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Model Output Discussion 29th December - Into mid-Winter.


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Gefs are quite a wide spread on solutions though a notable cluster keeping it cold (both surface and uppers) as others have noted and in line with the latest eps. Of course if we do return to a more mobile flow off the Atlantic (which remains an option) all those colder runs will be gone and the ten day cold spell will become rather shorter ! 

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Evening All For those of us who have been here for a long while there is times when you know you have to throw in the towel on chasing cold & times ( very rare ) when you 'just know' that the

Boom goodnight vienna

People being a bit harsh on Steve Murr, at least he has the balls to try and read and predict what may happen from his viewpoint rather than just posting what charts show.

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10 minutes ago, bluearmy said:

Gefs are quite a wide spread on solutions though a notable cluster keeping it cold (both surface and uppers) as others have noted and in line with the latest eps. Of course if we do return to a more mobile flow off the Atlantic (which remains an option) all those colder runs will be gone and the ten day cold spell will become rather shorter ! 

Do they keep it cold for a good part of the country or just the southeast?

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Definitely a move from the GFS ens in the last 12 hours, many more runs trying to extend the cold. Still lots of scatter and Op mild.

18z last night

GFSENS18_52_0_205.png

06z this morning

GFSENS06_52_0_205.png

P14 especially cold.

 GFSP13EU06_240_2.png

 

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06z

Fun and games hopefully commence Wednesday evening although previous runs have tempered expectation slightly.

h500slp.png

Chance of streamer activity NW but most ppn just to the NE :wallbash:

uksnowrisk.png

 

But....

HGT 500 chart a car crash at +189 with the euro high.

 

 

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Just now, Iceaxecrampon said:

06z

Fun and games hopefully commence Wednesday evening although previous runs have tempered expectation slightly.

h500slp.png

Chance of streamer activity NW but most ppn just to the NE :wallbash:

uksnowrisk.png

 

But....

HGT 500 chart a car crash at +189 with the euro high.

 

 

Just as a matter of interest  do  models take into consideration  streamers etc?  By that i mean do they forecast the chesire gap etc   because looking at the above chart it seems that the snow chance could  move alot more inland then is currently showing.

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1 hour ago, Man With Beard said:

The GEM, my favourite model of the moment, is interesting this morning. First time it's jumped on the easterly train (well a kind of easterly!) and would tie in extremely well with the top verifying D10 model, which is of course the ECM ensemble mean. 

gem-0-144.png?00  gem-0-168.png?00  gem-0-192.png?00  gem-0-216.png?00   gem-0-240.png?00

Yep looks like a cold continetal flow for the south and a warm flow up north, not quite what most are looking for but, I feel the likely out come for now. There's always room for improvements while in this pattern though. Like if the low to the west decides to push east under the low instead of over. Not looking likely on this chart though.

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Just the 4c difference in mean at 168... think if the ECM ENS suite is that wrong it's one of its biggest fails ever. The GFS is no stranger to fails so my head says back the ECM but Sod's law makes you think the other way

IMG_7415.GIF

IMG_7416.PNG

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54 minutes ago, weirpig said:

Just as a matter of interest  do  models take into consideration  streamers etc?  By that i mean do they forecast the chesire gap etc   because looking at the above chart it seems that the snow chance could  move alot more inland then is currently showing.

Not in my experience. I live in Kent, where we have the "Kent Streamer", and it hasn't reflected in the models in the past.

 

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1 hour ago, weirpig said:

It Certainly does  a much better run all around from the control   brings a chilly easterly towards us  will feel much more like winter.

Overall the 06z is rather on the mild side for the UK and into Central Europe. So every chance the cold spell could be extended.

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1 hour ago, weirpig said:

Just as a matter of interest  do  models take into consideration  streamers etc?  By that i mean do they forecast the chesire gap etc   because looking at the above chart it seems that the snow chance could  move alot more inland then is currently showing.

The NWP model output that you are considering certainly don't factor in small topographical features like the Cheshire Gap as the resolution of the model is not nearly fine enough to be able to do so.

As computing power continues to increase then the resolution of the models will be able to get to a point where they can consider topographical features and localised weather features such as the development of thunderstorms, but as yet that level of model run is not possible unless it is of a very narrow focus.

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10 minutes ago, GrrClark said:

The NWP model output that you are considering certainly don't factor in small topographical features like the Cheshire Gap as the resolution of the model is not nearly fine enough to be able to do so.

As computing power continues to increase then the resolution of the models will be able to get to a point where they can consider topographical features and localised weather features such as the development of thunderstorms, but as yet that level of model run is not possible unless it is of a very narrow focus.

Sorry but that is not correct, one can see Cheshire Gap, Thames streamers etc in the right conditions. Forecasting thunderstorms on a national basis, ie larger scale model is also done routinely with UK Met. I am sure someone will come along and give a better insight into my comment.

