Model Discussion And Chat 19th Feb.2012

[Robbie Garrett]

ecm spreads promote a fairly strong north sea depression around day 10. depending on how close the azores ridge is, things could get quite interesting re wind.

I would comment if I could see it in the ECM??

Just looking at the models, what temperature at 850hpa is the 596 dam line??

[phil nw.]

The unsettled interlude over the weekend looks like extending into Monday in the south east quadrant as that low is slow to move away.

http://www.meteociel.../fax/fax72s.gif

It looks a raw chilly and damp day here whilst other areas dry out and become much brighter although still with lower temperatures.

Some disagreement how long the more settled spell will last around midweek as the models show different placement of the Azores High and how far north it influences the UK.The ECM show a more anticyclonic influence at T144hrs whereas the UKMO and GFS bring fronts further south into Scotland.

The overall pattern though is one of persistant High pressure to our south/south west and low heights to the north with a flow from the west.

Edited March 2, 2012 by phil n.warks.

[bluearmy]

I would comment if I could see it in the ECM??

Just looking at the models, what temperature at 850hpa is the 596 dam line??

and not sure what you mean re the 596 dam line ???? are you talking actual thickness of 596 dam or that shown on a chart at the centre of a strong area of high pressure? (jn which case the chart thickness must be reduced by 0.87 x the surface pressure to obtain the actual thickness. ). it wont be 596dam robbie.

[johnholmes]

The weather for Sunday?

Looking at the 18z runs for GFS and NAE up to T+30 from 18z they are not that far off one another in the position or the depth of the low for Sunday, or not, depending on which model you base your forecast. By T+42 GFS has it not that far from the Isle of Wight, NAE shows it now as more of a trough somewhere between Brest and Bordeaux.

Take your pick

Edited March 2, 2012 by johnholmes

[Cloud 10]

ecm spreads promote a fairly strong north sea depression around day 10. depending on how close the azores ridge is, things could get quite interesting re wind.

Here are some examples from the 12z GEFS for that same timeframe.

http://modeles.meteo...-4-1-240.png?12

http://modeles.meteo...-7-1-240.png?12

http://modeles.meteo...20-1-240.png?12

The weather for Sunday?

Looking at the 18z runs for GFS and NAE up to T+30 from 18z they are not that far off one another in the position or the depth of the low for Sunday, or not, depending on which model you base your forecast. By T+42 GFS has it not that far from the Isle of Wight, NAE shows it now as more of a trough somewhere between Brest and Bordeaux.

Take you pick

Looks like it's down to the good old satellite/radar combo again!

[Tim Bland]

Can't post but 48hr NAE just out has snow for central southern England on Sunday!

Is it me or is the GFS stuck at 114hrs?

Edited March 2, 2012 by Tim Bland

[Lewis]

Can't post but 48hr NAE just out has snow for central southern England on Sunday!

The same model that showed 2 feet of snow for me last month

Joking aside, at the moment each and every model is on it's own, so it will be interesting to see what model is accurate. I doubt it'll be the NAE though, but I hope for those that want snow, it is

[Timmytour]

Can't post but 48hr NAE just out has snow for central southern England on Sunday!

Is it me or is the GFS stuck at 114hrs?

Not moved beyond 111hrs for me for a while now

[Mark Neal.]

Here is the 18z NAE for Sunday @ 6pm..

[Beasterly]

Interesting to see that latest NAE showing snow for much of southern england.

NAE T+48

[Cheese Rice]

Wouldn't rely on the NAE just yet. GFS has quite a difference with the northern most extent of the front. NMM will be coming in the reliable time frame tomorrow so we should have a better idea.

Interesting to see a big shift north by the NAE, could be further shifts tomorrow if the GFS is correct.

Edited March 2, 2012 by Cheese Rice

[Lewis]

Regarding the latest NAE.

There is of course validity there, like any other model, as each and every model member has it's own evolution with regards to the track, intensity of the low pressure system, how it pivots, and also precipitation placement and intensity.

The latest NAE shows rainfall turning to snow as the above poster suggested with the chart he posted, I've just taken a look at the full NAE data set "briefly" and conditions are supportive, during the heavier precipitation and towards the middle/back end of the precipitation, going by the NAE winds switch to a Northerly, so there's no modification so central Southern england and parts of the Midlands are best placed, the precipitation according to the NAE along with conditions look favorable for snowfall. Upper 850's of -5 to -6.

I think what all the models are struggling with is the exact track, and intensity of the low pressure system, we need to get that nailed first which of course we will as we nearer the time frame. The next most important thing is how modified the uppers become, will they either stay on the marginal side and get mixed out from the South, or will they get wrapped around the low, and filter colder air from the NE into the flow.

