it remains very similar to yesterdays as well.

UKMO 00z For the 28th October

Yesterday

Today

Thing's actually look like they have been placed more East very slightly we also see changes in the low pressure over Iceland that has been positioned more South East on today's run.

[Suburban Streamer]

Am I right in thinking that the ecm 32 dayer, naefs and 500mb charts are all suggesting a more western based -nao?

[Geordiesnow]

Thanks to some sort of ridging into Greenland, we may stay on the cool side after this brief chilly shot coming up but there is no real sign we are seeing the extensive blocking into Greenland as we saw previously so no real sustained cold shot however there does not to be appear much trend of a return to milder conditions.

[phil nw.]

Am I right in thinking that the ecm 32 dayer, naefs and 500mb charts are all suggesting a more western based -nao?

The trend in recent outputs are pointing that way SS-although i can`t confirm exactly the pattern the ECM 32day ens show as we don`t see them.

However if we look at the NAEFs for T192hrs we can see the westward regression in the current pattern expected next week.Alongside are the ECM 00z frames for T72hrs and thenT192hrs showing those heights more towards the Canadian sector.

So yes a west based -NAO looking likely in week 2.

[Met4Cast]

Slight Eastward shift on the 12z GFS which keeps the colder uppers over the UK for longer, another small upgrade in the short term

Edited October 23, 2012 by Daniel AKA WMD

[Gavin Hannah]

I think the GFS is going off on one with the 850 temps south of Greenland. That wee orange blob looks a bit optimistic.

[Isolated Frost]

Regarding the first bout of cold from the 'toppler' on Thursday to Saturday. GFS 12z not only upgrades that big time but also the pattern overall afterwards w/ a notable eastward shift and a series of n-s lows giving cold air travelling on top of the high. Basically the coldest air we can get w/out a strong upper high to the N or NW of us.

ECM 00z at +72 shows this well as the Labrador Sea upper low exerts it's influence on the Greenland pattern- the energy rides on top of the high from +72 and sprays low pressure systems east of the UK.

Shown well by the GFS latest output.

The best way to summarise the runs would probably be no prolonged cold spell or anything from a notably cold source, but the lack of energy riding into Greenland and a rather stubborn subtropical high is ensuring that it won't get overly mild if mild at all for the next week at least. A good bet would be cool/cold zonality and topplers for the near future. First of all is the issue of the cold and snow this Friday and Saturday and we will see the FAX and NMM 12z as well as the UK-GM and ECM 12z tonight to try and clarify the situation a touch more. The best bets for snow chances would be Scottish Highlands, lowland NE Scotland, N Scotland and perhaps N Wales, N Ireland and parts of NE England on Friday, especially in the afternoon and evening.

[lorenzo]

Good agreement on the 850 temps across the models at 72 hours. Fine tuning when it moves to mesoscale. Need to go hunting out the snow rules..

GEM/GFS/UKMO

GFS has a strong anomaly for the GH

.

That GEM run from 00z is wild from 156 to 180 with a low travelling right at us SW > NE, one to watch again once 12z finishes rolling through.

ECM off out of the blocks for the MJO projection, lower impact then the GFS of the last couple of weeks but perhaps a tentative progression to another Scandi block later in November..

Still, that's a wee bit ahead and lots to watch in next couple of days..

[latitude]

Im happy with the GFS up to 144. I wont look any further. The -5 line hangs around in the south a lot longer than previous runs.

[gottolovethisweather]

Basically the coldest air we can get w/out a strong upper high to the N or NW of us.

And furthermore, this may come across as a RAMP but this chart backs up precisely what you have stated.

The coldest pool in the globe at such a time is just across the North Sea. It lingers around Scandinavia for many a day too.

One thing's for sure Scandinavia looks like facing the brunt of a very cold spell, which could theorhetically last to t+324hrs or so, based on current output. Yes, this is only ONE run but a trend of sorts is nailed. From a coldie's perspective, where we go from here into November and beyond will be most interesting.

[A Winter's Tale]

Good evening. Another night of mostly low, widespread cloud cover for across much of England and Wales and across a good chunk of Scotland and Ireland with the exception being northern Scotland and a few parts of northern Ireland. Spots of drizzle should continue through the night in places - particulary central and eastern England and south eastern Ireland - however in northern Scotland a chilly night is on the cards with some frost but the very north of Scotland may see some cloudy conditions with a few showers. For the vast majority, tonight's minimum values should be between 10 to 14C.

