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Bottesford

Model Output Discussion

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With some pretty impressive charts (as far as cold winter weather goes) being produced by the models let the discussion continue!

Please keep on topic in this busy period and use one of the other threads for non model chat.

Don't forget 'My Model Summery' thread for a slower paced but equally interesting discussion on the upcoming weather & model output.

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12z ECM freebie has the T850s tonight, get under -8C eventually across UK,

http://www.ecmwf.int/samples/d/banner/page.html

though remember thicknesses are pretty low under that upper low over the N Sea, so snow would be possible even if temps are above -8C at 850mb too.

Although maybe the modern era will be sentenced to death next week laugh.gif

Perhaps we are entering the post modern winter era?

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I would be fairly sure that if the ECM 216-240 charts were to verify there

would be widespread maximum of -2 to -4c across the country.

Having said that it is rather irrelevant as it will almost certainly change.

The main thing is that there is unanimous agreement that a very cold and

snowy spell is practically certain.

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12z ECM freebie has the T850s tonight, get under -8C eventually across UK,

http://www.ecmwf.int/samples/d/banner/page.html

though remember thincknesses are pretty low under that upper low over the N Sea, so snow would be possible even if temps are above -8C at 850mb too.

Yes Nick, my only concerns are what Kold said....Nervous re 12z as that showed a warmer sector

and at some stage there was a possible invection fom SW.....Then we see UKMO and ECM go slower re

the projected cold output............

If we see that vigorous LOW tilt towards could be in trouble if the HP goes straight North....

But thats just opinion.

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Cracking charts tonight and overall probably the best evening of outputs I've ever seen. I wouldn't worry too much about the 850s at this point. IMO it's more likely that the uppers will get colder as we head towards the event because of the models underestimating the amount of cold that will be caught up in the shortwave.

Could it possibly get cold enough for some proper Stellar Dendrites??

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I've mentioned in another thread but will do so one more within the Model output, that Snow will fall and settle and that

is 100% guarenteed, most especially in the North east, the east and again the south east. The pre christmas period will see

a good fall, followed by shall we call it a lul in the weather during the 24 - 28th before bitter cold weather and once again

snowfall arrives in the east and most especially south east, in fact the post Christmas snow could be a lot heavier and possibly prolonged for the east and south east. Look to the 28th Dec for the onset of the next snowy cold spell. and 16/17 to 20th for the first snowy spell. Again this is not a matter of doubt, the models are for once correctly predicting what

will be the outcome. For snowlovers, a real feast awaits you within 10 days !

Cheers

PE

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Not bad GME 12Z 132h :crazy: <_< :rolleyes:

post-2721-12603888200756_thumb.png

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Yes Nick, my only concerns are what Kold said....Nervous re 12z as that showed a warmer sector

and at some stage there was a possible invection fom SW.....Then we see UKMO and ECM go slower re

the projected cold output............

If we see that vigorous LOW tilt towards could be in trouble if the HP goes straight North....

But thats just opinion.

Yes, I do share your concerns wrt that low dropping south across Scandi. Both GFS and ECM show milder sector being dragged south by this low from a pool of WAA over Iceland, so uppers become less cold after the initial easterly developing this weekend. but then both models pull the low SW and allow a bitter NE'erly to develop ... eventually.

We need to hope that the upper low/cold pool eventually turns SW over the N Sea rather than sink S or SE into central Europe otherwise we may not tap into those coldest air and there is still time for the models to change in respect of a less favourable track of the shortwave moving S early next week. Alot depends on how the low develops and interacts with the southward moving jet streak down the N Sea/Scandi. Still room for error in respect of modeling the shortwave ... which may in turn delay the backing west of the real of the frigid cold towards us.

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Am i right to suggest with this set up and the mildish north sea eastern england and the south east could see some lake effect snow but the only difference is it will be coming off the north sea ??

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This may shock some people i think ECM is a possible outcome.i know its bold saying that,all seams

okay to me.

The GFS and UkMO more likley But dont rule out ECM completly

The Evolution of ECM seams Plausable its not messy it any sense of the word and if this was years ago

i dont think we would rule out ECM .If you look at the way ECM brings in the cold it seams a pretty strainghtforward block.Looks like a simpler way to get the cold air in other than the other two models.

But we dont do simple in UK and Ireland do we:clap:

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Yep the shortwave is still a big issue to be resolved, the 12z ECM freebie does show though just how close -8C the air is around the LP, I'd guess the air would be about -6/7C at 850hpa in the warm sector of the low. On the plus side thicknesses really are low with it, but on the negative there is going to be our old friend modification and it will have an effect on the lower levels of the atmosphere.

Still this is all some way into the future yet and I'd take any one of the model outputs in a heartbeat tonight!

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Am i right to suggest with this set up and the mildish north sea eastern england and the south east could see some lake effect snow but the only difference is it will be coming off the north sea ??

Hi snowfall09

Yes you would get greatly advanced convective showers from the north sea. The problem initially would be whether the wet bulb is low enough on the coasts. Could initially be sleet

regards

Jan

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Am i right to suggest with this set up and the mildish north sea eastern england and the south east could see some lake effect snow but the only difference is it will be coming off the north sea ??