 

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8 minutes ago, GrrClark said:

The NWP model output that you are considering certainly don't factor in small topographical features like the Cheshire Gap as the resolution of the model is not nearly fine enough to be able to do so.

As computing power continues to increase then the resolution of the models will be able to get to a point where they can consider topographical features and localised weather features such as the development of thunderstorms, but as yet that level of model run is not possible unless it is of a very narrow focus.

THE GFS model goes down to 28km in resolution which would be sufficient to pick the streamer and the Met Office have MoGreps and UKV the latter of which is down to 1.5km resolution. ( http://www.metoffice.gov.uk/research/modelling-systems/unified-model/weather-forecasting).

 

Looking at the forecast GFS does seem to pick up a possible streamer although i suspect you will will have to wait until Wednesday onwards to hear specifics and greater accuracy from the Met as a result of MoGreps and UKV

 

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8 minutes ago, johnholmes said:

Sorry but that is not correct, one can see Cheshire Gap, Thames streamers etc in the right conditions. Forecasting thunderstorms on a national basis, ie larger scale model is also done routinely with UK Met. I am sure someone will come along and give a better insight into my comment.

 

 

6 minutes ago, FetchCB said:

THE GFS model goes down to 28km in resolution which would be sufficient to pick the streamer and the Met Office have MoGreps and UKV the latter of which is down to 1.5km resolution. ( http://www.metoffice.gov.uk/research/modelling-systems/unified-model/weather-forecasting).

 

Looking at the forecast GFS does seem to pick up a possible streamer although i suspect you will will have to wait until Wednesday onwards to hear specifics and greater accuracy from the Met as a result of MoGreps and UKV

 

My apologies if being misleading in my post.

I do appreciate that there are models within the forecasting suite that do have sufficient resolution to factor in local scale features, but my understanding was that the hemispheric modelling at day 5 is not run at a resolution that would consider that.

Always happy to be corrected.

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44 minutes ago, johnholmes said:

Sorry but that is not correct, one can see Cheshire Gap, Thames streamers etc in the right conditions. Forecasting thunderstorms on a national basis, ie larger scale model is also done routinely with UK Met. I am sure someone will come along and give a better insight into my comment.

 

Yes, John, we have that capability now but the model is not always right in the starting conditions or the evolution. The Arome 1,3 kilometre is a good example as will be the UKV (we don't get to see the output from that).

Zoom.

6925_hxv1.png

Wider view, you can barely see the wintry ppn on the mountain tops.

aromehd-42-10-0_ofp5.png

The slightly lower- res ARPEGE seeing the Gap.

tempresult_ltj4.gif

 

 

Edited by Nouska
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3 minutes ago, FetchCB said:

THE GFS model goes down to 28km in resolution which would be sufficient to pick the streamer and the Met Office have MoGreps and UKV the latter of which is down to 1.5km resolution. ( http://www.metoffice.gov.uk/research/modelling-systems/unified-model/weather-forecasting).

 

Looking at the forecast GFS does seem to pick up a possible streamer although i suspect you will will have to wait until Wednesday onwards to hear specifics and greater accuracy from the Met as a result of MoGreps and UKV

 

gfs op is 16km and ecm op is 9km.  these are the horizontal size of the blocks that the model breaks the atmosphere into - I'm not sure that its relevant to streamers/topographical features as the model must resolve across these resolution boundaries and takes these land effects into account.

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1 hour ago, weirpig said:

Just as a matter of interest  do  models take into consideration  streamers etc?  By that i mean do they forecast the chesire gap etc   because looking at the above chart it seems that the snow chance could  move alot more inland then is currently showing.

They actually do, to some extent. The EC can just about pick up general features such as a Cheshire Gap streamer, as can be seen on this precip chart on Thursday:

EC precip.png

The Euro4 can pick out features like that very well, although sometimes it overcooks the shower development. When it comes within range I'll try to remember to post a snippet to illustrate this :)

Edited by Nick L
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Just now, GrrClark said:

 

My apologies if being misleading in my post.

I do appreciate that there are models within the forecasting suite that do have sufficient resolution to factor in local scale features, but my understanding was that the hemispheric modelling at day 5 is not run at a resolution that would consider that.

Always happy to be corrected.

Mo problems. GFS is Global and the MetOffice Global model is down 17km  6 days out.

ECM I believe is now at 9km 

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4 minutes ago, Nick L said:

They actually do, to some extent. The EC can just about pick up general features such as a Cheshire Gap streamer, as can be seen on this precip chart on Thursday:

EC precip.png

The Euro4 can pick out features like that very well, although sometimes it overcooks the shower development. When it comes within range I'll try to remember to post a snippet to illustrate this :)

Nick you have done it now LOL

Cheshire Gap streamer Holy grail for me.

C.S

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