During Wednesday, many parts of England and Wales should continue to remain under low cloud extensive cloud cover but the very south of England, parts of northern Ireland, north western parts of England, south western Scotland and the central highlands should see some sunshine. The far north of Scotland for once should have a cloudier day with the bulk of sunshine a little further south across the grampians and lochaber. Some drizzle should continue across inland and some eastern parts of England and showers for the far north of Scotland. Wednesday's maximum values should be somewhere in the range of 10 to 16C. The night-time period should remain mostly overcast for many of us, still a few spots of drizzle in some central parts of England and some showers around the north of Scotland. Minimum values a little cooler at 6 to 12C.

Thursday should be a mostly dry day other than a few showers near the hebrides and possibly some light showers across north eastern England. The bulk of the cloud cover should be down the eastern side of England and Scotland, skies generally on the cloudy side for most but some sunny spells could be possible along the coastline of the Irish sea and across northern Ireland. A cooler day than of late with maximum temperatures of 9 to 13C. Thursday night could be on the cloudy side, a mostly dry one but in northern Scotland there could be a few showers and precipitation may come in the form as snow on the mountains. A frost for quite a bit of Scotland, temperatures 4 to 8C elsehwere.

On Friday we finally signs of something sunnier, a north/south split with sunny skies across Scotland and north eastern England. Ireland, Wales and the rest of England should have the cloudier skies with one or two shower showers. A few showers across northern and north eastern Scotland and these wintry in nature - particulary inland and on the high ground. A cold day for Scotland with maximum temperatures struggling at 4 to 7C, where skies are cloudy further south maximum temperatures should be between 8 to 10C. However as the day goes on the cloudy skies and colder conditons will continue to move further south so by Friday night there should be widespread clear skies other than perhaps a little cloud cover for the very south west of Ireland and in northern, north eastern Scotland and north eastern parts of England may be at a threat of a few showers and these could be wintry, particulary in Moray, the Inverness area, Aberdeenshire. A widespread ground frost north of the midlands and probably a widespread air frost north of Manchester. Northern Ireland, parts of Wales and southern England may see temperatures a bit above freezing - particulary in the cities.

Saturday is setting up to be a cold day with maximum temperatures of 6 to 8C in the cities. This time, England - particulary central and southern areas - should see the best of the sunshine with cloudier conditions further west and north. There may be some rain clipping the coasts of eastern England. Satuday night is looking like a cold one with lows of 0 to 2C in cities but more like 3 to 4C in Northern Ireland where there could be a little rain. Across northern and western parts of Scotland some rainfall seems likely, colder further east with a frost.

[bluearmy]

The coldest pool in the globe at such a time is just across the North Sea. It lingers around Scandinavia for many a day too.

the lowest area of 500mb heights GLW, but lower uppers over the acrtic and lower surface thicknesses in siberia.

i am interested to see no consistency in deep gfs fi to build a strong organised p/v. the 12z ends up with a decent attempt over siberia. wouldnt mind that re eurasian snowcover and its a fair way from the pole.

[gottolovethisweather]

the lowest area of 500mb heights GLW, but lower uppers over the acrtic and lower surface thicknesses in siberia.

i am interested to see no consistency in deep gfs fi to build a strong organised p/v. the 12z ends up with a decent attempt over siberia. wouldnt mind that re eurasian snowcover and its a fair way from the pole.

Thanks ba.

However, at the surface, I'm assuming that would result in some very early cold air, albeit over Scandinavia. I'm still learning and that is precisely why I should listen to the big boys and as I mostly do, keep out of the MOD thread.

Edited October 23, 2012 by gottolovethisweather

[BLAST FROM THE PAST]

UKMO not very good this evening I don't think, GFS 12z an absolute stonker of a run.......I await rhe ECM. UKMO has been very solid so interesting run. Only seen it on meteociel which IMO doesn't give a good overview.

BFTP

Edited October 23, 2012 by BLAST FROM THE PAST

[Isolated Frost]

BFTP, the UKMO moved the initial HLB a touch further south, moving it line with the GFS and ECM progression.

On the left is the ECM 12z solution for Friday 12pm, on the right is yesterday's ECM 12z solution for Friday 12pm. The hemispherical pattern is touched a bit north and and the HP cell has moved with it. We're likely to see a similar long-term solution from the Euro model- but the short-term Friday-Saturday looks better from a NE Britain perspective.

Here also are today's 12z solutions for +72 (Friday 12pm). UKMO looks a colder solution to me with the PFJ pulling south and the high pressure cell being a touch further NW.