The GFS chart below shows such a difference, and such difference will give a completely different set of weather conditions for many areas, close one to call.

Lewis

Edited March 2, 2012 by ~SFL~

[Eskimo]

Interesting scenario this weekend

[bluearmy]

The end of the ecm 00z run is for the benefit of robbie this morning !!

[Rocheydub]

Magnificent end to 00z ECM. Full on northerly!

[winterof79]

One of these days.......after an extremely poor winter for my area

http://www.wetterzen...cs/Recm2402.gif Instbility might come in to that one.

And as always the GFS

http://www.wetterzen...s/Rtavn3722.png .....I know :winky:

Although the GEM at 240 is not far away from the GFS at the same time frame

http://www.wetterzen...s/Rtavn2401.png

http://www.wetterzen...cs/Rgem2401.gif

I cannot believe i am having to resort to this though

While i am at it http://www.meteociel.fr/modeles/cfse_cartes.php?ech=240&mode=0&carte=0&run=10

Edited March 3, 2012 by winterof79

[Polar Maritime]

GFS ECM & CFS are all showing much colder scenario's mid month, from the North and East.

Edited March 3, 2012 by Polar Maritime

[bluearmy]

Magnificent end to 00z ECM. Full on northerly!

That's actually rather more significant than just a northerly with a full relocation of the Canadian vortex to scandi. Would set up a rather different second half of march than feb. Not sure ed has flagged this up as a likely scenario so I'll just take it as eye candy for the time being.

[Frosty.]

The 00z's are showing a good blast of polar maritime air next week alternating with less cold and milder interludes but the ecm then goes on to amplify the upstream pattern significantly with a proper arctic blast developing with bitterly cold air sweeping down the east of greenland towards the uk, the gfs 00z flirts with a northerly but then goes all anticyclonic although eventually the gfs shows a siberian blast heading towards the uk and even the north would not miss out (for a change), shame it's 2 weeks away.

[johnholmes]

well no agreement between GFS and UK versions this morning for tomorrow. Each has shifted slightly towards the other, GFS a touch further south for the main precipitation, NAE to me looks about the same in terms of position of it.

It gives about 3mm for here, GFS shows between 4 and 10mm dpeending which 'spot' I look at. Not yet looked at the Extra version to get a better idea of its detail. It looks like the heavier stuff will be 20-40 miles so south of this area.

Extra show 4mm for here the 12z yesterday had 25mm so its the GFS which has shifted most on this run.

The 12z MAY show within a 50 mile band the track we can expect tomorrow.

[nick sussex]

Looking at the ECM De Bilt ensembles there decent support for a colder spell in the extended range with the control following the mean and given the set up you'd expect to see colder conditions for northern areas of the UK.

http://www.weerplaza.nl/15daagseverwachting/default.asp?type=eps_pluim

However we have been here before with the models over amplifying the output in the extended range and then flattening the pattern out as it edges towards the 144hrs mark.

[NO LONGER POSTING]

Lol,,It makes me laugh that people even regard the models at +240..How many times has it showed that and then nothing comes up..Okay so one can hope but lets face it..Who knows..I bet my bottom dollar it is no where near as cold as that..In fact I think it is really going to begin to warm up after mid march

[Lewis]

Morning guys,

Just a little teaser from me this morning for you guys further South. Pulled from the NMM high res model. (Precipitation type)

Edited March 3, 2012 by ~SFL~

[Timmytour]

Lol,,It makes me laugh that people even regard the models at +240..How many times has it showed that and then nothing comes up..Okay so one can hope but lets face it..Who knows..I bet my bottom dollar it is no where near as cold as that..In fact I think it is really going to begin to warm up after mid march

Since this is the model discussion thread it seems appropriate to mention what the models are showing....even if it is FI. I don't see anyone taking them as gospel, but just expressing an interest in proportion to the extent of agreement between them.

[Lewis]

well no agreement between GFS and UK versions this morning for tomorrow. Each has shifted slightly towards the other, GFS a touch further south for the main precipitation, NAE to me looks about the same in terms of position of it.

It gives about 3mm for here, GFS shows between 4 and 10mm dpeending which 'spot' I look at. Not yet looked at the Extra version to get a better idea of its detail. It looks like the heavier stuff will be 20-40 miles so south of this area.

Extra show 4mm for here the 12z yesterday had 25mm so its the GFS which has shifted most on this run.

The 12z MAY show within a 50 mile band the track we can expect tomorrow.

The NMM has the heaviest of the precipitation just North of the Wash Southwards, judging by the precipitation charts and track on the NMM, we'll be both lucky to get 1mm.

lewis