Yes spot on, exactly the same dynamics. We had this a few years back where it snowed constantly for a week, unluckily the ground temps were too warm and we ended up with about 3 inches of slop..

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I would be fairly sure that if the ECM 216-240 charts were to verify there

would be widespread maximum of -2 to -4c across the country.

Having said that it is rather irrelevant as it will almost certainly change.

The main thing is that there is unanimous agreement that a very cold and

snowy spell is practically certain.

Ok lets calm down what we have at the moment is a turn to cooler weather up to T96 thats fairly nailed

Talks of 4ft snow drifts and -18 850hpa and constant posting of T240 charts are nice but its all F1

London will see from tomorrow 11c fri 8c sat 7c sun 6c mon 5c

Now 5c monday is F1

The cold is being put back

A unanimous agreetment with the models isnt the same as what will occur

Lets hope we get the F1 stuff but this is a model thread is it not ? As you say nothing is 'nailed' at T144 or T240

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Ok lets calm down what we have at the moment is a turn to cooler weather up to T96 thats fairly nailed

Talks of 4ft snow drifts and -18 850hpa and constant posting of T240 charts are nice but its all F1

London will see from tomorrow 11c fri 8c sat 7c sun 6c mon 5c

Now 5c monday is F1

The cold is being put back

A unanimous agreetment with the models isnt the same as what will occur

Lets hope we get the F1 stuff but this is a model thread is it not ? As you say nothing is 'nailed' at T144 or T240

ITS FI , not F1... it's not a grand prix chart watching contest!

Besides i'm waiting till atleast friday to see if we get this nailed or not , awaiting the 18Z

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ITS FI , not F1... it's not a grand prix chart watching contest!

Besides i'm waiting till atleast friday to see if we get this nailed or not , awaiting the 18Z

i'm wating till late sat/early monday to see if this is "nailed"

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Ok lets calm down what we have at the moment is a turn to cooler weather up to T96 thats fairly nailed

Talks of 4ft snow drifts and -18 850hpa and constant posting of T240 charts are nice but its all F1

London will see from tomorrow 11c fri 8c sat 7c sun 6c mon 5c

Now 5c monday is F1

The cold is being put back

A unanimous agreetment with the models isnt the same as what will occur

Lets hope we get the F1 stuff but this is a model thread is it not ? As you say nothing is 'nailed' at T144 or T240

Couldn't agree more and I was about to post almost the same thing. I still stick to what I said a few days ago, nothing is 'nailed' until the movement of the forthcoming HP is resolved. FI is still, as it has been for quite a while now, at around T90, so to be talking like everyone appears to be at present about what will happen at T144 onwards still seems a little precipitous to me. Nothing has changed as yet since Monday, we can be certain of a high pressure dominated weekend with some frost and fog, but that is all we can be certain of.

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I'd say confidence will increase significantly by Friday 12z given on the latest GFS things begin to get very interesting around the T120 mark. So 48 hours later the equivalent point in the run would be T72 which is normally fairly safe territory.

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I'd be very surprised if that short wave which develops into something larger near Copenhagen will be in that position although GFS and ECM (Particularly) have low heights in that area, is there any chance that the SW won't be dragged down and be further north leaving the majority of the UK in less cold and drier weather with maybe only Scotland seeing any effect? Just throwing a curve ball in with many other posters curve balls! :whistling:

Also note how the delay is getting longer and longer to be sure on any 'cemented' set-ups

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I would be fairly sure that if the ECM 216-240 charts were to verify there

would be widespread maximum of -2 to -4c across the country.

Having said that it is rather irrelevant as it will almost certainly change.

The main thing is that there is unanimous agreement that a very cold and

snowy spell is practically certain.

Disagree.

A period of Greenland/Iceland blocking is certain; but the profile of the jet-bifurcation and the approach of the shortwaves is not nailed and will change from run to run. We could easily end up in a situation of an uneventful col with marginal air, except for perhaps the far south-east getting the CAA.

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well this should wet people mouth watering picture for 180 hr if this happems the uk will grind to a halt!!!

post-4629-12603908383222_thumb.gif

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Disagree.

A period of Greenland/Iceland blocking is certain; but the profile of the jet-bifurcation and the approach of the shortwaves is not nailed and will change from run to run. We could easily end up in a situation of an uneventful col with marginal air, except for perhaps the far south-east getting the CAA.

Ello PP, on this occasion, rather unbelievably it will come off, of that I am certain, as I mentioned the charts are not going to change the general outcome, there will be fluctations, but fluctuations on a theme, of these things I am certain,

it will get very cold, it WILL snow and it will settle, in the NE, E, and SE. And just after Xmas, another very cold spell

will commence with further snowfall predominantly in the east but not exclusivly, again with a fair bit of snow,which WILL settle. :whistling:

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Ello PP, on this occasion, rather unbelievably it will come off, of that I am certain, as I mentioned the charts are not going to change the general outcome, there will be fluctations, but fluctuations on a theme, of these things I am certain,

it will get very cold, it WILL snow and it will settle, in the NE, E, and SE. And just after Xmas, another very cold spell

will commence with further snowfall predominantly in the east but not exclusivly, again with a fair bit of snow,which WILL settle. :whistling:

I'm not talking about general outcomes. This IS the UK folks, and margin for error is always an issue.

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