[SMU]

evening All- minimal posting time currently- I hope to get something more meaty up later-

Im currently reviewing the output to see if the prospect of back edge snow is appearing at 144-

Something to consider on the trough sinking south out of iceland...

http://www.meteociel.fr/modeles/ecmwf/runs/2012102312/ECH1-144.GIF?23-0

Possibly some for the North york moors & southern uplands....

S

[Summer Sun]

The weekend start cold with snow showers as far south as Yorkshire possible

High pressure trys the move in but it quickly gets shifted away in the next run

By 120h the high pressure at 96h quickly gets shifted back with low pressure taking over again

This cold air remains in place into next week with low pressure holding firm the North York Moors and high parts of Scotland should see a decent covering of snow by this time next week

Edited October 23, 2012 by Summer Sun

[johnholmes]

will it snow for me?

the DIY Net Wx kit to check-remember to adjust if you live on a hill, VERY roughly 1C per 100m, and MOST important the model needs to show precipitation over the nearest grid point for you to go any further!

http://forum.netweather.tv/topic/27989-how-to-try-and-forecast-snow/

[summer blizzard]

It should be noted that models indicate a wishbone effect so whilst it may snow as far south as Yorkshire, it won't more than a few miles inland.

[BLAST FROM THE PAST]

Love the ECM.....my thoughts of a month of big swings in pressure and temp gets off to a good start. Love that run, very very autumnal

BFTP

[Gibby]

Good evening. Here's my take on the 12zs from GFS, UKMO and ECM.

All models still agree on events short term as the current rather mild and slack East flow strengthens over the coming days as a cold front slips South over the UK at the end of the week. The dull, misty conditions will lift later in the week as temperatures drop dramatically behind the front. The weather would then be dry and cold with widespread night frost on Friday and Saturday night as a high pressure ridge slips South through Britain. A few wintry showers may affect the far North and East at the start of the weekend. From Sunday forwards things begin to separate between the models.

GFS then shows a deepening Low move ESE over the Northern Isles to Denmark with a cold front moving steadily SE through Britain carrying a band of rain and hill snow in the North as it goes. Winds then veer Northerly and cold weather with wintry showers return to all parts with snow to quite modestly sized hills in the North. This wintry flavour continues through to midweek with further night frosts away from exposure to the strength of the wind. Later in the week the weather turns even more disturbed with strong winds, wintry showers or longer periods of rain, sleet or snow for all as a very deep Low anchors itself over the UK for three or four days before the low complex fills and weakens late in FI with a change to milder and windy conditions in a strong SW flow ends the run following a ridge of high pressure east.

The GFS Ensembles show a relatively cold or rather cold pattern tonight with the weather turning increasingly unsettled as a period of cold zonality takes hold. the operational was fairly representative of the majority of the pack with regards to temperatures tonight with some large precipitation spikes North and South.

The Jet Stream flow shows the developing split flow continuing with the Northern arm currently blowing West to East well North of the UK turning more NW to SE over the UkK in the coming period to meet the Southern arm in the area around Spain in a week or so.

UKMO for noon on Monday shows a trough of \low pressure drifting slowly SE over the UK with a slack windflow over Britain. There would be rain at times in rather cold and raw conditions with snow restricted to the highest ground in Scotland.

ECM shows a much more organized trough sinking SE in association with Low pressure moving SE down the North Sea. A period of rain would be followed by cold and breezy weather with wintry showers late in the day on Monday. a ridge then follows SE over the UK giving a decent, fine and cold day following a sharp frost over Monday night. as the week progresses ECM takes a different route in sinking Low pressure down to the West of Britain cutting off the cold supply of air from the NW as well as bringing unsettled and windy conditions with showers or longer spells of rain to all areas with any wintryness confined to the highest mountains of Scotland although it would feel chilly out and about.

In Summary the Jury is out on the weather for next week. As always with Northern blocking setups the models struggle on evolutions beyond 4-5 days and slight differences in positioning of weather systems can have radical differences on the resulting weather conditions in any one place, especially for the UK and that's what we have tonight. Despite the pattern remaining one of Northern blocking this does not necessarily mean cold for the UK and with low pressure thrown in as we are likely to develop next week it's back to wind and cold rain as the most likely outcome from what I can see.

[mikeocarroll]

The GFS 12z ensembles are remarkably clustered in terms of 850hPA temps between 0 and -5, way out into FI. Here's for Powys (my location) but there is similar clustering for London, and not too much of a spread for Aberdeen:

I'm not sure that it signifies, as I've often seen whole ensemble suites flip from one solution to another, but it does show that the GFS has a fairly high confidence in its 12z operational output. Air pressure is less clustered but all ensemble members are showing the same broad trend, backing the operational.