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Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!


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Seeing as it's nice and early in the day, perhaps we can see the remainder of Saturday through without the hysterics expressed on the forum yesterday? Critical points of note are simple: 1. Amplifi

Well... good support in new EC Monthly by mid-Feb for GloSea5 signal re increased incidence of blocking. Indeed, by week 4, first output we've seen all winter with NO low MSLP anomalies anywhere on th

??? No warnings have been issued *because areal (and accumulation) continuity has been totally lacking*. Now we are seeing that manifesting in UKV/UKPP and other output, you can expect Ops Centre to

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I would argue that if it were the other way around and the op was cold outlier that it is highly likely that the upstream pattern wouldn't get a look in, in your post. After all, in your original post you didn't mention how the upstream pattern would affect the UK and the UK is the bit of the NH that the posters on this forum are interested in!

 

Oh dear thats a bit harsh. Sorry you think that way but I was looking for a reason why the op went against my thoughts and I looked for the main NH variable that was most obvious. That was the deep US trough. I then came to the assumption that the run was an outlier due to no cross model support for such a cold and deep trough. It did not matter what it showed over the UK due to that inconsistency upstream. I think my thoughts on ECM D8-10 charts are already well documented and the D7 ECM bias chart highlights my ongoing concern:

 

post-14819-0-98820800-1421617142_thumb.p

 

I rarely treat any 8-10 day ECM op with any respect, cold or otherwise when the pattern is as fluid as it is. You can see from its current D10 verification that it is performing very poorly, compared to its normal dominance:

 

post-14819-0-80275900-1421617678_thumb.p

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Slight shift West on the GFS, heart of England and Wales colder during Tuesday on this run.

 

Edit: Much of the midlands back in this if it verifies

Edited by Snowy L
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SW

Think of my post as a list of places unlikely to get snow with counties below the list on the cusp, if your names not down your currently progged to get PPN, however West Sussex & Hampshire are currently in the zone of rain sleet or snow ( with the snow most likely in the northern part of the counties & rain to the south)

 

 

So the 18z is out to 24, heights lower in the E & SE & the GFS finally separating the energy at t24 so we 'should' get the first slider low at 36 as a single closed system, if that's the case the trend west will certainly continue....

 

Also suddenly upgrading the uppers by a notch to -8c is the Central / South belt

http://modeles.meteociel.fr/modeles/gfs/runs/2015011818/gfs-1-36.png?18

 

The trend flicking between 36 (18z) & 42 (12z) is about 50 miles SW-

 

S

 

Steve sorry for being stupid.. but will that -8 850 upper do anything for snow potential in the south east.... i am just trying to find out about how you can tell the rain sleet and snow apart cheers 

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Now we are homing in on the Slider I would say the following counties are probably already out of the game

 

Suffolk, Norfolk, Lincs, Yorkshire (E ), Northumberland,Tyne & Wear, east Lothian, Berwickshire

 

On the cusp ( obviously eastern portions )

 

Kent,Essex,Cambridgeshire & Rutland...

 

S

 

I hope your confidence (mainly based on the ECM over UKMO and GFS?) is proven well placed Steve but I'm not entirely sharing the love for these model outputs the past 72 hours. It remains to be seen whether this is going to be a 'slider' at all. The centre of the low on ECMWF heads down out over the IoW, but not so much on UKMO or GFS and all three models continue to have some mild air spoiling the party.

 

My biggest concern though is the line of attack from the front. It's not oriented in enough of a NW to SE axis for my liking, the main push from west to east introduces too much mild into the mix so that any precipitation away from high ground in the north of England is marginal. This was the de facto position of the Countryfile forecast.

 

I can't say I can ever recall a situation like this producing anything more than some fleeting flakes before the rain and sleet sets in. Hope to goodness I'm wrong on that. It's certainly going to the wire, and for that reason I don't think any counties can be ruled in or out until a couple of hours before. I well remember the time in Devon we were told we'd miss everything, the front stalled and we were dumped on with snow I hadn't seen since childhood. However, the frontal angle was flat west-east and that's always the position I want to see for frontal snow UK: coming in from the north-west like this without a real cold easterly ahead doesn't tick the best boxes. But we shall see.

 

As for the quasi-easterly showing later on the GFS, the source across northern Germany is too mild:

 

 
However, much can change I guess between now and then. I live in hope.
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18z has some of the counties written off above as getting some decent snow (eg NE) on Tuesday night. Experience tells me this might be unlikely, but all the same.. what is it that leads people to think this solution is wrong?

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Unusually one of the places in the South looking better for snow is London, cold air haging in that area from the East.

12 hours of it using the GFS 0.25 precip charts...

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Round 2 on Friday night

gfs-0-126.png?18

gfs-1-126.png?18

Precipitation turns to snow as it pushes through the UK. Still a messy picture with rain, sleet, snow along with a slack easterly which could set up between the two events.

Edited by Captain shortwave
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GFS will always be too possessive with the Atlantic onslaught. I was hoping this new version would have some correction to this, but its a old problem that is still showing.

850's much better for Southern England

attachicon.gifNEW.png

With still around 2 days to go, any Precipitation chart is still as useless as a carpet fitters ladder.

im not to sure it is to progresive all todays models and yesterdays also show a breakdown by the end of the week Edited by igloo
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Very different frontal evolution on 18z. Firsy front gets rebuffed, 2nd front hits colder air due to this and stalls out whilst the cold undercits and turns it totally to snow. Good run for alot of the country thus far.

To be taken with a pinch of salt - I do feel for some it seems inevitable some will miss out.

post-19153-0-14316100-1421619684_thumb.jpost-19153-0-70924300-1421619707_thumb.jpost-19153-0-97558600-1421619741_thumb.j

GFS 18Z would cause troubles with the server - London is definitely in equation.

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Obviously GFS precip amounts shouldn't be taken too seriously at this stage, especially with snow. 18Z much better for snow prospects for a wider wearer as Kold Weather said a few posts back. Here is Snow accumulation GFS(take with salt).

post-15543-0-29199100-1421620105_thumb.j post-15543-0-87740100-1421620154_thumb.j post-15543-0-46681700-1421620161_thumb.j

post-15543-0-31674400-1421620169_thumb.j post-15543-0-51822200-1421620183_thumb.j post-15543-0-03957400-1421620194_thumb.j

post-15543-0-89736700-1421620204_thumb.j post-15543-0-99667900-1421620214_thumb.j post-15543-0-82269500-1421620222_thumb.j

Incidentally the Post from Steve on locations looks quite close when viewing the map.

Edited by Mark N
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GFS will always be too possessive with the Atlantic onslaught. I was hoping this new version would have some correction to this, but its a old problem that is still showing.

 

850's much better for Southern England

 

attachicon.gifNEW.png

 

With still around 2 days to go, any Precipitation chart is still as useless as a carpet fitters ladder.

 

 

All models suffer from the over progression.

 

If this was the old GFS it wouldn't have even gone for a slider just sent it all north. 

 

UKMO was over progressive yet it came back into swing.

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